Artificial organs
-
While extracorporeal membrane oxygenation (ECMO) is being used increasingly after pediatric cardiac surgery, criteria are lacking for initiating ECMO after bypass weaning. To develop clinically useful ECMO entry criteria based on parameters readily available, children were examined at postoperative pediatric intensive care unit (PICU) admission. Using hospital mortality as the primary outcome, univariate and multiple logistic regressions were performed to estimate the predictive value of clinical (age, weight, and diagnosis) and laboratory (arterial blood pressure, pH, lactate, creatine kinase, and arterial and central venous oxygen saturation [ScvO2]) variables. ⋯ Univariate regression demonstrated that age, weight, diagnosis, blood pressure, venous and arterial saturation, and lactate were significantly associated with postoperative mortality (p < 0.05). In multiple regression, ScvO2 and lactate level were found to be independent predictors and were used in a predictive model (ScvO2 odds ratio: 2.03-828.6, p = 0.016) (lactate odds ratio: 1.58 -4.20, p = 0.0002) (R2 = 0.70). Applying an 80% risk of mortality to establish entry criteria as in neonatal ECMO, PICU admission values of lactate > 70 mg/dl if ScvO2 < 60% or lactate >163 mg/dl if ScvO2 > 60% are proposed to serve as postoperative ECMO entry criteria if bypass weaning has been possible but is followed by low cardiac output.
-
The treatment of cardiogenic shock using inotropic agents and vascular volume expansion places an added burden on the heart. The resultant increase in cardiac work may cause myocardial ischemia and lead to cardiac arrest. Extracorporeal membrane oxygenation (ECMO) may be used to treat cardiogenic shock. ⋯ The rise in blood pressure associated with restoring systemic circulation afterloads the heart and can cause left atrial hypertension and pulmonary edema. ECMO does not automatically reduce cardiac work, especially in the presence of residual shunts. Left atrial drainage or decompression may be essential in certain patients both to avert pulmonary edema and to reduce cardiac work.
-
The hemostatic system poses a major problem in extracorporeal membrane oxygenation (ECMO). The foreign surface in the extracorporeal circuit activates platelets and the clotting system. To avoid loss of platelets and activation of the clotting system, anticoagulation is necessary. ⋯ Most ECMO centers use heparin for anticoagulation and the activated clotting time (ACT) for monitoring. Reduction of problems with hemostasis may be obtained with less thrombogenic surfaces, new anticoagulants with a short half-life, platelet inhibitors, protease inhibitors, or selective anticoagulation in the extracorporeal circuit. While there will probably never be a complete nonthrombogenic surface available and all anticoagulants will have some risk of bleeding, improvement can be obtained by a combination of measures including better surfaces, more sophisticated anticoagulation regimens, and close laboratory monitoring.