C. Meadows

Prevalence of Venous Thrombosis Following Venovenous Extracorporeal Membrane Oxygenation in Patients With Severe Respiratory Failure.

Objectives:Venovenous extracorporeal membrane oxygenation for patients with severe respiratory failure is increasingly common. There has been a significant change in the population, technology, and approach used for venovenous extracorporeal membrane oxygenation over the last 10 years. The objective of this study is to describe the prevalence of postdecannulation deep vein thrombosis in the cannulated vessel in adults who have received venovenous extracorporeal membrane oxygenation for severe respiratory failure. Design:A single-center, retrospective, observational cohort, electronic note review study. Setting:Tertiary referral university teaching hospital. Patients:Patients commenced on venovenous extracorporeal membrane oxygenation for severe respiratory failure. Interventions:None. Measurements and Main Results:We identified 103 patients commenced on extracorporeal membrane oxygenation with 81 survivors from December 2011 to February 2014. We performed postdecannulation venous Doppler ultrasound in 88.9% of extracorporeal membrane oxygenation survivors. The prevalence of deep vein thrombosis in the cannulated vessel following extracorporeal membrane oxygenation is 8.1/1,000 cannula days in patients who were screened. Conclusions:The prevalence of deep vein thrombosis following decannulation from extracorporeal membrane oxygenation for severe respiratory failure is clinically significant, and routine venous Doppler ultrasound following decannulation is warranted in this population.

Perioperative Extracorporeal Membrane Oxygenation to Facilitate Lung Resection After Contralateral Pneumonectomy.

A 75-year-old man previously underwent pneumonectomy for lung cancer. He subsequently had colorectal adenocarcinoma, and resection of metastases from his remaining lung was performed. Venovenous extracorporeal membrane oxygenation was used for perioperative respiratory support to facilitate intraoperative deflation of the remaining lung and optimization of the surgical field. Venovenous extracorporeal membrane oxygenation was continued postoperatively, allowing immediate extubation, thus avoiding strain on suture lines. Advantages, and potential risks, of venovenous extracorporeal membrane oxygenation for thoracic surgery are discussed.

CRITICAL CARE ECHO ROUNDS: Extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is an advanced form of organ support indicated in selected cases of severe cardiovascular and respiratory failure. Echocardiography is an invaluable diagnostic and monitoring tool in all aspects of ECMO support. The unique nature of ECMO, and its distinct effects upon cardio-respiratory physiology, requires the echocardiographer to have a sound understanding of the technology and its interaction with the patient. In this article, we introduce the key concepts underpinning commonly used modes of ECMO and discuss the role of echocardiography. Case A 38-year-old lady, with no significant past medical history, was admitted to her local hospital with group A Streptococcal pneumonia. Rapidly progressive respiratory failure ensued and, despite intubation and maximal ventilatory support, adequate oxygenation proved impossible. She was attended by the regional severe respiratory failure service who established her on veno-venous (VV)-ECMO for respiratory support. Systemic oxygenation improved; however, significant cardiovascular compromise was encountered and echocardiography demonstrated a severe septic cardiomyopathy (ejection fraction <15%, aortic velocity time integral 5.9 cm and mitral regurgitation dP/dt 672 mmHg/s). Her ECMO support was consequently converted to a veno-veno-arterial configuration, thus providing additional haemodynamic support. As the sepsis resolved, arterial ECMO support was weaned under echocardiographic guidance; subsequent resolution of intrinsic respiratory function allowed the weaning of VV-ECMO support. The patient was liberated from ECMO 7 days after hospital admission.

Acceptance and transfer to a regional severe respiratory failure and veno-venous extracorporeal membrane oxygenation (ECMO) service: predictors and outcomes

The use of extracorporeal membrane oxygenation for respiratory failure is high risk and resource intensive. In England, five centres provide this service and patients who are referred have four possible outcomes: declined transfer due to perceived futility; accepted in principle but remain at the referring centre with ongoing surveillance; retrieved using conventional ventilation; or retrieved on extracorporeal support. The decision‐making process leading to these outcomes has not previously been examined. We evaluated referrals to one centre and identified factors associated with each decision outcome. Five hundred and sixty‐four patients were analysed from January 2012 to October 2015. One hundred and fifty‐seven patients were declined; multivariate analysis demonstrated associated factors to be: age (odds ratio (95% confidence interval) 1.05 (1.04–1.07)); immunocompromise (4.95 (2.58–9.67)); lactate (1.11 (1.01–1.22)); duration of ventilation (1.08 (1.04–1.14)); and cardiac failure (3.22 (1.04–10.51)). Factors associated with the decision to retrieve an accepted patient were: plateau pressure (1.05 (1.01–1.10)); ratio of arterial oxygen partial pressure to fractional inspired oxygen (0.89 (0.85–0.93)); partial pressure of carbon dioxide in arterial blood (1.13 (1.03–1.25)); and the absence of non‐pulmonary infection (0.31 (0.15–0.61)). Only pH was independently associated with the decision to transfer on extracorporeal support (0.020 (0.002–0.017)). Six‐month survival in the declined, non‐retrieved, conventionally retrieved and extracorporeal‐retrieved groups was 16.6%, 71.1%, 76.7% and 72.1%, respectively, substantially supporting the decision‐making model. Survival in the accepted group exceeds that reported previously. However, a proportion of those declined do survive and some remotely managed patients die. This suggests the approach does not account for some important survival‐determining factors.

Intracardiac Right-to-Left Shunt Impeding Liberation From Veno-Venous Extracorporeal Membrane Oxygenation: Two Case Studies.

Objectives: Veno-venous extracorporeal membrane oxygenation is an increasingly used form of advanced respiratory support, but its effects on the physiology of the right heart are incompletely understood. We seek to illustrate the impact of veno-venous extracorporeal membrane oxygenation return blood flow upon the right atrium by considering the physiologic effects during interatrial shunting. Patients: Two veno-venous extracorporeal membrane oxygenation patients in whom an extracorporeal membrane oxygenation induced right-to-left interatrial shunt appears to have created a barrier to liberation from extracorporeal support. Conclusions: Veno-venous extracorporeal membrane oxygenation return flow generates a high-pressure jet that has potential to exert focal pressure upon the intra-atrial septum. In patients with potential for interatrial flow, this may lead to a right-to-left shunt, which becomes physiologically apparent only when sweep gas flow is ceased.