Cardiopulmonary resuscitation

Cardiopulmonary resuscitation is an organized, sequential procedure for managing circulatory arrest that includes assessment of circulatory and respiratory failure, basic life support (BLS) with chest compressions and artificial respiration, advanced cardiac life support (ACLS), and postresuscitation care.

Speed, efficiency, and correct performance of cardiopulmonary resuscitation determine a favorable neurological outcome. Rare exceptions are cases of profound hypothermia, when resuscitation measures were successful after a long period of circulatory arrest.

After confirmation of the absence of consciousness and breathing, a set of measures to support vital functions begins - maintaining the patency of the airways, breathing and blood circulation (ABC). In the presence of ventricular fibrillation (VF) or ventricular tachycardia (VT), defibrillation (D) is performed to restore normal heart rhythm.

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Maintaining airway patency and breathing

Ensuring airway patency is a priority.

Mouth-to-mouth resuscitation (in adults and children) or mouth-to-mouth-and-nose (in infants) should be initiated immediately. Regurgitation of gastric contents should be prevented by cricoid pressure until tracheal intubation has been achieved. In children, pressure should be moderate to avoid tracheal compression. Insertion of a nasogastric tube should be delayed until suction is established, as this procedure may cause regurgitation and aspiration of gastric contents. If ventilation causes significant gastric distension that cannot be relieved by the above methods, the patient is placed in a lateral position, epigastric pressure is applied, and the airway is monitored.

Defibrillation should not be delayed until tracheal intubation has been achieved. Chest compressions should be continued during tracheal preparation and intubation.

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Circulation

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Closed heart massage

In case of sudden loss of consciousness and collapse, it is necessary to immediately begin closed cardiac massage and artificial respiration. If defibrillation is possible during the first 3 minutes after circulatory arrest, it should precede closed cardiac massage.

Cardiopulmonary resuscitation technique

	One rescuer	Two rescuers	Inspiratory volume
Adults	2 breaths (1 sec each) after 30 shocks at a frequency of 100/min	2 breaths (1 sec each) after 30 shocks at a frequency of 100/min	Each breath is about 500 ml (avoid hyperventilation)
Children (1-8 years)	2 breaths (1 sec) after every 30 shocks at a frequency of 100/min	2 breaths (1 sec) after every 15 shocks at a frequency of 100/min	Smaller than in adults (enough to raise the chest)
Infants (up to one year)	2 breaths (1 sec) after every 30 shocks at a frequency of 100/min	2 breaths (1 sec) after every 15 shocks at a frequency of 100/min	Small breaths equal to the volume of the operator's mouth

When ensuring reliable patency of the airways, 8-10 breaths/min are performed without a break for closed cardiac massage.

Ideally, a pulse should be palpable during closed-chest cardiac massage, even though cardiac output is only 30-40% of normal. However, palpation of the pulse during cardiac massage is difficult. Monitoring of exhaled CO2 (etCO2) concentration provides a more objective assessment of cardiac output; patients with inadequate perfusion have low venous return to the lungs and correspondingly low etC0 ₂. Normal-sized pupils with preserved photoreactivity indicate adequate cerebral circulation and oxygenation. Preserved photoreactivity with dilated pupils indicates inadequate cerebral oxygenation, but irreversible brain damage may not yet have occurred. Persistently dilated pupils without a response to light also do not indicate brain injury or death, since high doses of cardiotonics and other drugs and the presence of cataracts can alter pupil size and response. Restoration of spontaneous breathing or opening of the eyes indicates restoration of blood circulation.

Unilateral chest compression may be effective, but it is contraindicated in patients with penetrating chest injury, cardiac tamponade, and during thoracotomy and cardiac arrest (in the operating room).

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Medicines for specialized cardiac care

Despite widespread and well-established use, no drug has improved hospital survival for patients with cardiac arrest. Some drugs help restore circulation and are therefore useful.

In patients with peripheral venous access, the administration of drugs is carried out against the background of bolus administration of fluids (in adults, a jet drip is opened; 3-5 ml in children), this is necessary for the drug to enter the central bloodstream. In patients without intravenous and intraosseous access, atropine and epinephrine can be administered into an endotracheal tube at a dose 2-2.5 times higher than the intravenous dose.

