Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
  • A61M16/0051—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes with alarm devices
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
  • A61M16/021—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes operated by electrical means
  • A61M16/022—Control means therefor
  • A61M16/024—Control means therefor including calculation means, e.g. using a processor
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
  • A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
  • A61M2016/0015—Accessories therefor, e.g. sensors, vibrators, negative pressure inhalation detectors
  • A61M2016/0018—Accessories therefor, e.g. sensors, vibrators, negative pressure inhalation detectors electrical
  • A61M2016/0021—Accessories therefor, e.g. sensors, vibrators, negative pressure inhalation detectors electrical with a proportional output signal, e.g. from a thermistor
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
  • A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
  • A61M2016/0027—Accessories therefor, e.g. sensors, vibrators, negative pressure pressure meter
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
  • A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
  • A61M2016/003—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter
  • A61M2016/0033—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical
  • A61M2016/0039—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical in the inspiratory circuit
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
  • A61M16/0003—Accessories therefor, e.g. sensors, vibrators, negative pressure
  • A61M2016/003—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter
  • A61M2016/0033—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical
  • A61M2016/0042—Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical in the expiratory circuit
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
  • A61M16/10—Preparation of respiratory gases or vapours
  • A61M16/1005—Preparation of respiratory gases or vapours with O2 features or with parameter measurement
  • A61M2016/102—Measuring a parameter of the content of the delivered gas
  • A61M2016/1025—Measuring a parameter of the content of the delivered gas the O2 concentration
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
  • A61M16/10—Preparation of respiratory gases or vapours
  • A61M16/1005—Preparation of respiratory gases or vapours with O2 features or with parameter measurement
  • A61M2016/102—Measuring a parameter of the content of the delivered gas
  • A61M2016/103—Measuring a parameter of the content of the delivered gas the CO2 concentration
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/50—General characteristics of the apparatus with microprocessors or computers
  • A61M2205/502—User interfaces, e.g. screens or keyboards
  • A61M2205/505—Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2230/00—Measuring parameters of the user
  • A61M2230/20—Blood composition characteristics
  • A61M2230/202—Blood composition characteristics partial carbon oxide pressure, e.g. partial dioxide pressure (P-CO2)
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2230/00—Measuring parameters of the user
  • A61M2230/20—Blood composition characteristics
  • A61M2230/205—Blood composition characteristics partial oxygen pressure (P-O2)
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2230/00—Measuring parameters of the user
  • A61M2230/40—Respiratory characteristics
  • A61M2230/43—Composition of exhalation
  • A61M2230/432—Composition of exhalation partial CO2 pressure (P-CO2)
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2230/00—Measuring parameters of the user
  • A61M2230/40—Respiratory characteristics
  • A61M2230/43—Composition of exhalation
  • A61M2230/435—Composition of exhalation partial O2 pressure (P-O2)
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2230/00—Measuring parameters of the user
  • A61M2230/60—Muscle strain, i.e. measured on the user

Definitions

• the invention relates to the field of ventilating human patients. More particularly, the present invention relates to an improved ventilator and method of operation for ventilation intervention and initiation, oxygenation, recruitment, ventilation, initial weaning, airway pressure release ventilation weaning, continuous positive airway pressure weaning, and continuous and periodic management and control of the ventilator.
• Airway pressure release ventilation is a mode of ventilation believed to offer advantages as a lung protective ventilator strategy.
• APRV is a form of continuous positive airway pressure (CPAP) with an intermittent release phase from a preset CPAP level. Similar to APRV allows maintenance of substantially constant airway pressure to optimize end inspiratory pressure and lung recruitment.
• the CPAP level optimizes lung recruitment to prevent or limit low volume lung injury.
• the CPAP level provides a preset pressure limit to prevent or limit over distension and high volume lung injury.
• the intermittent release from the CPAP level augments alveolar ventilation.
• Intermittent CPAP release accomplishes ventilation by lowering airway pressure.
• conventional ventilation elevates airway pressure for tidal ventilation. Elevating airway pressure for ventilation increases lung volume towards total lung capacity (TLC), approaching or exceeding an upper inflection point of an airway pressure - volume curve (P-V curve).
• the P-V curve includes two limbs joined by upper and lower inflection points: an inspiratory or inspiration limb that is opposite an expiratory or expiration limb. Limiting ventilation below the upper inflection of the P-V curve is one the goals of lung protective strategies.
• tidal volume reduction is necessary to limit the potential for over distension.
• Tidal volume reduction produces alveolar hypoventilation and elevated carbon dioxide levels.
• Reduced alveolar ventilation from tidal volume reduction has lead to a strategy to increase respiratory frequency to avoid the adverse effects of hypercapnia.
• increased respiratory frequency is associated with increase lung injury.
• increase in respiratory frequency decreases inspiratory time and lessens the potential for recruitment.
• increasing respiratory frequency increases frequency dependency and decreases potential to perform ventilation on the expiratory limb of the P-V curve.
• APRV During APRV, ventilation occurs on the expiratory limb of a pressure - volume curve. The resultant expiratory tidal volume decreases lung volume, eliminating the need to elevate end inspiratory pressure above the upper inflection point. Therefore, tidal volume reduction is unnecessary. CPAP levels can be set with the goal of optimizing recruitment without increasing the potential for over distension. Consequently, end inspiratory pressure can be limited despite more complete recruitment, while ventilation can be maintained. [008] APRV was developed to provide ventilator support to patients with respiratory failure. Clinical use of APRV is associated with decreased airway pressures, decreased dead space ventilation and lower intra-pulmonary shunting as compared to conventional volume and pressure cycled ventilation. APRV limits excessive distension of lung units, thereby decreasing the potential for ventilator induced lung injury (VILI), a form of lung stress. In addition, APRV reduces minute ventilation requirements, allows spontaneous breathing efforts and improves cardiac output.
• VILI ventilator induced lung injury
• APRV is a form of positive pressure ventilation that augments alveolar ventilation and lowers peak airway pressure.
• Published data on APRV has documented airway pressure reduction on the order of 30 to 40 percent over conventional volume and pressure cycled ventilation during experimental and clinical studies. Such reduction of airway pressure may reduce the risk of VILI.
• APRV improves ventilation to perfusion ratio (VA/Q) matching and reduces shunt fraction compared to conventional ventilation.
• VA/Q ventilation to perfusion ratio
• MIGET multiple inert gas dilution and excretion technique
• MIGET multiple inert gas dilution and excretion technique
• APRV is associated with reduction or elimination of sedative, inotropic and neuromuscular blocking agents. APRV has also been associated with improved hemodynamics. In a 10-year review of APRV, Calzia reported no adverse hemodynamic effects. Several studies have documented improved cardiac output, blood pressure and oxygen delivery. Consideration of APRV as an alternative to pharmacological or fluid therapy in the hemodynamically-compromised, mechanically-ventilated patient has been recommended in several case reports. [0011] APRV is a spontaneous mode of ventilation that allows unrestricted breathing effort at any time during the ventilator cycle.
• ALI/ARDS Acute Lung Injury/Acute Respiratory Distress Syndrome
• PEEP positive end expiratory pressure
• APRV expiratory flow is enhanced by utilization of an open breathing system and use of low (0-5 cmH20) end expiratory pressure.
• Ventilation on the expiratory limb of the P-V curve allows lower PEEP levels to prevent airway closure.
• Lower PEEP levels result when PEEP is utilized to prevent de-recruitment rather than attempting partial recruitment.
• Increasing PEEP levels increases expiratory resistance, conversely lower PEEP reduce expiratory resistance, thereby accelerating expiratory flow rates.
