First aid algorithm for electromechanical dissociation. Manifestation and causes of electromechanical dissociation. Adrenaline administration regimens

Electromechanical dissociation (EMD) is a type of circulatory arrest in which there is no mechanical response of myocardiocytes, despite preserved electrical activity of the heart. Clinically, in the absence of a pulse in the carotid arteries and the presence of other signs of OK, sinus bradycardia, other bradyarrhythmias, usually idioventricular rhythm with wide QRS can be seen on the ECG (Fig. 3).

Causes of EMD are:

· Severe hypovolemia (most common cause);

Hypoxia (inadequate ventilation, tension pneumothorax);

· Massive pulmonary embolism;

· Cardiac tamponade;

· Acidosis;

· Hyperkalemia.

At the prehospital stage, some of the indicated causes of EMD are irreversible (massive pulmonary embolism, traumatic injuries of the heart and aorta), a number of other causes make EMD a conditionally reversible condition if they are diagnosed simultaneously with resuscitation and can be eliminated (for example, intensive infusion therapy).

The duration of clinical death, as a reversible condition, accepted by International standards for resuscitation, is no more than 5 minutes, according to the Order of the Ministry of Health of the Russian Federation (No. 93, 04.03.03) 4-7 minutes, with hypothermia up to 1 hour.

Arrest of blood circulation with preserved electrical activity of the heart, different from its variants described above, is called electromechanical dissociation (EMD, electrical activity without a pulse). Common causes of EMD include:

§ final anaphylactic, hemorrhagic and other types of shock;

§ decompensated acidosis;

§ hypokalemia;

§ tension pneumothorax with mediastinal displacement;

§ pericardial tamponade;

§ atrial myxoma.

From a tactical point of view, EMD is very similar to the bradyarrhythmic variant of circulatory arrest, with the only significant difference that it often has a completely removable extracardiac cause. Assistance for EMD should begin with basic CPR and maintaining vascular tone by administering 1 mg of adrenaline every 3–5 minutes. Without interrupting these measures, it is necessary to try to carry out a differential diagnosis of the cause of EMD, without which “targeted” therapy for this condition is impossible.

If CPR is successfully completed, maintenance therapy must be continued immediately after restoration of the heart rhythm. In most cases, catecholamine support is required, the pace of which is selected individually. For recurrent VF or tachyarrhythmia, supportive care may include:

§ Amiodarone: maximum total dose of 2200 mg over 24 hours. Start of administration - rapid infusion of 150 mg intravenously over 10 minutes (15 mg × min -1), followed by a slow infusion of 360 mg over 6 hours (1 mg × min -1 ). Then a maintenance infusion of 540 mg over 18 hours (0.5 mg×min –1). Monitoring of heart rate and blood pressure is necessary, since bradycardia and hypotension are possible.

§ Lidocaine: saturating dose of 1–1.5 mg×kg –1 to a total dose of 3 mg×kg –1 (if lidocaine was not administered before), then a continuous infusion at a rate of 1–4 mg×min –1.

§ Novocainamide: infusion at a rate of 20 mg×min –1 until the arrhythmia is relieved, the QT is prolongated by more than 50% of the original or a dose of 17 mg×kg –1 is reached. If necessary, it is possible to increase the rate of administration to 50 mg×min –1 (up to a total dose of 17 mg×kg –1). Maintenance infusion is carried out at a rate of 2–5 mg×min –1.

It must be remembered that the final success of CPR depends not only on the knowledge and skills of each of its participants, but also on the clarity of the organization, the ability and desire to work in one team.

Electromechanical dissociation- absence of mechanical activity of the heart in the presence of electrical activity (i.e. ECG on the monitor, in the clinic of circulatory arrest). The prognosis is often poor.

The causes of EMD are hypovolemia, hypoxia, acidosis, severe hyperkalemia, hypothermia, massive pulmonary embolism, valvular pneumothorax, cardiac tamponade, overdose of certain medications, or an unacceptable combination of them (for example, intravenous administration of b-blockers and calcium antagonists).

