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ECMO


ECMO

The ECMO procedure refers to extracorporeal membrane oxygenation. The ECMO device is generally similar to the artificial circulatory device used in open cardiac surgery. This device, if necessary, provides a replacement of the function of the heart and lungs. So, when the patient is connected to the ECMO device, blood from the patient enters through the main tubes to the oxygenator, which acts as an “artificial lung”, namely, in it the blood is saturated with oxygen and carbon dioxide is removed from it; after that, the blood is heated to the required temperature using a special temperature – regulating device and pumped back into the body.

It’s worth noting that ECMO is used when conventional treatments don’t work. In addition, ECMO does not cure heart or lung diseases, but only provides time to restore their functions.

In general, there are two main types of ECMO – veno-venous ECMO and veno-arterial ECMO.

Indications for VV-ECMO
In case of veno-venous ECMO, blood from the patient is taken from the vein using a special pump, passes through an oxygenator and returns back to the vein, thus replacing the function of the lungs. Venous cannulas can be inserted into the femoral veins, jugular or axillary veins. In addition, it is possible to use a two-way venous cannula with a single injection site.

The main life-threatening conditions in which veno-venous ECMO is connected include:

Indications for VA-ECMO
In veno-arterial ECMO, blood from the patient is also taken from the vein using a special pump, passes through the oxygenator and returns back to the artery, which allows replacing the function of the heart and partially lungs. The venous cannula is usually inserted into the femoral vein, less often into the jugular or axillary one. The arterial cannula is most often located in the femoral artery.

Veno-arterial ECMO is used for:

ECMO support
While on ECMO, the patient may be prescribed certain medications, including:

Usually, while ECMO is running, doses of medications that have been used to improve heart and lung function may be reduced.

Complications on ECMO
The main complications that occur during ECMO include:

ECMO completion
To stop ECMO, a surgical team is needed to remove the cannulas. Usually, before stopping ECMO, the patient is given several tests to confirm adequate heart and lung function. After removing the cannulas, the doctor uses small stitches to close the place where the cannulas were installed.

 

 

ECCO2R

ECCO2R or extracorporeal removal of carbon dioxide is one of the methods of extracorporeal life support, the main purpose of which is to remove carbon dioxide directly from the patient’s blood.

Indications for ECCO2R include not only optimization of lung protection in the treatment of acute respiratory distress syndrome (ARDS), but also Type 2 respiratory failure caused by exacerbation of severe asthma and chronic obstructive pulmonary disease (COPD), or temporarily as a “bridge” to lung transplantation.

The main characteristics that separate ECCO2R from other extracorporeal life support (ECLS) methods, there is a need for a much smaller caliber of cannulas required for vascular access (due to the lower need for blood flow rate through the membrane for gas exchange in order to remove carbon dioxide). In particular, to remove carbon dioxide from the blood, blood flow through the extracorporeal membrane at a rate of 300-500 mL/min is sufficient, which is due to the better solubility of carbon dioxide in the blood compared to oxygen.

In general, today, ECCO2R is considered an intermediate stage between conventional mechanical ventilation and full support with veno-venous ECMO. Thanks to this technique, about 50% of the lung function for removing carbon dioxide is replaced, which reduces the ventilation parameters on the mechanical ventilation device and thus reduces the load on damaged lungs.

The cannulas used for this procedure have a caliber of 13 to 17Fr, and they are usually inserted percutaneous using the Seldinger technique. As for the pump that provides blood flow to the gas exchange membrane outside the patient’s body, today electromagnetic centrifuge pumps are used, in which mechanical injuries to the blood are minimized.

We should also mention the availability of devices for ECCO2R, which do not have pumps that use the pressure difference between an artery and a vein to provide blood flow through a gas exchange membrane that removes CO2.

The main complications that occur during ECCO2R include:

 

 

ECPR

Extracorporeal cardiopulmonary resuscitation (commonly known as ECPR) is a method of cardiopulmonary resuscitation (CPR) that involves the additional use of an extracorporeal membrane oxygenation (ECMO) device to oxygenate the patient’s blood. The portable ECMO device is used as a supplement to the standard CPR.

A patient with cardiac arrest with ineffective CPR is injected with percutaneous cannulas into the femoral vein and artery. At the same time, it was found that the use of ECPR allows restoring cerebral blood flow more effectively than only with external compressions.

An important element is that by connecting ECMO in a patient with cardiac arrest, doctors get additional time to analyze causal pathology in order to improve long-term survival and neurological outcomes.

As for the selection of patients for admission to the ECPR, it depends on the place where the cardiac arrest occurred – in a medical facility or outside it.

Criteria for selecting patients for the ECPR outside a medical facility

The criteria for selecting patients for the ECPR outside a medical facility are as follows:

Criteria for selecting patients for the ECPR in a medical facility
Criteria for selecting patients for the ECPR in a medical facility:

 

Conducting the ECPR

After cardiac arrest is established, cardiopulmonary resuscitation begins in accordance with local algorithms. With the help of emergency medical services and intensive care teams, patients are evaluated for the presence of criteria for inclusion in the ECPR. A set of criteria, depending on the location of cardiac arrest, is used for continuing cardiac compressions. In order to assess possible reversible causes associated with cardiac arrest, the clinical history of patients is reviewed. Patients are also checked for contraindications, such as pre-existing neurological disorders or a significant restriction on the ability to engage in daily activities. Standard CPR protocols continue to be applied to patients who are considered unfit for the ECPR. As soon as the patient is considered eligible for ECPR, the appropriate ECPR team is notified.

After confirming that the patient is eligible for the ECPR, the cannulation process begins. During short pauses during chest compressions, vascular catheterization is performed using a modified Seldinger technique to access both the femoral artery and the femoral vein using ultrasound. The arterial cannula moves to the descending aorta, and the venous cannula moves to the inferior vena cava. The position of the cannulas is confirmed by a chest X-ray.

After successful cannulation is confirmed, 5,000 units of heparin are administered intravenously and ECMO is started with a target blood flow of 3 l/min. After stabilization of the patient, it is transferred for further treatment of causal pathology, for example, to angiography. Trying to avoid limb ischemia, a third cannula is also inserted in some centers. This third cannula is inserted distally into the femoral artery to allow perfusion of the lower limb.

Complications of the ECPR
The main complications that occur during ECPR include:

CDDE

CDDE or ECMO for donation after cardiac death is a type of extracorporeal life support, which consists in temporarily maintaining the function of organs after heart death and then collecting them for transplantation. Cardiac death is death based more often on cardiopulmonary criteria (irreversible cessation of blood circulation and lung function) than on neurological criteria (brain death).

As with conventional ECMO, heparin is administered intravenously before cannulation begins. Cannulas are placed in the femoral artery and vein on the same side. Cannulation time may vary according to local protocols. So, in some centers, instead of placing cannulas, vessels are catheterized with a 7F femoral catheter, which subsequently helps to quickly place cannulas and start ECMO after death is announced. Subsequently, a balloon for aortic occlusion is passed through another femoral artery. The balloon moves up to the thoracic aorta and swells. This ensures isolated perfusion of the abdominal organs and excludes the heart and brain from circulation.

To date, a number of studies have been published that have confirmed the effectiveness of extracorporeal support in donation after cardiac death. The available data not only highlight the growth of the donor pool, but also reflect the functional equivalence of donor organs compared to donors who died from brain death. Most of the available studies relate to kidney transplantation, but there is little data on other organs.

 





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