WO2014126457A1

WO2014126457A1 - Respiration monitoring system and method, mask, breathing circuit and breathing circuit filter for use in such system and method, and computer program

Info

Publication number: WO2014126457A1
Application number: PCT/NL2013/050094
Authority: WO
Inventors: Johannes Martinus HUITINK
Original assignee: Stichting Vu-Vumc
Priority date: 2013-02-15
Filing date: 2013-02-15
Publication date: 2014-08-21
Also published as: EP2994046A1

Abstract

In a system and method of monitoring a respiration of a patient, an SpO2 signal and a CO2 signal are provided and processed to establish an output signal indicating a respiration status, being one of a "call for help" status, a "perform tracheotomy" status and a "normal situation" status, depending on conditions determined from the SpO2 signal and the CO2 signal over time, weight data, length data and age data of the patient.

Description

Respiration monitoring system and method, mask, breathing circuit and breathing circuit filter for use in such system and method, and computer program

FIELD OF THE INVENTION

The invention relates to the field of patient monitoring, and more specifically to the field of monitoring a respiration from a patient based on signals obtained for the patient. In particular, the present invention relates to a respiration monitoring system and method, breathing mask, breathing circuit and breathing circuit filter for use in such system and method, and a computer program.

BACKGROUND OF THE INVENTION

In e.g. cardiopulmonary resuscitation, anesthesia, emergency medicine, intensive care medicine and first aid, proper airway management is vital to ensure that there is an open pathway between a patient's lungs and the outside world, and that the lungs are safe from aspiration. In nearly all circumstances, airway management is the highest priority for clinical care, since if there is no airway, there can be no breathing and no oxygenation of blood. In such circumstances, circulation (and hence all vital body processes) will cease in a short time. So, a first step in almost all clinical treatments is to provide oxygen to the lungs.

Nowadays, many airway management tools are available on the market. Guidelines have been written by important medical societies.

Nevertheless, mistakes and failures in airway management still frequently occur because of the human factor in such management. Doctors and nurses often make mistakes because situation awareness is lost. Crew resource management research has found that during stressful situations people make many mistakes.

Situation(al) awareness is defined as the perception of environmental elements within an amount of time and space, the comprehension of their meaning, and the projection of their status in the near future. Situation awareness is a field of study concerned with perception of the environment critical to decision-makers in complex, dynamic areas like aviation, air traffic control, power plant operations, military command and (emergency) services such as fire fighting and police tasks.

Even in a well-equipped operating theatre and with a team of clinicians all technically skilled, failure to respond appropriately to an unanticipated emergency may happen, with failure to follow protocols, failure to use equipment properly, failure to maintain situation awareness, failure to prioritize and make decisions properly, all in a short time. Leadership may be confused, and communication problems may arise despite attempts to speak up by the team. Benefits of the team skills and awareness present may be lost.

In these and other clinical situations, difficulties in airway management may occur unexpectedly in all patients. This can lead to brain damage and death. A so-called 'cannot intubate - cannot ventilate/oxygenate' situation can proceed swiftly to a life threatening event if it is not dealt with correctly.

WO 2004/049912 discloses a respiratory monitor which uses monitors and displays visible to all clinical personnel. The respiratory monitoring system alerts clinicians of potential problems while automatically taking steps to gather additional information. A real-time visual indicator of airway management procedures (oxygenation, ventilation) and effect is provided. Multiple thresholds that trigger corresponding indicators such as color-coded LEDs provide a quantized display of the effect of airway management procedures. The respiratory effect can also be displayed by the intensity of the LEDs. Other arrays of LEDs provide graded level of alarms.

In environments like an operating theatre, intensive care unit, ambulance or emergency room, the number of visual and audible indications, such as alarms, for clinicians treating a patient is high. Such indications still require the clinician to decide to take a certain action or not within a very brief period of time, and to at least pay intermittent attention to all such indications. Under these conditions, the clinician may lose a sense of time.

Therefore, there is a need for limiting the number of indications, in particular during airway management of a patient. Furthermore, there is a need to automatically and timely provide such indications, in particular only those which are most critical in the airway management. Still further, there is a need for indications which leave little or no room for doubt about the patient's respiratory condition, and which can lead to timely actions without any intervention of the clinician, so that the clinician's time and attention is saved for the primary tasks to be carried out.

SUMMARY OF THE INVENTION

It would be desirable to provide a method and system which improves patient safety. It would also be desirable to provide a method and system to guide medical staff during life threatening events that may unexpectedly occur during airway management. It would further be desirable to provide a method and system to advise the medical staff in time when it is really necessary to do a life saving tracheotomy. A surgical airway or tracheotomy is the ultimate and most definitive step in providing an open airway by making an incision just below the vocal cords. To better address one or more of these concerns, in a first aspect of the invention a system for monitoring a respiration of a patient is provided, the system comprising:

signal inputs for receiving input signals, the signal inputs comprising:

an Sp02 signal input for receiving an Sp02 signal representing an oxygen saturation value over time in the blood of the patient; and

a C02 signal input for receiving a C02 signal representing a carbon dioxide pressure value over time in the air breathed by the patient;

a processing device comprising a timer device, wherein the processing device is configured to process the Sp02 signal and the C02 signal;

an output for providing an output signal based on the processing,

wherein the processing device is configured to establish the output signal to indicate a respiration status, being one of a "call for help" status, a "perform tracheotomy" status, and a "normal situation" status.

