Emergency care

Providing emergency care in urgent conditions at all stages raises a number of fundamental issues that require immediate and correct solutions. The doctor must, in the shortest possible time, orient himself in the circumstances of the disease or injury, perform a syndrome-based assessment of vital system disorders, and provide the necessary medical care. The effectiveness of the treatment depends largely on the completeness of the information available to the doctor. Diagnostic capabilities in providing emergency care remain limited, which determines the focus of the doctor's actions on the most urgent measures, postponing pathogenetic and etiotropic therapy for later.

The basis of providing assistance in emergency and critical conditions are emergency measures to correct respiratory and circulatory disorders. It is extremely important to distinguish between the main and secondary, to separate the means of etiologic, pathogenetic and symptomatic therapy. It is necessary to follow a certain sequence of diagnostic and therapeutic measures. Emergency therapeutic measures should go in parallel or even precede a detailed examination of the patient. It is extremely important to identify patients with a high risk of developing respiratory and cardiac arrest. Identification should be based on the anamnesis, a thorough examination and examination of the patient. In approximately 80% of cases, clinical signs of deterioration of the condition quickly develop in the first few hours before cardiac arrest. The most common clinical precursors are respiratory disorders, tachycardia and decreased cardiac output.

Stages of emergency care

When providing emergency assistance, the following stages are usually distinguished:

The initial stage is the time from the moment of injury or illness until the arrival of medical units (15-20 minutes). The absence of medical workers and the inability of eyewitnesses to provide competent first aid at this stage leads to a horrifyingly unjustified mortality rate of 45 to 96%. 2. The stage of providing professional medical care:

• pre-evacuation preparation (15-20 minutes) - includes the time required to assess the patient's condition and carry out measures to prepare for his transportation to the hospital;
• evacuation (8-15 minutes) - transporting the patient to the hospital. Experience shows that at this stage there is a significant deterioration in the condition of 55-75% of victims. The mortality rate for multiple injuries among them is 21-36%.

The concept of the "golden hour"

For patients in critical condition (especially with severe trauma), the time factor is of great importance. Therefore, the concept of the "golden hour" has been introduced - the period from the moment of injury until specialized care is provided to the victim in a hospital. Care provided during this period of time significantly increases the victim's chances of survival. If the victim is delivered to the operating room within the first hour after receiving the injury, the highest level of survival is achieved. Conversely, if circulatory disorders in traumatic shock are eliminated later than sixty minutes after the injury, severe disorders in the vital systems of the body may become irreversible.

The concept of "golden hour" is very conditional. Based on the understanding of the pathogenesis of an emergency condition, severe trauma with shock, it can be stated: the faster the destructive process launched by tissue hypoxia is stopped, the greater the chances of a favorable outcome.

Personal safety of medical personnel

When providing assistance, medical personnel may be exposed to a threat to their own health and life. Therefore, before examining a patient, it is necessary to make sure that there is no danger to the medical personnel themselves (active traffic, electricity, gas pollution, etc.). Precautions should be taken and available protective devices should be used.

Medical workers should not enter the area where victims are located if it is dangerous and requires special training or equipment. Work in such conditions is the prerogative of rescue teams trained and equipped accordingly (work "at height", in gas-filled or fire-engulfed rooms, etc.).

Healthcare personnel may be exposed to risks when patients are exposed to toxic substances or contagious infections.

For example, if the accident is due to poisoning with potent gases (hydrogen cyanide or hydrogen sulfide gas), any assisted ventilation should be through a mask with a separate exhalation valve. These substances can cause injury to the person providing assistance when inhaling air contained in the victim's lungs (through mouth-to-mouth breathing, an airway, or through a face mask).

Various corrosive chemicals (concentrated acids, alkalis, etc.), as well as organic phosphates and other substances that can easily be absorbed through the skin or digestive tract, are extremely toxic and dangerous.

During resuscitation, the main microorganism that caused personnel infection was most often Nesseria meningitidis. There are isolated reports in the specialized literature of tuberculosis infection during resuscitation.

During treatment, beware of sharp objects. All cases of HIV transmission were the result of damage to the skin of rescuers or accidental pricks with a needle/medical instrument.

Transmission of cytomegalovirus, hepatitis B and C viruses during cardiopulmonary resuscitation has not been reported in the literature.

Those providing medical care must use protective goggles and gloves. To prevent the transmission of airborne infections, face masks with a one-way valve or devices that seal the patient's airways (endotracheal tubes, laryngeal masks, etc.) must be used.

Syndromological approach

In the practice of providing emergency care in urgent conditions, it is necessary to limit ourselves to establishing the main syndrome that is predominant in severity (a syndrome is a non-specific clinical phenomenon, i.e., the same complex of pathological manifestations may be a consequence of conditions with different etiologies). Considering the specific features of treating emergency conditions (maximum efforts to provide emergency care with a minimum of information), the syndromological approach is quite justified. But fully adequate treatment can only be carried out when a final diagnosis is established that takes into account the etiology, pathogenesis, and pathomorphological substrate of the disease.

The final diagnosis is based on a comprehensive, complex study of the main systems and organs (anamnestic information, results of medical examination, instrumental and laboratory research data). The diagnostic process is based on the urgency of treatment measures, the prognosis of the disease for life, the danger of treatment measures in case of erroneous diagnosis and the time spent on confirming the supposed cause of the emergency condition.

