RU2255723C2 - Method for carrying out prolonged artificial pulmonary ventilation - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: method involves setting respirator operation parameter values taking into account height h, age a and patient body mass m; proper value of thoracic pulmonary extensibility C_prop is determined with patient body mass taken into account. Positive pressure at the end of expiration as forced ventilation characteristic with thoracic pulmonary extensibility taken into account. Then, forced volume-controlled artificial pulmonary ventilation is carried out. Breathing frequency and inhaled volume are adjusted to achieve normal lung ventilation followed by auxiliary lung ventilation.

EFFECT: reduced negative influence upon lungs, systemic and cerebral hemodynamic characteristics; retained pulmonary gas exchange.

4 cl, 3 dwg

Description

The method relates to medicine and can be used in resuscitation in the treatment of patients with acute respiratory failure, requiring long-term mechanical ventilation (IVL).

Currently, the most common method of long-term mechanical ventilation is ventilation by injection. Blowing devices are highly reliable, simple and convenient to use, equipped with microprocessors. The medical industry produces a huge number of diverse respiratory respirators. The ventilation of the lungs with modern respiratory respirators is usually set by setting 7-10 parameters. The selection of some of them (minute volume of ventilation (MOB), tidal volume (BEF), respiratory rate (BH)) is described in detail in the literature. The choice of other parameters (speed and shape of the inspiratory flow (F), inspiratory to expiratory ratio, inspiratory pause duration (T _plateau ), positive end-expiratory pressure (PEEP), inspiratory pressure in a pressure-controlled mode (P _PC ), pressure support (P _PS )) in modern literature is consecrated extremely insufficient. Currently, doctors do not have the technology to comprehensively configure all the parameters of modern ventilation. The current situation has led to the fact that the capabilities of modern respirators are not fully utilized.

At the same time, the right choice of respiratory support parameters largely determines its effectiveness and results. Mechanical ventilation is designed not only to normalize gas exchange in the lungs, but, being a rather crude intervention in the regulation mechanisms of vital processes, it should damage them as little as possible. The same, although to a lesser extent, relates to assisted ventilation [Kassil V.L., Leskin G.S., Vyzhigina M.A. Respiratory support. - M., 1997. - P.195].

In this regard, it is necessary to refine the methods of forced and auxiliary ventilation of the lungs in order to reduce their negative impact on the patient.

2 main methods of mechanical ventilation are used by automatic respiratory respirators: ventilation, controlled (adjustable) in volume, and ventilation, controlled (adjustable) in pressure.

Both ventilation methods have pros and cons compared to each other. The main advantage of volume-controlled ventilation is the respiratory volume stability guaranteed by the settings of the respirator. With the volumetric method of artificial respiration, the stability of the minute ventilation volume is easier to achieve than with pressure-controlled ventilation. This statement is true both for forced ventilation of the lungs, and for auxiliary. With the volumetric method of ventilation, ventilation disorders such as hyperventilation, hypoventilation, and volume trauma are less likely to occur.

However, ventilation in volumetric mode does not limit airway pressure; in this connection, there is a possibility of its uncontrolled growth up to the development of lung barotrauma.

In contrast, pressure-controlled lung ventilation limits the airway pressure to the set inspiratory pressure or support pressure. In this regard, the main advantage of pressure-controlled lung ventilation over volume ventilation is a lower risk of lung barotrauma. In addition, the limitation of pressure on inspiration helps to reduce the incidence of negative hemodynamic reactions. Therefore, pressure-controlled ventilation is widely used both during forced and during assisted ventilation in situations where a reduction in intrathoracic pressure and prevention of barotrauma of the lungs are required (unstable hemodynamics, high intracranial pressure, acute lung damage).

At the moment, when conducting volume-controlled ventilation, the difficulties are:

1) setting the optimal inspiratory flow rate;

2) setting the optimal level of positive pressure at the end of exhalation (PEEP), which would have the maximum anti-edematous, anti -lectatic effect and at the same time would not cause baro-, volumotrauma and hemodynamic depression;

3) setting the optimal duration of the inspiratory pause;

4) setting the optimal shape of the curve of the flow rate on inspiration.

When conducting pressure-controlled ventilation, the main difficulties are:

1) setting the optimal inspiratory pressure and (or) support pressure, which would ensure normoventilation and respiratory comfort of the patient;

2) setting the optimal level of positive pressure at the end of exhalation (PEEP), which would have the maximum anti-edematous, anti -lectatic effect and at the same time would not cause baro-, volumotrauma and depression of hemodynamics.

The most common starting ventilation method is volume-controlled ventilation. This is done in order to ensure patient safety, since volume-controlled ventilation provides the patient with guaranteed minute ventilation volume, which is especially important in the near post-aggressive period (after surgery, anesthesia, resuscitation, damage to organs and systems of the body as a result of illness or injury).

The respirator is set in pressure-controlled ventilation mode against the background of a volume-controlled mechanical ventilation. In this regard, the known methods for carrying out mechanical ventilation always contain a description of the settings of the respirator in a volume-controlled mode, and not always in a pressure-controlled mode.

A known method of calculating the parameters of mechanical ventilation [Kassil V.L., Leskin G.S., Vyzhigina M.A. Respiratory support. - M. - 1997. - S.195-204], according to which:

a) the patient is weighed, calculate the tidal volume (TO) according to the formulas:

b) add the found value of DO and the standard value of the respiratory rate (8-14 per min) in the respirator settings menu;

C) by changing the respiratory rate, choose the minute volume of ventilation (MOB), providing respiratory comfort for the patient;

g) calculate the gas flow on inspiration (F, l / min) according to the formula:

e) changing the duration of the inspiratory pause and the shape of the inspiration curve, choose the ratio of inspiration to expiration (I / E), at which PaO ₂ / FiO _{2 is} maximum;

f) establish the minimum oxygen fraction in the respirable mixture (FiO ₂ ), providing RaO ₂ more than 100 mm Hg, SaO ₂ - 95-96%.

The method has disadvantages:

1) does not take into account the growth, due and overweight of the patient, age, in connection with which there is a high probability of developing barotrauma and volumotrauma in patients with overweight and in the elderly;

2) the level of average pressure in the patient’s airways is not taken into account, which can lead to its excessive uncontrolled growth;

3) the extensibility of the lungs and chest is not taken into account, which can lead to an increase in average airway pressure and maximum inspiratory pressure;

4) the definition of PaO ₂ and SaO ₂ is used as an oxygenation criterion — invasive and expensive procedures that do not provide real-time information (on line); they cannot be repeated as often as necessary;

5) pulse oximetry data (determination of SpO ₂ ) as a criterion of oxygenation are not taken into account;

6) capnography data are not taken into account as a criterion for the adequacy of ventilation;

7) the calculated values of the inspiratory flow rate (F) for patients with high extensibility of the lungs are underestimated, and for patients with low extensibility - overestimated;

8) there is no methodology for calculating inspiratory pressure in a pressure-controlled mode (P _PC );

9) there is no methodology for calculating the value of positive pressure at the end of expiration (PDKV).

Closest to the claimed is a method for determining the parameters of mechanical ventilation [Marino P. Intensive care. - M. - 1998. - S.348-350], according to which:

a) the patient is weighed, calculate the tidal volume (TO) according to the formulas:

b) calculate the minute volume of ventilation according to the formula:

c) calculate the respiratory rate according to the formula:

d) set the calculated parameters in the respirator settings menu, conduct a volume-controlled mechanical ventilation.

e) with the help of a gas analyzer, capnograph, pulse oximeter, oxygraph, BH and DO are adjusted to achieve normoventilation and normoxemia.

e) when switching to assisted ventilation (VVL), the level of inspiratory pressure (support pressure, P _PS ) is found at which the inspiratory support pressure is determined by dividing the maximum airway pressure of the patient by inspiration (P _mvd ) by three. This method assumes that the patient is not able to maintain pressure three times higher than P _mvd without fatigue.

g) find the optimal positive pressure at the end of expiration (PEEP) by measuring the extensibility of the lungs and oxygen delivery. These indicators are measured at various empirically selected PEEP levels. This method of selecting PDKV is called "PDKV titration". The optimal level of PEEP is considered optimal at which lung extensibility and oxygen delivery are maximal.