• Sustained inflation results in increased lung recruitment (increased functional lung units and increased recoil pressure) and ventilation along the expiratory limb (reduced PEEP and expiratory flow resistance), improving expiratory flow reserve.
• release from a sustained high lung volume increases stored energy and recoil potential, further accelerating expiratory flow rates. Unlike low volume ventilation, release from a high lung volume increases airway caliber and reduces downstream resistance.
• EELV end expiratory lung volume
• Ventilation decreases as pleural pressure surrounding the dependent regions lowers transalveolar pressure differentials.
• Full ventilatory support during controlled ventilation promotes formation of dependent atelectasis, increase VA/Q mismatching and intrapulmonary shunting.
• Increasing airway pressure can re-establish dependent trans-pulmonary pressure differential but at the risk of over distension of nondependent lung units.
• spontaneous breathing can increase dependent transpulmonary pressure differentials without increasing airway pressure.
• APRV allows unrestricted spontaneous breathing during any phase of the mechanical ventilator cycle.
• spontaneous breathing can lower pleural pressure, thereby increasing dependent transpulmonary pressure gradients without additional airway pressure.
• Increasing dependent transpulmonary pressure gradients improves recruitment and decreases VA/Q mismatching and shunt.
• APRV provides spontaneous breathing and improved VA/Q matching, intrapulmonary shunting and dead space.
• APRV with spontaneous breathing increased cardiac output.
• spontaneous breathing during pressure support ventilation was not associated with improved V/Q matching in the dependent lung units.
• PSV required significant increases in pressure support levels (airway pressure) to match the same minute ventilation.
• NMBA neuromuscular blocking agents
• NMBA sedation and neuromuscular blocking agents
• VILI Ventilator induced lung injury
• lung protective strategy focused on low tidal volume ventilation to limit excessive distension and VILI.
• Amato in 1995 and in 1998 utilized lung protective strategy based on the pressure-volume (P-V) curve of the respiratory system.
• Low tidal volumes (6 ml/kg) confined ventilation between the upper and lower inflection points of the P-V curve.
• End expiratory lung volume was maintained by setting PEEP levels to 2 cmH20 above the lower inflection point.
• Amato demonstrated improved survival and increased ventilator free days.
• subsequent studies by Stewart and Bower were unable to demonstrate improved survival or ventilator free days utilizing low tidal volume ventilation strategy.
• Amato utilized elevated end expiratory pressure in addition to tidal volume reduction. Such important differences between these studies limited conclusions as to the effectiveness of low tidal ventilation limiting ventilator associated lung injury (VALI).
• VALI low tidal ventilation limiting ventilator associated lung injury
• the shape of the inspiratory P-V curve is sigmoidal and is described as having three segments.
• the curve forms an upward concavity at low inflation pressure and a downward concavity at higher inflation pressures. Between the lower concavity and the upper concavity is the “linear" portion of the curve.
• the pressure point resulting in rapid transition to the linear portion of the curve has been termed the "lower inflection point".
• the lower inflection point is thought to represent recruitment of atelectatic alveolar units.
• the increasing slope of the P-V curve above lower inflection point reflects alveolar compliance. Above the inflection point, the majority of air spaces are opened or "recruited". Utilizing the lower inflection point of the inspiratory P-V curve plus 2 cmH20 has been proposed to optimize alveolar recruitment. Optimizing lung recruitment prevents tidal recruitment / de-recruitment and cyclic airway closure at end expiration. Ultimately, optimizing lung recruitment could potentially reduce shear force generation and low volume lung injury.
• such an improved method and ventilator device would also be able to capture the real-time patient condition information used by a clinician in monitoring patient response to the initial APRV parameters, and to generate a more automated feedback loop that would enable the improved method or device to be automatically reconfigured within clinically preferred operational and protocol constraints.
• a new method and apparatus is needed that would also enable more accurate and smaller adjustments to the various APRV parameters that is presently possible with the present day equipment and methods, which must be manually adjusted. Such manual adjustments often result in unfavorable patient response that results from inaccurate adjustments or adjustments that cannot be made with enough precision due to the constraints or limited capabilities of the presently available equipment.
• a ventilator or ventilator system for assisting the respiratory function of a patient under the direction of a clinician contemplates the ventilator having a computerized, operation controller or control module or computing device that is in electronic communication with a intra-ventilator and or extra-ventilator electrical or data circuit or data network.
• the controller also preferably includes a display, which can be a touch screen display or any other suitable display, including application-specific, customized display that incorporate data input or receiving devices into the display, with or without a touch screen capability.
• the controller or computing device also preferably includes a memory or storage capability that can include hard disk drives removable drives and any desired form of storage device.
• Input devices are also desirable and can include keyboards, mouse pointers, data entry tablets, voice-activated input devices, and electronic media reading devices, among many others.
• Additionally contemplated input devices include wired and wireless communications components for networking, data transfer, data capture, and data monitoring such as monitoring communications from electro-impedance tomography devices, ultrasound equipment, computed and computer-aided tomography devices, digital output fluoroscopes, x-ray equipment, magnetic resonance imaging and spectroscopy equipment, minimally invasive surgical and bronchoscope visualization devices, and similarly capable equipment.
• the inventive ventilators of the invention also preferably include a gas supply pump and or pressurized gas source.
• the gas pump or source supplies positive pressure gas to the patient through a gas circuit or network of pipes, tubes, hoses, or other types of conduits.
• the gas network or circuit may also include at least one and more preferably a plurality of valves and supply and exhaust ports. More preferably, a number of valves may be incorporated that can be electronically in communication with the controller or computing device for actuation.
• Such valves can typically be included inline with the supply and exhaust ports and can be operable in cooperation with the various types of sensors discussed elsewhere herein. What are often referred to as back-check valves, which enable fluid flow in one direction but which prevent fluid flow in an opposite direction.
• Such check valves may be included in the gas circuit or network to protect various components and the patient from unexpected and or undesirable pressures or pressure shock. In this way, protection can be afforded to the patient, pump or pressurized gas source, sensors, and other equipment.
• contemplated gas supply pump or pressurized gas source also may preferably incorporate, either alone or in combination with any of the other features described elsewhere herein, a negative pressure or vacuum capability that is contemplated to be compatible for use with negative pressure thoracic or full-body cylinders, which are also sometimes referred to by those skilled in the ventilation and respiratory technical fields as single, biphasic, or multiphasic iron-lung or cuirass ventilators.
• the ventilators practiced according to the invention also preferably include any number of optional detectors, sensors, or detection devices, that can be used alone or in any combination to sample and determine pressures of the supplied gas, inspired gas, expired gas, at rest, inflection point, and many different types of dynamic patient airway pressures.
• Other useful sensors can include peripheral, central, and airway gas concentration sensors that can be positioned extracorporeal ⁇ in the case of well-known capnometers (for detecting carbon-dioxide concentrations) or infrared oximeters (for detecting oxygen concentrations).
• These types of devices can be attached to extremities such as fingers, toes, or ear lobes, which make it very convenient to sample, monitor, and detect peripheral concentrations or saturations of carbon dioxide (SpO2) and oxygen (SpO2).
• central line catheters or other techniques can enable monitoring of arterial 02 and CO2 gas concentrations (PaO2, PaCO2), which can have clinical value in certain ventilation modes of operation or protocols discussed elsewhere herein.
• pressure and gas concentration sensors are more preferably configured to electronically communicate with the contemplated controller or computing device of the ventilator so that the realtime and or near real time data can be monitored as described in more detail below.