Inspection of the crime scene

Examination of the location of the unconscious patient can help to establish the cause of the development of his serious condition. Thus, finding the victim in a garage with a car with the engine running (or with the ignition on) most likely indicates carbon monoxide poisoning.

You should pay attention to unusual odors, the presence of packages and bottles of medicines, household chemicals, medical certificates and documents that the patient has with him.

The location of the patient can provide certain information. If he is on the floor, this indicates a rapid loss of consciousness. The gradual development of the pathological process is indicated by the presence of the victim in bed.

Clinical examination

In order to rationally use the available opportunities when assessing the condition of a patient or patients, it is customary to conduct a primary and secondary examination. This division allows for a universal approach and the right decision to be made on the choice of the optimal further tactics for managing the patient.

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Initial examination

The initial examination of the victim (no more than 2 minutes) is carried out to determine the cause that poses an immediate threat to life at the time of examination: obstruction of the airways, external bleeding, signs of clinical death.

During the initial examination, you should hold the victim's head in one hand (the patient may have a cervical spine injury), gently shake him by the shoulder and ask: "What happened?" or "What's wrong with you?" Then the level of consciousness is assessed according to the following scheme.

Assessing the level of consciousness

• The patient is conscious - can state his name, location and day of the week.
• There is a reaction to speech - the patient understands speech, but is unable to correctly answer the three questions above.
• Pain response - reacts only to pain.
• There is no reaction - does not respond to either speech or pain.

Assess the airway. Ensure that the airway is open or identify and treat existing or potential airway obstructions.

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Breathing assessment

It is checked whether the victim is breathing, whether the breathing is adequate or not, whether there is a risk of respiratory distress. It is necessary to identify and eliminate all existing or potential factors that may cause deterioration of the patient's condition.

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Evaluation of blood circulation

Is there a pulse, are there signs of severe internal or external bleeding, is the victim in shock, is the capillary refill rate normal? Existing or potential threatening factors should be identified and eliminated.

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Secondary inspection

A secondary examination of the patient is carried out after the immediate threat to his life has been eliminated. This is a more detailed examination. During its implementation, it is necessary to assess the general condition of the victim, the level of consciousness, the degree of existing circulatory and respiratory disorders. The patient should be examined, listened to and palpated "from head to toe". The medical examination should also include an assessment of general and focal neurological symptoms, as well as available methods of functional examination and laboratory diagnostics. It is necessary to establish a preliminary diagnosis or the leading sign of injury.

Assessment of the general condition of the patient

In clinical practice, five degrees of severity of the general condition are most often distinguished:

1. satisfactory - consciousness is clear, vital functions are not impaired;
2. moderate severity - clear consciousness or moderate stupor, vital functions are slightly impaired;
3. severe - deep stupor or stupor, severe disorders of the respiratory or cardiovascular system;
4. extremely severe - comatose state of I-II degree, severe respiratory and circulatory disorders;
5. terminal state - coma of the third degree with severe disturbances of vital functions.

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Collection of anamnesis and clarification of the circumstances of the development of an emergency condition

In situations where immediate action is required, there is little time to collect anamnesis. However, after the therapy begins to produce positive results, it is still necessary to obtain the necessary information.

The anamnesis and clarification of the circumstances of the emergency condition should be collected as soon as possible. A targeted survey scheme should be used to obtain the most complete information.

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Algorithm for clarifying the circumstances of the development of an emergency condition

1. Who? Identity of the patient (full name, gender, age, occupation).
2. Where? Place of illness (at home, on the street, at work, in a public place, at a party, etc.).
3. When? Time of appearance of the first signs of the disease (time from the onset of the disease).
4. What happened? Brief description of the existing disorders (paralysis, convulsions, loss of consciousness, vomiting, increased body temperature, changes in pulse, breathing, swallowing, etc.).
5. Because of what, after what? Circumstances, usual and unusual situations immediately preceding the disease (alcohol abuse, injuries, physical injuries, severe mental shocks, hospital stays, illnesses suffered at home, overheating, animal bites, vaccinations, etc.).
6. What was before? Changes in condition from the moment of illness to examination (a brief description of the rate of development and the sequence of development of disorders - sudden or gradual onset, increase or decrease in the severity of existing disorders).
7. Treatment measures taken from the time of illness until examination (list of medications taken, treatment measures used and their degree of effectiveness).
8. History of chronic diseases (diabetes, mental illness, cardiovascular disease, etc.).
9. The presence of similar conditions in the past (time of occurrence, signs and symptoms of diseases, their duration, whether inpatient care was required, how it ended).

If the patient's condition allows (or after it has stabilized as a result of treatment), it is necessary to collect information about him in the most detailed way. The collection is carried out by questioning relatives, friends and other persons who were with the patient, and by carefully examining the room or place where the patient is, as well as by searching for and studying medical documents and items that allow us to determine the cause of the emergency (medicines, food, etc.).

