CHICAGO – Venovenous extracorporeal membrane oxygenation will save perhaps a third of patients who – despite maximum ventilator support – go into end-stage respiratory failure after trauma, according to investigators from the University of Maryland, Baltimore.
“Institutions without the available expertise and ICU capabilities should promptly refer patients with end-stage respiratory failure secondary to trauma to a tertiary care center. Venovenous ECMO [extracorporeal membrane oxygenation] life support may be their only chance for survival and should not be overlooked due to fear of complications,” they concluded.
ECMO usually requires heparin anticoagulation to prevent clots; the fear of subsequent bleeding is one of the things that prevents ECMO’s widespread use in trauma. As a result, “a lot of patients who need ECMO lung support don’t get it,” said Dr. Sarwat Ahmad, of the university.
Dr. Ahmad and her colleagues, however, found that ECMO did not lead to worse outcomes in their lung failure patients.
Their conclusions come from a review of 39 adult blunt and penetrating trauma patients who received ECMO at the university’s Level I trauma center over the past 9 years.
Thirty-two patients had venovenous ECMO mostly for acute respiratory distress; maximal ventilator support, adjunctive medications, and chest therapy did not help. ECMO outflow was from the femoral vein, and blood was returned to the internal jugular vein. Twelve patients (38%) survived, which “is good in this scenario because they otherwise would have died,” Dr. Ahmad said.
The mean pre-ECMO P/F ratio – arterial oxygen partial pressure to fractional inspired oxygen – among the survivors was 98 mm Hg. Values below 100 mm Hg indicate severe lung injury, but some patients had values approaching 200 mm Hg, meaning that ECMO was a good idea even in patients with less severe lung injury.
Seven patients received venoarterial ECMO mostly for cardiac arrest, with outflow from the femoral vein and blood returned via the femoral artery. The patients were pulseless on arrival, so bypassing the heart seemed the only option, but none of them survived. Because of that, the investigators concluded that venoarterial ECMO is “not going to help” in trauma patients, Dr. Ahmad said.
One of the 12 survivors and over half of those who died had injury severity scores above 40 points. Also, Glasgow coma scores below 8 points were far more common among patients who died.
All 12 of the survivors and 14 of the 27 who died were anticoagulated with heparin. “We didn’t see an increased incidence of complications between those who got heparin and those who did not” and, overall, there wasn’t a higher incidence of complications in ECMO patients, compared with other trauma patients. “Even traumatic brain injury patients didn’t do any worse on ECMO. We don’t think that the fear of complications should turn you away from using ECMO,” Dr. Ahmad said.
Dr. Ahmad has no disclosures; there was no external funding for the work.