First-line drugs. Norepinephrine is the main drug used in cardiac arrest, but there is increasing evidence of its ineffectiveness. Typically, its administration is repeated every 3-5 minutes. Norepinephrine is an a- and b-adrenergic agonist. The a-adrenergic effect increases coronary diastolic pressure and subendocardial perfusion during cardiac massage, increasing the likelihood of effective defibrillation. The b-adrenergic effect is unfavorable, since it increases the myocardial oxygen demand and causes vasodilation. Intracardiac administration of norepinephrine is not recommended due to the risk of complications in the form of pneumothorax, coronary vessel damage, and cardiac tamponade.

A single dose of 40 U vasopressin may be an alternative to norepinephrine (in adults only); however, its use prior to norepinephrine administration is not considered justified.

Atropine has a vagolytic effect, increases heart rate and conduction in the atrioventricular node. It is used for asystole (except in children), bradyarrhythmia and high-grade atrioventricular block, but its effect on patient survival has not been proven.

Amiodarone is given as a single dose if defibrillation is ineffective after administration of norepinephrine or vasopressin. Amiodarone may be effective if VF or VT recur after cardioversion; in this case, a reduced dose is given again after 10 minutes, and then the drug is given as a continuous infusion.

Medicines used in cardiopulmonary resuscitation

Medicines	Dosages for adults	Doses for children	Comment
Adenosine	6 mg, then 12 mg (2 times)	0.1 mg/kg, then 0.2 mg/kg (2 times) Maximum dose 12 mg	Intravenous bolus with infusion of solutions, maximum dose 12 mg
Amiodarone for VF/VT (with unstable hemodynamics)	300 mg	5 mg/kg	Intravenous jet infusion over 2 minutes
In VT (with stable hemodynamics	150 mg immediately, then drip infusion: 1 mg/min for 6 hours, then 0.5 g/min for 24 hours	5 mg/kg for 20-60 min May be repeated, but do not exceed 15 mg/kg/day	The first dose is administered intravenously over 10 minutes.
Amprinon	Immediately 0.75 mg/kg over 2-3 minutes, then drip infusion 5-10 mcg/kg/min	Immediately 0.75-1 mg/kg for 5 min, can be repeated up to 3 mg/kg, then infusion: 5-10 mcg/kg/min	500 mg in 250 ml of 0.9% NaCI solution, infusion rate 2 mg/ml
Atropine	0.5-1 mg 1-2 mg Endotracheally	0.02 mg/kg	Repeat after 3-5 minutes until effect is achieved or total dose is 0.04 mg/kg; minimum dose is 0.1 mg
Ca chloride	1g	20 mg/kg	10% solution contains 100 mg/ml
Glycerate	0.66 g	Not applicable	22% solution, 220 mg/ml
Gluconate	0.6 g	60-100 mg/kg	10% solution contains 100 mg/ml
Dobutamine	2-20 mcg/kg/min; start with 2-5 mcg/kg/min	Also	500 mg in 250 ml 5% glucose contains 2000 mcg/ml
Dopamine	2-20 mcg/kg/min; start with 2-5 mcg/kg/min	Also	400 mg in 250 ml 5% glucose contains 1600 mcg/ml
Norepinephrine Bolus	1 mg	0.01 mg/kg	Repeat after 3-5 minutes At Necessities
Endotracheally	2-2.5 mg	0.01 mg/kg	8 mg in 250 ml 5% glucose - 32 mcg/ml
Infusion	2-10 mcg/min	0.1-1.0 mcg/kg/min
Glucose	25 g in 50% solution	0.5-1 g/kg	Avoid high concentrations: 5% solution - 10-20 ml/kg; 10% solution - 5-10 ml/kg 25% solution - 2-4 ml/kg (for older children, into large veins)

Other drugs. Calcium chloride solution is recommended for patients with hyperkalemia, hypermagnesemia, hypocalcemia and in case of overdose of calcium channel blockers. In other cases, when the concentration of intracellular calcium already exceeds the norm, additional calcium administration is contraindicated. Cardiac arrest in patients on hemodialysis occurs as a result of or against the background of hyperkalemia, so calcium administration is indicated if it is not possible to immediately determine the potassium level. When administering calcium, it is necessary to remember that it increases the toxicity of digitalis preparations, which can cause cardiac arrest.