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Definition of the state of consciousness

Determining the state of consciousness allows assessing the degree of danger of the existing lesion to the patient's life, allows determining the volume and directions of necessary studies, and choosing the type of emergency care (neurosurgical intervention or intensive care). At the pre-hospital stage, the Glasgow Coma Scale is usually used, which allows assessing the degree of impaired consciousness in adults and children over 4 years of age. The assessment is carried out using three tests that evaluate the reaction of opening the eyes, speech and motor reactions. The minimum number of points (three) means brain death. The maximum (fifteen) indicates clear consciousness.

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Skin

The color and temperature of the skin of the extremities give an idea of the patient's condition. Warm to the touch pink skin and pink nails indicate sufficient peripheral blood flow and are considered a positive prognostic sign. Cold pale skin with pale nails indicates centralization of blood circulation. "Marbling" of the skin, cyanosis of the nails, the color of which easily turns white when pressed and does not recover for a long time, indicates the transition from spasm of peripheral vessels to their paresis.

The presence of hypovolemia is indicated by decreased turgor (elasticity) of the skin. Turgor is determined by taking a fold of skin between two fingers. Normally, the skin fold quickly disappears after the fingers are removed. With decreased skin turgor, it remains unstraightened for a long time - the "skin fold" symptom.

The degree of dehydration can be determined by intradermal injection of 0.25 ml of physiological solution into the forearm. Normally, the papule is absorbed within 45-60 minutes. With a mild degree of dehydration, the absorption time is 30-40 minutes, with a moderate degree - 15-20 minutes, with a severe degree - 5-15 minutes.

In some pathological conditions, swelling of the lower extremities, abdomen, lower back, face and other parts of the body appears, which indicates hypervolemia. The contours of the swollen parts of the body are smoothed out, after pressing the skin with a finger, a pit remains, which disappears after 1-2 minutes.

Body temperature

By measuring the central and peripheral body temperature, one can fairly reliably judge the hemoperfusion of the peripheral parts of the extremities. This indicator serves as an integrative temperature characteristic of microcirculation and is called the "rectal-cutaneous temperature gradient". The indicator is easy to determine and represents the difference between the temperature in the lumen of the rectum (at a depth of 8-10 cm) and the skin temperature on the dorsum of the foot at the base of the first toe.

The plantar surface of the first toe of the left foot is the standard place for monitoring skin temperature; here it is normally 32-34 °C.

The rectal-cutaneous temperature gradient is quite reliable and informative for assessing the severity of the victim's shock condition. Normally, it is 3-5 °C. An increase of more than 6-7 °C indicates the presence of shock.

The rectal-cutaneous temperature gradient allows for an objective assessment of the state of microcirculation in various states of the body (hypotension, normo- and hypertension). Its increase over 16 °C indicates a fatal outcome in 89% of cases.

Monitoring the dynamics of the rectal-cutaneous temperature gradient allows monitoring the effectiveness of anti-shock therapy and makes it possible to predict the outcome of shock.

As an addition, a comparison of the temperature in the external auditory canal/oral cavity and axillary temperature can be used. If the latter is lower than the former by more than 1 °C, the perfusion of peripheral tissues is probably reduced.

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Evaluation of the circulatory system

The initial assessment of the circulatory system is carried out on the basis of an analysis of the characteristics of the pulse, arterial and central venous pressure, and the state of the myocardium - using electrocardioscopy or electrocardiography.

Heart rate. Normally, the heart rate is about 60-80 beats per minute. Its deviation in one direction or another in patients in critical condition should be considered an unfavorable sign.

A significant decrease or increase in heart rate can cause a drop in cardiac output to the level of hemodynamic instability. Tachycardia (more than 90-100 beats per minute) leads to increased cardiac work and an increase in its oxygen demand.

In sinus rhythm, the maximum tolerable heart rate (that is, maintaining adequate blood circulation) can be calculated using the formula:

HR max = 220 - age.

Exceeding this rate can cause a decrease in cardiac output and myocardial perfusion even in healthy individuals. In coronary insufficiency and other pathological conditions, cardiac output can decrease with a more moderate tachycardia.

It should be taken into account that sinus tachycardia in hypovolemia is an adequate physiological reaction. Therefore, hypotension in this condition should be accompanied by compensatory tachycardia.

The development of bradycardia (less than 50 beats per minute) can lead to circulatory hypoxia, as well as a critical decrease in coronary blood flow and the development of myocardial ischemia.

The main causes of severe bradycardia in emergency medicine are hypoxemia, increased vagal tone, and high-degree cardiac conduction blocks.

The normal healthy heart adapts to physiological or pathological depressions of heart rate via the Starling mechanism. A well-trained athlete may have a resting heart rate of less than 40 beats per minute without any adverse effects. In patients with impaired myocardial contractility or compliance, bradycardia of less than 60 beats per minute may be associated with a significant decrease in cardiac output and systemic arterial pressure.

In case of rhythm disturbances, pulse waves may follow at unequal intervals, the pulse becomes arrhythmic (extrasystole, atrial fibrillation, etc.). The number of heartbeats and pulse waves may not match. The difference between them is called pulse deficit. The presence of cardiac rhythm disturbances can significantly worsen the patient's condition and is subject to corrective therapy.

Measuring blood pressure provides valuable information about the overall hemodynamic state. The simplest way to measure blood pressure is to palpate the pulse on the radial artery using a sphygmomanometer cuff. This method is convenient in emergency situations, but is not very accurate in cases of low pressure or in the presence of vasoconstriction. In addition, this method can only determine systolic blood pressure.