EMD is often observed after late electrical pulse therapy for ventricular fibrillation or flutter due to depletion of myocardial energy reserves (with VF, the energy consumption in the myocardium is even greater than during normal heart function).

Tactics for electromechanical dissociation

1. Basic resuscitation measures(artificial respiration, cardiac massage; if possible, intubation and mechanical ventilation with increased oxygen content).
2. Adrenalin 1 mg IV, repeated every 3-5 minutes. If there is no effect, the dose is increased. If venous access is not established, adrenaline can be administered endotracheally at a dose of 2-2.5 mg.
3. Identification and elimination causes of electromechanical dissociation.

4. Administration of fluid in case of hypovolemia, as well as in each case of electromechanical dissociation, not eliminated by adrenaline.
5. Atropine for severe bradycardia.
6. Sodium bicarbonate (exclude alkalosis), in case of prolonged circulatory arrest, or immediately if the presence of acidosis is known (severe acidosis leads to total vasodilation and decreased contractility that cannot be eliminated by sympathomimetics).

7. Maintenance therapy - vasopressor drugs. The drug of choice is dopamine (dopamine, dopmin). Dopamine is a unique drug. By changing the infusion rate, it is possible to selectively influence dopaminergic, b-, and a-adrenergic receptors. When administered at a rate of up to 2 mcg/kg/min. The dopaminergic effect predominates (dilation of the renal vessels), 2-10 mcg/kg/min. -stimulation of predominantly beta-adrenergic receptors of the heart, more than 10 mcg/kg/min - a-adrenergic receptors (vasoconstriction); 15-20 mcg/kg/min. - pronounced cardiotonic and vasopressor effect. Dopamine, unlike adrenaline, isuprel, etc., increases the myocardial oxygen demand to a lesser extent. Adrenaline, in the form of an infusion of 2-10 mcg/min, is indicated for severe bradycardia and in case of dopamine ineffectiveness.
8. Glucocorticosteroids- prednisolone 90-120 mg (or the equivalent of another corticosteroid) helps restore the sensitivity of the myocardium to sympathomimetics.

Restoration of blood circulation during electromechanical dissociation is carried out taking into account its cause, since only its elimination allows restoration of cardiac output. All etiological factors contributing to the occurrence of electromechanical dissociation can be divided into three main groups:

1. “empty heart”, when the blood flow to the right, and with them to the left, is significantly reduced;
2. “small circle blockade”, when blood from the right side does not flow to the left;
3. “heart weakness”, when both the blood flow to the heart and its entry into the left sections are not impaired, but myocardiocytes are not able to perform mechanical work.

If electromechanical dissociation is caused by critical hypovolemia, the main therapeutic measure of the first stage of stage II cardiopulmonary resuscitation is vascular filling. For this purpose, crystalloid solutions and solutions of hydroxyethyl starch are used. At the same time, ensuring globular blood volume fades into the background.

When the heart is compressed during tamponade, the therapeutic measure is puncture of the pericardial cavity with aspiration of the contents. In case of tension pneumothorax, it is necessary either to unload it using constant aspiration of the contents of the pleural cavity, or to convert a closed tension pneumothorax into an open one. If there is a sharp decrease in vascular tone, a drip infusion of vasoconstrictor drugs, for example, norepinephrine, is performed. The starting infusion rate for this drug is 2 mcg/min. If necessary, increase the speed. It must be remembered that norepinephrine is injected only into large veins, because pronounced spasm of the microvessels of the vascular wall can lead to its necrosis.

Electromechanical dissociation, caused by pulmonary embolism, requires the use of thrombolytic therapy using medications containing streptokinase, for example, streptolyase. The drug is administered at a rate of 30 drops per minute at a dose of 250,000 units in 50 ml of isotonic sodium chloride solution, then 10,000 units/hour for 4-8-12 hours. The total dose of streptolyase is 500,000-1,000,000 units. For the same purpose, rt-PA (recombinant tissue plasminogen activator) is used intravenously for 3-6 hours.