• inventive ventilator also contemplates incorporation of any number of equally suitable fluid flow rate sensors that also may be adapted to communicate with the data network, the data circuits, and or directly with the controller or control module or computing device, and either wirelessly any or over wired connections.
• flow rate monitoring devices can be employed in multiple places in the gas network or circuit to monitor total amount of gas supplied, inspired, expired, as well as the speed that such is occurring or has occurred. With this information, pressure can be compared to total volume or rate of volumetric or mass flow of gas so that the novel ventilators can better control and ensure proper ventilation of the target respiratory system of the patient.
• the sensors can be arranged as a sensor array to simultaneously monitor any one or any number of ventilation-related parameters so as to maximize control over the ventilation procedure to ensure the best possible protocol implementation under the circumstances.
• any of the noted sensors may be position proximate to and or about the gas supply and or exhaust ports, among other places in the gas network or circuit.
• a command module, command routine, algorithm, commander, firmware, or program may preferably be resident in the memory or storage components of the controller or computing device.
• the command module is preferably operative to control the sensors, to control the supply pump, to receive communications or images or information from other devices, to receive input from the clinician or another via any of the contemplated input devices, and to operate the display to present prompts and or display important information pertaining the ventilation process.
• the command module may also be optionally configured to preferably communicate various ventilator information to other devices, other wireless or wired networks, to the display for contemporaneous viewing, and to other remote devices and locations as may be desired.
• the control module may adjustably and or variably actuate the pump or pressure source to vary the volume and or pressure supplied thereby.
• control module or command routine may more preferably be modified to also automatically, manually, or otherwise operate any of the plurality of valves, either alone or in combination with the control of the pump, for even more rigorous control over the pressure, volume, flow rate, and gas supply cycle times available for use in ventilating the patient. More preferably, the control module or command routine may preferably be adapted to coordinate such control of the valves with sampling of or receipt of information from any of the contemplated sensors to establish increased accuracy in sampling one or more pressure readings, gas concentrations, and or volume or mass flow rates anywhere in the gas circuit or network, or about the patient undergoing ventilation.
• the present invention also contemplates operational compatibility with any number of conventionally accepted, investigational, and experimental ventilation modes. More preferably, the operational capability of the invention enables many heretofore unavailable hybrid modes wherein the innovative ventilator automatically changes its mode of operation in response to patient progress or difficulties.
• the ventilator can be configured to commence ventilation in a mandatory breath mode, and to monitor various patient pressure, volumetric, and gas concentration responses, among other responses, that may indicate a patient who was formerly heavily sedated and unable to breath, has suddenly started to attempt to breathe spontaneously.
• the inventive ventilation will automatically switch among many modes of operation including from full-support mandatory breath modes, to various modes having lesser degrees of breathing support, so as to cooperate with the patient's attempts to breathe independently.
• the new ventilator of the invention is preferably preconfigured with various automated and reconfigurable modes of operation.
• the optionally preferred configurations of the invention enable the clinician to select any particularly desired automated mode of operation.
• the clinician may also select an automated mode of operation and then modify only the desired parameters. Even further, the clinician may ignore the fully automated modes, and may enter preferred settings to select a fully customized mode of operation suitable for purposes any conceivable ventilation protocol or mode of operation.
• the ventilator incorporates the controller or control module or computing device to have three primary operational modules including, for purposes of example but not for purposes of limitation, an initial setup module, an adjustment and maintenance module, and a weaning module.
• the initial setup module includes among other elements, an optimal end expiratory lung volume (OEELV) assessment mode that monitors a number of key patient parameters to ascertain and periodically compute the OEELV.
• OEELV optimal end expiratory lung volume
• the adjustment and maintenance module includes oxygenation, recruitment, and ventilation modes of operation and protocols that are tightly constrained to rigorously and aggressively monitor and protect the key aspects of these ventilation operational modes. This is accomplished using precisely bounded monitoring paradigms that enable very gradual and extremely accurate changes to manage CO2 ventilation, to ensure optimal oxygen saturation, and when needed to exercise and maximize alveolar recruitment and prevent de-recruitment. If any parameters experience unexpected or uncontrolled hysteresis, alarm events are triggered to enable intervention.
• the weaning module includes an initial weaning protocol that enables close monitoring and small, slow changes to assess patient response to reduced ventilator support with rapid fall back to full support as needed. With positive patient response, the initial weaning protocol enables complete ventilator reconfiguration into subsequently less supportive ventilation protocols for further weaning. Also included in the weaning module is an airway pressure release ventilation or APRV protocol mode wherein spontaneous patient breathes are closely monitored so that support can be weaned as the patient gains control and consistency. With continued improvement, control is passed to the continuous positive airway pressure or CPAP protocol mode, which cycles up to a maximum CPAP support mode, that is then gradually reduced to a minimal support mode until an extubate pressure is reached, whereafter the patient is completely weaned from the ventilator.
• APRV protocol mode airway pressure release ventilation or APRV protocol mode
• any of preferred or optional variations of the inventive ventilator may be predefined with or may receive and capture a number of parameters that can control how the ventilator operates in its various modes of operation.
• the controller or computing device may access stored parameters, may obtain new parameters from remote devices via wired or wireless communications, and may accept user input via the noted touch-screen display or any of the other input devices.
• the information is typically stored in a database or an array that is stored in the memory or storage of the controller or computing device.
• these parameters are accessibly stored in one or more initialization parameter database(s), which may be resident in the controller memory or storage.
• initialization parameters can be accessed and displayed or communicated to any other device.
• additional subsets of parameters may be grouped together in arrays such as one or more model patient data arrays or elements, which can be predefined to represent optimum ventilator settings that are well-suited for a particular type of presenting patient or disease.
• such data arrays or initialization parameter databases may include, among other parameters and information, a positive end expiratory pressure or PEEP, a target peripheral 02 concentration or an SpO2 quantity, an end tidal CO2 or etCO2 quantity, a fraction of inspired 02 or FiO2 quantity, an high pressure or P(high) that defines the maximum inspired pressure during mandatory or positive pressure assisted breathes, a low pressure or P(low) that can define a minimum pressure to be used during expiration and which can be zero or non-zero.
• Other parameters can include a high time or T(high) that represents a period of inspiration and a low time or T(low) that can represent an small period of time during which expiratory gas is expelled.
• the ventilator may also be configured so that the command module can receive such initialization settings from the user or the clinician via the input device.
• Such settings can include those described elsewhere herein or any other possibly desirable parameters that can improve the use of the ventilator.
• the command module or routine samples, polls, or otherwise communicates with any or all of the sensors in the array and measures the patient's actual data.
• a series of such sensor readings may be sampled so that an entire array of such data elements can be used to monitor patient response, ventilator performance, and to adapt the ventilator performance in response to patient status and condition.
• sensor data that can be gathered may optionally include a patient SpO2 partial pressure (PP) or quantity, a patient etCO2 PP or quantity, a peak expiratory flow rate (PREF), an end expiratory lung volume (EELV) and an spontaneous frequency or machine respiratory frequency.
• PP patient SpO2 partial pressure
• PREF peak expiratory flow rate
• EELV end expiratory lung volume
• the actual patient data array elements can be compared by the command module to any of the stored data to ascertain ventilator performance and patient response. For further example, such actual data may be compared to the one model patient data array. In this way, it can be determined whether the patient is responding favorably to ventilation. In another example, if the patient is responding well to ventilation, then a comparison between the patient's SpO2 and etCO2 and a comparable model patient data set would be acceptable. If acceptable, then the control routine can compute or generate a flag or Boolean value such as a SpO2 goal value and an etCO2 goal value that can be set to true, meaning the actual patient measurements indicate all is well.