More accurate, but requiring more time and the use of a phonendoscope, is the measurement by auscultation of Korotkoff sounds over the arteries in the cubital fossa.

Currently, indirect measurement of blood pressure using automated oscillometry is becoming increasingly popular.

The accuracy of the various electronic devices for noninvasive blood pressure measurement currently available is no better, and sometimes even worse, than with standard methods. Most models are inaccurate at systolic pressures below 60 mmHg. In addition, high blood pressure is underestimated. Pressure determination may not be possible during episodes of arrhythmia, and oscillometers are not able to detect sharp jumps in blood pressure.

In patients with shock, invasive methods of measuring blood pressure are preferable, but at present they are of little use in the prehospital stage (although technically these methods do not present great difficulties).

Systolic blood pressure within 80-90 mm Hg indicates a dangerous but compatible with maintaining the main vital functions deterioration. Systolic pressure below 80 mm Hg indicates the development of a life-threatening condition requiring immediate emergency measures. Diastolic pressure above 80 mm Hg indicates an increase in vascular tone, and pulse pressure (the difference between systolic and diastolic pressure is normally 25-40 mm Hg) less than 20 mm Hg - a decrease in the stroke volume of the heart.

The magnitude of arterial pressure indirectly characterizes cerebral and coronary blood flow. Autoregulation of cerebral blood flow maintains the constancy of cerebral blood flow with changes in mean arterial pressure from 60 to 160 mm Hg due to regulation of the diameter of the supply arteries.

When the limits of autoregulation are reached, the relationship between mean arterial pressure and volumetric blood flow become linear. When systolic arterial pressure is below 60 mm Hg, cerebral vessel reflation is disrupted, as a result of which the volume of cerebral blood flow begins to passively follow the level of arterial pressure (with arterial hypotension, cerebral perfusion decreases sharply). But it should be remembered that arterial pressure does not reflect the state of organ and tissue blood flow in other parts of the body (except for the brain and heart).

Relative stability of arterial pressure in a patient with shock does not always indicate the maintenance of the body's normal physiological optimum, since its immutability can be achieved by several mechanisms.

Blood pressure depends on cardiac output and total vascular resistance. The relationship between systolic and diastolic blood pressure can be considered as the relationship between stroke volume and minute volume of blood circulation on the one hand and resistance (tone) of peripheral vessels on the other. Maximum pressure mainly reflects the volume of blood ejected into the vascular bed at the moment of cardiac systole, since it is determined mainly by the minute volume of blood circulation and stroke volume. Blood pressure can change as a result of changes in the vascular tone of peripheral vessels. An increase in vascular resistance with an unchanged minute volume of blood circulation leads to a predominant increase in diastolic pressure with a decrease in pulse pressure.

The normal mean arterial pressure (MAP) is 60-100 mm Hg. In clinical practice, the mean arterial pressure is calculated using the formulas:

SBP = BP diast + (BP syst - BP dist)/3 or SBP = (BP syst + 2A D diast)/3.

Normally, in a patient lying on his back, the mean arterial pressure is the same in all large arterial vessels. There is usually a small pressure gradient between the aorta and the radial vessels. The resistance of the vascular bed has a significant effect on the blood supply to the body's tissues.

A mean arterial pressure of 60 mmHg may provide abundant blood flow through a greatly dilated vascular bed, whereas a mean arterial pressure of 100 mmHg may be inadequate in malignant hypertension.

Errors in blood pressure measurement. The pressure determined by sphygmomanometry is characterized by inaccuracy when the cuff width is less than 2/3 of the arm circumference. The measurement may show an elevated blood pressure in the case of using a cuff that is too narrow, as well as in the presence of severe atherosclerosis, preventing compression of the brachial artery by pressure. In many patients with hypotension and low cardiac output, the points of muffling and disappearance of tones during determination of diastolic pressure are poorly distinguishable. During shock, all Korotkov tones may be lost. In this situation, Doppler ultrasound cardiography helps to detect systolic pressures below the hearing threshold.

The state of central hemodynamics can be quickly assessed by the ratio of pulse rate and systolic pressure. The following nomogram is convenient for determining the severity of the condition and the need for emergency measures.

Normally, the systolic pressure is twice the pulse rate (120 mm Hg and 60 beats per minute, respectively). When these values equalize (tachycardia up to 100 per minute and a decrease in systolic pressure to 100 mm Hg), we can talk about the development of a threatening condition. A further decrease in systolic blood pressure (80 mm Hg and below) against the background of tachycardia or bradycardia indicates the development of a shock condition. Central venous pressure is a valuable, but very approximate indicator for assessing the state of central hemodynamics. It is a gradient between intrapleural pressure and pressure in the right atrium. Measuring central venous pressure allows indirectly assessing venous return and the state of contractile function of the right ventricle of the myocardium.

Central venous pressure is determined using a catheter inserted into the superior vena cava through the subclavian or jugular vein. A Walchchan central venous pressure measuring device is connected to the catheter. The zero mark on its scale is set at the level of the midaxillary line. Central venous pressure characterizes venous return, which mainly depends on the volume of circulating blood, and the ability of the myocardium to cope with this return.