Such a system, based on the input of only the Sp02 and the C02 signal, and time measurements, is simple, yet effective in supporting the clinician during airway management. With the system, and a proper way of communicating the respiration status to the clinician, it can be assured that expert assistance will be called for at a proper time without intervention of the clinician, based on the output signal indicating a "call for help" status. It can further be assured that a life saving tracheotomy can be performed when absolutely necessary, based on the output signal indicating a "perform tracheotomy" status. Still further, it can be assured that the clinician recognizes a normal situation, based in the output signal indicating a "normal situation" status.

According to the present invention, the output signal indicates the "call for help" status at least under any (i.e. one or more than one) of the following conditions (a) - (f):

(a) an oxygen saturation value less than 88 - 96%, in particular 92%, and a decrease of the oxygen saturation value is greater than 8 - 12%, in particular 10%, per minute;

(b) no C02 signal representing a capnogram for 4.5 - 5.5 minutes, in particular 5 minutes;

(c) a first oxygen saturation value is less than 76 - 84%, in particular 80%, and remaining less than 76 - 84 %, in particular 80%, during a predetermined time period;

(d) oxygen saturation value falls below 76 - 84%, in particular 80%, and does not rise to above 86 - 94%, in particular 90%, within the predetermined time period;

(e) a C02 signal representing a first capnogram takes longer than 3 - 4 minutes, in particular 3.5 minutes, plus the predetermined time period;

(f) no C02 signal representing two consecutive capnograms of at least 18 - 22 mm Hg, in particular 20 mm Hg, during the predetermined time period.

According to the present invention, the output signal indicates indicates the "perform tracheotomy" status under any (i.e. one or more than one) of the following conditions (g) - (i): (g) an oxygen saturation value less than 76 - 84%, in particular 80%, during at least 2.5 - 3.5 minutes, in particular 3 minutes, and no C02 signal representing a capnogram for 4 - 6 minutes, in particular 5 minutes;

(h) a decrease of the oxygen saturation value of more than 27 - 33 %, in particular 30%, in 1.5 - 2.5 minutes, in particular 2 minutes, not followed by an increase of the oxygen saturation value to above 81-89%, in particular 85%, within 0.5 - 1.5 minutes, in particular 1 minute;

(i) an oxygen saturation value less than 66 - 74%, in particular 70%, not followed by an increase of the oxygen saturation value to above 86 - 94%, in particular 90%, within 1 minute, and no C02 signal representing a capnogram.

According to the present invention, the output signal indicates the "normal situation" status under any (i.e. one or more than one) of the following conditions (j) - (I):

(j) none of the conditions (a) - (i) have occurred;

(k) any of the conditions (a) - (i) have occurred, and a C02 signal representing 3 consecutive capnograms of at least 18 - 22 mm Hg, in particular 20 mm Hg, and an oxygen saturation value of at least 86 - 94%, in particular 90%;

(I) an oxygen saturation value greater than 84 - 92%, in particular 88%, and an increase thereof during at least 0.5 - 1.5 minutes, in particular 1 minute.

Here, a C02 signal is taken to represent the carbon dioxide pressure value as a function of time in the air respired by a patient, and a capnogram is taken as the C02 pressure as a function of time during one inhalation followed by one exhalation. Instead of a C02 signal being defined as the carbon dioxide pressure value as a function of time, within the scope of this disclosure it can also be defined as a carbon dioxide concentration value (in percent) as a function of time, with an appropriate conversion of the pressure values into concentration values.

In a second aspect of the invention a method for monitoring a respiration of a patient is provided, the method comprising:

providing an Sp02 signal, the Sp02 signal representing an oxygen saturation value over time in the blood of the patient;

providing a C02 signal, the C02 signal representing a carbon dioxide pressure value over time in the air breathed by the patient;

processing the Sp02 signal and the C02 signal; and

establishing an output signal based on the processing, the output signal indicating a respiration status, being one of a "call for help" status, a "perform tracheotomy" status and a "normal situation" status,

wherein the conditions under which each status is indicated by the output signal are (a)- (0. (9)-( . ^and OHO. respectively, as explained above. As has been shown by numerous cases in the past, in many critical events, the human factor is a leading cause for mistakes. With the system and method of the present invention, the severity of the clinical situation is continuously monitored, to prevent a loss of situation awareness for the clinician during critical events. Immediately when it is certain that a specified status ("call for help", "perform tracheotomy", or "normal situation") has been reached, this is reflected in the output signal of the system. With the output signal reflecting the status, a clear communication to the clinician can be triggered, such as a light having a specific meaningful color and/or specific audible speech. A loss of sense of time of the clinician can be prevented.

In a third aspect of the present invention, a breathing mask with a light source for use in the system of the invention is provided.

