Extracorporeal life support (ECLS) is defined as total or partial diversion of a patient’s circulating blood volume into a device that can act as a “lung,” providing oxygenation and carbon dioxide removal, and a pump, which can act like a “heart,” providing circulatory support, or a combination of both functions for patients suffering from both cardiac and pulmonary failure. Adapted from heart-lung machines used for cardiopulmonary bypass, this temporary form of support was termed extracorporeal membrane oxygenation (ECMO) in the past.1–4 Because of vast changes in the circulatory devices now available and the patient populations being treated, however, the term ECMO is being replaced by ECLS as the designation for extracorporeal life support of a variety of indications and devices. Both are used interchangeably in the chapter. Figure 20-1 shows an example of an early cardiopulmonary bypass circuit.
Early cardiopulmonary bypass circuit. (Courtesy of Heidi Dalton MD, with permission.)
ECLS was first developed to provide respiratory support in premature infants who had inadequate lung development to support gas exchange compatible with life. Difficulties with intracranial hemorrhage secondary to the heparinization required to prevent clotting of the artificial membrane lung and the circuit, however, caused ECLS to quickly fall out of favor in this population. Work continued, and following the development of the silicone-membrane oxygenator by Kolobow and others, ECLS was successfully applied to term newborns with respiratory failure.5,6 One of the first of these patients was a newborn named Esperanza (which means hope) by the neonatal intensive care unit nursing staff who were caring for her at the University of California at Irvine in 1976. Esperanza had hypoxemia secondary to what we now would call persistent pulmonary circulation of the newborn. Dr. Robert Bartlett and colleagues were doing research on ECMO at the University of California at Irvine and were contacted for assistance with Esperanza. Their laboratory device was quickly approved by the institutional review board for emergency use, and adapted and applied in an attempt to save Esperanza. The procedure worked well and Esperanza is now a grown woman with children of her own. Following this event, other centers reported success in the use of ECLS in newborns with respiratory failure from diseases such as meconium aspiration syndrome, persistent pulmonary hypertension, and congenital diaphragmatic hernia.7–10
This initial success was met with some skepticism, and a randomized controlled trial of ECMO or ECLS versus conventional ventilation was undertaken in newborns with persistent pulmonary hypertension in the late 1980s. This was a two-phase project: if excessive mortality or benefit was noted in one group, the next twenty patients would be treated with the more successful therapy.11 The safety monitoring board stopped Phase 1 of the study when four of the ten patients in the conventional arm died while all nine of the patients in ...