Normally, the value of central venous pressure is 60-120 mm H2O. Its decrease to less than 20 mm H2O is a sign of hypovolemia, while an increase of more than 140 mm H2O is caused by the suppression of the pumping function of the myocardium, hypervolemia, increased venous tone or obstruction of blood flow (cardiac tamponade, pulmonary embolism, etc.). That is, hypovolemic and distributive shocks cause a decrease in central pressure, and cardiogenic and obstructive shocks cause an increase.

An increase in central venous pressure above 180 mm H2O indicates decompensation of cardiac activity and the need to stop or limit the volume of infusion therapy.

If the central venous pressure is within 120-180 mm H2O, a trial jet infusion of 200-300 ml of fluid into the vein can be used. If there is no additional increase or it is eliminated within 15-20 minutes, the infusion can be continued by reducing the infusion rate and monitoring the venous pressure. A central venous pressure level below 40-50 mm H2O should be regarded as evidence of hypovolemia requiring compensation.

This test serves as a key test for determining hemodynamic reserves. Improvement of cardiac output and normalization of systemic blood pressure without the development of symptoms of excessive cardiac filling pressure makes it possible to adjust the infusion and drug therapy.

Capillary refill rate. When assessing the state of blood circulation, it is useful to check the pulse filling and the rate of refilling of the nail bed capillaries (spot symptom). The duration of filling of the nail bed capillaries after pressure is normally no more than 1-2 seconds, and in shock it exceeds 2 seconds. This test is extremely simple, but is not very popular in clinical practice, since it is difficult to accurately determine the moment and time of disappearance of the pale spot on the skin after pressure.

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Respiratory system assessment

When assessing the respiratory system, factors such as the rate, depth, and character of breathing, the adequacy of chest movements, and the color of the skin and mucous membranes should be considered first. A careful examination of the neck, chest, and abdomen is required to differentiate paradoxical movements. Auscultation of the lung fields should be performed to determine the adequacy of air supply and to detect bronchial obstruction or pneumothorax.

The normal respiratory rate is 12-18 per minute. An increase in the respiratory rate above 20-22 per 1 minute leads to a decrease in the effectiveness of the respiratory function, since this increases the proportion of dead volume in the minute ventilation of the lungs and increases the work of the respiratory muscles. Rare breathing (less than 8-10 per 1 minute) is associated with the risk of developing hypoventilation.

It is extremely important to assess the degree of patency of the upper respiratory tract in patients at risk of developing their obstruction. In case of partial obstruction of the upper respiratory tract, the patient is conscious, agitated, complains of difficulty breathing, coughing, and noisy breathing.

Inspiratory stridor is caused by obstruction at or below the larynx. The presence of expiratory wheezes indicates lower airway obstruction (collapse and obstruction during inspiration).

With complete obstruction of the upper respiratory tract, breathing is not heard and there is no movement of air from the oral cavity.

Gurgling sounds during breathing indicate the presence of liquid or semi-liquid foreign bodies in the respiratory tract (blood, stomach contents, etc.). Snoring sounds occur when the pharynx is partially blocked by the tongue or soft tissue. Laryngeal spasm or obstruction produces sounds reminiscent of "crowing".

Various pathological conditions may cause disturbances in the rhythm, frequency and depth of breathing. Cheyne-Stokes breathing is characterized by a series of gradually increasing depth of breaths, alternating with periods of shallow breathing or short pauses in breathing. A disordered, arrhythmic alternation of deep and shallow breaths may be observed with a distinct difficulty in exhaling - Biot's breathing. In patients with impaired consciousness, in an extremely serious condition, against the background of acidosis, Kussmaul breathing often develops - a pathological breathing characterized by uniform, rare respiratory cycles, deep noisy inhalation and forced exhalation. In some diseases, wheezing breathing (sharp, irregularly occurring convulsive contractions of the diaphragm and respiratory muscles) or group breathing (alternating group breaths with gradually lengthening respiratory pauses) develops.

Atonal breathing is also distinguished, which occurs during the dying process after the terminal pause. It is characterized by the appearance of a short series of breaths (or one shallow breath) and indicates the onset of agony.

The necessary information can be provided by determining the type of respiratory failure. Thus, with increased excursions of the abdominal muscles with simultaneous exclusion of the chest muscles from the act of breathing (abdominal type), in some cases it is possible to assume damage to the cervical spinal cord. Asymmetry of chest movements indicates the presence of pneumothorax, hemothorax, unilateral damage to the phrenic or vagus nerve.

When assessing the state of the respiratory system, it is necessary to take into account such clinical symptoms as cyanosis, sweating, tachycardia, arterial hypertension.

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Instrumental examination methods

If 10 years ago it had to be stated that, unfortunately, a doctor at the stage of providing emergency care is practically deprived of the opportunity to instrumentally examine patients, then at present the situation has changed radically. A large number of portable devices have been created and introduced into clinical practice, allowing, using qualitative or quantitative methods, to provide complete information about the condition of patients in real time and at the scene of the incident.

Electrocardiography

Electrocardiography is a method of graphically recording electrical phenomena that occur in the heart when membrane potentials change.