Magnesium sulfate does not improve resuscitation outcomes in randomized trials. However, it may be useful in patients with hypomagnesemia (due to alcoholism, prolonged diarrhea).

Procainamide is a second-line drug for the treatment of refractory VF or VT. It is not recommended for use in children with unstable hemodynamics.

Phenytoin is rarely used in the treatment of VF or VT unless these rhythm disturbances are caused by digitalis intoxication or are unresponsive to other medications.

NaHC0 ₃ is no longer recommended for use except in cases of circulatory arrest caused by hyperkalemia, hypermagnesemia or overdose of tricyclic antidepressants with complex ventricular arrhythmias. In pediatric practice, it is prescribed if cardiopulmonary resuscitation continues for more than 10 minutes, provided that ventilation is good. When using NaHC0 _3, it is necessary to measure the pH of arterial blood before the start of the infusion and after every 50 mEq (1-2 mEq/kg for children).

Lidocaine and bretylium are no longer used in CPR.

Treatment of rhythm disturbances

VF/VT with unstable hemodynamics. Defibrillation is performed once. The recommended discharge strength for a biphasic defibrillator is 120-200 J, for a monophasic defibrillator - 360 J. If cardioversion is unsuccessful, 1 mg of norepinephrine is administered intravenously and the procedure is repeated after 4-5 minutes. 40 U of vasopressin can be administered intravenously once instead of epinephrine (not allowed in children). Cardioversion is repeated with the same strength 1 minute after the drug administration (the justification for increasing the discharge strength for a biphasic defibrillator has not been established). If VF continues, 300 mg of amiodarone is administered intravenously. If VF/VT resumes, a 6-hour amiodarone infusion is started at a dose of 1 mg/min, then 0.5 mg/min.

Asystole. To exclude error, it is necessary to check the contacts of the ECG monitor electrodes. If asystole is confirmed, a transcutaneous pacemaker is installed and 1 mg of norepinephrine is administered intravenously, repeated after 3-5 minutes, and 1 mg of atropine intravenously, repeated after 3-5 minutes, to a total dose of 0.04 mg/kg. Electrical pacing is rarely successful. Note: atropine and pacing are contraindicated in pediatric practice for asystole. Defibrillation is unacceptable in case of proven asystole, since the electrical discharge damages the nonperfused myocardium.

Electrical dissociation is a condition in which blood circulation in the body stops despite satisfactory cardiac complexes on the ECG. In case of electrical dissociation, it is necessary to administer intravenously as a rapid infusion 500-1000 ml (20 ml/kg) of 0.9% NaCl solution and 0.5-1.0 mg of norepinephrine, which can be administered again after 3-5 minutes. If the heart rate is less than 60 per minute, 0.5-1.0 mg of atropine is administered intravenously. Cardiac tamponade causes electrical dissociation in case of exudative pericarditis or severe chest trauma. In this case, it is necessary to perform pericardiocentesis immediately.

Termination of resuscitation measures

Cardiopulmonary resuscitation is continued until spontaneous circulation is restored, death is declared, or one person is physically unable to continue CPR. In hypothermic patients, CPR should be continued until the body temperature rises to 34 °C.

Biological death is usually declared after an unsuccessful attempt to restore spontaneous circulation within 30-45 minutes of cardiopulmonary resuscitation and specialized cardiac care. However, this assessment is subjective, despite the fact that it takes into account the duration of the period of absence of circulation before treatment, age, previous condition and other factors,

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Providing assistance after successful resuscitation

Restoration of spontaneous circulation (ROSC) is only an intermediate goal of resuscitation measures. Only 3-8% of patients with ROS survive to hospital discharge. To maximize the outcome, it is necessary to optimize physiological parameters and take measures to treat concomitant diseases. In adults, it is especially important to recognize myocardial infarction and begin reperfusion therapy (thrombolysis, percutaneous transluminal coronary angioplasty) as soon as possible. It is important to remember that thrombolysis after aggressive CPR can lead to cardiac tamponade.

