Andersons pediatric cardiology 1722

Temporary Extracorporeal Life Support Temporary extracorporeal life support (ECLS) comprises the use of ECMO or ventricular assist devices (VADs) to provide support to children with acute circulatory failure, at the point when conventional medical management is failing Typically the cardiovascular function of these patients cannot adequately support the circulation, despite the use of mechanical ventilation and pharmacologic agents In addition, the institution of mechanical support provides the opportunity for a period of myocardial rest Temporary mechanical support also provides an opportunity for additional assessment in order to rule out residual or unrecognized anatomic problems The end point for temporary mechanical support would be either myocardial recovery, or as a bridge to a longer-term device and, ultimately, transplantation The use of ECLS, ECMO, or VAD in patients with acute circulatory failure has continued to increase since the late 1980s A recent report from the Extracorporeal Life Support Organization (ELSO) registry states a worldwide increase of ECMO to support patients with critical cardiopulmonary dysfunction refractory to conventional therapy The number of participating pediatric centers reporting cases increased from 147 in 2009 to 227 in 2017.3 Basic Principles ECLS is a complex, low-volume, and high-risk therapy Therefore clinicians involved are responsible for maximizing the chances of its success for each patient This requires a streamlined approach to all decision-making, optimal timing of support initiation, an ongoing commitment to investigate, and optimize factors that may increase the chances of successful discontinuation The delivery of ECLS by a dedicated team of practitioners, with appropriate training and familiarity with the technology and collaborative decision-making, is a key factor that determines the success of this complex therapy This is achieved in part through regular use of ECLS in dedicated centers, commitment to ongoing education, uniform approach to the design of the circuitry, and avoiding unnecessary variability, which would increase the likelihood of error.34 Indications for Extracorporeal Life Support The spectrum of patients for whom mechanical support is offered has broadened over time, and absolute contraindications for support rarely exist In principle, support should only be considered if the patient is expected to recover to a reasonable level of function with or without additional intervention The most common indications for cardiac ECLS are postcardiotomy circulatory failure for infants and children with a critical low cardiac output state early after surgery for congenital heart disease,35 fulminant myocarditis,36,37 postoperative pulmonary hypertension,38 early graft failure after cardiac transplantation,39 and as a resuscitative tool in infants and children during cardiac arrest.40 In our institution between 2014 and 2016, there were 62 ECMO deployments for cardiac support in infants and children The predominant cardiac indications for support in these patients were congenital cardiac defects in 68% and 33%, respectively The most common congenital cardiac lesion requiring ECMO support in neonates was hypoplastic left heart syndrome There were 16 children (representing 20%) requiring ECMO support for cardiomyopathy and myocarditis Our local practice has shifted over the past decade to earlier institution, including deployment in the operating room As a result, there was only one episode of extracorporeal cardiopulmonary resuscitation (ECPR) during this period Contraindications to Extracorporeal Life Support The presence of severe preexisting brain injury or a new parenchymal intracerebral hemorrhage would be considered in most centers to be relative contraindication to mechanical support This is because the anticoagulation required for mechanical support carries a significant risk of causing new hemorrhage or worsening of existing bleeds and ischemic or embolic brain injury In addition, patients with severe residual anatomic lesions that cannot be improved would be considered poor candidates for support in most centers, for example infants with total anomalous pulmonary venous connection and diffuse pulmonary vein stenosis, who cannot be weaned from bypass Despite wellrecognized high-risk patient groups (see below), there are no specific patient subgroups for whom mechanical support would be absolutely contraindicated Timing of Extracorporeal Life Support ECLS activation should be considered at a stage where the risk of escalating pharmacologic agents outweigh the benefits of a period of myocardial rest, rather than a last resort treatment for patients who will otherwise surely die, and ideally before cardiopulmonary arrest Delays in the institution of ECLS may result in a missed window of opportunity to complete appropriate, timely interventions Furthermore, the survival of infants and children requiring support following surgery for congenital cardiac disease is generally better when support is instituted early in the operating room rather than later in the ICU.41 Choice and Mode of Mechanical Support Depending on the device used, ECLS can provide complete or partial circulatory support Although each device has unique characteristics, available pumps can be classified into three types: centrifugal pumps, volume-displacement pumps, and axial-flow pumps The superior blood handling properties of centrifugal blood pumps have led to their almost universal use for temporary ECMO, VAD, and percutaneous cardiopulmonary support.42 When choosing the mode of support (ECMO vs VAD), ECMO continues to be the appropriate mode of support for patients with both cardiac and pulmonary impairment, for infants with pulmonary hypertension, and for ECPR (Table 64.4) Support with a VAD would be the preferred approach for infants or children with dysfunction of one ventricle and preserved pulmonary function and adequate function of the contralateral ventricle In patients with biventricular dysfunction and adequate pulmonary function, the decision to use ECMO or biventricular assist devices for temporary circulatory support is more institutional dependent, particularly in small children Table 64.4 Mode of Extracorporeal Support in Children With Circulatory Failure Indication Cardiac arrest Failure to wean from bypass or Early postoperative low cardiac output state Isolated ventricular dysfunction Biventricular dysfunction Pulmonary hypertension ECMO/VAD ECMO Comments Default mode of support for children receiving CPR Single VAD BIVAD/ECMO Institutional preference may be for ECMO, especially in smaller infants ECMO Identical cannulation but no oxygenator