Neurological Injury in Adults Treated with Extracorporeal Membrane Oxygenation

Abstract & Commentary

By Halinder S. Mangat, MD, Assistant Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Mangat reports no financial relationships relevant to this field of study.

Synopsis: Extracorporeal membrane oxygenation is associated with a high mortality and a high incidence of neurological complications including stroke, subarachnoid hemorrhage, and brain death.

Source: Mateen FJ, et al. Neurological injury in adults treated with extracorporeal membrane oxygenation. Arch Neurol 2011; Epub ahead of print. doi:10.1001/archneurol.2011.209.

Extracorporeal membrane oxygenation (ECMO) is a mechanism for external mechanical blood oxygenation. It is reserved for patients who suffer acute severe respiratory failure and have failed maximal conventional management. The cause of the respiratory failure may be primarily lung related or of cardiac origin.

ECMO was first investigated as early as 1954.1 It traditionally has been used in children, but with improved technology ECMO now increasingly is employed in adults. However, the morbidity and mortality remain high due to the severity of the underlying diseases.

Mateen et al review the neurological outcomes in adult patients undergoing ECMO in a single institution over an 8-year period. Eighty-seven patients were treated with ECMO; the main indications for ECMO were post-cardiopulmonary arrest and post-cardiotomy respiratory failure. Survival was 52% at 7 days and 44% at 30 days after ECMO was discontinued. Patients who did not have CPR prior to ECMO survived longer (19 days vs 15 days in those who had CPR). Withdrawal of support occurred in 36% of patients who underwent ECMO.

Neurological complications occurred in 50% of patients and included new onset coma of varying degrees. Coma was attributed to anoxic brain injury, metabolic encephalopathy, or undefined cause, and all three conditions occurred with similar incidence. There were a smaller number of patients who suffered strokes and brain death.

Neuroimaging was abnormal in 15 of 24 patients studied. Autopsy consistently demonstrated pathological findings of hypoxia-ischemia and hemorrhage (9/10 patients).

Commentary

ECMO is a life-saving intervention that can be used in various clinical scenarios. In the H1N1 epidemic in Australia-New Zealand, more than 200 predominantly young adults were treated for severe acute respiratory distress syndrome. More than one-third received ECMO and mortality was 21%.2 ECMO also has been used to transport patients to tertiary centers when use of conventional mechanical ventilation was not deemed safe.3 And more recently, the use of ECMO after in-hospital cardiac arrest showed improved outcomes.4 Patients can be supported on ECMO while awaiting lung transplant.

There are numerous factors that determine outcome after a severe illness requiring ECMO. Most important is the underlying cause of cardiorespiratory failure as well as pre-morbid state. In this cohort, patients who received CPR had worse outcome. This may well be related to the cardiopulmonary arrest than ECMO. Furthermore, anticoagulation can lead to intracranial hemorrhage just as in patients who are anticoagulated for reasons other than use of ECMO. This may manifest as intracerebral, intraventricular, or subarachnoid hemorrhage.

Brain imaging abnormalities appear to be more common in patients undergoing venoarterial ECMO than those undergoing venovenous ECMO.5 This might suggest a causative role for arterial cannulation and manipulation. With newer techniques, complications may be reduced. Javidfar et al6 report the use of a bicaval dual-lumen catheter for veno-venous ECMO. This allows access via only one site (internal jugular), reduces recirculation, and allows the patient to participate in physical therapy and be more mobile.

Of note in the above study is that not all patients were examined by a neurologist during their illness in the intensive care unit. Given the high incidence of neurological complications from a singular intervention, it would appear that neurological consultation be sought early on to assess the neurological effect of the precipitating illness. This will help detect new neurological signs while the patient remains on ECMO and will help treat and offset further complications.

References

1. Gibbon JH Jr. Application of a mechanical heart and lung apparatus to cardiac surgery. Minn Med 1954;37:180-185.

2. The Australian and New Zealand Extracorporeal membrane oxygenation (ANZ ECMO) Influenza investigators. Extracorporeal membrane oxygenation for 2009 Influenza A (H1N1) acute respiratory distress syndrome. JAMA 2009;302:1888-1895.

3. Forrest P, et al. Retrieval of critically ill adults using extracorporeal membrane oxygenation: An Australian experience. Intensive Care Med 2011;37:824-830.

4. Shin TG, et al. Extracorporeal cardiopulmonary resuscitation in patients with inhospital cardiac arrest: A comparison with conventional cardiopulmonary resuscitation. Crit Care Med 2011; 39: 1-7.

5. Risnes I, et al. Cerebral outcome in adult patients treated with extracorporeal membrane oxygenation. Ann Thorac Surg 2006;81:1401-1406.

6. Javidfar J, et al. Use of bicaval dual-lumen catheter for adult venovenous extracorporeal membrane oxygenation. Ann Thorac Surg 2011;91:1763-1769.