The method has disadvantages

1. When calculating the tidal volume, the height, due and overweight of the patient, age are not taken into account, which is why there is a high probability of developing barotrauma and volumotrauma in patients with overweight and in the elderly.

2. The extensibility of the lungs and chest is not taken into account, which can lead to an increase in average airway pressure and maximum inspiratory pressure,

3. The method for determining the level of inspiratory pressure (P _PS ) is intended only for intermittent or auxiliary ventilation and cannot be used for forced ventilation.

4. When calculating the inspiratory support pressure (P _PS ) by this method, low values of P _PS - 5-10 cm water column are obtained. - often insufficient to achieve the required tidal volume, especially in patients with restrictive disorders.

5. To calculate the optimal PEEP for oxygen delivery dynamics, it is necessary to have information on the oxygen content in arterial blood and cardiac output. Information on the latter can be obtained far from every intensive care intensive care unit in Russia.

6. The method allows to determine the optimal PEEP only at the time of measurement. However, the established optimal PEEP allows you to increase the extensibility of the lungs during the first breaths after installation. Then the optimal PEEP may become non-optimal (excess) when the lungs begin to bloat excessively. In this case, the risk of baro- and volumotrauma increases. Thus, the optimal PEEP is optimal only for a limited period of time until the mechanical properties of the lungs undergo significant changes.

We believe that the PDKV selection method, aimed at increasing lung extensibility and oxygen delivery, is advisable to combine with other methods of lung stretching and oxygen delivery, which can reduce PDKV during mechanical ventilation (kinetic therapy, nitric oxide inhalation, ventilation with helium). In this case, the risk of developing unwanted effects of PDKV is reduced.

7. The “titration” selection method for PEEP has been shown to patients with severe restrictive disorders (acute lung damage) and cannot be used to prevent restrictive disorders in patients without a significant reduction in lung extensibility with safe oxygen delivery. That is, the method is suitable only for the treatment of advanced stages of acute lung damage.

The objective of the present invention is to improve the quality of treatment of patients with respiratory failure by optimizing long-term artificial lung ventilation based on the anthropometric characteristics of the patient, the state of gas exchange and distensibility of the lungs - chest when changing modes of mechanical ventilation.

The problem is solved by the fact that during long-term ventilation of the patient’s lungs, the patient is weighed, respirator performance parameters are set: minute ventilation volume (MOB), tidal volume (BF), respiratory rate (BH), a forced ventilation is carried out, volume-controlled, and BH and DO are adjusted to achieve normoventilation and normoxemia, determine the positive pressure at the end of expiration (PEEP), switch to assisted ventilation. Additionally, the growth (h), age (a) of the patient are taken into account, and taking into account the data obtained, DOs are calculated by the formula:

where DO - tidal volume, ml,

m _must - due body weight of the patient, kg,

m _huts - excess body weight of the patient, kg;

calculate the initial minute volume of ventilation (MOB _beg ) according to the formula:

where MOV _nach - the initial minute volume of ventilation, l / min,

K is the coefficient of increase in metabolism in patients with stress: with mild stress, K is 1.2; with moderate stress - 1.4; with severe stress - 1.6; with fever, K increases by 0.1 for every degree above 37 ° C;

m _must - due body weight of the patient, kg,

m _huts - excess body weight of the patient, kg;

determine proper thoracopulmonary extensibility (C _should) by the formula:

where C _must - due thoracopulmonary extensibility, ml / cm Vogt;

m _Dolj - due weight, kg

m _huts - overweight, kg,

and - age, years.

Find the initial gas flow rate on inspiration (F _beg ) by the formula:

where F _nach - initial gas flow rate on a breath, l / min, C _should - due thoracopulmonary extensibility mL / cm of water column Establish the parameters obtained to, BH, F _beginning, MOV _{beginning of} the setting menu respirator and begin ventilator adjustable in volume, with a constant or decreasing gas flow form inspiratory selected that form a gas stream at inspiration, at which the mean airway pressure (P _media ) below, set the "auto-breathe" function.

Set the initial duration of the inspiratory pause (T _plateau ) so that the initial ratio of inspiration to expiration (I / E _beginning ) is equal to 1 / 1.5; with stable haemodynamics establish an initial positive end expiratory pressure (PEEP _nach) vod.st 5 cm, with unstable haemodynamic is set PEEP _beginning 2 cm water column

The patient is synchronized with a respirator, the actual thoracopulmonary extensibility (C) is determined, the level of positive end-expiratory pressure for forced ventilation is calculated and established (PDKV _prin ) according to the formula:

where PDKV _prin - positive pressure at the end of exhalation for forced ventilation, cm Vg.

C _should - due thoracopulmonary extensibility mL / cm of water column,

C - actual thoracopulmonary extensibility, ml / cm water Find and set the inspiratory flow rate (F) according to the formula:

where F is the inspiratory flow rate, l / min,

C _should - due thoracopulmonary extensibility mL / cm of water column,

C - actual thoracopulmonary extensibility, ml / cm water

Calculate and establish the ratio of inspiration to expiration (I / E) according to the formula:

where I / E is the ratio of inspiration to expiration,

C _should - due thoracopulmonary extensibility mL / cm of water column

In the process of forced mechanical ventilation, adjustable in volume, C is determined at least 1 time in 12 hours and when C is changed, PEEP and F are corrected, T _{plateau is} adjusted to achieve patient respiratory comfort.

Go to pressure-controlled forced ventilation, for which the initial inspiratory pressure for pressure-controlled forced ventilation (P _RSnach ) is calculated and set, according to the formula:

where R _RSnach - the initial inspiratory pressure in the forced ventilation mode, regulated by pressure,

DO - tidal volume, ml,

C - actual thoracopulmonary extensibility, ml / cm water

Set the ratio of inspiratory to expiratory equal to the calculated.

P _RSnach adjusted to achieve a tidal volume mode, the regulated pressure (DL _RS), 10% more to give P _RS.

In the process of forced pressure-controlled mechanical ventilation, C is determined at each change in the patient’s body position at least 1 time in 8 hours, and when C is changed, PEEP values _are adjusted, and P _RS , the ratio of inspiration to expiration (I / E) is adjusted to achieve respiratory comfort the patient.

Switch from forced ventilation to the mode of assisted ventilation, calculate and install PEEP for assisted ventilation (PEEP _assist ) according to the formula:

where PEEP _recall - positive pressure at the end of exhalation for assisted ventilation, cm water column,

C _should - due thoracopulmonary extensibility mL / cm of water column,

C is the actual thoracopulmonary extensibility, ml / cm water column;

Sens - sensitivity of the trigger of the respirator, cm water; calculate and set the initial support pressure (P _PSnach ) for auxiliary ventilation, pressure-controlled, according to the formula:

where P _PSnach - initial support pressure in the mode of assisted ventilation, pressure-controlled,

DO - tidal volume, ml,

C - actual thoracopulmonary extensibility, ml / cm water

P _{PS is started.} To achieve tidal volume in pressure-controlled auxiliary mode ( _PS ), 10% more BP and P _{PS is} obtained, inspiratory to expiratory ratio (I / E) is adjusted to achieve patient respiratory comfort.

During auxiliary ventilator regulated pressure is determined at each change of body position of the patient at least 1 per 8 hours, and a change is corrected C _aux PEEP and P _PS.

Installation oxygen fraction delivered to the respirator breathing circuit (FiO _2), produced under the control of the data pulse oximetry or blood gas analysis to achieve 94-100% SpO _2, PaO ₂ 75-200 mm Hg, the change by changing the MOB _nach produce BH under the control of capnography data to achieve EtCO ₂ from 32 to 45 mm Hg, MOB is obtained.

Determine the type of the patient's constitution, finding a proper body weight (m _should) by the formula:

wherein m _Dolj - due weight, kg

h - height, m

type of constitution: asthenic - 1, normosthenic - 2, hypersthenic - 3.