In a fourth aspect of the present invention, a breathing circuit with a light source for use in the system of the invention is provided.

In a fifth aspect of the present invention, a breathing circuit filter with a light source for use in the system of the invention is provided.

In a sixth aspect of the present invention, a computer program is provided for the processing device of the respiration monitoring system to establish the output signal.

These and other aspects of the invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 depicts a block diagram of an embodiment of a system according to the present invention.

Figure 2 depicts a flow diagram of an embodiment of a method according to the present invention.

Figure 3 depicts a perspective, exploded view of a breathing mask, a breathing circuit, a breathing circuit filter and a fitting for use in an embodiment of the system according to the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS Figure 1 depicts, in block diagram form, a system 2 for monitoring a respiration of a patient. The system 2 is indicated by a dashed line. The system 2 comprises a processing device 4, configured to process input signals, and to provide one or more output signals based on the processing. Input signals, provided at corresponding signal inputs of the processing device 4, comprise an Sp02 signal 6 representing an oxygen saturation value over time in the blood of the patient, a C02 signal 8 representing a carbon dioxide pressure value over time in the air breathed by the patient, and may further comprise a patient data signal 10 representing a weight value, a length value and/or an age value. Said input signals 6, 8, 10 may be separate signals provided at separate signal inputs, or may be separate signals provided at one signal input, or may be one composite signal provided at one signal input. Alternatively or additionally, the system 2 may comprise a receiver 12 for wirelessly receiving the Sp02 signal 6, the C02 signal 8 and/or the patient data signal 10. The input signals 6, 8, 10 may originate from different monitoring devices, or from one central monitoring device. The patient data signal 10 may be generated by a user operating an input device 9, e.g. comprising a real or virtual keyboard or any other input means, and coupled to the processing device 4. The patient data signal 10 may also be generated by software retrieving the patient data from a database coupled to the processing device 4, or in any other suitable way.

The processing device 4 processes the input signals 6, 8 and/or 10 to form an output signal 11.

The processing device 4 comprises a timer device 14 to measure time in relation to the input signals 6, 8, 10.

The system 2 may be powered by an internal battery 16, in particular a rechargeable battery 16, to be independent from external energy sources. However, an interface for a power supply, such as a mains supply, may be provided also. Alternatively or additionally, the system 2 may be powered from an inductor 18 which inductively and wirelessly receives power through inductive coupling with another inductor (not shown in Figure 1) located outside the system 2.

The system 2 may comprise an on/off switch 20 to switch the system 2 on and off. When the system is switched on, it may initially be in a stand-by mode, awaiting specific input through the input signals 6, 8, 10.

In an embodiment, the on/off switch 20 is operated automatically, according to any of the embodiments described below.

In an embodiment of an automatically operated on/off switch 20, the on/off switch 20 comprises a reed contact 21 which is operated by a magnet when installing the system 2 in a designated location. In another embodiment, the on/off switch 20 comprises a temperature sensor 22, wherein the on/off switch 20 is configured to switch on when the temperature sensor 22 senses a temperature above a threshold temperature, and wherein the on/off switch 20 is configured to switch off when the temperature sensor 22 senses a temperature below a threshold temperature. In an embodiment, the temperature sensor 22 is configured to sense a body temperature of a patient, and said threshold temperature may be higher than room temperature and lower than a body temperature.

Alternatively or additionally, the on/off switch 20 may comprise a motion sensor 24, wherein the on/off switch 20 is configured to switch on when the motion sensor 24 senses a motion, and wherein the on/off switch 20 is configured to switch off when the motion sensor 24 senses no motion. Within this disclosure, a motion sensor may be embodied as a position sensor, sensing a change of position, which is a motion from one position to another position.

Alternatively or additionally, the on/off switch 20 may comprises a pressure sensor 26, wherein the on/off switch 20 is configured to switch on when the pressure sensor 26 senses a pressure above a threshold pressure, and wherein the on/off switch 20 is configured to switch off when the pressure sensor 26 senses a pressure below a threshold pressure. The pressure sensor 26 may be configured to sense a pressure exerted on a part of a breathing assembly comprising a breathing mask, a breathing circuit, and a breathing circuit filter mounted in the airway formed by the breathing mask and the breathing circuit. As an example, a pressure exerted on a breathing mask above the threshold pressure may activate the system 2 to accept input signals 6, 8 and 10 and to be standby.

The output signal 11 of the processing device 4 may be supplied to a light emitting device 30 comprising a light source 32 configured to emit light of different colors, in particular green, blue and red light, wherein the color is determined by the properties of the output signal 11. The light source 32 may be composite light source comprising separate lights of different colors which can be controlled separately.

The output signal 1 1 of the processing device 4 may further be supplied to a speech generating device 34 comprising a speaker 36 for producing a sound, in particular audible speech, depending on a status indicated by the output signal 11.

The output signal 1 1 of the processing device 4 may further be supplied to a display device 38, providing a visual indication of a status indicated by the output signal 11.

The output signal 11 of the processing device 4 may further be supplied to a communication device 40. The communication device 40 is configured to at least send an alert message to one or more receivers (such as pagers, tracers and other mobile

communication devices). The communication device 40 may further be configured to receive a confirmation message confirming receipt of the alert message by one or more of the receivers, and/or confirming the receiver(s) taking an action.

