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VERIFIED CONTENTAuthor: lek. Katarzyna Banaszczyk

ECMO stands for extracorporeal blood oxygenation. During the current COVID-19 pandemic, we often hear about the use of ECMO in the treatment of patients. What is this procedure and what are its types? When are there indications for extracorporeal circulation?

ECMO- from the English language Extracorporeal Membrane Oxygenation - is extracorporeal blood oxygenation, i.e. a process involving oxygenation (oxygenation) of blood, i.e. saturating it with oxygen, and additionally cleaning it from carbon dioxide.

A special blood oxygenator is used for this process. Thanks to its use, gas exchange is possible - only that it does not take place in the patient's lungs, but outside his body. ECMO is used in patients whose lungs are so insufficient that they are unable to carry out gas exchange on their own and to meet the oxygen needs of tissues and cells.

The ECMO system, which allows for gas exchange, consists of several parts, which mainly include:

  • special cannulas - enable the connection of the patient's circulatory system with the equipment,
  • pump - drives the blood movement,
  • oxygenator - mentioned above, is responsible for oxygenating the patient's blood.

ECMO - types of extracorporeal blood oxygenation

Typical extracorporeal blood oxygenation takes blood from the patient's venous system - oxygenated blood also returns to the veins, which is called veno-venous ECMO.

There is also venous-arterial ECMO - they are used in patients who need not only respiratory support, but also circulation support. In this case, blood is drawn from the venous system, and after it is oxygenated, it is transferred to the arterial system.

Extracorporeal blood oxygenation - indications for use

The main indication for connecting the patient to extracorporeal circulation is acute respiratory failure, which is potentially reversible, i.e. the patient has the prognosis to regain normal respiratory function of the lungs.

Respiratory failure is a condition in which there is a significant decrease in the concentration of oxygen in the blood (i.e. hypoxemia in the medical language). It is respiratory failurepartial.

If there is also an increase in the concentration of carbon dioxide in the blood (hypercapnia), this condition is called complete respiratory failure. The consequence of respiratory failure is tissue hypoxia, which leads to multi-organ failure, and eventually to the patient's death.

A special indication for extracorporeal blood oxygenation is acute respiratory distress syndrome (ARDS) - it is a form of acute respiratory failure described above.

ARDS is not caused by heart disease or heart failure. Lung damage in the ARDS mechanism is most often due to infection (sepsis), injuries, drowning, but also due to the severe course of the COVID-19 disease.

It is worth mentioning that ECMO is also used during cardiac surgery, for example during bypass surgery, or when planning a heart transplant.

Respiratory failure and ARDS - clinical symptoms

It is worth mentioning here about the symptoms presented by patients with respiratory failure. It should be mentioned here above all:

  • severe breathlessness,
  • cough,
  • fever,
  • chest pain,
  • hemoptysis,
  • cyanosis - a bluish color of the skin,
  • tachycardia - i.e. increased heart rate, typically>100 beats per minute,
  • tachypnoe - increasing the breathing rate,
  • increased work of the respiratory muscles (diaphragm, intercostal muscles),
  • paradoxical breathing movements of the chest wall and abdominal wall.

Extracorporeal blood oxygenation - contraindications to ECMO

Unfortunately, in a situation of respiratory failure, not every patient can be qualified for the use of ECMO. Situations that disqualify from this form of respiratory support are:

  • severe systemic conditions such as decompensated heart failure
  • severe immunosuppression - that is, a decrease in the patient's immunity, which may result, for example, from HIV infection or the use of immunosuppressive therapy (drugs),
  • intra-pelvic bleeding - it is a contraindication to the administration of heparin, i.e. an anticoagulant (heparin is typically administered in a continuous infusion),
  • irreversible damage to the lungs or other organs - no prognosis of improvement, despite the use of ECMO, this applies to patients with advanced respiratory diseases such as pulmonary fibrosis or COPD (chronic obstructive pulmonary disease),
  • patient's disagreement to connect toextracorporeal circulation,
  • age criterion - over 65,
  • long-term mechanical lung ventilation (more than 7-10 days under a respirator).

ECMO in newborns - when is it indicated?

Extracorporeal circulation can also be used in newborns with respiratory failure and / or cardiovascular failure. To use ECMO, certain conditions must be met, including:

  • child's weight over 2000 g,
  • completed fetal age - 35th week of pregnancy,
  • presence of a treatable disease,
  • consent by the legal guardians of the child.

The most common medical conditions that lead to the need to connect a newborn to the ECMO are:

  • RDS - a syndrome of breathing disorders, manifested in a child with cyanosis, increased respiratory rate, tachycardia, as well as grunting and visualization of the work of additional respiratory muscles. RDS has many causes, including pneumonia and cardiovascular disease,
  • persistent pulmonary hypertension - its essence is the maintenance of blood circulation in the child after birth, which is characteristic during fetal life - then the vessels in the lungs do not open and blood circulation in this area does not start, this phenomenon applies to about 1-2 in 1,000 newborns,
  • diaphragmatic hernia - it is a congenital defect, which consists in the presence of a defect in the diaphragm, which in turn may lead to the displacement of the abdominal organs to the chest (the diaphragm separates these two spaces),
  • congenital pneumonia - predisposing to this is frequent urinary tract infections in the mother, fever and respiratory infection in the mother before delivery, premature drainage of amniotic fluid, as well as prolonged labor,
  • meconium aspiration syndrome - also called meconium aspiration syndrome, meconium about the first table excreted by the child after birth. It happens that a child will donate meconium during its intrauterine life, which predisposes it to enter the respiratory system. This may disturb the patency of the bronchioles and damage the alveoli.

ECMO in COVID-19 disease

Although in most cases the COVID-19 disease is relatively mild, some patients, unfortunately, develop pneumonia and respiratory failure, which require the use of a ventilator, and sometimes extracorporeal circulation.

According to the guidelines, PEEP is used during respiratory therapy - i.e. positive end expiratory pressure,thanks to which the collapse of the alveoli is prevented and the oxygen concentration in the breathing mixture is reduced, which may reduce tissue damage. Lying on your stomach is also beneficial.

In certain specific situations, anaesthesiologists qualify the patient for extracorporeal circulation if previous interventions and treatment are not sufficient.

In order to prevent the severe course of COVID-19 disease, hospitalization and respiratory failure, it is worth getting vaccinated against this disease. Vaccines are now available at vaccination centers right away. Let's also remember about the booster dose.

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Category:

Cardiology