At the age of the patient (a) 30 years or younger with _{should be} determined by the formula:

where C _should - calculated thoracopulmonary extensibility mL / cm of water column,

m _Dolj - due weight, kg

m _huts - overweight, kg

SUBSTANTIATION OF THE METHOD, NOVELTY OF THE METHOD

The inventive method is based on taking into account the extensibility of the lungs - chest and on the principle of minimizing the average pressure in the airways, the use of which allows to reduce the negative impact of mechanical ventilation by blowing on the lungs, systemic and cerebral hemodynamics while maintaining adequate pulmonary gas exchange and respiratory comfort.

In the vast majority of cases, an indication for prolonged mechanical ventilation is a violation of ventilation-perfusion relationships and a decrease in lung extensibility due to the development of acute lung damage (ARP), which is based on uneven interstitial pulmonary edema. The use of mechanical ventilation by the method of injection in case of acute respiratory infections is pathogenetically justified, since the positive inside chest pressure exerts an anti-edematous effect on lung tissue. To enhance this effect, create a positive pressure at the end of exhalation (PEEP), invert inspiration to expiration, and the more pronounced pulmonary edema and restriction, the greater the values of PEEP and a greater inversion of inspiration have to be applied. It is noted that with an increase in PEEP and lengthening of inspiration, the anti-edema effect of mechanical ventilation on the lungs is improved, proportional to the average intrathoracic pressure. In conditions of mechanical ventilation in patients with ARP, arterial blood oxygenation directly depends on the generated average pressure in the alveoli. The equivalent of mean pressure in the alveoli is the average airway pressure measured in the trachea (P _cf. P, P _media ). Moreover, the more pronounced restriction of the lungs, the greater the values of P _{cf. mp} (P _media ) are needed. [Vlasenko A.V., Neverin V.K. Optimization of parameters of mechanical ventilation of the lungs with controlled volume in patients with acute bilateral and unilateral parenchymal lung injury // Manual for doctors. - M. - 2002. - 48 p.].

Based on the foregoing, we can conclude: the value of the average airway pressure is a valuable diagnostic indicator, the measurement of which during mechanical ventilation in patients with TBI makes it possible to select the optimal ventilation mode in order to stop interstitial pulmonary edema, increase arterial blood oxygenation, and prevent ventilation-dependent intracranial elevation pressure.

It is known that in case of restrictive disorders in the lungs, the anti-edematous and anti -lectatic effects of ventilation by the method of blowing, non-pulmonary tissue is generated by medium pressure in the alveoli.

It follows that when setting the ventilation mode, the value of P _avtr created by the respirator should be directly proportional to the degree of restriction. In turn, P _cf. depends on the characteristics of the ventilation mode: tidal volume, respiratory rate, inspiratory flow, inspiratory duration, expiratory flow, level of positive pressure at the end of expiration (PDKV), inspiratory inspiratory pressure in a pressure-controlled mode . Therefore, in order for the listed parameters of mechanical ventilation to provide P _cf. adequate to restriction, they should also be proportional to thoracopulmonary extensibility.

Thus, taking into account lung and chest extensibility allows a differentiated approach to the ventilation of patients with and without restrictive (decreased extensibility) disorders. Therefore, we included the indicator of thoracopulmonary extensibility in the formulas for calculating the inspiratory flow rate, PEEP, inspiratory pressure in a pressure-controlled mode, and support pressure.

Elongation of the lungs (compliance, compliance) is one of the main most informative criteria for acute lung damage. In practical activities, it is more accessible to determine the general lung compliance - the chest, which has age-related changes. The extensibility of the lungs - chest in the majority of people begins to decline from the age of 30 years [Shik L.L., Kanaev N.N. Guide to the clinical physiology of respiration. - M., 1980 .-- 376 p .; Physiological basis of human health. Ed. B.I. Tkachenko. - St. Petersburg. - Arkhangelsk - 2001. - P.291-328].

The principle of minimizing the negative effect of mechanical ventilation on hemodynamics is achieved by lowering the average airway pressure (P _media ). The smallest P _environments occurs during full inhalation (when the breath ended at the beginning of the exhalation) and expiration (when the exhalation ended at the beginning of the inhalation). This can be achieved by the right choice: a) the gas flow rate on the inspiration and the shape of its curve, b) the tidal volume, c) the respiratory rate, d) the ratio of inspiration to expiration.

The described method for calculating the parameters of long-term mechanical ventilation in order to optimize it is most appropriate to use during the mechanical ventilation with modern microprocessor-based servoventilators (servorespirators), since they provide the ability to control all the parameters mentioned in the method: tidal volume, respiratory rate, inspiratory flow, inspiration duration, expiratory time , the level of positive pressure at the end of expiration (PEEP), the magnitude of inspiratory pressure on inspiration in a pressure-controlled mode, the shape of the sweat curve and on inspiration. It is preferable to use a decelerating (lowering) form of the inspiratory flow curve, since minimization of the average airway pressure during the decelerating inspiratory flow curve is achieved while maintaining a more physiological ratio of inspiration to expiration. It is also permissible to use a constant or sinusoidal shape of the flow curves on inspiration. The accelerating (rising) form of inspiration is not used with this method.

The novelty of the method lies in the fact that when determining MOB, DO, BH, C, the _calculation takes into account height, age, type of human constitution.

This allows you to calculate the ventilation parameters taking into account the mechanical properties of the respiratory system associated with morphological and age-related changes, and reduce airway pressure during mechanical ventilation, thereby reducing the negative effects of ventilation by injection on hemodynamics, to achieve its stability.

Formulas are proposed that allow one to obtain MOB, DO, BH, R _PC and PDKV data for forced ventilation, P _PS and PDKV for auxiliary ventilation taking into account age, height, type of constitution and mass. After synchronizing the patient with the respirator, methods for adjusting P _PC and P _PS to achieve the calculated DO, inspiratory to expiratory ratio (I / E) to achieve respiratory comfort, BH and DO using capnography to achieve EtCO ₂ 30-40 mm Hg are proposed. , FiO ₂ according to pulse oximetry to achieve SpO ₂ 94-100%.

This allows you to achieve normoventilation or moderate hyperventilation, normoxemia, respiratory comfort, to avoid an increase in airway pressure and complications such as barotrauma and volumotrauma of the lungs, restrictive disorders. Capnography and pulse oximetry provide real-time gas exchange information.

Determination of lung extensibility at least 1 time in 8 hours with subsequent correction of PDKV and F allows timely elimination of inferiority of inspiration and exhalation. As a result, the method allows ventilation of the lungs with the most physiological inspiratory to expiratory ratios (from 1: 1 to 1: 3), with the most physiological forms of the inspiration curve (decreasing, constant), with the failure, if possible, of a long inspiratory pause (more than 0, 4 sec for a decreasing form of flow on inhalation, more than 0.8 sec for a constant form of flow on inspiration) and from high values of positive pressure of the end of exhalation (PDKV, more than 10 cm water column).

The combination of essential signs of “sparing mechanical ventilation” prevents auto-PDKV and reduces the negative effect of mechanical ventilation on hemodynamics while maintaining adequate pulmonary gas exchange and respiratory comfort.

Thus, the method is intended to optimize the traditional long-term mechanical ventilation, in which the ventilation mode is changed, with the aim of ensuring adequate ventilation of the lungs at all stages of the forced and auxiliary mechanical ventilation. All 4 criteria for the adequacy of mechanical ventilation (IVL) are achieved:

- compliance of gas exchange with the metabolic needs of the patient (lack of oxygen debt, normoventilation), which is achieved by taking into account the data of pulse oximetry, capnography, and the study of the acid-base state of the blood (KHS);

- stability of systemic and organ hemodynamics (the absence of a negative effect of mechanical ventilation on the work of the heart, brain), which is achieved through the use of the principle of minimizing the average pressure in the airways;

- compliance of ventilation with the mechanical properties of the lungs - chest (absence of baro-, volumotrauma), which is achieved by taking into account thoracopulmonary extensibility (C);

- respiratory comfort of the patient (lack of dyspnea, the presence of synchronization of the patient with a respirator), the achievement of which is a prerequisite for the correction of mechanical ventilation, especially during assisted ventilation.