If the cause of electromechanical dissociation is acute heart failure, cardiotonic drugs are used, primarily adrenaline hydrochloride, dopamine and dobutrex. All three drugs are administered by drip, starting with a minimum dose, the infusion rate is increased until the effect is achieved, but not higher than the maximum dose. Adrenaline hydrochloride can be administered as a bolus of 1 mg every 5 minutes.

Based on materials from L.V. Usenko

ECG waves and intervals

Action potential

Adrenaline administration regimens

Asystole

Ventricular fibrillation

Ventricular fibrillation

10. Ventricular fibrillation

11. Ventricular fibrillation

12. Ventricular fibrillation

13. Ventricular fibrillation

14. Pulseless ventricular tachycardia

15. Torsades de pointes

16. Ideoventricular rhythm

17. Electromechanical dissociation

18. Electromechanical dissociation

19. Electromechanical dissociation

20. Electromechanical dissociation

Electromechanical dissociation of the heart is classified as a cardiac pathology. In this condition, the heart cannot contract on its own. This diagnosis is most often made to hospital patients. In such a situation, it is necessary to urgently resuscitate the patient. If this is not done, death may occur.

Electromechanical dissociation (EMD, EALD, ineffective electrical activity of the heart or impaired pumping function with preservation of electrical activity) is a type of cessation of blood flow in which there is no mechanical response of myocardiocytes, even though the electrical activity of the heart is preserved.

There is no pulse in the carotid artery, but the ECG can show the presence of sinus bradycardia, other bradyarrhythmias, usually an idioventricular rhythm with a wide QRS.

EABP characterizes the presence of an electrical impulse in the heart against the background of circulatory arrest. In this state, it is impossible to feel the pulse, and the pressure drops to a critical level (30-40 millimeters of mercury). In all organs and systems there is a cessation of nutrition.

In other words, electrical activity remains in the heart, but its mechanical contraction is insufficient to ensure proper blood circulation.

A number of reasons causing pathology

The main reasons due to which pathology develops and cardiac contractions stop include the following:

With myocardial rupture and cardiac muscle tamponade, a sudden development of electromechanical dissociation is observed, occurring without convulsive symptoms. However, cardiac and pulmonary resuscitation is largely ineffective. EMD caused by other reasons does not have a sudden onset. It increases gradually against the background of the development of symptoms of the underlying disease.

Before hospitalization, some of the listed causes of EMD are irreversible (eg, cardiac injury). Caused by some other causes, EMD can be conditionally reversible if they are diagnosed and eliminated along with resuscitation efforts. Patients who have reversible pathologies quickly identified and corrected have a greater chance of survival.

Signs

The main signs of EMD include the absence or sharp decrease in the number of myocardial contractions. To identify pathology, we focus on the following signs detected during the diagnostic process:

Diagnostics

Since cardiac arrest is an emergency, the pathology should be diagnosed as quickly as possible. In such circumstances, time is counted in minutes. For EMD, standard measures that take a lot of time are not suitable. Diagnosis in this case consists of:

Therapy

A number of therapeutic measures performed by physicians for EALD include the following:

Risks and forecasts

The prognosis for patients with pumping dysfunction with preserved electrical activity is not the best. High probability of death. This is especially true in cases where doctors were unable to ensure timely identification and correction of reversible factors.

There is a relationship between the electrocardiogram readings and the prognosis of the patient's condition. The higher the rate of abnormalities on the ECG, the less chance the patient has of recovering from electromechanical dissociation.

People suffering from numerous chronic diseases have weakened bodies. For this reason, it is more difficult for them to cope with this cardiac pathology.

Prevention

Preventive measures include the following:

In situations involving the occurrence of EMD, every minute counts. Any delay in time is fraught with serious consequences for the patient, including death. Due to brain hypoxia, the patient may remain disabled, even if resuscitation measures have given positive results.