• a flag or Boolean value such as a SpO2 goal value and an etCO2 goal value that can be set to true, meaning the actual patient measurements indicate all is well.
• control routine can poll pressure sensors and flow sensors during certain points in the inspiration and expiration phases of ventilation to ascertain an optimal end expiratory lung volume (OEELV), which can provide clinically relevant feedback identifying patient response and ventilator performance.
• OEELV optimal end expiratory lung volume
• the ventilator may be configured to modify its behavior in response to unfavorable patient response. For further example, assume the SpO2 was unfavorable and the SpO2 goal value is false, which indicates undesirable oxygenation.
• the command module can preferably determine that increased or modified ventilation is warranted to achieve the desired SpO2 level. To that end, the command module will adjust the operation of the pump, and functioning of the valves, and perhaps the concentration of supplied oxygen in the pressurized gas supply, and may thereby increase the P(high) the pressure increment, it may increase the T(high) by the time increment.
• the command module can instead set a flag or Boolean constant, such as an initial weaning value to be true, which can serve to notify other modules of the ventilator that weaning may begin.
• a flag or Boolean constant such as an initial weaning value to be true
• control routine can modify the pump and valve operation to establish operation suitable for recruitment, which can include increasing P(high) by one or more P(inc), increasing T(high) by one or more T(inc)s, and or adjusting T(low) by one or more T(inc)s.
• the controller or computing device may make adjusts to the ventilator operation whereby an oxygenation flag or Boolean value is set to be true, which can invoke an oxygenation module that can poll the sensors to measure the peak expiratory flow rate and can then compute an angle of deceleration of gas flow so that an appropriate time adjustment may be made, or so that T(low) maybe decreased the T(inc).
• the ventilator can invoke an alveolar ventilation approach wherein the command module compares the spontaneous frequency to the machine respiratory frequency, ascertains the P(high), T(high), computes a minute ventilation (MV) value, adjusts the supply pump and valves to increase T(high) and P(high) by respective T(inc) and P(inc).
• MV minute ventilation
• a minute ventilation and recruitment module may be invoked wherein the MV is computed as a function of the currently in use P(high) and T(high), and adjustments are made to the P(high) and T(high).
• an initial weaning module may be utilized wherein the command module or command routine samples the machine respiratory frequency and spontaneous respiratory frequency to ascertain that spontaneous breathing is occurring at a certain rate. Comparing this rate to a predefined rate gives a good indication of whether an initial weaning protocol can be employed. If so, then the command routine can test for apnea and tachypnea. If neither condition is indicated, then the ventilator can be switched to a more suitable mode, such as an APRV mode, which makes it much easier for the intubated patient to breath spontaneously
• a more suitable mode such as an APRV mode
• the ventilator operates in another mode wherein weaning failure criteria can be considered in comparison to the actual patient data that is being monitored.
• weaning failure criteria a FiO2 threshold, a SpO2 threshold, a spontaneous tidal volume, a minute ventilation quantity, and an airway occlusion pressure (PO.1) are compared to the patient's actual values. If the patient fails to meet these criteria, then weaning is discontinued temporarily and more breathing support is given to the patient. In weaning failure, the control routine increases the P(high) and decreases T(high).
• the command module repeatedly initiates the cyclic weaning protocol wherein P(high) is decreased.
• the airway occlusion pressure PO.1 is measured and trended over time by a PO.1 Module is used to assess the work of breathing during spontaneous breathes. In the preferred embodiments, this is used to assess the impact of weaning and the resultant work of breathing, as is explained in connection with other modules elsewhere herein.
• the command module changes ventilator operation again, and monitors P(high) until a continuous positive airway pressure (CPAP) threshold is reached, which enables another conversion of the ventilator operation into a CPAP mode.
• CPAP continuous positive airway pressure
• the command module begins to gradually reduce the CPAP pressure until an extubate threshold pressure is reached.
• one method of use involves entering settings via the input device including at least one of (i) an automated initialization setting and (ii) a parameter to be stored in the memory that includes at least one of (a) a positive end expiratory pressure quantity, (b) a SpO2 quantity, (c) an etCO2 quantity, (d) a FiO2 quantity, (e) a high pressure, (f) a low pressure, (g) a high time, (h) a low time; (i) a pressure increment, (j) a time increment, (k) a tidal volume, (I) a respiratory frequency, (m) a pressure-volume slope, (n) a trigger pressure, and (o) a predetermined weaning failure criteria including at least one of a FiO2 threshold, a
• the command routine receives the settings from the clinician via the input device and commands the controller to actuate the supply pump. This commences respiratory assistance to the patient whereby the gas circuit communicates with the patient using one each of the FiO2 quantity, the high and low pressure, and the high and low time.
• Patient actual data array elements are measured by using the command routine to communicate with the plurality of sensors. Measurement of at least one of (i) a patient SpO2 quantity, (ii) a patient etCO2 quantity, (iii) a peak expiratory flow rate, (iv) an end expiratory lung volume and (v) an spontaneous frequency, is taken.
• the command routine compares the patient actual data array to at least one of the settings and compute at least one of a SpO2 goal value, an etCO2 goal value, and an optimal end expiratory lung volume, which values are used to determine whether the patient should be initially weaned, undergo recruitment and increased oxygenation, or be maintained in an unaltered state of ventilation.
• the cyclic weaning is initiated by adjusting at least one of the supply pump and the plurality of valves to decrease the P(high) by one or more pressure increments.
• any of the monitoring devices, sensors, computers, or computing devices may be connected with any of the other components wirelessly or with a wire. Any of the contemplated components may also be in communication with any of the other components across a network, through a phone line, a power line, conductor, or cable, and or over the internet.
• the resident software program may have numerous features that, for purposes of example without limitation, enable [0070] More preferably, such resident software program and or programs may enable any of the contemplated information to be communicated by text, voice, fax, and/or e- mail messages either periodically, when certain predefined or predetermined conditions occur such as predefined alarm events or conditions, and or when anomalous, unexpected, or expected power readings occur and or are detected.
• FIG. 1 shows a ventilator and system in accordance with the present invention
• FIG. 2 shows a schematic diagram of the operation of the ventilator and system of FIG. 1 ;
• FIGs. 3a and 3b are schematic diagram of an OEELV mode of operation of the ventilator and system of FIG. 1 ;
• FIG. 4 shows a schematic diagram of the interrelationships between the modules of operation of the ventilator and system of FIG. 1 ;
• FIG. 5 shows a schematic diagram of an oxygenation mode of operation of the ventilator and system of FIG. 1 ;
• FIG. 6 is a schematic diagram of a recruitment mode of operation of the ventilator and system of FIG. 1 ;
• FIG. 7 is a schematic diagram of a ventilation mode of operation of the ventilator and system of FIG. 1 ;
• FIG. 8 is schematic diagram of an initial weaning mode of operation of the ventilator and system of FIG. 1 ;
• FIG. 9 is schematic diagram of an ARPV weaning mode of operation of the ventilator and system of FIG. 1 ;
• FIG. 10 is a schematic diagram of a CPAP weaning mode of operation of the ventilator and system of FIG. 1 ;
• FIG. 11 is an area diagram of an OEELV mode and assessment of operation of the ventilator and system of FIG. 1 ;
• FIG. 12 is an area diagram of an OEILV mode and assessment of operation of the ventilator and system of FIG. 1 ;
• FIG. 13 is an area diagram of a spontaneous mode and assessment of operation of the ventilator and system of FIG. 1 ;
• FIG. 14 is a schematic airway pressure versus time tracing for airway pressure release ventilation
• FIG. 15 is a airway pressure versus time tracing during the inspiratory P(high) phase of ventilation;
• FIG. 16 is an airway volume versus pressure curve illustrating a shift from the inspiratory limb to the expiratory limb thereof;
• FIG. 17 is an inspiratory and expiratory gas flow versus time tracing for airway pressure release ventilation;
• FIG. 18 is an expiratory gas flow versus time tracing;
• FIG. 19 is a set of expiratory gas flow versus time tracing illustrating determination of whether flow pattern is normal, restrictive or obstructive based on the shape of the tracing.