The light emitting device 30, the speech generating device 34, the display device 38, and the communication device 40 may be separate from the system 2, or may be part of the system 2, as indicated by a dash-dotted line. Figure 2 shows a flow diagram of steps of an embodiment of a processing performed by the processing device 4 of the system 2 in response to the input Sp02 signal 6 and the C02 signal 8. For this purpose, the processing device 4 may be programmed to perform the processing. The processing device 4 may comprise a processor (not shown) having a computer program loaded therein. The computer program contains computer instructions enabling the processing device 4 to perform the processing. The computer program is based on sequence of steps, such as the sequence elucidated below as an example. However, other sequences of the same steps are possible. The processing device 4 may be a dedicated processing device, or may be part of a processing unit performing also other tasks, such as other monitoring tasks, than respiration monitoring.

The processing device 4 at least temporarily stores the values of the input signals 6, 8, 10. The Sp02 signal 6 and the C02 signal 8 are stored in a series of values over time, using the timer device 14.

In step 200, the system 2 is switched on using the on/off switch 20.

In step 201 , the processing device 4 receives the input Sp02 signal 6.

In step 202, the processing device 4 receives the input C02 signal 8.

In step 203, the processing device 4 receives the patient data signal 10.

In step 204, a predetermined time period is selected, based on the patient data signal. If a BMI calculated from a weight value and a length value contained in the patient data signal exceeds a BMI threshold value, such as at least 28, in particular about 30, then a

predetermined time period is selected to be less than 0.5 minute, in particular about 0 minute, otherwise the predetermined time period may be selected to be between 0.5 and 1.5 minute, in particular about 1 minute. If an age value contained in the patient data signal exceeds an age value threshold value, such as at least 66, in particular about 70, then predetermined time period is selected to be less than 0.5 minute, in particular about 0 minute, otherwise the predetermined time period may be selected to be between 0.5 and 1.5 minute, in particular about 1 minute.

In step 206, a condition (a) is tested by the processing device 4, in which condition (a) the Sp02 signal 6 represents an oxygen saturation value less than 92% and a decrease of the oxygen saturation value is greater than 10% per minute.

In step 208, a condition (b) is tested by the processing device 4, in which condition (b) no C02 signal representing a capnogram is detected for 5 minutes.

In step 210, a condition (c) is tested by the processing device 4, in which condition (c) a first oxygen saturation value is less than 80% and remains less than 80% during a predetermined time period. In step 212, a condition (d) is tested by the processing device 4, in which condition (d) an oxygen saturation value falls below 80% and does not rise to above 90% within the predetermined time period.

In step 214, a condition (e) is tested by the processing device 4, in which condition (e) a C02 signal representing a first capnogram takes longer than 3.5 minutes plus the predetermined time period.

In step 215, a condition (f) is tested by the processing device 4, in which condition (f) there is no C02 signal representing two consecutive capnograms of at least 20 mm Hg during the predetermined time period.

If in any of the steps 206-215 a respective condition (a)-(f) is found not to be satisfied

(indicated by an arrow marked N), then a next condition is tested. However, if in any one of the steps 206-215 a respective condition (a)-(f) is found to be satisfied (indicated by an arrow marked Y), then an output signal 11 indicating a "call for help" status is generated, as shown in step 216.

In step 218, a condition (g) is tested by the processing device 4, in which condition (g) the Sp02 signal represents an oxygen saturation value less than 80% during at least 3 minutes, and there is no C02 signal representing a capnogram for 5 minutes.

In step 220, a condition (h) is tested by the processing device 4, in which condition (h) the Sp02 signal represents a decrease of the oxygen saturation value of more than 30% in 2 minutes, not followed by an increase of the oxygen saturation value to above 85% within 1 minute.

In step 222, a condition (i) is tested by the processing device, in which condition (i) the Sp02 signal represents an oxygen saturation value less than 70%, not followed by an increase of the oxygen saturation value to above 90% within 1 minute, and no C02 signal representing a capnogram.

If in any of the steps 218-220 a respective condition (g)-(h) is found not to be satisfied (indicated by an arrow N), then a next condition is tested. However, if in any one of the steps 218-222 a respective condition (g)-(i) is found to be satisfied (indicated by an arrow marked Y), then an output signal 1 1 indicating a "perform tracheotomy" status is generated, as shown in step 224.

If in step 222 condition (i) is found not to be satisfied (indicated by an arrow N), then an output signal 1 1 indicating a "normal situation" status is generated, as shown in step 226.

In step 228 following step 216, a condition (k) is tested by the processing device 4, in which condition (k) the C02 signal represents 3 consecutive capnograms of at least 20 mm Hg, and the Sp02 signal represents an oxygen saturation value of at least 90%. If in step 228 condition (k) is found not to be satisfied (indicated by an arrow N), then a next condition is tested. However, if in step 228 condition (k) is found to be satisfied (indicated by an arrow marked Y), then an output signal 11 indicating a "normal situation" status is generated according to step 226.

