Impairment of Venous Drainage on Extracorporeal Membrane Oxygenation Secondary to Air Trapping in Acute Asphyxial Asthma.

The inability to adequately support a patient on extracorporeal membrane oxygenation (ECMO) due to impaired drainage is not an uncommon occurrence during support. Typically, the causes include hypovolemia, kinks in the circuit, cannula malposition, or inadequate cannula size. In this report we present an uncommon etiology of this problem. A 3-year-old female presented to our hospital in status asthmaticus and pulseless electrical activity (PEA). This was a result of dynamic hyperinflation of the lungs causing physical obstruction of venous return to the heart. Upon initiating venoarterial (VA) ECMO, we experienced inadequate drainage that did not improve despite multiple interventions. This resolved with the addition of an inhaled anesthetic gas to treat this patient's severe bronchospasm. This case illustrates the importance of considering a patient's physiology or disease state and how that may affect the mechanics of ECMO support.

Initial experience with recombinant antithrombin to treat antithrombin deficiency in patients on extracorporeal membrane oxygenation.

Acquired antithrombin (AT) deficiency has been associated with patients on extracorporeal membrane oxygenation (ECMO) as a result of hemodilution, blood coagulation activation, and the use of heparin. Replacement of AT has been typically utilized through the use of fresh-frozen plasma or AT concentrate. Antithrombin alfa (ATryn) is a recombinant form of AT (rAT) with an identical amino acid sequence as that of plasma-derived antithrombin. The primary objective of this study is to examine the relationship of rAT dose to measured plasma antithrombin activity in a small series of patients who received rAT while on ECMO. A retrospective chart review was performed of all patients at Medical City Children's Hospital who received ATryn while supported on ECMO between December 2011 and April 2012. Five patients were identified and the patients' weight, bolus dose of ATryn, drip rate of ATryn, and AT blood levels were collected for analysis. The median age of these patients was 1 month (range, 1 day to 3.75 years). Because no dosing guidelines exist for pediatric ECMO, a starting dose of ATryn was chosen based on the manufacturer's labeled indication (prevention of thromboembolic events in patients with AT hereditary deficiency). The median dose of rAT was 368 IU/kg/day (range, 104-520 IU/kg/day) to obtain AT activity level of 80-120%. The average time to reach the targeted AT activity level (80-120%) was 12.7 hours (range, 11-17 hours). Our findings suggest that the published ATryn dose may be inadequate to reach desired AT activity concentrations for pediatric patients on ECMO. Difference in patient population, use of extracorporeal circuits, and the use of heparin are likely explanations for this finding. We would also recommend frequent checking of AT levels while delivering this drug because making timely adjustments is necessary for achieving and maintaining the target AT activity level.

Construction of a pulmonary artery pump for unifocalization and repair of pulmonary atresia with ventricular septal defect and major aortopulmonary collaterals.

Single-stage repair has been presented as the treatment of choice for pulmonary atresia with ventricular septal defect and major aortopulmonary collaterals. This surgical approach may result in the difficult decision of whether to close the ventricular septal defect. This decision may significantly affect the postoperative course of the patient. There are several diagnostic techniques clinicians may use to help them decide if closure is indicated. One technique is to modify an extracorporeal circuit to deliver precise flow rates of blood into the newly created pulmonary arterial system, at the same time supporting the patient during the operative procedure. While this technique is not novel, there is only a single published description of the circuit. This report is brief and does not discuss potential complications that these modifications may cause. Therefore, it is the purpose of this paper to describe a circuit modification to perform this diagnostic measurement as well as elucidating potential risks of this technique.

Aprotinin dosing: how much is enough?

Coagulopathy and postoperative bleeding continue to be a major concern for patients undergoing cardiac surgery with cardiopulmonary bypass. Pharmacologic attenuation of this morbidity has been one area that clinicians have held in high interest. Aprotinin, a serine protease inhibitor, has been shown to be effective in reducing bleeding as well as the need for blood component transfusions. Although effective, aprotinin is an expensive drug and this, in conjunction with a cost-conscious community, has led clinicians to determine what is the lowest effective dose of aprotinin. From these studies, various aprotinin dosing regimens have been studied with differing results. The purpose of this work is to review the effectiveness of the various dosing strategies and to examine potential benefits of a dosing regimen based on a patient's weight, which may allow clinicians to achieve the maximal benefits from aprotinin without overdosing patients.