The method is carried out by modern servo-fans in intensive care units and intensive care units in patients with intact gas transport function of blood (absence of hemic hypoxia). The method is effective against the background of regular patient positioning (changes in body position, kinetic therapy) and rehabilitation of the tracheobronchial tree.

The method is carried out as follows.

Before starting mechanical ventilation, the patient’s mass is determined (m, kg), his height (h, cm) is measured, and his age (a, years) is recorded.

Finding the proper (m _should kg) and excess mass (m _huts kg) by the formulas:

wherein m _Dolj - proper patient weight, kg

m _huts - excess body weight of the patient, kg;

m - actual patient weight, kg

type of constitution: asthenic - 1, normosthenic - 2, hypersthenic - 3,

h - height, m

If the patient does not have excess weight (m _log ≤ 0), then the amount of excess weight is taken as zero:

m _huts = 0.

Determine the initial minute volume of ventilation (DOM _beg , ml / min) according to the formula:

where MOV _nach - the initial minute volume of ventilation, l / min,

K is the coefficient of increase in metabolism in patients with stress: with mild stress, K is 1.2; with moderate stress - 1.4; with severe stress - 1.6; with fever, K increases by 0.1 for every degree above 37 ° C.

If there is no stress, then the coefficient of increase in metabolism is 1 (K = 1). If no excess weight, the MOB = K × m × 100 _Dolj.

Find the tidal volume (DO, ml)

DO = m _must × 7 + m _log × 3.

Find respiratory rate (BH, 1 / min)

BH = MOV _beginning / TO.

Determine calculated thoracopulmonary extensibility (C _should) according to the formulas

для пациентов старше 30 лет с избытком массы (а>30, m_изб≥ 0).

for patients over 30 years old with excess weight (a> 30, m _log ≥ 0).

With _must = m _must -m _huts / 3, for patients 30 years of age and younger with excess weight (a ≤ 30, m _huts ≥ 0),

C _{should Dolj} = m - (A-30) / 3, for patients older than 30 years without excess weight (a> 30, m _huts <0)

With _must = m _must , for patients 30 years of age and younger without excess weight (a ≤ 30, m _huts <0),

where C _should - estimated lung compliance - chest ml / cm vod.st;

m _Dolj - due weight, kg

m _huts - overweight, kg,

and - age, years.

Find the initial gas flow rate on inspiration (F _beg , l / min) according to the formula

The received data DO, BH, F _beg , MOB _beg enter in the settings menu of the respirator. Prior to connecting the patient to the respirator, a forced volume-controlled ventilator (VCV in IPPV, CMV mode) is started, with a constant or decreasing form of gas flow during inspiration, at which the average airway pressure (P _medium ) is lower. Connect the function "automatic sigh". Set the duration of the inspiratory pause (plateau) so that the initial ratio of inspiration to expiration (I / E _beginning ) is 1 / 1.5.

It is advisable to do all of the above calculations and settings of the respirator before the patient enters the intensive care unit - while he is in the operating room or in the emergency room (in the sanitary inspection room). To perform calculations and adjust the ventilation mode, the anesthetist taking the patient must inform the resuscitator in advance of the height, weight, age and type of patient constitution.

After setting the ventilation mode, the patient is connected to the respirator.

Hereinafter, at all stages of mechanical ventilation, the oxygen fraction supplied by the respirator to the respiratory circuit (FiO ₂ ) is set under the control of the data of a pulse oximeter or gas analyzer to achieve SpO ₂ 94-100%, PaO ₂ 75-200 mm Hg. Are corrected by changing the MOB _nach BH to achieve EtCO ₂ or PaCO ₂ from 32 to 45 mm Hg according to a capnograph or gas analyzer, get MOB.

The patient is synchronized with a respirator (analgesia, muscle relaxation, temporary hyperventilation) to exclude spontaneous respiratory activity.

Using a respirator, spirograph or respiratory monitor determine the extensibility of the lungs-chest (thoracopulmonary extensibility, C, ml / cm Wg).

Calculate and establish the level of positive pressure of the end of expiration for forced ventilation (PDKV _prin ) according to the formula

where PDKV _prin - positive pressure at the end of exhalation for forced ventilation, cm Vg.

C _should - due thoracopulmonary extensibility mL / cm of water column,

C - actual thoracopulmonary extensibility, ml / cm water;

Find and set the inspiratory flow rate using the formula

where F is the inspiratory flow rate, l / min,

C _should - due thoracopulmonary extensibility mL / cm of water column,

C - actual thoracopulmonary extensibility, ml / cm water Calculate and establish the ratio of inspiration to expiration (I / E) by the formula

where I / E is the ratio of inspiration to expiration,

C _should - due thoracopulmonary extensibility mL / cm of water column,

C - actual thoracopulmonary extensibility, ml / cm water Set the length of the inspiratory pause (T _plateau ) so that the ratio of inspiration to expiration corresponds to the calculated I / E.

If the respirator allows for forced pressure-controlled ventilation and there are clinical indications for it, then go to a pressure-controlled ventilation, for which the initial inspiratory pressure (P _PCnach ) for pressure-controlled forced ventilation is calculated and set according to the formula :

where R _PCnach - initial inspiratory pressure in the mode of forced ventilation, pressure-controlled,

DO - tidal volume, ml,

C - actual thoracopulmonary extensibility, ml / cm water Set the inspiratory to expiratory ratio equal to the calculated I / E.

Regulate P _PCinit , to achieve tidal volume in a pressure-controlled mode (DO _PC ), 10% more DO and receive P _PC .

When switching according to clinical indications from forced mechanical ventilation to the auxiliary ventilation mode, PDKV for auxiliary ventilation of the lungs is calculated and installed (PDKV _aux ) according to the formula

where PEEP _recall - positive pressure at the end of exhalation for assisted ventilation, cm water column,

C _should - due thoracopulmonary extensibility mL / cm of water column,

C is the actual thoracopulmonary extensibility, ml / cm water column;

Sens - sensitivity of the trigger of the respirator, cm water If the respirator allows pressure-controlled assisted ventilation and there are clinical indications for it, then the initial support pressure (P _PSnach ) is calculated and set. For pressure-assisted lung ventilation, according to the formula

where P _PSnach - initial support pressure in the mode of assisted ventilation, pressure-controlled,

DO - tidal volume, ml,

C - actual thoracopulmonary extensibility, ml / cm water

P _{PS is adjusted first} to achieve tidal volume in the auxiliary pressure-controlled mechanical ventilation (BEFORE _PS ), 10% more BEF and receive P _PS .

In the process of forced and auxiliary mechanical ventilation, controlled by pressure, C is determined at each change in the patient’s body position at least 1 time in 8 hours and when C is changed, the maximum permissible concentration of _prin and P _RS (for forced ventilation), maximum _permissible ventilation and P _PS (for auxiliary ventilation), adjust the inspiratory to expiratory ratio (I / E) to achieve respiratory comfort. Set the minimum inspiratory to expiratory ratio (I / E), which ensures the patient's respiratory comfort. In the case when respiratory comfort is not achieved (the patient is not synchronized with the respirator), other methods of synchronizing the patient with the respirator are performed (analgesic sedation, muscle relaxation, temporary hyperventilation).

If the respirator does not allow for auxiliary ventilation, regulated by pressure, or there are no clinical indications for its use, then they switch to auxiliary ventilation, adjustable in volume.

In the process of forced ventilation and an auxiliary regulated by volume, determined from 1 time to 12 hours, and when changing from _{the received} corrected PEEP, PEEP _aux and F, after which the duration of the inspiratory pause is adjusted to achieve a breathing comfort. The minimum duration of an inspiratory pause (T _plateau ) is established, at which the patient's respiratory comfort is ensured. In the case when respiratory comfort is not achieved (the patient is not synchronized with the respirator), other methods of synchronizing the patient with the respirator are performed (analgesic sedation, muscle relaxation, temporary hyperventilation).