In step 230, a condition (I) is tested by the processing device 4, in which condition (I) the Sp02 signal represents an oxygen saturation value greater than 88% and an increase thereof during at least 1 minute. If in step 230 condition (I) is found not to be satisfied

(indicated by an arrow N), then the processing continues at step 202. However, if in step 230 condition (I) is found to be satisfied (indicated by an arrow marked Y), then an output signal 1 1 indicating a "normal situation" status is generated according to step 226.

Following step 226, the processing continues at step 202.

The output signal 1 1 indicating a "normal situation" status in step 226 may be supplied to the light emitting device 30 to cause the light source 32 to emit light having a first color, e.g. a green color.

The output signal 1 1 indicating a "call for help" status in step 216 may be supplied to the light emitting device 30 to cause the light source 32 to emit light having a second color, e.g. a blue color. The light may be intermittent with an appropriate duty cycle, and/or the light may have varying intensity.

Based on the output signal 1 1 indicating the "call for help" status, the communication device 40 receiving the output signal 1 1 may automatically activate a paging or messaging system calling expert assistance. At the same time, the output signal 1 1 indicating the "call for help" status may be supplied to the speech generating device 34 to cause the speaker 36 to produce audible speech "call for help activated" or words of similar meaning, which can be heard by clinicians working on the patient. The clinicians will understand that a serious situation has arisen, and should start with taking appropriate measures immediately while waiting for expert assistance.

Once the call for help has been acknowledged or confirmed by the expert assistance, the speech generating device 34 may cause the speaker 36 to produce audible speech "help coming" or words of similar meaning, which can be heard by the clinicians working on the patient to inform them of the progress made.

In an embodiment, the system 2 may comprise a manual input device (indicated by M), such as a button (not shown) to manually generate the output signal 1 1 indicating a "call for help" status, as indicated in step 217, thereby overriding the automatic functioning of the system 2 if an expert is needed right away.

The output signal 1 1 indicating a "perform tracheotomy" status in step 224 may be supplied to the light emitting device 30 to cause the light source 32 to emit light having a third color, e.g. a red color. The light may be intermittent with an appropriate duty cycle, and/or the light may have varying intensity. At the same time, the output signal 1 1 indicating the "perform tracheotomy" status may be supplied to the speech generating device 34 to cause the speaker 36 to produce audible speech "perform tracheotomy" or "consider tracheotomy" or words of similar meaning, which can be heard by clinicians working on the patient. This should urge the clinicians to perform or consider a tracheotomy on the patient without delay or much further deliberation.

Under any of the conditions (a)-(l), the processing device 4 may cause the display device 38 to show: an Sp02 icon indicating an oxygen saturation value problem, a C02 icon indicating a carbon dioxide value problem, and a time icon indicating a time problem. If such problems are absent, then the respective icon may not be shown on the display 38. As an example, if condition (a) is met, then the Sp02 icon can be shown, possibly showing the actual oxygen saturation value. If condition (b) is met, then the C02 icon and the time icon can be shown on the display 38, where the time icon possibly shows an hourglass and the time passed. Under conditions (j)-( . ^no i^con needs to be shown.

Figure 3 shows an exploded view of a breathing mask 300, a breathing circuit 302, a breathing circuit filter 304, and a fitting 306.

The breathing mask 300 is designed to provide a non-invasive ventilation of a patient, and in use will cover the nose and mouth of the patient. The breathing mask 300 comprises a base 310 connected to a soft ring-shaped cushion 312. The base 310 is provided with a pipe 314 providing an airway to the nose and mouth of a patient when the breathing mask 300 rests on a patient's face and the cushion 312 fits tightly against the patient's face. The base 310 may be made from a rigid or flexible and elastic material, such as a plastic material. The base material may be at least partially transparent. The cushion 312 may be made from a flexible and elastic material, such as a plastic material. The cushion 312 may be filled with a gas, such as air, or a fluid or gel for the cushion 312 to be able to adapt optimally to the shape of a patient's face. The cushion material may be at least partially transparent. The breathing mask 300 may be disposable.

The breathing circuit 302 comprises an elbow-shaped tubular coupling part 320 and a tubular part 322. The breathing circuit 302 may be made from a plastic material, where the coupling part 320 and the tubular part 322 are sufficiently rigid to perform their respective functions of providing an airway.

The breathing circuit filter 304 is designed to be arranged in the airway formed by the breathing circuit 302 and the breathing mask 300, to filter the air passing in the airway.

The fitting 306 is optional, and is designed to provide an airway.

The coupling part 320 of the breathing circuit 302 may be configured to be coupled to any of the pipe 314 of the base 310 of the breathing mask 300, the breathing circuit filter 304, and to the fitting 306 in an airtight manner. Similarly, the pipe 314 of the base 310 of the breathing mask 300 may be configured to be coupled to any of the coupling part 320 of the breathing circuit 302, the breathing circuit filter 304, and the fitting 306 in an airtight manner. Similarly, the breathing circuit filter 304 may be configured to be coupled to any of the coupling part 320 of the breathing circuit 302, the pipe 314 of the base 310 of the breathing mask 300, and the fitting 306 in an airtight manner. Similarly, the fitting 306 may be configured to be coupled to any of the coupling part 320 of the breathing circuit 302, the pipe 314 of the base 310 of the breathing mask 300, and the breathing circuit filter 304 in an airtight manner.

