**1. Introduction**

Extra corporeal membrane oxygenator (ECMO) is a type of cardiopulmonary life support in which blood is withdrawn from the venous system, circulated outside the

body by a mechanical pump, and oxygenated carbon dioxide is removed with the help of a membrane oxygenator and then pumped back into the arterial (VA-ECMO) or venous system [1, 2]. ECMO provides an opportunity for both heart and lungs to rest and recover while body perfusion is maintained. Also, it helps to prolong the lives of patients on the waitlist for transplants list [3].

The history of ECMO dates back to 1944 when Kloff et al. were able to oxygenate blood when it was passed through the chambers of their artificial kidney [4]. Nine years after this breakthrough accomplishment, it was clinically applied when John Gibbon in 1953 repaired an atrial septal defect in an 18-year-old female on cardiopulmonary bypass (CPB) [5, 6]. After the introduction of Mayo-Gibbon machine in 1955, oxygenator becomes an integral part of CPB machine used for repairing cardiac defects [7]. In 1972, CPB machine was used for the first time for prolonged cardiopulmonary support for shock lung in a 24-year trauma patient with tear in thoracic aorta and other orthopedic injuries. The patient was supported on CPB machine for 75 hours and subsequently recovered [8]. Other cases quickly followed where CPB was used for prolonged cardiopulmonary support called extracorporeal life support (ECLS) [9, 10]. However, consistently poor outcomes in the majority of patients led to abandonment of ECMO. In 1976, Robert Bartlett used ECMO on a neonate suffering from meconium aspiration pneumonitis as rescue therapy. The baby recovered after 3 days and was successfully weaned from ECMO. This also led to the revival of ECMO to use as ECLS [11]. Earlier ECMO circuits had many problems including large circuits, large priming volume, the presence of bladder reservoir that increased the risk of air embolism, and roller pump that increased the risk of hemolysis, air, and particle embolism. Further, earlier ECMO was highly labor-intensive requiring constant vigilance to prevent the accidents. The ECMO circuit was initially optimized by Ken Litzie in 1983 decreasing the parts and intricacy of the machine, allowing for rapid deployment in a nonhospital setting [12]. With further improvement in machine design, use of centrifugal flow pumps with magnetically levitated rotating heads and use of silicone membrane oxygenators have made ECMO circuit low profile and less labor-intensive, and support the patient on ECMO safely for days to weeks without major complications. Although the origin of both CPB and ECMO machines is from same root, there are significant differences between both as summarized in **Table 1** [13].

Despite significant improvement in the ECMO circuit design, until 2009, ECMO was frequently used only for pediatric patients with good outcome. However, use of veno-venous ECMO (VV-ECMO) during the swine flu pandemic in 2009 with good outcome led to the revival of ECMO in adults. This was further boosted by successful use of ECMO in patients with COVID pneumonia during recent pandemic. Presently, ECMO circuit can be easily transported in both air and ground ambulances and instituted in a variety of cardiac and noncardiac conditions at various facilities like in the ward, operating room, cath lab, and even in the fields (mobile ECMO programs) at the site of cardiac arrest (CA) and even with ongoing cardiopulmonary resuscitation (CPR). Further, ECMO can provide robust biventricular as well as respiratory support in patients with severe refractory CS for prolonged duration with a patient being extubated and ambulant. Full VA-ECMO support offers time to perform diagnostic and therapeutic interventions while maintaining appropriate hemodynamics and gas exchange and organ perfusion.

In this chapter, we will review basics of ECMO and various indications of ECMO in patients with cardiogenic shock (CS) and cardiac arrest.

*Overview of Venoarterial Extracorporeal Membrane Oxygenation (VA-ECMO) Support… DOI: http://dx.doi.org/10.5772/intechopen.105838*


#### **Table 1.**

*Comparison of ECMO and CPB.*

#### **1.1 Components**

ECMO circuit consists of venous and arterial cannulas for drainage and return of blood, respectively, a hollow fiber membrane oxygenator for blood oxygenation and carbon dioxide (CO2) clearance, and a centrifugal pump for propelling the blood. The presence of membrane oxygenator is a critical distinguishing feature of ECMO from other acute mechanical circulatory support (AMCS) devices.

#### **1.2 Cannulation technique**

ECMO can be placed centrally or peripherally. Central VA-ECMO is usually placed in post-cardiotomy setting, when venous drainage cannula is placed in the right atrium (RA) or superior vena cava (SVC) and inferior vena cava (IVC) separately and oxygenated blood is returned directly into the ascending aorta. For the management of CS, peripheral VA-ECMO is most commonly performed and femoral artery (FA), and femoral vein (FV) is the most commonly cannulated. Alternate site of cannulation is axillary artery or subclavian artery for arterial return and internal jugular vein (IJV) for venous drainage. Artery can be cannulated percutaneously under fluoroscopic guidance or surgically with a chimney graft. The advantages of whole upper body cannulation are ambulation, lower risk of infection, limb ischemia, cannula site bleeding, and ease of maintaining sterility. However, more time-consuming needs the presence of a surgeon. On the other hand, femoral cannulation can be easily done percutaneously by an individual trained in ECMO cannulation and is rapid. Appropriate size cannula should be selected to reduce the risk of vascular injury and at the same time maintain the low negative inflow (preferably <−50 mmHg) and low outflow (<300 mmHg) pressures [14]. In our center, when femoral artery is cannulated for VA-ECMO, we always insert a 6 Fr distal reperfusion cannula into the superficial femoral artery to mitigate the risk of distal limb ischemia and splice into the arterial limb of the circuit (**Figure 1**).