• FIG. 20 is a set of airway pressure versus time tracings illustrating ventilation weaning by successive reductions in pressure P(high) and substantially contemporaneous increases in time T(high).
• FIG. 1 one possible embodiment of a ventilator and ventilator system 10 is illustrated, which is in communication with a patient P undergoing ventilation therapy.
• the ventilator or ventilator system 10 also preferably includes a gas supply pump and or pressurized gas source 12 having a positive pressure port 14, and optionally a negative pressure port 16.
• the gas pump or source 12 supplies positive pressure gas 12 and can also supply negative pressure or a vacuum 14 for non-invasive negative pressure applications such as iron-lung or similar therapies.
• a wide variety of commercially available ventilators may be modified according to the principles of the invention and one such device includes what is referred as the model EvitaXL, which is available from Draeger Medical, Inc. of Telford, Pennsylvania, USA, and Lubeck, Germany.
• the ventilator also preferably includes a controller or control module or computing device 20 that is in electronic communication with an intra-ventilator and or extra-ventilator electrical or data circuit or data network 22.
• the controller 20 also preferably includes a display 28.
• the display 28 may be a conventional device that receives unidirectional signals from the controller 20, but may also be any of a number of possibly preferred bidirectional devices such as a touch-screen display that can be used as an input device 28, and which may also have a data entry capability such as a built-in keyboard or keypad similar to keyboard input device 28 shown in FIG. 1 .
• the controller or computing device 20 also preferably includes a memory 24 or storage capability 24 that can include flash drives, optical media, hard disk drives, solid state disk drives, random access memory, non-volatile memory, removable storage devices, remote internet-based storage devices, network appliance-type devices, and the like.
• a memory 24 or storage capability 24 can include flash drives, optical media, hard disk drives, solid state disk drives, random access memory, non-volatile memory, removable storage devices, remote internet-based storage devices, network appliance-type devices, and the like.
• the supply pump or pressurized gas source 12 communicates positive or negative pressure to the patient P through a gas circuit or network of tubes 40.
• the gas network or circuit 40 may also include an inspiration or supply port 42 and an expiratory or exhaust port 44.
• a number of valves are usually also included to control and meter fluid flow and would preferably include a supply valve 46, a sensor valve 50, and an exhaust valve 52, all of which would likely be in communication with the controller 20 via the data network 22 so that the command module 30 may control and operate the valves automatically to start and stop ventilation and to control pressure and flows rates to the patient during operation.
• the supply and exhaust valves 46 and 52 may be also operable to periodically close for short periods of time to enable pressure sensors to obtain various static pressure readings.
• the sensor valve may be operable to close to protect various sensors from pressure circuit transients and also to prevent spurious readings such as when the ventilator 10 may be automatically responding to patient improvements or relapses by changing modes of operation from mandatory breathing support to augmentative support modes.
• diagnostic imaging devices that can be incorporated into the operation of the ventilator of the invention to communicate quantitative pulmonary function information such lung volume, dead space ratios, and the like.
• Additional and possible useful devices may also include, for purposes of example without limitation, electro- impedance tomography devices 70, ultrasound equipment 80, computed and computer- aided tomography devices 90, and other types of Doppler imaging sensors 95 that may enable various quantitative or subjective pulmonary function imagery.
• detectors also have utility for purposes of the invention to enable precise control and analysis of volumetric and mass flow rates as well as pressures of the supplied gas, inspired gas, and expired gas, which in turn enables calculation of various other static and dynamic pulmonary function parameters as is discussed in more detail elsewhere herein.
• a group of sensors 54 can be arrayed proximate to the ventilator and patient P.
• An oximeter or 02 saturation sensor 56 may be used peripherally to ascertain peripheral or venous 02 content SpO2 and a Capnography sensor or capnometer or CO2 sensor 58 may be used to determine end tidal or peripheral CO2 saturation levels (etCO2, SpCO2).
• etCO2, SpCO2 end tidal or peripheral CO2 saturation levels
• invasive methods can be used such as central line catheters to assess pulmonary arterial 02 and CO2 levels using a PaO2 sensor 60 and or a PaCO2 sensor 62.
• an airway pressure sensor or pressure gauge 64 can be placed in a number of places along the gas network or circuit, and is more preferably positioned proximate to the supply and exhaust ports 42, 44 at the intubation site of the patient P.
• An airway flow sensor 66 can be similarly positioned to enable monitoring of volumetric flow rates of inspiratory and expiratory gases.
• thoracically mounted strain gauges to enable monitoring of chest movement during pulmonary breathing cycles, which can be an additionally source of volumetric pulmonary patient function as well as a source of patient work expended for spontaneous breaths.
• the ventilator also incorporates the control module 20 and or the command module 30 to include three primary operational modules including, for purposes of example but not for purposes of limitation, an initial setup module or protocol 100, an adjustment and maintenance module 200, and a weaning module 250.
• initial setup module or protocol 100 a number of initial parameters are set based upon input from the clinician or by accessing a predefined set of parameters.
• FIGS. 2, 3, and 4 the preliminary initialization routines will be described.
• the clinician may enter their preferred settings 110 into the display 26 or input device 28.
• any number of possible predefined automated settings 120 may accessed and used as defined or customized in whole or in part to prepare the ventilator 10 for operation.
• the settings 110, 120 are populated with various other initialization parameters 130 during the operation of the initial setup module 100.
• the command module 30 invokes an OEELV mode or assessment routine 150.
• the initial setup module 100 includes the optimal end expiratory lung volume or OEELV mode or assessment routine 150.
• the OEELV mode 150 periodically and on demand will determine a ventilation range as a function of obstructiveness of the lung and the hypoventilation, nominal, and or hybercarbic condition of the patient P.
• the OEELV mode 150 determines whether the computationally ascertained OEELV is in the range appropriate for the conditional status of the patient P. For example without limitation, if the patient P has obstructive lungs, and is experiencing high range hypoventilation, then an appropriate or desired OEELV should be in the range of about 30% to 40%.
• the novel OEELV mode or assessment protocol can effect very fine adjustments of actual OEELV mode 150 to stimulate optimum conditioning of the ventilated patient's P pulmonary response. To wit, adjustments of 0.5 seconds in T(low) will enable slow and gradual optimization of the OEELV best suited to the disease modality.
• the principles of the invention in this aspect are also suitable for even more gradual changes in time, and can include milliseconds and smaller and larger orders of magnitude.
• the OEELV mode 150 relinquishes control for a period of time and again the command module 30 resume control to next invoke the adjustment and maintenance module 200, which includes an oxygenation mode 300, a recruitment mode 400, and a ventilation mode 500.
• the module 200 and its component modes 300, 400, 500 include protocols configured to rigorously monitor and protect the key aspects of the patient's physiological ventilation and pulmonary response profile to enable maximized recovery and weaning with the minimum of pulmonary injury risk.
• the patient's SpO2 and etCO2 are continuously monitored via the respective SpO2 and etC02 sensors 56, 58 to ensure a target or goal of SpO2 of at least about 95% and etCO2 of no more than between about 34 to 45 mmHg are maintained (FIG. 4).