Dynamic correction of the respirator settings is carried out against the background of regular patient positioning (changes in body position, kinetic therapy) and rehabilitation of the tracheobronchial tree.

EXAMPLE 1

Patient E., 37 years old, diagnosis: penetrating thoracoabdominal stab wound on the left, wound of the interventricular septum of the heart, not penetrating the heart cavity, through wound of the diaphragm, hemothorax on the left, traumatic shock of 3 degrees. The condition at admission is extremely serious, due to respiratory failure, traumatic shock. Severe cardiac pain syndrome. Consciousness is oppressed to moderate stunning. The skin is pale cyanotic, covered with cold sweat. Visible mucous membranes are anemic, low humidity. Independent breathing, auscultation weakened on the left in the lower parts, respiratory rate of 28 per minute. Radiographic: hemothorax on the left. Blood pressure 90/50 mm Hg, heart rate 120 beats per minute. The abdomen is painful in the epigastrium on the left. Diuresis is reduced. Conducted anti-shock measures. The patient is weighed. Body weight 88 kg. The height was determined - 185 cm. The body temperature was measured - 36.8 ° C. The type of constitution (physique) was determined - normostenic. The degree of stress was assessed - severe, since the patient was in a state of shock, there was a pain syndrome. Based on the degree of stress, the metabolic rate of increase is -1.6.

According to vital indications, an operation was performed: thoracotomy on the left, suturing of wounds of the heart and diaphragm, drainage of the pleural cavity according to Bulau on the left. Anesthesia: endotracheal anesthesia, central ketamine analgesia. Given that the patient was shown long-term mechanical ventilation, the resuscitation anesthesiologist calculated the parameters of artificial ventilation, according to which the respirators RO-6 (in the operating room) and Puritan Bennett 7200 AE (in the intensive care unit) were configured. The following calculations were performed:

_Dolj m = (22 + type constitution) × h ² = (22 + 2) × 1,85 ² = 82,14≈ 82 kg

m = mm _{gage Dolj} = 88-82 = 6 kg

MOV _nach = K × (m × _{Dolj 100-G} + m × 60) = 1,6 × (82 × 100 + 6 × 60) = 13696≈ 13700 ml / min.

To _Dolj = m × 7 + _m-G = 82 × 3 + 7 × 6 × 3 = 592≈ 590 ml.

BH = MOU _nach / ML = 13700/590 = 23,22≈ 23 min.

According to the calculated parameters, a respirator RO-6 is configured, which allows only forced ventilation, adjustable in volume, with a ratio of inspiratory to expiratory 1/2. Given the post-hypoxic state, pure oxygen was supplied to the respiratory circuit (nitrous oxide was not shown). Thus, ventilation during the operation was carried out with a respiratory volume of 590 ml with a frequency of 23 inspirations per minute, with an inspiratory to expiratory ratio of 1/2, with a supply of 100% oxygen. During the operation, during the revision of the pericardium and suturing of the heart wound, 3 consecutive cardiac arrests lasting 1 minute each occurred. During stops, direct cardiac massage was performed. Hemodynamics was stabilized against the background of the introduction of vasopressors, cardiotonics and hormones on the figures: pulse 106 per minute, blood pressure 120/70 mm Hg The total duration of hypotension is less than 70 mm Hg. amounted to 20 minutes. Subsequently, hemodynamics was maintained at normal numbers by the introduction of catecholamines. Prior to the operation, the resuscitation anaesthesiologist calculated the parameters of artificial ventilation, supplementing MOB, DO, BH, for the planned prolonged mechanical ventilation in the intensive care unit with a Puritan Vennett 7200 AE respirator. The proper thoracopulmonary extensibility (C) and inspiratory flow (F) were calculated.

Since patient E. is older than 30 years and has excess body weight (a> 30, m _log ≥ 0), the proper thoracopulmonary extensibility was calculated by the formula:

Since the true (actual) thoracopulmonary extensibility in the operating room could not be determined (there was no respiratory monitor, spirograph), we calculated the initial flow rate for inspiration by the formula:

The obtained data to, BH, F _calc, MOV _beginning made in the settings menu respirator Puritan Bennett 7200 AE. We established a constant shape of the flow curve on inspiration, turned on the “automatic breath” function (two breaths with a volume of 900 ml 12 times per hour). To achieve an inspiratory to expiratory ratio of 1 / 1.5, an inspiratory pause (plateau) of 0.4 seconds was established.

The patient was transported from the operating room to the intensive care unit, continued forced ventilation, regulated by volume, with a supply of 80% oxygen (empirically). SpO _{2 was} determined - 100%. Determined RaO ₂ - 245 mm RT.article Empirically reduced the value of FiO ₂ from 0.8 to 0.6, while SpO ₂ - 99%, RaO; - 198 mmHg

Since the synchronization of the patient with a respirator in the near postoperative period was good, no measures were taken to adapt the patient to the respirator. Thoracopulmonary extensibility was determined - 46 ml / cm of water. We calculated the inspiratory flow rate (F), the positive pressure at the end of the exhalation for forced ventilation (PDKV _prin ), and the ratio of inspiratory to expiratory (I / E). The following calculations were done:

F = (C _should + 2C) / 3 = (78 + 2 × 46) / 3 = 56,6≈ 57 l / min,

_Received PEEP = 5 (C _should -C) / C + 2 = 5 (78-46) / 46 + 2 = 5,48≈ 5,5 cm water column

I / E = (C _should + C) / 3 C = (78 + 46) / (3 × 46) = 0.89 = 1 / 1,12≈ 1 / 1.1

The inspiratory pause duration (T _plateau ) of 0.57 s was established so that the ratio of inspiratory to expiratory corresponded to the calculated one.

Indications for compulsory pressure-controlled mechanical ventilation were evaluated. Given the severity and instability of the patient’s condition, the lack of conditions for the development of pulmonary barotrauma and in order to prevent hypoventilation and hypoxemia with possible undetected progression of pulmonary edema, it was decided that there are currently no indications for switching to controlled ventilation.

Ventilation was continued in the established mode, regulated by volume, measures were taken to normalize homeostasis, lavage of the tracheobronchial tree, chest percussion massage. During this period, the patient was rotated (positioned) 8 times, 2 times after 12 hours thoracopulmonary extensibility was determined (C). To determine the actual thoracopulmonary extensibility (C), the patient was additionally synchronized with a respirator using promedol (20 mg), sibazon (10 mg). Subsequently, 10 mg morphine was used to synchronize the patient with a respirator.

During this period, thoracopulmonary extensibility has not changed significantly. The patient's condition remained extremely serious due to postresuscitative disease.

24 hours after surgery, thoracopulmonary extensibility decreased to 37 ml / cm2 of water. The conclusion was made about the increase in interstitial pulmonary edema. Given the progression of pulmonary edema, the emergence of conditions for the development of barotrauma of the lungs, put indications for the transition to forced ventilation, regulated by pressure. Calculated and installed P _PSnach , _{PDKV prin} , I / E according to the formulas:

Corrected P _PSfirst , To achieve DO _RS 10% more (DO × 1.1 = 0.59 × 1.1 = 0.65) and received P _PS = 19 cm water column

In the future, C was determined with each change in the patient’s body position 1 time in 2 hours. Thoracopulmonary extensibility (C) gradually increased. Twice, when C was _changed , P _Rachn , _{PDKV prin} , I / E were calculated and adjusted according to the above formulas. 2 days after surgery With 57 ml / cm water Calculated and installed P _Pnach , _{PDKV prin} , I / E:

Correction P _PFirstly , to achieve DO _PС 10% more (DO × 1.1 = 0.59 × 1.1 = 0.65) was not required, since at Р _РС 11 cm water column tidal volume was 0.66 liters.

When there are signs of spontaneous respiratory activity, the ratio of inspiration to expiration was adjusted - I / E was set to 1 (1 / 0.9) - the minimum value at which the patient's respiratory comfort was ensured (there was no spontaneous breathing).

They continued forced pressure-controlled ventilation, drug synchronization of the patient with a respirator, refrained from switching to auxiliary ventilation due to gross violations of neurodynamics in the brain stem structures (manifestation of posthypoxic encephalopathy).

