Future of ECMO in Cardiac surgery
VA-ECMO is indicated when patients fail to be weaned off CPB or clinically deteriorates significantly during the course of staying on intensive care stay. ECMO provides a longer support for a few days to allow for recovery of the cardiopulmonary system, compared to a few hours of support with CPB. VA-ECMO confers several advantages that helps increasing patient survival and reduce mortality rates. CPB needs a large amount of unfractionated heparin as it utilises a venous reservoir which causes blood to stagnate. CPB also causes blood to pool in the heart chambers and respiratory circulatory system, which result in an increase in activated clotting time.
Whereas, VA-ECMO does not utilise a venous reservoir and is made of shorter tubes. There is reduced occurrence of thrombosis allowing for a reduction in the dosage of unfractionated heparin which can then reduce bleeding complications. Hence, VA-ECMO use in refractory PCCS has been shown to provide significant survival benefits without which mortality would be inevitable. Increased age, renal failure and long use of ECMO support are the most frequently reported adverse prognostic factors .
Over the recent years, the use of ECMO has greatly increased. According to ELSO, the use of adult ECMO increased by about tenfold over the past decade. This is likely following a ground-breaking study, the CESAR trial, which showed a significant increase in survival without severe disability when ECMO was used instead of conventional ventilation. Early initiation of ECMO has been shown to result in higher survival rates and decreasing the dosage of vasoactive drugs by increasing cardiac output and rapidly decreasing arterial lactate levels after cardiovascular surgery. This is shown in a study which compared two groups of patients where the patients with early initiation ECMO failed to be weaned off CPB once, while the patients with delayed ECMO failed to weaned off thrice.This could help provide a guide as to when ECMO should be initiated in patients after cardiac surgery to improve outcomes.
ECMO technology is constantly evolving and improving, with more compact and durable components being introduced in recent times. Wearable ambulatory ECMO has been developed and trialled in patients with severe cardiopulmonary failure awaiting transplant. Compact ECMO is achievable by the use of hollow fibre membranes arranged in stacks with centrifugal pumps. This allows increased patient mobility which helps with rehabilitation and early mobilisation allowing patients to walk and exercise, preventing muscle atrophy allowing shorter recovery time and placing patients in a better physiological state for heart or lung transplant. It also helps to decrease total costs by about 11% compared to traditional ECMO use. This could soon be the new future of ECMO, which is currently still a complex and bulky piece of equipment resulting in patients being bedbound, slowing recovering.
Unfortunately, ECMO is a very costly form of life support at about £45,000  per patient. It is also resource intensive, requiring a high level of expertise to use it. An article states that the National Specialist Commissioning Group only funds ECMO to certain specialist centres, restricting its access which is inappropriate and unacceptable considering its great benefits to patients’ survival rates. Whereas, in other parts of the world such as the US and Europe, ECMO is routinely used. It is contentious to say whether the UK has too many restrictions to use of ECMO or if the UK is being too prudent. VA ECMO is not commissioned by the National Health Service (NHS) for PCCS and the price of it is forked out by individual hospitals in the UK. Most recently, ECMO is being used widely in COVID-19 patients where they may develop cardiac arrhythmias and shock. About 15% to 30% of patients with the viral pneumonia developed acute respiratory distress syndrome (ARDS) where the WHO recommendations included ECMO as a part of the management. The role of ECMO for COVID-19 patients is still unclear and is dependent on the mechanism which the virus harms the body. If it causes septic shock and multiorgan failure, the management will likely shift away from ECMO as it may be less helpful in these instances. Although inconclusive, an article brought up concerns about the use of ECMO in COVID-19 patients, suggesting healthcare professionals evaluate the IL-6 concentration and lymphocyte count before and during ECMO, as ECMO increases IL-6 levels and decreases lymphocyte count. More studies should be carried out to determine the usefulness of ECMO in this situation, especially when they need an emergency cardiac surgery.