The breathing mask 300 may be provided with a light source 32a being part of a light emitting device 30. Preferably, the light source 32a is placed on the base 310 at a location directed to the chin of a patient, so that the light source 32a is well visible for any clinician being near a body of a patient provided with the breathing mask 300. A ring-shaped light guide 33a may be provided to guide light emitted by the light source 32a to produce a ring of light visible for any clinician being near the patient provided with the breathing mask 300. Instead of guiding light through the light guide 33a, transparent material of the base 310 may guide light from the light source 32a to produce a lit base.

The light source 32a may be mounted at the outside (the side facing away from the patient's face) of the breathing mask 300 and/or at the inside (the side facing to the patient's face) of the breathing mask 300, or may be embedded in a mask wall. Other, or additional locations of the light source 32a than the location directed to the chin of the patient can be selected to improve the visibility of the light source 32a.

The breathing circuit 302 may be provided with a light source 32b being part of a light emitting device 30. Preferably, the light source 32b is placed on the coupling part 320 or the tubular part 322 at a location to be facing away from the breathing mask 300, so that the light source 32b is well visible for any clinician being near a patient having the breathing circuit 302 coupled to the breathing mask 300. An elongated light guide 33b extending in the longitudinal direction of the tubular part 322 of the breathing circuit 302 is provided to guide light emitted by the light source 32b to produce a line of light visible for any clinician being near the patient. Instead of guiding light through the light guide 33b, transparent material of the breathing circuit 302 may guide light from the light source 32b to produce a lit tube.

Alternatively or additionally, the breathing circuit filter 304 and/or the fitting 306 may be provided with a light source 32c, 32d, respectively.

The breathing mask 300 may be provided with a light blocker 500 to prevent light from any of the light sources 32a, 32b, 32c and 32d from reaching the eyes of the patient.

Any of the light sources 32a, 32b, 32c and 32d may be connected to the base 310, breathing circuit 302, breathing circuit filter 304 and fitting 306, respectively, by a sticker, such as sticker 502 shown for light source 32d. A similar arrangement of a light source and a sticker may be used to couple the light source to a part of the body of the patient, such as the forehead of the patient. Each of the light sources 32a, 32b, 32c and 32d may be connected to electrical conductors, which may be part of a cable, for powering the light sources. Other

arrangements, in which the light sources are powered by a battery or by an inductive device, e.g. from the breathing circuit filter 304, are also possible. In an embodiment, electrical conductors 510, shown in dashed lines, are provided in the breathing circuit 302 to protect them from damage, and to prevent inadvertent disconnection from the corresponding light source.

During use of the respiration monitoring system, which is described here by way of example, the patient data comprising weight, length and age are provided to the system. The light source(s) may then start to emit green light in an intermittent way to indicate that the system is functional and ready to be used for the particular patient having the patient data. If the light source is on or in the breathing mask, the breathing mask will intermittently be colored green. If incomplete patient data are provided, or if patient data excluding use of the system have been provided, the intermittent green light will not show.

When the system is ready to be used, an anesthesia or intubation procedure may be started. If the patient, during use of the respiration monitoring system, does not need use of the breathing mask, the mask may be removed from the patient and put on a support. This support preferably is located within the field of vision of the clinician. The breathing mask and the support interact to activate the processing steps as indicated in steps 201 and following according to Figure 2. For this purpose, the mask may comprise a switch such as a reed contact, for example.

Then, the breathing mask shows a constant green color, indicating that the respiration monitoring system has been activated. This indication may be supplemented by an audible speech signal output confirming "system activated".

Depending on the C02 signal and the Sp02 signal over time, the color of the breathing mask may remain the same, or change to indicate a change in the output signal of the respiration monitoring system indicating a particular respiration status. The clinician will notice the color change of the breathing mask easily, since it is in his or her field of vision. Corresponding audible speech signals and indications on a visual display further support the decision taking process of the clinician.

As explained above, in a system and method of monitoring a respiration of a patient, an Sp02 signal and a C02 signal are provided and processed to establish an output signal indicating a respiration status, being one of a "call for help" status, a "perform tracheotomy" status and a "normal situation" status, depending on conditions determined from the Sp02 signal and the C02 signal over time, weight data, length data and age data of the patient.

It is noted that the term 'patient' used throughout this specification may refer to a human patient or to an animal patient. As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting, but rather, to provide an understandable description of the invention.

The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language, not excluding other elements or steps). Any reference signs in the claims should not be construed as limiting the scope of the claims or the invention.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The term coupled, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically.

A single processing unit or other unit may fulfil the functions of several items recited in the claims.

The term computer program is defined as a sequence of instructions designed for execution on a computer system (processing device). A program, computer program, or software application may include a subroutine, a function, a procedure, an object method, an object implementation, an executable application, an applet, a servlet, a source code, an object code, a shared library/dynamic load library and/or other sequence of instructions designed for execution on a computer system.