In the future, C was determined with each change in the position of the patient's body. Thoracopulmonary extensibility gradually increased. Calculation and adjustment of P _PCnach and PDKV _prin , I / E were carried out according to the above formulas. 8 days after surgery With 70 ml / cm vod. By this time, the patient had a positive dynamics in neurological status, it was possible to transfer the patient to auxiliary breathing in SIMV mode with pressure support. The trigger sensitivity (Sens) is set to 3 cm water column.

We calculated and installed P _PSnach , P _PCnach , _{PDKV auxiliary} , I / E:

P _PSnach = 0.9 × DO / C = 0.9 × 590/70 = 7.58≈ 8 cm water column

P _PCnach = 1.1 × DO / C = 1.1 × 590/70 = 9.27≈ 9 cm water column

_Aux PEEP = 5 (C _should -C) / C + Sens + 2 = 5 (78-70) / 70 + 3 + 2 = 5,57≈ 5,6 cm water column

I / E = (C _should + C) / 3 C = (78 + 70) / (3 × 70) = 0.7 = 1 / 1,4≈ 1 / 1.4

We adjusted P _{PS first} , to achieve the DO _PS , 10% more than expected (DO × 1.1 = 0.59 × 1.1 = 0.65) and received P _PS = 7 cm water column Correction P _{PC first} , to achieve the _PC is 10% more than necessary (DO × 1.1 = 0.59 × 1.1 = 0.65 L) was not required, since at P _PC 9 cm water column tidal volume was 0.65 liters. The ratio of inspiration to expiration was adjusted - I / E was set equal to 1 / 1.2 - the minimum value at which the patient's respiratory comfort was achieved.

On the 14th day of treatment, the patient made significant progress in general condition and neurological status. Thoracopulmonary extensibility - 72 ml / cm water It was decided to transfer the patient to another regimen of assisted mechanical ventilation - spontaneous breathing under positive airway pressure with pressure support (CPAP + PS). Set the trigger sensitivity (Sens) to 1 cm water column

We calculated and set _PSnach P, P _PCnach, PEEP _Aux.

P _PSnach = 1.1 × DO / C = 1.1 × 590/72 = 7.37≈ 7 cm water column

_Aux PEEP = 5 (C _should -C) / C + Sens + 2 = 5 (78-72) / 72 + 1 + 2 = 3,42≈ 3,4 cm water column

P _{PS was} adjusted _first to achieve a _{PS of} 10% more than expected (DO × 1.1 = 0.59 × 1.1 = 0.65 L) and received P _PS = 8 cm of water.

During a prolonged mechanical ventilation in the intensive care unit, oxygen was supplied to the respiratory circuit (FiO ₂ 0.6-0.25), which ensured normal hemoglobin saturation with oxygen (SpO ₂ 94-99% according to pulse oximetry). Against the background of infusion-transfusion therapy, the hemoglobin level did not decrease below 90 g / l.

On the 22nd day after the operation, the patient was successfully transferred to spontaneous breathing and extubated. On the 23rd day he was transferred to the department of cardiovascular surgery. Outcome: improvement.

EXAMPLE 2

Patient Sh., 18 years old, diagnosis: septicopyemia, purulent epiduritis, hematogenous osteomyelitis of the right tibia, drives on the left, infiltration of the middle third of the left shoulder. The condition at admission is extremely serious, due to septic shock, respiratory failure. Consciousness is oppressed to deep stunning. Pain in the thoracic spine is expressed. The skin is pale cyanotic, warm. The right knee joint is enlarged, hyperemic, painful, its mobility is impaired. Visible mucous membranes are anemic, low humidity. Independent breathing, respiratory rate 38 per minute. Blood pressure 80/40 mm Hg, heart rate 120 beats per minute.

Diuresis is reduced. Conducted anti-shock measures. The patient is weighed. Body weight 49 kg. The height was determined - 163 cm. The body temperature was measured - 38.0 ° C. The type of constitution (physique) was determined - asthenic. The degree of stress was assessed - severe, since the patient was in a state of shock, there was a pain syndrome. Based on the degree of stress and body temperature, the metabolic rate of increase is 1.7.

According to emergency indications, an operation was performed: hemilaminectomy C ₆ , Th ₁ , Th ₃ , Th ₅ , Th ₇ , Th ₉ , Th ₁₁ , drainage of the epidural space; osteoperforation of the tibia on the right, staging of drainage, opening of the infiltrate of the middle third of the left shoulder, thoracotomy on the left, suturing of wounds of the heart and diaphragm, drainage of the pleural cavity by Bulau on the left. Anesthesia: endotracheal anesthesia, central analgesia with fentanyl and ketamine. Given that the patient was shown long-term mechanical ventilation, the resuscitation anesthesiologist calculated the parameters of artificial ventilation, according to which the respirators RO-6 (in the operating room) and Puritan Bennett 7200 AE (in the intensive care unit) were configured. The following calculations were performed:

m _must = (22+ type of constitution) × h ² = (22 + 1) × 1.63 ² = 61.1≈ 61 kg,

There is no excess mass, that is, m _huts = 0.

MOV _nach = K × (m × _{Dolj 100-G} + m × 60) = 1,7 × (61 × 100 × 60 + 0) = 10370≈ 10400 ml / min.

To _Dolj = m × 7 + _m-G = 61 × 3 + 7 × 0 = 427≈ 3 × 430 ml.

BH = MOU _nach / ML = 10400/430 = 24,19≈ 24 min.

According to the calculated parameters, the respirator RO-6 is configured. During anesthesia, pure oxygen was supplied to the respiratory circuit (nitrous oxide was not shown). Thus, ventilation during the operation was carried out with a tidal volume of 430 ml, with a frequency of 24 inspirations per minute, with an inspiratory to expiratory ratio of 1/2, with a supply of 100% oxygen. During the operation, hemodynamics was stabilized against the background of the introduction of vasopressors, cardiotonics and hormones in numbers: pulse 120 min, blood pressure 100/60 mm Hg Subsequently, hemodynamics was maintained at normal numbers by the introduction of catecholamines. Prior to the end of the operation, the resuscitation anaesthesiologist calculated the parameters of artificial ventilation, supplementing the MOV _begin , DO, BH, for the planned prolonged mechanical ventilation in the intensive care unit with a Puritan Bennett 7200 AE respirator. The proper thoracopulmonary extensibility (C) and inspiratory flow (F) were calculated.

Since patient C. is younger than 30 years old (a <30), the proper thoracopulmonary extensibility was calculated by the formula:

Since the true (actual) thoracopulmonary extensibility in the operating room could not be determined (there was no respiratory monitor, spirograph), we calculated the initial flow rate for inspiration by the formula:

The obtained data to, BH, F _calc, MOV _beginning made in the settings menu respirator Puritan Bennett 7200 AE. We established a constant shape of the flow curve on inspiration, turned on the “automatic breath” function (two breaths with a volume of 700 ml 12 times per hour). To achieve an inspiratory to expiratory ratio of 1 / 1.5, an inspiratory pause (T _plateau ) of 0.4 sec duration was established.

The patient was transported from the operating room to the intensive care unit, continued forced ventilation, regulated by volume with a supply of 80% oxygen (empirically). Spo _{2 was} determined - 100%. The PaO _{2 was} determined to be 288 mmHg. Empirically reduced the value of FiO ₂ from 0.8 to 0.5, while SpO ₂ - 100%, PaO ₂ - 203 mm Hg

Since the synchronization of the patient with a respirator in the near postoperative period was good, no measures were taken to adapt the patient to the respirator. Thoracopulmonary extensibility was determined - 35 ml / cm of water. We calculated the inspiratory flow rate (F), the positive pressure at the end of the exhalation for forced ventilation (PDKV _prin ), and the ratio of inspiratory to expiratory (I / E). The following calculations were done:

F = (C _should + 2C) / 3 = (61 + 2 × 35) / 3 = 43,7≈ 44 l / min,

_Received PEEP = 5 (C _should -C) / C + 2 = 5 (61-35) / 35 + 2 = 5,71≈ 5,7 cm water column

I / E = (C _should + C) / 3 C = (61 + 35) / 3 = 0.91 × 35 = 1 / 1,09≈ 1 / 1.1

The duration of the inspiratory pause (T _plateau ) was set to 0.6 s, so that the ratio of inspiration to expiration corresponded to the calculated one.

