Extracorporeal membrane oxygenation use in patients with traumatic brain injury

Introduction

Traumatic brain injury (TBI) is a relative contraindication for extracorporeal membrane oxygenation (ECMO) due to bleeding complications and anticoagulation required for the ECMO circuit.^1,2 However, bleeding complications, including intracranial hemorrhage and anticoagulation requirements may be reduced with modern circuits. We report the successful use of venovenous ECMO using our low-dose anticoagulation protocol in two TBI patients with severe acute respiratory distress syndrome (ARDS).

Cases

Patient 1

The first patient was an 18-year-old man admitted after being struck by a vehicle. His initial Glasgow Coma Scale score (GCS) was 14, but he became combative and required endotracheal intubation. His Injury Severity Score (ISS) was 27. A head computed tomography (CT) scan revealed a right parieto-occipital epidural hematoma, right frontal subarachnoid hemorrhage and hemorrhagic contusions (Figure 1A). An external ventricular drain and bolt were placed; due to his well-controlled intracranial pressure (ICP), neurosurgical intervention was not required. On hospital day 4, he developed pneumonia and severe ARDS, with nadir partial pressure of arterial oxygen (PaO₂) to fraction of inspired oxygen (FiO₂) ratio of 42. Lung protective ventilation was attempted; however, hypercapnea led to an ICP crisis and the progressive hypoxemia resulted in decreased brain tissue oxygen (PbO₂). Our center’s ECMO team was consulted and the patient was cannulated with a 31 French Avalon Elite™ bicaval dual-lumen cannula (Maquet, Rastatt, Germany) which was our standard for ECMO transport at that time. A heparin infusion was titrated according to our standard low-dose anticoagulation protocol; activated partial thromboplastin time (aPTT) target for patients receiving ECMO is 40-60 seconds. The median aPTT was 47 seconds for the ECMO run. Once on ECMO, his cerebral perfusion pressure, ICP, PbO₂, PaO₂ and PaCO₂ were maintained within acceptable ranges. His neurologic exam improved and he was following commands by ECMO day 11, decannulated on ECMO day 13 and extubated 6 days later. He made a complete neurologic recovery

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Figure 1.

A) Patient 1 CT head; B) Patient 2 CT head.

Discussion

The incidence of ARDS in patients with isolated TBI is 20-30% and is an independent predictor of poor outcomes. ³ The management of TBI includes minimizing ICP by targeting PaCO₂ between 30-35 mmHg and avoiding hypoxemia. However, lung protective ventilation in ARDS may result in hypercapnea and methods to improve oxygenation, such as high PEEP, may decrease cerebral perfusion pressure.

ECMO can improve control of PaCO₂ and PaO₂ in patients with cerebral and pulmonary insults when optimized ventilator management is inadequate. However, TBI is a relative contraindication to ECMO, given the need for anticoagulation, bleeding complications and circuit-related thrombocytopenia. Several case series report the successful use of ECMO in TBI patients, both with and without systemic anticoagulation.^2,4–6 We typically see 10 pure TBI cases and 70 subdural hemorrhages from falls yearly in our neuro-ICU. In our experience, we used our standard heparinization at the initial cannulation with a 2000U IV heparin bolus and maintained a low aPTT target throughout the ECMO run. We have demonstrated safety and efficacy of using a heparinized ECMO circuit to support TBI patients with ARDS. The risks of severe hypoxemia and elevated ICP must be weighed against the risk of intracerebral hemorrhage in a coordinated discussion between critical care, ECMO and neurology teams.