A computer program may be stored and/or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

Claims

WO 2014/126457 " 1 ° " PCT/NL2013/050094 CLAIMS

1. A respiration monitoring system for monitoring a respiration of a patient, comprising: signal inputs for receiving input signals, the signal inputs comprising:

an output for providing an output signal based on the processing,

wherein the processing device is configured to establish the output signal to indicate a respiration status, being one of a "call for help" status, a "perform tracheotomy" status, and a "normal situation" status,

wherein the output signal indicates the "call for help" status under at least one of the conditions (a) - (f):

(f) no C02 signal representing two consecutive capnograms of at least 18 - 22 mm Hg, in particular 20 mm Hg, during the predetermined time period, and

wherein the output signal indicates the "perform tracheotomy" status under at least one of the conditions (g) - (i):

(g) an oxygen saturation value less than 76 - 84%, in particular 80%, during at least 2.5 - 3.5 minutes, in particular 3 minutes, and no C02 signal representing a capnogram for 4 - 6 minutes, in particular 5 minutes;

(h) a decrease of the oxygen saturation value of more than 27 - 33 %, in particular 30%, in 1.5 - 2.5 minutes, in particular 2 minutes, not followed by an increase of the oxygen saturation value to above 81-89%, in particular 85%, within 0.5 - 1.5 minutes, in particular 1 minute; (i) an oxygen saturation value less than 66 - 74%, in particular 70%, not followed by an increase of the oxygen saturation value to above 86 - 94%, in particular 90%, within 1 minute, and no C02 signal representing a capnogram, and

wherein the output signal indicates the "normal situation" status under at least one of the conditions (j) - (I):

(j) none of the conditions (a) - (i) have occurred;

2. The respiration monitoring system of claim 1 , wherein the predetermined time period is between 0.5 minute and 1.5 minutes, in particular about 1 minute.

3. The respiration monitoring system of claim 1 or 2, further comprising a light emitting device for receiving the output signal, the light emitting device comprising a light source configured to emit light of different colors, each different color corresponding to a different status of the output signal.

4. The respiration monitoring system of claim 3, wherein the light emitting device is configured to emit green light, if the output signal indicates a "normal situation" status.

5. The respiration monitoring system of claim 3, wherein the light emitting device is configured to emit blue light, if the output signal indicates a "call for help" status.

6. The respiration monitoring system of claim 3, wherein the light emitting device is configured to emit red light, if the output signal indicates a "perform tracheotomy" status.

7. The respiration monitoring system of any of the preceding claims, comprising a battery, in particular a rechargeable battery for supplying power to the system.

8. The respiration monitoring system of any of the preceding claims, comprising an inductor for wirelessly receiving power for supplying power to the system.

9. The respiration monitoring system of any of the preceding claims, comprising a receiver for wirelessly receiving the Sp02 signal and/or the C02 signal.

10. The respiration monitoring system of any of the preceding claims, comprising an on/off switch to switch the respiration monitoring system on and off.

1 1. The respiration monitoring system of claim 10, wherein the on/off switch comprises a reed contact.

12. The respiration monitoring system of claim 10, wherein the on/off switch comprises a temperature sensor, and wherein the on/off switch is configured to switch on when the temperature sensor senses a temperature above a threshold temperature, and wherein the on/off switch is configured to switch off when the temperature sensor senses a temperature below a threshold temperature,

13. The respiration monitoring system of claim 10, wherein the on/off switch comprises a motion sensor, and wherein the on/off switch is configured to switch on when the motion sensor senses a motion, and wherein the on/off switch is configured to switch off when the motion sensor senses no motion.

14. The respiration monitoring system of claim 10, wherein the on/off switch comprises a pressure sensor, and wherein the on/off switch is configured to switch on when the pressure sensor senses a pressure above a threshold pressure, and wherein the on/off switch is configured to switch off when the pressure sensor senses a pressure below a threshold pressure.

15. The respiration monitoring system of any of claims 3-14, wherein the light source of the light emitting device is configured to be coupled to a part of the body of the patient.

16. The respiration monitoring system of any of claims 3-14, wherein the light source of the light emitting device is coupled to, or configured to be coupled to a breathing mask for the light source to be visible from the outside of the breathing mask.

17. The respiration monitoring system of claim 16, wherein the light source is arranged at inside of the breathing mask, and wherein the breathing mask is made of a transparent material.

18. The respiration monitoring system of claim 16 or 17, wherein the light emitting device comprises a sticker for adhering the light source to the breathing mask.

19. The respiration monitoring system of any of claims 16-18, wherein the breathing mask comprises a light guide extending on or in the breathing mask, the light guide being configured for guiding light radiated from the light source.

20. The respiration monitoring system of any of claims 16-19, wherein the breathing mask comprises a light blocker configured to prevent light from the light source from reaching the eyes of the patient.

21. The respiration monitoring system of any of claims 3-14, wherein the light source of the light emitting device is coupled to, or configured to be coupled to a breathing circuit for the light source to be visible from the outside of the breathing circuit.