• the command module 30 next passes control to oxygenation mode 300, which is described in more detail specifically in FIGS. 4 and 5.
• oxygenation mode 300 assumes control for a short period of time
• the SpO2 is again referenced so that adjustments may be effected as required in the fractionally inspired 02, which is otherwise referred to as the FiO2 parameter. See, 360, FIG. 5.
• the command module 30 cooperates with the oxygenation mode 600 to assess whether a P(high) pressure adjustment must be made or whether the initial weaning mode 600 is invoked. If the patient P is responding well, and if the FiO2 and Spo2 quantities are suitable, then control will be transferred to the initial weaning mode 600, which is discussed in more detail elsewhere herein.
• the oxygenation mode 300 and command module 30 assess the P(high) condition 380. If P(high) is adjusted 390, then another iteration of the OEELV mode is also conducted to support the optimum OEELV mode 150 discussed earlier. As control returns again to the oxygenation mode 300, P(high) is again assessed to determine 370 whether recruitment mode 400 is warranted or whether P(high) must again be adjusted. Assuming for purposes of further illustration that recruitment mode 400 is indicated, the oxygenation mode 300 relinquishes control to command module 30, which invokes the recruitment mode 400. [00109] Referring now also to FIG.
• recruitment mode 400 reevaluates the P(high) condition in a different context 420, 430, 450, as depicted in more detail in FIG. 6.
• P(high) becomes unmanageable 450
• an alarm signal is annunciated to effect immediate intervention.
• P(high) is adjusted 460, 470, 480 to improve the pulmonary conditioning of patient P and the SpO2 is again iteratively re-examined 310 while recruitment mode 400 continues attempts to increase lung surface, reduce dead space, and re-inflate alveolar units as much as possible until SpO2 values 310 indicate the need for oxygenation mode 300.
• command module 30 can interrupt recruitment as needed and transfer control or invoke a more important mode when required by patient physiology.
• command module 30 detects inbound information from feedback loop 180 describing increased etC02 values approaching or exceeding desired limits, control can revoked by command module 30 so that ventilation mode 500 can be invoked.
• commander or command module 30 invokes ventilation mode 500 to redress an actual or approaching out of limit etCO2 condition.
• the ventilation mode 500 reevaluates end tidal CO2 levels 510, reassesses OEELV conditions 150, and then assesses patient breath spontaneity 570 against the set rate or respiratory frequency values obtained from the clinician 110 or automated settings 120. If breathing spontaneity remains at or below the set rate 570, then an alveolar ventilation sub-mode 504 is affected to adjust T(high) 530, 540 and P(high) 370, 390 as may be needed to further optimize pulmonary response.
• an alveolar ventilation sub- mode 506 is effected whereby T(high) 530, P(high) 370 are adjusted separately, and then in combination 520 for lower values of P(high).
• the minute ventilation sub-mode 506 evaluates Vt 560 to determine whether recruitment mode 400 is warranted.
• the command module 30 reconfigures the ventilator 10 away from the mandatory breath control mode and invokes an assisted breathing mode.
• the commander 30 invokes an airway positive release ventilation or APRV mode 700, which can be much more comfortable for the recovering pulmonary patient P.
• the APRV mode 700 reverifies the pulmonary conditioning of the patient P and examines P(high) 610.
• the APRV mode 700 institutes a new parameter evaluation set referred to herein as the weaning failure criteria 710.
• the APRV mode 700 effects additional adjustments 720 to wean or reduce the patient's reliance on the mandatory breathing modality of the ventilator 10.
• This weaning process and re-evaluation 720, 730, 710 continues to iterate if well-tolerated by the patient P until P(high) is less than or equal to a pressure of only 20 centimeters of water.
• the command module 30 again completely reconfigures the operational profiles of the ventilator 10.
• the commander or command module 30 invokes the continuous positive airway pressure or CPAP mode 800 in a maximum CPAP positive pressure assistance mode, which speeds up the process of removing the patient P from reliance on the ventilator 10. Even still, however, the patient P continues to be evaluated against the weaning failure criteria 710, and for gross and undesirable deviations from acceptable pulmonary response limits. As the patient's recovery accelerates, the CPAP mode 800 decreases assistance 820, 830, 840, 850, until an extubate pressure 860 is reached. Hereafter, the clinician intervenes and extubates the weaned patient P.
• one particularly useful variant includes a modified OEELV mode 1050, that can incorporated as an improvement to the OEELV mode 150, or which may be included as an independent mode capable of operating and cooperating with OEELV mode 150.
• a modified OEELV mode 1050 that can incorporated as an improvement to the OEELV mode 150, or which may be included as an independent mode capable of operating and cooperating with OEELV mode 150.
• the proposed and optionally preferred OEELV 1050 mode is ideally functioning for the duration of the ventilation therapy and is operative to continuously optimize EELV, or end expiratory lung volume, of the therapeutic patient P.
• the derived OEELV is a function of disease state (see, e.g., FIGS. 3a & 3b), and the patient's pulmonary responsiveness to the oxygenation mode 300, recruitment mode 400, and ventilation mode 500.
• the OEELV mode 1050 optimizes EELV by adjusting the T(low) time period.
• the OEELV mode 1050 also validates the acquired information by using multiple sampling, averaging, and various statistical methods over time for validation and error detection.
• Adjustments of the OEELV are based upon the elements and flow and time reference points acquired during the P(low) / T (low) cycle.
• Flow and time reference points within the flow / time area which is established by the P(low) / T(low) cycle, may be used to measure and calculate changes occurring in lung volume during the P(low) / T(low) cycle.
• the preferred OEELV mode 1050 measures the peak expiratory flow rate (PEFR) 1100, the decay phase 1110, and the truncation phase 1120 to calculate (a) the angle of deceleration (ADEC) of gas flow and the termination of the flow of gas to determine optimal T(low) adjustment.
• the OEELV mode 1050 thereby enables a heretofore unavailable dynamic adjustment, which more accurately and more responsively establishes and maintains the most optimal actual OEELV of the patient P.
• An analysis of FIG. 11 ought to reveal to those skilled in the arts that an extrapolation phase 1130 may be used to calculate a residual volume and pressure as a function of time.
• the decay phase 1110 represents the decaying energy drive and the downstream resistance to gas flow.
• the flow termination phase or truncation phase 1120 establishes the location or region where the flow can be determined either as a function of the disease process, or the parameter setting that was input by the user or clinician.
• the extrapolation phase 1130 can be used graphically and or algebraically to determine and calculate pressure, volume, and time.
• the OEELV mode 1050 or 150 suggest adjustments to at least one of P(high), P(low), T(high), or T(low). In the instance where de-recruitment is detected, either P(high) or T(high) should be increased, or T(low) should be decreased, or some combination thereof should be effected. On the other hand, if recruitment is detected in this way, P(high) should be decreased, T(high) or T(low) should be increased, or some combination thereof should be effected.
• the present invention also contemplates in any of the embodiments of the invention an optimal end inspiratory lung volume or OEILV mode 1200 than can further augment aspects of the recruitment mode 400 of FIG. 6.
• the OEILV mode 1200 is optionally or preferably invoked by the command module 30 as needed. More preferably, the OEILV mode 1200 is invoked by the recruitment mode 400. Even more preferably, the OEILV mode 1200 is invoked by the recruitment mode 400 at any moment outside the actual recruitment phases or inspiratory pressurization because the OEILB mode 1200 ideally assesses for derecruitment and is active or engaged only during the machine or ventilator 10 breath.
• the OEILV mode 1200 monitors the existing sensor data to identify changes in flow and time during the P(high) / T(high) cycle of ventilation.
