The Effect of Inhaled Nitric Oxide on the Course of Extracorporeal Membrane Oxygenation and the Occurrence of Hemorrhagic Complications

Premature and Extracorporeal Life Support: Is it Time? A Systematic Review

Early preterm birth < 34 gestational weeks (GA) and birth weight (BW) <2 kg are relative contraindications for extracorporeal membrane oxygenation (ECMO). However, with improved technology, ECMO is presently managed more safely and with decreasing complications. Thus, these relative contraindications may no longer apply. We performed a systematic review to evaluate the existing literature on ECMO in early and late (34-37 GA) prematurity focusing on survival to hospital discharge and the complication intracranial hemorrhage (ICH). Data sources: MEDLINE, PubMed, Web of Science, Embase, and the Cochrane Database. Only publications in the English language were evaluated. Of the 36 included studies, 23 were related to ECMO support for respiratory failure, 10 for cardiac causes, and four for congenital diaphragmatic hernia (CDH). Over the past decades, the frequency of ICH has declined (89-21%); survival has increased in both early prematurity (25-76%), and in CDH (33-75%), with outcome similar to late prematurity (48%). The study was limited by an inherent risk of bias from overlapping single-center and registry data. Both the risk of ICH and death have decreased in prematurely born treated with ECMO. We challenge the 34 week GA time limit for ECMO and propose an international task force to revise current guidelines. At present, gestational age < 34 weeks might no longer be considered a contraindication for ECMO in premature neonates.

Platelet dysfunction in a large-animal model of endotoxic shock; effects of inhaled nitric oxide and low-dose steroid

OBJECTIVE

The role of inhaled nitric oxide in the treatment of shock remains controversial and further translational research is needed. Long-term observation studies using a model of endotoxin-induced shock to assess the effect of inhaled nitric oxide on platelet aggregation have not yet been reported.

APPROACH AND RESULTS

The tests were carried out in an animal model of shock in two 10-h periods. During the first 10 h, endotoxin was infused and the inhibition of platelet aggregation was evaluated; following the termination of endotoxin infusion, the restoration of platelet aggregation was assessed for 10 h. A total of 30 pigs were used (NO group, N = 14; control, N = 16). In the NO group, nitric oxide inhalation (30 ppm) was started 3 h after endotoxin infusion and continued until the end of the study. Treatment with NO selectively decreased pulmonary artery pressure at 4 (p = 0.002) and 8 h (p = 0.05) of the experiment as compared to the control. Endotoxin significantly reduced platelet aggregation, as indicated by the decreased activity of platelet receptors: ASPI, ADP, collagen, and TRAP during the experiment (p < 0.001). Endotoxin had no significant effect on changes in the response of the receptor after ristocetin stimulation. After stopping endotoxin infusion, a significant restoration of receptor activity was observed for collagen and TRAP, while ASPI and ADP remained partially depressed. Inhaled nitric oxide did not cause additional inhibition of platelet aggregation, either during or after endotoxin challenge.

CONCLUSIONS

A profound reduction in platelet aggregation was observed during endotoxic shock. After stopping endotoxin infusion a restoration of platelet receptor activity was seen. The inhibition of platelet aggregation induced by endotoxin infusion was not intensified by nitric oxide, indicating there was no harmful effect of inhaled nitric oxide on platelet aggregation.

Cerebral aspects of neonatal extracorporeal membrane oxygenation: a review

BACKGROUND

Neonatal extracorporeal membrane oxygenation (ECMO) is a lifesaving therapeutic approach in newborns suffering from severe, but potentially reversible, respiratory insufficiency, mostly complicated by neonatal persistent pulmonary hypertension. However, cerebral damage, intracerebral hemorrhage as well as ischemia belong to the most devastating complications of ECMO.

OBJECTIVES

The objectives are to give insights into what is known from the literature concerning cerebral damage related to neonatal ECMO treatment for pulmonary reasons.

METHODS

A short introduction to ECMO indications and technical aspects of ECMO are provided for a better understanding of the process. The remainder of this review focuses on outcome and especially on (potential) risk factors for cerebral hemorrhage and ischemia during ECMO treatment.

RESULTS

Although neonatal ECMO treatment shows improved outcome compared to conservative treatment in cases of severe respiratory insufficiency, it is related to disturbances in various aspects of neurodevelopmental outcome. Risk factors for cerebral damage are either related to the patient's disease, EMCO treatment itself, or a combination of both.

CONCLUSION

It is of ongoing importance to further understand pathophysiological mechanisms resulting in cerebral hemorrhage and ischemia due to ECMO and to develop neuroprotective strategies and approaches.

Effects of inhaled nitric oxide on hemostasis in healthy adults treated with heparin: a randomized, controlled, blinded crossover study

Background

Effects of nitric oxide (NO) on hemostasis have been studied in various investigational settings, but data regarding inhaled NO on bleeding and platelet function are conflicting. It is not known if inhaled NO has an effect when administered with drugs that influence hemostasis. This trial evaluated effects of inhaled NO on hemostasis in the presence of heparin using aspirin as a positive control.

Patients/Methods

Twelve healthy adult males were enrolled in a single-center, randomized, single-blind, four-way crossover trial. Subjects received 80 ppm NO or medical air (placebo) inhalation for 30 min with simultaneous injection of placebo or heparin. Aspirin capsules were used as a positive control. Parameters of hemostasis were measured before treatment and at post-treatment intervals.

Results

Activated clotting time (ACT), prothrombin time (PT) and activated partial thromboplastin time (aPTT) increased only in groups that received heparin. Areas under the curve for ACT in heparin groups receiving inhaled NO were judged to be equivalent to those receiving medical air for both 0- to 4-h (ratio: 1.00; 90% CI, 0.90-1.11) and 0- to 24-h time intervals (ratio: 1.01; 90% CI, 0.92-1.12). Changes in bleeding time and platelet aggregation were observed only in aspirin groups. No clinically significant changes in hemoglobin, red blood cell counts or haematocrit were observed in any group.

Conclusions

Inhaled NO, when administered with heparin, exhibited no significant additive effects on ACT, PT, aPTT, bleeding time or platelet aggregation.