22. The respiration monitoring system of claim 21 , wherein the light source is arranged at inside of the breathing circuit, and wherein the breathing circuit is made of a transparent material.

23. The respiration monitoring system of claim 21 or 22, wherein the light emitting device comprises a sticker for adhering the light source to the breathing circuit.

24. The respiration monitoring system of any of claims 21-23, wherein the breathing circuit comprises a light guide extending on or in the breathing circuit, the light guide being configured for guiding light radiated from the light source.

25. The respiration monitoring system of any of claims 21-24, wherein the breathing circuit comprises a cable for supplying power and/or the input signals.

26. The respiration monitoring system of any of claims 3-25, wherein the light source of the light emitting device is configured to be coupled to a breathing circuit filter for the light source to be visible from the outside of the breathing circuit filter.

27. The respiration monitoring system of claim 26, wherein the light source is arranged on a fitting configured to be fitted between the breathing circuit filter and a breathing mask.

28. The respiration monitoring system of claim 26 or 27, wherein the light emitting device comprises a sticker for adhering the light source to the breathing circuit filter.

29. The respiration monitoring system of any of the preceding claims, further comprising a communication device configured to receive the output signal, and to send an alert message to at least one receiver, if the output signal indicates a "call for help" status.

30. The respiration monitoring system of any of the preceding claims, further comprising a speech generating device configured to receive the output signal and to produce different audible speech, each different audible speech corresponding to a different status of the output signal.

31. The respiration monitoring system of claim 30, wherein the speech generating device is configured to produce audible speech "call for help activated" or words of similar meaning, if the output signal indicates a "call for help" status.

32. The respiration monitoring system of claim 30, wherein the speech generating device is configured to produce audible speech "perform tracheotomy" or "consider tracheotomy" or words of similar meaning, if the output signal indicates a "perform tracheotomy" status.

33. The respiration monitoring system of any of the preceding claims, the signal inputs further comprising:

a patient data input for receiving a patient data signal including a weight value and a length value of the patient,

wherein the processing device further is configured to:

calculate a body mass index, BMI, from the weight value and the length value; compare the BMI with a BMI threshold value; and

select the predetermined time period to be less than 0.5 minute, in particular 0 minute, if the BMI exceeds the BMI threshold value.

34. The respiration monitoring system of claim 33, wherein the BMI threshold value is greater than 28, in particular 30.

35. The respiration monitoring system of any of the preceding claims, the signal inputs further comprising:

a patient data input for receiving a patient data signal including an age value of the patient;

wherein the processing device further is configured to:

compare the age value with an age threshold value; and WO 2014/126457 ^{" u "} PCT/NL2013/050094 select the predetermined time period to be less than 0.5 minute, in particular 0 minute, if the age value exceeds the age threshold value.

36. The respiration monitoring system of claim 35, wherein the age threshold value is greater than 66, in particular 70.

37. A method of monitoring a respiration of a patient, comprising:

processing the Sp02 signal and the C02 signal;

(j) none of the conditions (a) - (i) have occurred;

38. The respiration monitoring method of claim 37, wherein the predetermined time period is between 0.5 minute and 1.5 minutes, in particular about 1 minute.

39. The respiration monitoring method of claim 37 or 38, further comprising generating light of different colors, each different color corresponding to a different status of the output signal.

40. The respiration monitoring method of claim 39, comprising generating light having colors green, blue and red, and corresponding to the "call for help" status, the "perform tracheotomy" status, or the "normal situation" status, respectively.

41. The respiration monitoring method of any of claims 37-39, further comprising generating audible speech, in particular "call for help activated" or words of similar meaning, and

"perform tracheotomy" or "consider tracheotomy" or words of similar meaning, based on the "call for help" status, or the "perform tracheotomy" status, respectively, of the output signal.

42. The respiration monitoring method of any of claims 37-41 , further comprising:

providing a patient data signal, the patient data signal including a weight value and a length value of the patient,

wherein the step of processing further comprises:

calculating a body mass index, BMI, from the weight value and the length value;

comparing the BMI with a BMI threshold value; and

select the predetermined time period to be less than 0.5 minute, in particular 0 minute, if the BMI exceeds the BMI threshold value

43. The respiration monitoring method of claim 42, wherein the BMI threshold value is greater than 28, in particular 30.

44. The respiration monitoring method of any of claims 37-43, further comprising:

providing a patient data signal, the patient data signal including an age value of the patient,

wherein the step of processing further comprises:

comparing the age value with an age threshold value; and

selecting the predetermined time period to be less than 0.5 minute, in particular 0 minute, if the age value exceeds the age value threshold value.

45. The respiration monitoring method of claim 44, wherein the age threshold value is greater than 66, in particular 70.

46. A breathing mask for use in the system of any of claims 16-20.

47. A breathing circuit for use in the system of any of claims 21-25.

48. A breathing circuit filter for use in the system of any of claims 26-28.

49. A computer program comprising computer instructions for causing the processing device of claim 1 , 33 or 35 to establish the output signal, or for causing a processing device to perform the processing of claim 37 to establish the output signal.