The electrocardiogram normally shows positive P and RwT waves, negative Q and S waves. Sometimes an inconstant U wave is observed.

The P wave on the electrocardiogram reflects the excitation of the atria. Its ascending knee is caused mainly by the excitation of the right atrium, the outgoing knee - by the excitation of the left. Normally, the amplitude of the P wave does not exceed -2 mm, the duration is 0.08-0.1 seconds.

The P wave is followed by the PQ interval (from the P wave to the beginning of Q or R). It corresponds to the time of impulse conduction from the sinus node to the ventricles. Its duration is 0.12-0.20 seconds.

When the ventricles are excited, the QRS complex is recorded on the electrocardiogram. Its duration is 0.06-0.1 seconds.

The Q wave reflects excitation of the interventricular septum. It is not always registered, but if it is present, the amplitude of the Q wave should not exceed 1/4 of the amplitude of the R wave in this lead.

The R wave is the highest wave of the ventricular complex (5-15 mm). It corresponds to almost complete propagation of the impulse through the ventricles.

The S wave is registered with full excitation of the ventricles. As a rule, it has a small amplitude (2.5-6 mm), and may not be expressed at all.

After the QRS complex, a straight line is recorded - the ST interval (corresponds to the phase of complete depolarization, when there is no potential difference). The duration of the ST interval varies widely depending on the rapid heartbeat. Its displacement should not exceed 1 mm from the isoelectric line.

The T wave corresponds to the repolarization phase of the ventricular myocardium. Normally, it is asymmetrical, has an ascending knee, a rounded apex, and a steeper descending knee. Its amplitude is 2.5-6 mm. Its duration is 0.12-0.16 seconds.

The QT interval is called electrical systole. It reflects the time of excitation and recovery of the ventricular myocardium. The duration of QT varies significantly depending on the heart rate.

In emergency and terminal conditions, standard lead II is usually used for assessment, which allows for better differentiation of a number of quantitative indicators (for example, differentiation of small-wave ventricular fibrillation from asystole).

The second standard lead is used to determine cardiac arrhythmia, lead V5 - to identify ischemia. The sensitivity of the method in identification is 75%, and in combination with the data of lead II it increases to 80%.

Electrocardiographic changes in various pathological conditions will be described in the relevant sections.

Cardiac monitors, devices that constantly record an electrocardiographic curve on the monitor display, have become widely used in emergency care practice. Their use makes it possible to quickly determine heart rhythm disturbances, myocardial ischemia (ST segment depression), and acute electrolyte disorders (primarily K+ changes).

Some cardiac monitors allow computer analysis of the electrocardiogram, in particular the ST segment, which allows for the early detection of myocardial ischemia.

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Pulse oximetry

Pulse oximetry is an informative non-invasive method for continuous assessment of arterial blood hemoglobin oxygen saturation (SpO2) and peripheral blood flow. The method is based on measuring light absorption in the body area under study (earlobe, finger) at the height of the pulse wave, which makes it possible to obtain saturation values close to arterial (along with a plethysmogram and heart rate values).

Oxygen-bound hemoglobin (HbO2) and non-oxygenated hemoglobin (Hb) absorb light of different wavelengths differently. Oxygenated hemoglobin absorbs more infrared light. Deoxygenated hemoglobin absorbs more red light. The pulse oximeter has two LEDs on one side of the sensor that emit red and infrared light. On the other side of the sensor is a photodetector that measures the intensity of the light flux falling on it. The device determines the magnitude of arterial pulsation by the difference between the amount of light absorbed during systole and diastole.

Saturation is calculated as the ratio of the amount of HbO2 to the total amount of hemoglobin, expressed as a percentage. Saturation correlates with the partial pressure of oxygen in the blood (normal PaO2 = 80-100 mm Hg). At PaO2 80-100 mm Hg SpO2 is within 95-100%, at 60 mm Hg SpO2 is about 90%, and at 40 mm Hg SpO2 is about 75%.

Compared with invasive methods of determining blood oxygenation (SaO2), pulse oximetry provides the ability to quickly obtain information, allows you to assess the level of organ blood flow and the adequacy of oxygen delivery to tissues. Pulse oximetry data showing oxyhemoglobin saturation of less than 85% with an oxygen concentration in the inhaled mixture of over 60% indicate the need to transfer the patient to artificial ventilation.

There is now a wide range of portable pulse oximeters, both mains-powered and battery-powered, that can be used at the scene of an accident, at home, or when transporting patients in an ambulance. Their use can significantly improve the diagnosis of respiratory disorders, promptly identify the risk of hypoxia, and take steps to eliminate it.

Sometimes, pulse oximetry does not accurately reflect lung function and PaO2 levels. This is often seen in:

• incorrect placement of the sensor;
• bright external light;
• patient movements;
• decreased perfusion of peripheral tissues (shock, hypothermia, hypovolemia);
• anemia (with hemoglobin values below 5 g/l, 100% blood saturation may be observed even with a lack of oxygen);
• carbon monoxide poisoning (high concentrations of carboxyhemoglobin can give a saturation value of about 100%);
• disturbance of the heart rhythm (changes the pulse oximeter's perception of the pulse signal);
• presence of dyes, including nail polish (which may cause low saturation values). Despite these limitations, pulse oximetry has now become the accepted standard of monitoring.