Indications for compulsory pressure-controlled mechanical ventilation were evaluated. Given the severity and instability of the patient’s condition, the lack of conditions for the development of pulmonary barotrauma and in order to prevent hypoventilation and hypoxemia with possible unnoticed progression of pulmonary edema, it was decided that there are currently no indications for switching to controlled ventilation.

Ventilation was continued in the established mode, regulated by volume, measures were taken to normalize homeostasis, lavage of the tracheobronchial tree, chest percussion massage. During this period, the patient was rotated (positioned) 8 times, thoracopulmonary extensibility (C) was determined 2 times. To determine the actual thoracopulmonary extensibility (C), the patient was additionally synchronized with a respirator using promedol (10 mg), sibazon (10 mg). Subsequently, 5 mg sibazon was used to synchronize the patient with a respirator.

24 hours after surgery, thoracopulmonary extensibility increased to 40 ml / cm Vg. Given the stabilization of the state of hemodynamics and gas exchange, put indications for the transition to forced ventilation, controlled by pressure. Calculated and installed P _PCnach , _{PDKV prin} , I / E according to the formulas:

Correction P _{PC initially was} not required, since the _PC was 0.48 liters, that is, 10% more than the _PC (DO × 1.1 = 0.43 × 1.1 = 0.47).

In the future, C was determined with each change in the patient’s body position, after 2-3 hours. Thoracopulmonary extensibility gradually decreased, due to the development of acute lung damage. Twice the calculation and adjustment of P _PCnach , _{PDKV prin} , I / E were performed according to the above formulas. 3 days after surgery With 30 ml / cm water calculated and installed P _PCnach , _{PDKV prin} , I / E:

Corrected P _PC to _begin to achieve a _{PC of} 10% more TO (TO × 1.1 = 0.43 × 1.1 = 0.47), received P _PC 15 cm water column

When signs of spontaneous respiratory activity appear, the ratio of inspiration to expiration is adjusted - I / E is set to 1 (1 / 0.8) - the minimum value at which the patient's respiratory comfort is ensured (there was no spontaneous breathing).

For 8 days, continued forced mechanical ventilation, medical synchronization of the patient with a respirator, refrained from switching to auxiliary ventilation due to persistent acute catabolic due to sesssis.

C was determined with each change in the patient’s body position. Thoracopulmonary extensibility gradually increased. Calculation and adjustment of P _PCnach , _{PDKV prin} , I / E were carried out according to the above formulas. 9 days after surgery With 41 ml / cm water By this time, the patient had done positive dynamics - he began to regress sepsis, it became possible to transfer the patient to auxiliary breathing in SIMV mode with pressure support. The trigger sensitivity (Sens) I cm water.st.

We calculated and installed P _PSnach , P _PCnach , _{PDKV auxiliary} , I / E:

P _PSstart = 0.9 × DO / C = 0.9 × 430/41 = 9.44≈ 9 cm water column

P _PCnach = 1.1 × DO / C = 1.1 × 430/41 = 11.54≈ 12 cm water column

_Aux PEEP = 5 (C _should -C) / C + Sens + 2 = 5 (61-41) / 41 + 1 + 2 = 5,44≈ 5,4 cm water column

I / E = (C _should + C) / 3 C = (61 + 41) / (3 × 41) = 0,83≈ 1 / 1.2

Corrected P _PS to _start to achieve DO 10% more than expected (DO × 1.1 = 0.43 × 1.1 = 0.47) and received P _PS = 10 cm water column Correction of P _PC , _first , to achieve DO _PS 10% more DO (DO × 1.1 = 0.43 × 1.1 = 0.47) was not required, since at P _PC 12 cm water column tidal volume was 0.49 liters. The ratio of inspiration to expiration was adjusted - I / E was set equal to 1 / 1.1 the minimum value at which the patient's respiratory comfort was achieved.

On the 12th day of treatment, the patient made significant progress in general condition. Thoracopulmonary extensibility - 47 ml / cm water It was decided to transfer the patient to another regimen of assisted mechanical ventilation-spontaneous breathing under positive airway pressure with pressure support (CPAP + PS). Set the trigger sensitivity (Sens) to 0.5 cm water column.

We calculated and set _PSnach P, P _PCnach, PEEP _Aux.

P _PSnach = 0.9 × DO / C = 0.9 × 430/47 = 8.23≈ 8 cm water column

_Aux PEEP = 5 (C _should -C) / C + Sens + 2 = 5 (61-47) / 47 + 0.5 + 2 = 3,99≈ 5,4 cm water column

Correction of P _{PS was} not _initially required, since at P _PS = 8 cm _{water column} DO _PS was equal to 0.47, that is, 10% more DO.

During a prolonged mechanical ventilation in the intensive care unit, oxygen was supplied to the respiratory circuit (FiO ₂ 0.5-0.25), which ensured normal hemoglobin saturation with oxygen (Spo ₂ 94-99% according to pulse oximetry). Against the background of infusion-transfusion therapy, the hemoglobin level did not decrease below 90 g / l.

On the 18th day after the operation, the patient was successfully transferred to spontaneous breathing and extubated. On the 22nd day he was transferred to the department of pediatric emergency surgery. Outcome: improvement.

According to the claimed method examined 26 patients with traumatological, neurotraumatological, neurosurgical profiles, requiring DIVL and not having the initial specific lung damage. The control was a group of 23 patients, comparable in gender, age, pathology, and treatment. Mechanical ventilation in both groups was carried out with Puritan-Bennett 7200, Puritan-Bennett 7200ae, Bear 1000 respirators. The groups differed in the method of setting the mechanical ventilation parameters.

In the control group, the parameters of mechanical ventilation were established according to the traditional method [Marino P. Intensive care. - M. - 1998. - P.348-350]: tidal volume (BEF), minute volume of ventilation (MOB), respiratory rate (BH) were calculated by the formulas:

Set the calculated parameters in the respirator settings menu, performed a volume-controlled mechanical ventilation. Using a gas analyzer, a capnograph, a pulse oximeter, the BH and DO were adjusted to achieve normoventilation and normoxemia. The inspiratory pressure controlled by the respirator in the forced ventilation mode controlled by pressure was selected empirically to achieve the calculated DO. When switching to assisted artificial lung ventilation (VIVL), the level of inspiratory pressure (support pressure, P _PS ) was found at which the inspiratory support pressure was obtained by dividing the maximum airway pressure of the patient by inspiration (P _mvd ) by three. The optimal positive end-expiratory pressure (PEEP) was found by measuring lung extensibility and oxygen delivery. These indicators were measured at various empirically selected, PEEP levels. The level of PEEP was considered optimal at which lung extensibility and oxygen delivery are maximal.

In the main group, the ventilation parameters were set according to the proposed method.

Respiratory mechanics were examined using respirators, a Datex Capnomac-Ultima respiratory monitor. Daily, the following parameters were compared that characterize the effectiveness of respiratory therapy: PaCO ₂ , P _peak , P _medium , C, PEEP level, F, P _PC , P _PS , duration of normal ventilation, dose of sedatives, painkillers and muscle relaxants to synchronize the patient with a respirator.

Statistical data processing was carried out in the Instat program.

Research results

Figure 1, 2, 3 shows the dynamics of thoracopulmonary extensibility (C), the level of positive end-expiratory pressure (PEEP), the level controlled by the pressure respirator in a pressure-controlled mode (P _PC ) depending on the method of conducting long-term mechanical ventilation. The results show that when using the proposed method for conducting long-term mechanical ventilation (in the main group), it is possible to increase thoracopulmonary extensibility at an earlier date, to reduce the PEEP and the level of P _PC . In addition, a significant decrease in heart rate (p <0.05) and doses of vasopressor, cardiotonic, sedative, muscle relaxant drugs was obtained in the main group. Transient differences in the studied parameters on the 6th day of the study were due to the fact that the bulk of the patients of the main group was transferred to spontaneous breathing and excluded from the study. The main group left the most severe patients with acute lung damage, requiring higher values of PDKV and P _PC .