• the OEILV mode 1200 is active over time during the machine breath and acquires recorded reference points of the flow / time course to P(high) / T(high) cycle.
• the OELIV mode 1200 uses this acquired data to identify changes in flow and time coordinate grid during the P(high) / T(high) cycle. If such changes are in fact identified, the OEILV mode 1200 may preferably communicate a message to the commander 30, the recruitment mode 400, and or over the feedback loop 180, to initiate recruitment.
• the OEILV mode 1200 may also suggest and or effect manual or automated adjustments to P(high) and or T(high) to further minimize actual or prospective de-recruitment and or to improve the pulmonary conditions of the ventilation therapy and or the response or conditioning of the patient P.
• the OEILV mode 1200 when active, preferably may also intermittently adjust P(high), T(high), or both, and or may notify the commander 30, the feedback loop 180, and or other modes of the recommended adjustments, and or may communicate to the clinician manually or automatically so as to seek clinical intervention if warranted.
• These adjustments in P(high), T(high), or both, may be applied in an occasional, intermittent, and / or cyclic manner, and may be effected either manually, through informative messages, or through automation.
• P(high), T(high), or both may be applied in an occasional, intermittent, and / or cyclic manner, and may be effected either manually, through informative messages, or through automation.
• the OEILV mode 1200 may preferably incorporate a resistive element 1210 that occurs during the onset of the machine breath, an inflection point 1250 that correlates with an inflection or a half-way point of the machine breath cycle, and an elastic element 1220 that corresponds with the relaxing subsequent to the machine breath. It is important to note that the OEILV mode 1200 measures the resistive-elastic transition point 1250 to determine if the slope of the elastic element 1220 changes.
• the inquiry seeks to learn whether the elastic element 1220 becomes more acute in de-recruitment and less acute in recruitment.
• Those skilled in the arts may come to understand that the combination of information available from FIGS. 11 and 12 and the accompanying discussion herein enables a heretofore unavailable means of more accurately discerning whether recruitment has been accomplished or whether de-recruitment has occurred.
• the various modes now available and according to the principles of the invention enable more accurate and more automated systems for better managing and mitigating recruitment and derecruitment during many possible ventilation therapy protocols.
• the breathing spontaneity can be further assessed using an optionally preferred spontaneous mode 1340 that is graphically depicted in FIG. 13.
• This spontaneous mode 1340 may be further invoked by any of the other modes, modules, and routines of the inventive ventilator. Even so, this spontaneous mode 1340 may find special utility in being optionally invoked through the command module 30 alone and or by either the ventilation mode 500 and or by the initial weaning mode 600. [00128] In addition to comparing the actual spontaneous breaths per unit time of the patient P, this mode 1340 also may preferably assess and analyze the nature of spontaneous breathing to identify and quantify breathing effort, otherwise referred to as the "work of breathing". More preferably, the spontaneous mode 1340 assesses the effect of weaning on the work of breathing.
• any of the sensors described elsewhere herein can be elastically or tightly affixed to the thorax of the patient to sense and record movement, and solid-state or similarly capable accelerometers can also be used to gain additional data points that can be used to compute actual work expended to breath.
• data points can be correlated against a spontaneous breath initiation phase 1360, a spontaneous peak phase 1370, and a spontaneous termination phase 1380.
• such data can be adduced during any of the spontaneous breath evaluations 570, 580 (FIGS. 7, 8) occurring during the ventilation and initial weaning modes 500, 600, as well as any other suitable time.
• These additional indicia of the pulmonary conditioning and response of the patient P can further illuminate the patient's true cardiopulmonary physiology, which can lessen the risk that a patient is prematurely removed from ventilation therapy due to patient resistance or other issues.
• the invention also contemplates initiating ventilation of a patient in an APRV mode 700 based on initial oxygenation and ventilation settings.
• the patient P can then have the safety of the mandatory breath capability of the ventilator 20 while commencing ventilation therapy with a less intrusive profile.
• the ARPV airway pressure during expiration (P(low)) is substantially zero throughout ventilation to allow for the rapid acceleration of expiratory gas flow rates.
• the fraction of oxygen in the inspired gas (RO2) is initially set at about 0.5 to 1 .0 (i.e. about 50% to 100%).
• the highest airway pressure achieved during inspiration (P(high)) must be sufficiently high to overcome airspace closing forces and initiate recruitment of lung volume.
• P(high) may suitably be initialized at a default value of about 35 cmH20.
• P(high) may be established based either on the severity and type of lung injury or based on recruitment pressure requirements. The latter method is preferred in cases where the ventilation/perfusion ratio is less than or equal to about two hundred millimeters of mercury (200 mmHg).
• the ventilation perfusion ratio is preferably monitored continuously. It is the ratio of the partial pressure of oxygen in the blood of the patient to the fraction of oxygen present in the inspired gas (i.e. PaO2/FiO2 but is commonly abbreviated as P/F).
• the invention contemplates establishment of P(high) at a value of between about 35 mmHg and 40 mmHg but preferably not appreciably above 40 mmHg. In cases where P(high) is initially established at a default value of about 35 cmH20, P(high) is reduced from such a value once P/F exceeds about 250 mmHg. Initiation of ventilation also requires the establishment of time (duration) settings for inspiration and expiration.
• the duration of the positive pressure phase (T(high)) is established at a value within the range of about 5.0 to about 6.0 seconds unless the measured PaCO2 is greater than about 60 mmHg. In that case, T(high) is more preferably set to a lower initial value of within the range of about 4.0 to 5.0 seconds.
• the duration of the ventilator release phase (T(low)) may suitably be initialized at a value within the range of 0.5 to 0.8 seconds with about 0.7 seconds being a preferred default value.
• ventilation continues in a repetitive APRV mode cycle generally as illustrated in FIG. 14. During management of ventilation in accordance with the invention, the initial values of one or more of these parameters are re-assessed and modified in accordance with measured parameters as has been described in connection with earlier descriptions.
• a principal goal is to maintain the level of carbon dioxide in the blood of the ventilated patient (PaCO2) at a level of less than or equal to about 50 mmHg.
• PaCO2 the level of carbon dioxide in the blood of the ventilated patient
• arterial PaCO2 is monitored continuously or measured as clinically indicated and the ventilator controlled to adjust ventilation as follows. Any time after ventilation has commenced, but preferably soon thereafter or promptly upon any indication of hypercarbia (PaCO2 above about 50 mmHg), the setting of T(low) is optionally but preferably checked and re-adjusted if necessary.
• optimal end expiratory lung volume is maintained by titration of the duration of the expiration or release phase by terminating T(low) based on expiratory gas flow.
• the flow rate of the expiratory gas is measured by the ventilator and checked in relation to the time at which the controller of the ventilator initiates termination of the release phase.
• the expiratory exhaust valve should be actuated to terminate the release phase T(low), at a time when the flow rate of the expiratory gas has decreased to about 25% to 50% of its absolute peak expiratory flow rate (PEFR).
• PEFR absolute peak expiratory flow rate
• An example is illustrated in FIG. 17. In that example, T(low) terminates by controlling the expiratory exhaust valve to terminate the release phase when the expiratory gas flow rate diminishes to 40% PEFR.
• T(high) is increased by about 0.5 seconds while maintaining P(high) substantially unchanged. Should the patient remain hypocarbic as indicated by subsequent measure of PaCO2, weaning in the manner to be described may be initiated provided oxygenation is satisfactory and weaning is not otherwise contraindicated based on criteria to be described further below.
• the hypercarbic patient though is not to be weaned.