Laboratory studies after CPR include arterial blood gases, complete blood count (CBC), and serum chemistry including electrolytes, glucose, blood urea nitrogen, creatinine, and markers of myocardial injury (CK will usually be elevated due to skeletal muscle injury during CPR). Arterial PaO2 should be maintained within normal limits (80-100 mmHg), Hct slightly above 30%, glucose 80-120 mg/dL, and electrolytes, especially potassium, within normal limits.

Stabilization of blood pressure. The mean arterial pressure (MAP) should be 80 mmHg in elderly patients or more than 60 mmHg in young and previously healthy people. In patients with hypertension, the target systolic BP should be 30 mmHg lower than the pressure that could have been before the circulatory arrest.

In patients with low MAP or evidence of left ventricular failure, pulmonary artery catheterization may be required to monitor cardiac output, pulmonary artery occlusion pressure (PAOP), and mixed venous O2 saturation (an assessment of peripheral perfusion) to optimize drug therapy. Mixed venous O2 saturation should be greater than 60%.

In patients with low MAP, low CVP or PAWP, hypovolemia should be corrected with discrete administration of 250 ml of 0.9% NaCl solution. In elderly patients with moderately decreased MAP (70-80 mm Hg) and normal or increased CVP/PAWP, it is advisable to start inotropic support with dobutamine, starting with a dose of 2-5 mcg/kg/min. Milrinone or amrinone can be used. If there is no effect, a drug with dose-dependent inotropic and vasoconstrictor action - dopamine. Alternatives are adrenaline and peripheral vasoconstrictors norepinephrine and phenylephrine. Vasoactive drugs should be used in minimal doses that allow maintaining MAP at the minimum acceptable level, because they can increase vascular resistance and reduce organ perfusion, especially in the intestine. These drugs increase the load on the heart with its reduced reserves. If MAP remains below 70 mmHg in patients with myocardial infarction, intra-aortic balloon pumping should be performed. Patients with normal MAP and high CVP/PAWP are treated with either inotropic agents or afterload reduction with nitroprusside or nitroglycerin.

Intra-aortic balloon counterpulsation is used when cardiac output is low due to decreased left ventricular pump function refractory to medical treatment. A balloon catheter is advanced through the femoral artery retrogradely into the thoracic aorta distal to the left subclavian artery. The balloon is inflated during each diastole, improving coronary perfusion, and deflated during systole, reducing afterload. The value of this technique is that it allows time to be gained in cases where the cause of heart failure can be corrected surgically.

Treatment of arrhythmia. Although VF or VT may recur after CPR, antiarrhythmic drugs are not given prophylactically because they do not improve outcome. In principle, such arrhythmia can be treated with procainamide or amiodarone as described above.

Postresuscitation supraventricular tachycardia with high levels of endogenous and exogenous catecholamines requires treatment if it is prolonged and associated with hypotension or signs of coronary ischemia. For this purpose, intravenous esmolol infusion is prescribed, starting with a dose of 50 mcg/kg/min.

Patients who have cardiac arrest due to VF or VT without myocardial infarction are candidates for an implantable cardioverter defibrillator (ICD). This device recognizes the arrhythmia and either defibrillates or maintains a predetermined rhythm.

Neurological support. CNS dysfunction occurs in 8-20% of adults who have had a cardiac arrest. Brain damage is the result of direct ischemic action on neurons and edema.

Damage may develop 48-72 hours after CPR.

Maintaining adequate oxygenation and cerebral perfusion may reduce the likelihood of cerebral complications. Hyperglycemia should be avoided as it may increase postischemic brain injury. Glucose administration should be avoided except in cases of hypoglycemia.

There is no convincing evidence for the benefit of moderate hypothermia. The use of numerous pharmacological agents (antioxidants, glutamate inhibitors, calcium channel blockers) is of high theoretical interest. Their effectiveness has been demonstrated in animal models, but has not been confirmed in human studies.

