Practice of extracorporeal membrane oxygenation in adult patients: a single-centre experience

Extracorporeal membrane oxygenation (ECMO) is used as a treatment modality in patients with severe but potentially reversible cardiorespiratory failure that is not responding to conventional treatments. Practice of ECMO for neonatal respiratory failure has now become evidence-based practice supported by randomised controlled trials. Efficacy of ECMO in treating adult patients with severe respiratory failure is currently being investigated in a multicentre randomised controlled trial in the UK – the CESAR trial http://www.cesar-trial.org. The aim of this study is to review the practice of ECMO in adult patients and to identify complications of ECMO associated with mortality.

This study is a retrospective review of case records, microfilms and our database between August 1989 and May 2004. All adult patients (aged 18 years or more) who received ECMO for severe respiratory failure at our hospital were included. The indication for use of ECMO in respiratory failure is a Murray score of more than 3 or a pH of less than 7.2 with uncompensated hypercapnoea not responsive to conventional ventilation. Venovenous ECMO was used in most of the patients with respiratory failure and venoarterial ECMO was used in patients with primary cardiac failure. Complications on ECMO were classified as mechanical (if the complication was related to the ECMO circuit used) or patient complications.

A total of 269 adult patients received ECMO in our unit. ECMO was used for respiratory failure in 94% (pneumonia 54.6%, primary ARDS 14.5%, secondary ARDS 8%, status asthamaticus 1.86% and other causes in 15% of patients) and cardiac failure in 6% of patients. Out of these, 42 patients were excluded from the analysis as they were part of the CESAR trial. The over all survival to discharge was 65%. Complete data on the complications were available in 222 out of 227 patients. The incidence of mechanical and patient-related complications were as follows.

Mechanical complications: clots in oxygenator 94 (42.3%), clots in bladder 55 (24.8%), oxygenator failure 51 (23.0%), clots in bridge 47 (21.2%), cracks on connectors 18 (8.1%), pump malfunction 15 (6.8%), cannula problems 13 (5.9%), race way/tubing rupture 4 (1.8%) and air in circuit 2 (0.9%).

Patient-related complications: cardiac failure requiring inotropes 115 (51.8%), renal 102 (45.9%), infections 60 (27.0%), arrhythmias 50 (22.5%), cannula site bleeding 32 (14.4%), metabolic 32 (14.4%), pulmonary 29 (13.1%), gastrointestinal haemorrhage 15 (6.8%), clinical brain death 8 (3.6%), hypertension requiring vasodilator therapy 6 (2.7%), cerebral infarction 2 (0.9%), and intra-cranial bleeding 2 (0.9%).

The mean number of complications is 3.06 (standard deviation 2.48) per patient. Multiple logistic regression analysis of these complications revealed cannulation site bleeding, hypertension, cardiac arrhythmias and pulmonary complications were independently associated with mortality and none of the mechanical complications were associated with mortality.

ECMO is a viable option in managing adult patients with severe but potentially reversible respiratory and cardiac failure. Mechanical complications of ECMO are not associated with mortality in such patients. This may be because of the expert care of the ECMO circuit by the dedicated ECMO specialists.