Capnometry and capnography

Capnometry is the measurement and digital display of the concentration or partial pressure of carbon dioxide in the inhaled and exhaled gas during the patient's respiratory cycle. Capnography is the graphic display of these same indicators in the form of a curve.

Methods for assessing carbon dioxide levels are highly valuable because they allow one to judge the adequacy of ventilation and gas exchange in the patient's body. Normally, the pCO2 level in exhaled air is 40 mm Hg, i.e. approximately equal to alveolar pCO2 and 1-2 mm Hg lower than in arterial blood. There is always an arterial-alveolar gradient of partial CO2 tension.

Typically, in a healthy person, this gradient is 1-3 mm Hg. The difference is due to the uneven distribution of ventilation and perfusion in the lung, as well as blood shunting. If there is lung pathology, the gradient can reach significant values.

The device consists of a gas sampling system for analysis and the analyzer itself.

Infrared spectrophotometry or mass spectrometry are commonly used to analyze the gas mixture. The change in partial pressure of carbon dioxide in the patient's respiratory tract during inhalation and exhalation is graphically displayed by a characteristic curve.

The curve segment AB reflects the flow of CO2-deprived dead space air into the analyzer (Fig. 2.5). Starting from point B, the curve goes up, which

Caused by the inflow of a mixture containing CO2 in increasing concentrations. Therefore, section BC is shown as a curve rising steeply upwards. By the very end of exhalation, the air flow velocity decreases, and the CO2 concentration approaches the value called the end-expiratory CO2 concentration - EtCO2 (section CD). The highest CO2 concentration is observed at point D, where it closely approaches the concentration in the alveoli and can be used for an approximate assessment of pCO2. Segment DE reflects a decrease in concentration in the analyzed gas, caused by the inflow of a mixture with a low CO2 content into the respiratory tract at the beginning of inhalation.

Capnography to a certain extent reflects the adequacy of ventilation, gas exchange, CO2 production and the state of cardiac output. Capnography is successfully used to monitor the adequacy of ventilation. Thus, in case of accidental intubation of the esophagus, unintentional extubation of the patient or obstruction of the endotracheal tube, a marked decrease in the level of pCO2 in the exhaled air is noted. A sudden decrease in the level of pCO2 in the exhaled air most often occurs with hypoventilation, airway obstruction or an increase in dead space. An increase in pCO2 in the exhaled air most often occurs with changes in pulmonary blood flow and hypermetabolic states.

According to the 2010 ERC and AHA guidelines, continuous capnography is the most reliable method for confirming and monitoring endotracheal tube position. There are other methods for confirming endotracheal tube position, but they are less reliable than continuous capnography.

During transport or movement of patients, there is an increased risk of endotracheal tube dislodgement, so rescuers should continually monitor the ventilation rate using a capnogram to confirm endotracheal tube position.

When measuring expired CO2, it is taken into account that blood passes through the lungs, and therefore the capnogram can also act as a physiological indicator of the effectiveness of chest compressions and ROSC. Ineffective chest compressions (due to patient characteristics or caregiver actions) result in low PetCO2 values. A decrease in cardiac output or recurrent cardiac arrest in patients with ROSC also leads to a decrease in PetCO2. Conversely, ROSC can cause a sharp increase in PetCO2.

[ 41 ], [ 42 ], [ 43 ]

Determination of troponin and cardiac markers

Express diagnostics of myocardial infarction is easily performed at the pre-hospital stage using various high-quality test systems for determining "Troponin I". The result is determined 15 minutes after applying blood to the test strip. Currently, express test systems have been created for the diagnosis of myocardial infarction, based on high-quality immunochromatographic detection of several markers at once (myoglobin, CK-MB, Troponin I).

Quantitative determination of cardiac marker concentration is possible using immunochemical express analyzers. These are portable devices (weight 650 g, dimensions: 27.5 x 10.2 x 55 cm), the operating principle of which is based on the use of highly specific immunochemical reactions. The accuracy of the studies is highly comparable with laboratory immunochemical analysis methods. The parameters determined are troponin T (measurement range 0.03-2.0 ng / ml), CK-MB (measurement range 1.0-10 ng / ml), myoglobin (measurement range 30-700 ng / ml), J-dimer (measurement range 100-4000 ng / ml), natriuretic hormone (NT-proBNP) (measurement range 60-3000 pg / ml). The time to obtain the result is from 8 to 12 minutes from the moment of blood collection.

[ 44 ], [ 45 ], [ 46 ], [ 47 ], [ 48 ], [ 49 ], [ 50 ], [ 51 ]

Measuring glucose levels

Standards for providing emergency care to patients with impaired consciousness require measuring blood glucose levels. This study is carried out using a portable glucometer. To use the glucometer, you need a pen for puncturing the skin, sterile lancets and special test strips, a substance

Which reacts with blood. The assessment of the glucose concentration level depends on the type of device. The principle of operation of photometric models is based on the coloring of the indicator area due to the reaction of blood and the active substance. The color saturation is analyzed using a built-in spectrophotometer. Electrochemical devices, on the contrary, measure the strength of the electric current that appears as a result of the chemical reaction of glucose and the enzyme substance of the test strip. Devices of this type are characterized by ease of use, obtaining a quick (from 7 seconds) measurement result. A small amount of blood (from 0.3 µl) is required for diagnostics.