The technique used in the method to adjust the ventilation parameters before connecting the patient to the respirator made it possible to select adequate ventilation parameters in advance for patients with different height, body weight, age in 60% of cases versus 33.3% in the control group (stage 1), accelerated the further 2 times setting the respirator, facilitated the correction of ventilation parameters during the entire period of mechanical ventilation.

Research findings

1. Taking into account the anthropometric characteristics of patients allows the installation of respirator parameters during a long mechanical ventilation 2 times faster than traditionally.

2. The use of a method of conducting long-term mechanical ventilation, based on the account of thoracopulmonary extensibility and on the principle of minimizing the average airway pressure, during prolonged mechanical ventilation helps to reduce airway pressure, reduces the heart rate, and the dose of cardiotonics.

3. The use of the proposed method for conducting long-term mechanical ventilation promotes the growth of thoracopulmonary extensibility from 3 days.

4. The use of the proposed method for conducting prolonged mechanical ventilation facilitates the synchronization of the patient with a respirator, reduces the dose of sedatives, muscle relaxants.

Claims (4)

1. A method of conducting long-term artificial lung ventilation (IVL), including weighing the patient, setting the respirator's working parameters: minute ventilation volume (MOB), respiratory volume (DO), respiratory rate (BH), oxygen fraction supplied by the respirator to the respiratory circuit (FiO ₂₎ holding the forced ventilator, controlled by volume, and an adjustment to the BH to achieve normoventilyatsii, defining a positive end-expiratory pressure (PEEP) with a transition to the auxiliary ventilation, characterized in that the complementary to observe the corresponding height (h), age (s) of a patient and given the received data calculated by the formula to DO = 7 × m + m _Dolj-G; where DO - tidal volume, ml; m _must - due body weight of the patient, kg; m _huts - excess body weight of the patient, kg, calculate the initial minute volume of ventilation (MOB _beg ) according to the formula MOB _nach = K × (100 × m _Dolj + 60 × _m-G), where MOV _nach - the initial minute volume of ventilation, l / min; K is the coefficient of increase in metabolism in patients with stress: with mild stress, K is 1.2; with moderate stress - 1.4; with severe stress - 1.6; with fever, K increases by 0.1 for every degree above 37 ° C; m _must - due body weight of the patient, kg; m _huts - excess body weight of the patient, kg; determine proper thoracopulmonary extensibility (C _should) by the formula C _must = m _must -m _huts / 3- (a-30) / 3; where C _must - due thoracopulmonary extensibility, ml / cm vod; m _must - due body weight of the patient, kg; m _huts - excess body weight of the patient, kg; a - age, years; find the initial gas flow rate on inspiration ((F _beg ) according to the formula _Nach F = 0,8 × C _should, where F _beg - the initial gas flow rate on inspiration, l / min; C _should - due thoracopulmonary extensibility ml / cm vod.st .; set parameters obtained to, BH, F _beginning, MOV _{beginning of} the setting menu respirator and begin ventilator adjustable in volume, with a constant or decreasing gas flow form inspiratory selected that form a gas stream at inspiration, at which the mean airway pressure (P _environments ) below, set the “automatic breath” function; establish the initial duration of the inspiratory pause (T _plateau ) so that the initial ratio of inspiration to expiration (1 / E _beginning ) was equal to 1 / 1,5; with stable haemodynamics establish an initial positive end expiratory pressure (PEEP _nach) 5 cm water column, with unstable haemodynamic is set PEEP _nach vod.st 2 cm .; synchronize the patient with a respirator, determine the actual thoracopulmonary extensibility (C), calculate and establish the level of positive end-expiratory pressure for forced ventilation (PDKV _prin ) according to the formula _Received PEEP = 5 (C _should -C) / 2 + C, where PDKV _prin - positive pressure at the end of exhalation for forced ventilation, cm water; C _should - due thoracopulmonary extensibility mL / cm of water column, C is the actual thoracopulmonary extensibility, ml / cm water column; find and set the inspiratory flow rate (F) according to the formula F = (C _should + 2C) / 3 where F is the inspiratory flow rate, l / min; C _should - due thoracopulmonary extensibility mL / cm of water column, C - actual thoracopulmonary extensibility, ml / cm water; calculate and establish the ratio of inspiration to expiration (I / E) according to the formula I / E = (C _should + C) / 3C where I / E is the ratio of inspiration to expiration; C _should - due thoracopulmonary extensibility mL / cm of water column, in the process of forced mechanical ventilation, adjustable in volume, C is determined at least 1 time in 12 hours and when C is changed, PEEP and F are adjusted, T _{plateau is} adjusted to achieve respiratory comfort of the patient; go to pressure-controlled forced ventilation, for which the initial inspiratory pressure for pressure-controlled forced ventilation (P _PCnach ) is calculated and set, according to the formula P _PCnach = 1.1 × DO / S, where R _PCnach - initial inspiratory pressure in the mode of forced ventilation of the lungs, regulated by pressure; DO - tidal volume, ml; C - actual thoracopulmonary extensibility, ml / cm water; calculate and establish the ratio of inspiration to expiration according to the previously given formula; regulate P _PCnach to achieve tidal volume in a pressure-controlled mode (DORs), 10% more DO and receive P _PC ; the process of forced ventilation, an adjustable pressure is determined at each change of position of the body of the patient at least 1 time 8 hours, and a change with adjustment of PEEP _{is received} and F _PC, regulate the ratio of inspiration to expiration (I / E) in order to achieve the respiratory comfort of the patient ; go from forced ventilation to the mode of assisted ventilation, calculate and install PEEP for assisted ventilation (PEEP _assist ) according to the formula PEEP _recall = 5 (С _due -С) / С + 2 + Sens, where PDKV _aux - positive pressure at the end of exhalation for assisted ventilation, cm water; C _should - due thoracopulmonary extensibility ml / cm vod.st .; C - actual thoracopulmonary extensibility, ml / cm water; Sens - sensitivity of the trigger of the respirator, cm water column, calculate and set the initial support pressure (P _PSnach ) for auxiliary ventilation, pressure-controlled, according to the formula P _PSnach = 0.9 × DO / S, where R _PSnach - initial support pressure in the mode of assisted ventilation, pressure-controlled; DO - tidal volume, ml; C is the actual thoracopulmonary extensibility, ml / cm water column; regulate P _{PS, in} order to achieve tidal volume in the auxiliary pressure-controlled ventilation (DO _PS ), 10% more DO and receive P _PS , adjust the ratio of inspiration to expiration (I / E) to achieve respiratory comfort of the patient; during auxiliary ventilator regulated pressure is determined at each change of body position of the patient at least 1 time 8 h and at change of PEEP is corrected _aux C and P _PS. 2. The method according to p. 1, characterized in that the installation of the oxygen fraction supplied by the respirator to the respiratory circuit (FiO ₂ ) is carried out under the control of pulse oximetry or blood gas analysis to achieve SpO ₂ 94-100%, PaO ₂ 75-200 mm Hg, a change in the MOV _nach by changing the BH is carried out under the control of capnography data to achieve EtCO ₂ from 32 to 45 mm Hg, get MOB. 3. The method of claim. 1, characterized in that the body due macsu (m _{should) be} determined based on the type of patient constitution formula _Dolj m = (22 + type constitution) × h ² wherein m _Dolj - due weight in kilograms; h - height, m; type of constitution: asthenic - 1, normosthenic - 2, hypersthenic - 3. 4. The method according to p. 1, characterized in that C _must at the age of the patient (a) 30 years and younger is determined by the formula C _dol = m _must -m _huts / 3, where C _dol - estimated thoracopulmonary extensibility, ml / cm water; m _Dolj - due weight in kilograms; m _huts - overweight, kg

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