Pediatric Cerebral Manifestation Category Scale

Points	Category	Description
1	Norm	Mental development is age appropriate
2	Mild disorders	Minimal neurological impairment that is controlled and does not interfere with daily functioning. Preschool-aged children have minimal developmental delay, but more than 75% of daily functioning checkpoints are above the 10th percentile. Children attend regular school but are in an age-appropriate grade, or children complete an age-appropriate grade but fail because of cognitive impairment.
3	Moderate disorders	Severe neurological impairment that is uncontrolled and affects daily life. Most daily functioning benchmarks are below the 10th percentile. Children attend special school due to cognitive impairment.
4	Severe disorders	Preschool-aged children have daily activity scores below the 10th percentile and are highly dependent on others for daily living. School-aged children are unable to attend school and are dependent on others for daily living. Abnormal motor activity in preschool-aged and school-aged children may include non-purposeful, decorticative, or decerebrate responses to pain.
5	Coma or vegetative state	Unconscious state
6	Death

'The category is based on the worst manifestation of any criterion. Only neurological disorders are considered. Conclusions are made only on the basis of medical records or the words of the guardian.

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Complications of closed cardiac massage

Liver injury is the most severe (sometimes fatal) complication, usually occurring when chest compression is applied below the sternum. Rupture of the stomach is rare, usually when the stomach is distended with air. Rupture of the spleen is rare. More common is regurgitation and aspiration of gastric contents, followed by aspiration pneumonia, which can be fatal.

Rib fractures are sometimes unavoidable because the shocks must be deep enough to ensure adequate blood flow. Children rarely have fractures because of the elasticity of the rib cage. Lung tissue damage is rare, but pneumothorax may occur with rib fractures. Heart injuries are rare without cardiac aneurysm. The risk of these complications is not a reason to refuse CPR.

Monitoring and intravenous access. ECG monitoring is established. Intravenous access is established; having two vascular accesses reduces the likelihood of its loss during CPR. Peripheral venous access is preferred with a large-bore forearm catheter. If peripheral access is not possible in adults, central venous access (subclavian or internal jugular vein) should be established. Intraosseous and femoral access are preferred in children. Insertion of a long femoral venous catheter that is advanced into a central vein is very practical since it does not require interruption of CPR, but this procedure is complicated by the inability to palpate the femoral artery pulsation. The type of infusion solution and its volume depend on the clinical situation. Slow infusion of normal saline is usually used to maintain open vascular access. In hypovolemia, large volumes of crystalloids, colloids, and blood products are recommended.

Defibrillation

The most common arrhythmia during cardiac arrest is VF; cardioversion should be performed as soon as possible. VT with ineffective hemodynamics is treated in the same way as VF.

In the absence of defibrillation, a precordial blow is used. A strong precordial blow is rarely effective and is not recommended for children. One or two blows are delivered to the border of the middle and lower third of the sternum with a clenched fist from a height of 20-25 cm above the sternum.

Defibrillation is more effective than antiarrhythmic drugs; although its effectiveness decreases by 10% with each minute. The contact electrodes of the defibrillator are placed between the clavicle and the second intercostal space to the right (from the operator) of the sternum and on the apex of the heart in the 5th or 6th intercostal space. When applying the electrodes, a conductive paste or gel is used; some defibrillators have the conductive material already built into the electrodes. Cardioversion is performed once (previously, 3 times were recommended). The discharge energy for biphasic defibrillators is 120-200 J (2 J/kg for children); for monophasic ones - 360 J. Immediately after cardioversion, the heart rhythm is not assessed; this is done after 2 minutes of cardiopulmonary resuscitation; with constant monitoring, this can be done earlier. Each successive discharge is produced with energy of the same or greater power (maximum 360 J, 2-4 J/kg in children). If VF or VT persists, drug therapy is administered.

Special circumstances

In the event of an electric shock, it is necessary to ensure that the patient is not in contact with the source of electricity. To do this, it is necessary to move the victim to a safe place with any non-metallic object in order to begin cardiopulmonary resuscitation.

In drowning cases, artificial respiration can be started in shallow water, while effective cardiac massage requires placing the person on a hard surface.

If the circulatory arrest occurs after an injury, breathing must first be restored. Movements in the cervical spine should be minimal, without throwing the head back and pushing the jaw forward. In most cases of severe injury, closed cardiac massage will not be effective due to significant blood loss or brain damage incompatible with life. In case of cardiac tamponade or tension pneumothorax, decompression with a needle must be performed immediately, otherwise all resuscitation measures will be ineffective.

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