Measurement of blood gases and electrolytes

Express testing of blood gas composition and electrolytes (including at the hospital stage) became possible with the development of portable analyzers. These are mobile and precise devices with easy operation that can be used anywhere and at any time (Fig. 2.9). The speed of measuring the parameters varies from 180 to 270 seconds. The devices have a built-in memory that stores the analysis results, identification number, date and time of the analysis. Devices of this type are capable of measuring pH (ion concentration - activity of H+), partial pressure of CO2 (pCO2), partial pressure of O2 (pO2), concentration of sodium ions (Na+), potassium (K+), calcium (Ca2+), blood urea nitrogen, glucose and hematocrit. The calculated parameters are the concentration of bicarbonate (HCO3), total CO2, base excess (or deficit) (BE), hemoglobin concentration, O2 saturation, corrected O2 (O2CT), the sum of the bases of all blood buffer systems (BB), standard base excess (SBE), standard bicarbonate (SBC), arterial-alveolar O2 gradient, respiratory index (RI), standardized calcium (cCa).

Normally, the body maintains a constant balance between acids and bases. The pH is a value equal to the negative decimal logarithm of the concentration of hydrogen ions. The pH of arterial blood is 7.36-7.44. In acidosis, it decreases (pH < 7.36), in alkalosis it increases (pH> 7.44). pH reflects the ratio of CO2, the content of which is regulated by the lungs, and the bicarbonate ion HCO3, the exchange of which occurs in the kidneys. Carbon dioxide dissolves to form carbonic acid H2CO3, the main acidic component of the internal environment of the body. Its concentration is difficult to measure directly, so the acidic component is expressed through the content of carbon dioxide. Normally, the CO2/HCO3 ratio is 1/20. If the balance is disturbed and the acid content increases, acidosis develops, if the basis PaCO2: partial pressure of carbon dioxide in arterial blood. This is the respiratory component of acid-base regulation. It depends on the frequency and depth of breathing (or the adequacy of mechanical ventilation). Hypercapnia (PaCO2> 45 mmHg) develops due to alveolar hypoventilation and respiratory acidosis. Hyperventilation leads to hypocapnia - a decrease in the partial pressure of CO2 below 35 mmHg and respiratory alkalosis. In case of violations of the acid-base balance, respiratory compensation is activated very quickly, therefore it is extremely important to check the values of HCO2 and pH to find out whether the changes in PaCO2 are primary or they are compensatory changes.

PaO2: partial pressure of oxygen in arterial blood. This value does not play a primary role in the regulation of acid-base balance if it is within the normal range (not less than 80 mmHg).

SpO2: saturation of hemoglobin in arterial blood with oxygen.

BE (ABE): base deficit or excess. Generally reflects the amount of blood buffers. An abnormally high value is characteristic of alkalosis, low values are characteristic of acidosis. Normal value: +2.3.

HCO-: plasma bicarbonate. The main renal component of acid-base balance regulation. Normal value is 24 mEq/l. A decrease in bicarbonate is a sign of acidosis, an increase is a sign of alkalosis.

Monitoring and evaluation of the effectiveness of the therapy

In addition to the initial assessment of the patient's condition, dynamic monitoring is necessary during the treatment, especially during transportation. The adequacy of the therapy should be assessed comprehensively, according to several criteria, and in stages, depending on the stage of intensive care.

Monitoring vital functions of the body over time is an integral technology in emergency medicine practice. In critical conditions, these functions change so quickly that it is very difficult to keep track of all the changes. The resulting disorders are polyfunctional, occur simultaneously and in different directions. And the doctor needs objective and most complete information about the functioning of vital systems in real time to manage and replace the impaired functions. Therefore, it is imperative to introduce standards for monitoring vital functions into the clinical practice of emergency medicine - dynamic control of functional correction and management of vital functions in patients and victims in critical condition.

Monitoring is not only important, but also a fundamentally irreplaceable set of actions, without which effective management of patients in critical conditions is impossible. At the initial stage of providing assistance, it is impossible to carry out most diagnostic measures and modern monitoring of vital functions. Therefore, the assessment of such easily interpretable indicators in any conditions as the level of consciousness, pulse, arterial and central venous pressure, and diuresis come to the forefront for assessing the adequacy of the intensive care provided. These indicators allow us to judge to a sufficient extent the adequacy of the therapy provided in the first hours of the development of an emergency condition.

For example, the adequacy of infusion therapy can be judged by the amount of diuresis. Adequate urine production most likely suggests adequate perfusion of other vital organs. Achieving diuresis within 0.5-1 ml/kg/h indicates adequate renal perfusion.

Oliguria is a decrease in the rate of diuresis to less than 0.5 ml/kg/h. Urine output less than 50 ml/h indicates decreased tissue and organ perfusion, less than 30 ml/h indicates the need for urgent restoration of peripheral blood flow.

With anuria, the volume of diuresis per day is less than 100 ml.

In the event of the development of cerebral insufficiency in a patient, dynamic monitoring of the level of consciousness, the appearance of general cerebral symptoms, dislocation syndrome, etc. is of great importance.