• the invention contemplates assessment of the expiratory flow pattern before making significant further adjustments to ventilation parameters. This assessment can readily be carried out by a software program stored within the control unit of the ventilator which carries out automated analysis of the expiration flow versus time tracing. As illustrated in FIG. 19, normal expiratory flow is characterized by flow which declines substantially monotonically from the onset of the release phase through its termination and does not fall off prematurely or abruptly. Restrictive flow in contrast declines rapidly from the onset of the release phase to zero or a relatively small value.
• FIG. 18 illustrates a gas flow pattern with a noticeable inflection point.
• the control unit of the ventilator is programmed to determine reference points during the P(low) / T(low) cycle. Flow and time reference points within the flow / time area, which is created or established by the P(low) / T (low) cycle, may be used to measure and calculate changes occurring in lung volume during the P(low) / T(low) cycle.
• the invention contemplates adjusting T(low) before making any other significant adjustments to ventilation parameters. This can be done according to either of two alternative methods.
• One method is to adjust T(low) to a predetermined value according to whether flow is either obstructive or restrictive but allowing T(low) to remain at its previous value if flow is normal.
• T(low) should be adjusted to less than about 0.7 seconds.
• obstructive flow calls for a T(low) of greater duration, preferably greater than about 0.7 seconds with 1 .0 to 1.2 being typical.
• Sedation of the patient can be evaluated by any suitable technique such as the conventional clinical technique of determining an SAS score for the patient. If the patient appears over-sedated based on the SAS score (SAS score greater than about 2) or otherwise, reduction of sedation should be considered and initiated if appropriate. Thereafter, T(high) should be increased by about 0.5 seconds and P(high) increased concomitantly by about 2 cmH2O. After allowing sufficient time for these adjustments to take effect on the patient, PaCO2 should be re-evaluated. If the patient remains hypercarbic, T(high) should be increased again by about 0.5 seconds and P(high) again increased concomitantly by about 2 cmH20.
• SAS score greater than about 2 SAS score greater than about 2
• PaCO2 should be re-evaluated. If the patient remains hypercarbic, T(high) should be increased again by about 0.5 seconds and P(high) again increased concomitantly by about 2 cmH20.
• PaCO2 should then be reassessed and concomitant increases of about 0.5 seconds in T(high) and about 2 cmH20 in P(high) repeated until the patient is no longer hypercarbic. However, the total duration of T(high) should not be increased beyond a maximum of about fifteen (15) seconds.
• Management of oxygenation in accordance with the invention is carried out with the goal of maintaining the level of oxygen in the arterial blood of the ventilated patient (PaO2) at a value of at least about 80 mmHg and a maintaining saturation level (SaO2) of at least about 95%.
• PaO2 the level of oxygen in the arterial blood of the ventilated patient
• SaO2 a maintaining saturation level
• Preferably fluctuations of PaO2 are held within a target range of about 55 mmHg and 80 mmHg.
• the ventilator would be controlled to progressively decrease the fraction of oxygen in the inspired gas (FiO2) by about 0.5 about every thirty minutes to one hour with the objective of maintaining a blood oxygen saturation level (SaO2) of about 95% at a P(high) of about 35 and an FiO2 of about 0.5.
• FiO2 blood oxygen saturation level
• PaCO2 a PaCO2 of less than about 50 mmHg
• weaning is not otherwise contraindicated.
• FiO2 is not decreased. Instead, P(high) is increased to about 40 cmH20 and T(high) increased substantially contemporaneously by about 0.5 seconds.
• T(high) is controlled to sustain recruitment while P(high) is reduced to gradually reduce airway pressure.
• FIG. 20 illustrates, this is achieved by carrying out a series of successive incremental reductions in P(high) while substantially contemporaneously carrying out a series of successive incremental increases in T(high) so as to induce gradual pulmonary stress relaxation as FIG. 15 illustrates.
• the pulmonary pressure versus volume curve shifts progressively from its inspiratory limb to its expiratory limb as illustrated in FIG. 16.
• weaning may be carried out in two stages, the first of which is more gradual than the second.
• P(high) is reduced by about 2 cmH20 about every hour.
• T(high) is increased by about 0.5 to 1 .0 seconds up to, but not in excess of a T(high) of about 15 seconds in total duration.
• the fraction of oxygen in the inspired gas FiO2
• the patient's ability to maintain unassisted breathing is assessed, preferably for at least about 2 hours or more. Criteria for such assessments include: a) SpO2 of at least about 0.90 and/or PaO2 of at least about 60 mmHg; b) tidal volume of not less than about 4 ml/kg of ideal bodyweight; c) respiration rate not significantly above about 35 breaths per minute, and d) lack of respiratory distress, with such distress being indicated by the presence of any two or more of the following: i) Heart rate greater than 120% of the 0600-hour rate (though less than about 5 minutes above such rate may be considered acceptable) ii) marked use of accessory muscles to assist breathing; iii) thoroco-abdominal paradox; iv) diaphoresis and/or v) marked subjective dyspnea.
• CPAP at an airway pressure of about 10 cmH20 should be resumed and monitoring and reassessment carried out as needed. However, if criteria a) through d) above are all satisfied, the patient may be transitioned to substantially unassisted breathing such as by extubation with face mask, nasal prong oxygen or room air, T-tube breathing, tracheotomy mask breathing or use of high flow CPAP at about 5 cmH20.
• substantially unassisted breathing such as by extubation with face mask, nasal prong oxygen or room air, T-tube breathing, tracheotomy mask breathing or use of high flow CPAP at about 5 cmH20.
• the patent should be reassessed at least about every two hours and more frequently if indicated. Blood gas measurements (PaO2 and SaO2 and PaCO2) on which govern control of ventilation according to the invention should be monitored not less frequently than every two hours though substantially continuous monitoring of all parameters would be considered ideal.
• At least one special assessment should be conducted daily, preferably between 0600 and 1000 hours. If not possible to do so, a delay of not more than about four hours could be tolerated. Weaning should not be initiated or continued further unless: a) at least about 12 hours have passed since initial ventilation settings were established or first changed, b) the patient is not receiving neuromuscular blocking agents and is without neuromuscular blockade, and c) Systolic arterial pressure is at least about 90 mmHg without vasopressors (other than "renal" dose dopamine).
• a trial should be conducted by ventilating the patent in CPAP mode at about 5 cmH20 and an FiO2 of about 0.5 for about five (5) minutes. If the respiration rate of the patient does not exceed about 35 breaths per minute (bpm) during the five (5) minute period weaning as described above may proceed. However, if during the five (5) minute period the respiration rate exceeds about 35 bpm it should be determined whether such tachypnea is associated with anxiety. If so, administer appropriate treatment for the anxiety and repeat the trial within about four (4) hours. If tachypnea does not appear to be associated with anxiety, resume management of ventilation at the parameter settings in effect prior to the trial and resume management of ventilation as described above. Re-assess at least daily until weaning as described above can be initiated.
• the embodiments of the present invention are suitable for use in many respiratory assistance applications that involve the use of ventilators and ventilator systems and methods of operation thereof.
• the various configurations and capabilities of the inventive ventilator and system and method of operation can be modified to accommodate nearly any conceivable respiratory assistance application and or requirement.
• the arrangement, capability, and compatibility of the features and components of the novel ventilators, systems, and methods of operation and use described herein can be readily modified according to the principles of the invention as may be required to suit any particular critical and or routine care and or hospital, assisted care, or home care application or situation.
• inventive ventilators, systems, and methods are suitable for use with nearly all types of ventilation equipment including but not limited to positive pressure or negative pressure respiratory assistance devices.

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• 2008
  • 2008-06-02 CA CA3165969A patent/CA3165969A1/en active Pending
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• 2014
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