Extracorporeal membrane oxygenation

Morphine pharmacokinetics during continuous infusion of morphine sulfate for infants receiving extracorporeal membrane oxygenation

OBJECTIVES

To determine a) if serum morphine concentration changes during the first 3 hrs of extracorporeal membrane oxygenation (ECMO); and b) if absorption of morphine onto the membrane oxygenator is responsible for these changes. Also, morphine clearance during the first 5 days of ECMO was studied.

DESIGN

Prospective, open-label study with consecutive patient enrollment.

SETTING

Neonatal intensive care unit at a university-affiliated, children's hospital.

SUBJECTS

Eleven neonates with severe persistent pulmonary hypertension of the newborn receiving continuous intravenous infusions of morphine sulfate and requiring ECMO.

INTERVENTIONS

Blood samples were obtained from the subjects and ECMO circuits at predetermined time intervals.

MEASUREMENTS AND MAIN RESULTS

Serum morphine concentration was determined using high-performance liquid chromatography. Morphine concentrations were no different from baseline at 5 mins, 1 hr, or 3 hrs after beginning ECMO. There was no significant difference in morphine concentration from samples taken immediately proximal and distal to the membrane oxygenator at 5 mins, 1 hr, and 3 hrs after the start of ECMO. Morphine clearance was calculated on days 1, 3, and 5 of ECMO. The mean value for morphine clearance was 11.7 +/- 9.3 (SD) ml/min/kg (range 2.6 to 34.5).

CONCLUSIONS

The initiation of ECMO does not lead to a significant decrease in serum morphine concentration and there is no uptake of morphine onto the membrane oxygenator of the ECMO circuit. Morphine clearance for infants receiving ECMO is variable.

Twenty-four-hour venoarterial extracorporeal membrane oxygenation without systemic heparinization in dogs

Venoarterial extracorporeal membrane oxygenation (ECMO) was performed in five dogs without systemic heparinization to assess the feasibility of heparin-free ECMO. The surfaces of the inverted hollow-fiber-type oxygenator and circuit of the ECMO system were coated with heparin by the endpoint-attached (covalent-bonded) technique. No heparin was administered to the animal except for a small dose to maintain patency of the arterial line (1 IU/h). ECMO was run for 24 h at a pump flow of 50 ml/kg · min and was successful throughout the experiment in four of the five dogs. Scanning electron microscopy did not detect any blood clots in the oxygenator or circuit except for inside and outside the cannulas that were not coated with heparin in the carotid artery and jugular vein. Activated clotting time (ACT), fibrinogen, and anti-thrombin III (AT-III) activity remained within the normal physiological range. Serum heparin concentrations were low throughout the experiment, indicating minimal heparin release. Platelet levels decreased and fibrinopeptide B β15-42 (FPB β15-42) increased significantly after 6 h ECMO. D-dimer levels did not change throughout the experiment. ECMO was discontinued in one case after successful a 23-h run because of macroscopic clot formation at the oxygenator blood inlet. ACT had suddenly increased to 160 s approximately 1 h prior to this clot formation. These results suggest that the amount of systemic heparinization required can be substantially reduced by a heparin-coated ECMO system. Total abolishment of heparin administration in pediatric venoarterial ECMO may be possible by refinement of this technique. Monitoring of AT-III and FPB β15-42 in addition to ACT may be useful for early diagnosis of latent but ongoing coagulopathies during ECMO.

Role of ECMO in neonatal myocardial infarction

A neonate with myocardial infarction who failed to respond to conventional treatment was supported by extracorporeal membrane oxygenation (ECMO). Severe mitral valve regurgitation necessitated mitral valve replacement while receiving ECMO following which the infant was successfully weaned. ECMO should be considered for potentially treatable causes of catastrophic heart failure.

Resection of a massive sacrococcygeal teratoma using hypothermic hypoperfusion: a novel use of extracorporeal membrane oxygenation

A 33-week-gestation infant with a massive sacrococcygeal teratoma weighted 4,000 g, but the actual weight of the infant was approximately 1,500 g. With the potential for massive blood loss and impaired lung compliance during resection, some type of cardiopulmonary support was necessary. Resection was undertaken with the assistance of venoarterial extracorporeal membrane oxygenation (ECMO) and hypothermic hypoperfusion. Immediately after removal of the tumor, which weighted 2,420 g, the infant was decannulated from ECMO, and the carotid artery was primarily reconstructed end-to-end. The amount of intraoperative blood loss was 550 mL Postoperatively, the child weighted 1,580 g. Follow-up head ultrasound results were normal, and the patient has done well. This is the first reported case in which ECMO with hypothermic hypoperfusion was used for resection of a massive tumor. This experience shows that ECMO is both useful and safe as a means of temporary cardiopulmonary support for resection of massive tumors in infants.

Gas exchange across native lungs and extracorporeal membrane in neonates and pigs during extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is a commonly used treatment modality for severe neonatal respiratory failure. The aim of the present study was to evaluate the relationship between ECMO blood flow and gas exchange across the native lungs and the extracorporeal membrane. In three healthy pigs, the ECMO flow correlated significantly with oxygen transfer (VO2) across the membrane (n = 12, r = .90, P < .001) and inversely with VO2 across the lungs (n = 12, r = -.75, p < .005). In three pigs with acute respiratory distress syndrome induced by repeated bronchoalveolar lavage, flow also significantly correlated with VO2 across the membrane (n = 9, r = .93, P < .001) and inversely with VO2 across the lungs (n = 9, r = -.97, P < .001). Eight neonates had measurements taken at different time intervals and different flow rates during ECMO. The ECMO flow correlated significantly with VO2 across the membrane (n = 45, r = .61, P < .001) and inversely with VO2 across the lungs (n = 15, r = -.54, P < .05). The relationship between carbon dioxide transfer (VCO2) and ECMO flow rates had the same trend as VO2 on all occasions. It is concluded that the ECMO flow rate is one of the main determinants of gas exchange across the lungs and the membrane.

Anticoagulation and hemostasis in cardiac surgical patients

Optimizing anticoagulation and hemostasis during cardiopulmonary bypass and perioperatively helps to ensure the best possible clinical outcome. This article reviews the pharmacology of unfractionated and low-molecular weight heparin, aprotinin, desmopressin, dextran, antiplatelet agents, warfarin, and direct thrombin inhibitors. Their use is discussed in the context of coronary artery surgery, valvular surgery, and mechanical cardiac support devices, as well as in the management of acute ischemic syndromes, atrial fibrillation, and prevention and treatment of venous thromboembolism. Progress in the development and utilization of these anticoagulants and antiplatelet agents has supported the major advances that have been achieved in cardiac surgery.

Repair of a laryngotracheoesophageal cleft in an infant by means of extracorporeal membrane oxygenation

Few survivors have been reported following attempted repair of laryngotracheoesophageal clefts (LTECs). The major challenge is maintaining oxygenation, both during the surgical repair and during the postoperative period of healing. We report a neonate with an LTEC extending to the carina whose successful repair was facilitated by extracorporeal membrane oxygenation (ECMO) begun intraoperatively and continued postoperatively for 11 days. The intraoperative surgical exposure of the defect was excellent. Postoperative trauma to the fresh tracheal repair from ventilatory pressures and endotracheal tube motion was eliminated through the use of ECMO. The patient was discharged without a tracheotomy and with a normal voice, cry, and swallow. According to this result, the use of ECMO may represent a significant advance in facilitating the correction of major laryngotracheoesophageal anomalies. The rationale, advantages, disadvantages, and potential pitfalls of this approach are presented, as well as preoperative and postoperative documentation of our results.