Extracorporeal Support
Extracorporeal life support (ECLS) was first used successfully
to treat refractory respiratory failure in the 1970s. Although ECLS has proven benefits
in the neonatal population (known as extracorporeal membrane oxygenation [ECMO]),
its use in adult patients dropped significantly after a National Institutes of Health-sponsored
trial in 1979 showed no difference in mortality when this expensive, labor-intensive,
high-risk modality was used.[269]
Newer technology,
including heparin-bonded circuitry, allowed its resurgence in the 1980s, and multiple
studies since that time have shown a benefit, especially when its use is coupled
with "lung rest" ventilator strategies. ECLS has numerous indications in patients
with post-traumatic respiratory failure. Case reports describe the benefit of ECLS
in treating ARDS after blunt pulmonary injury[270]
and smoke inhalation injury.[271]
Rapid institution
of this modality may have been key to the excellent survival rate (100%) in these
patients. It is generally accepted that TBI is a relative contraindication to ECLS
because of the need for systemic heparinization. However, another case report described
successful use of ECLS for 7 days, including a bedside thoracotomy and lung resection
while on ECLS; all of this was accomplished without additional heparinization, and
this patient also survived.[272]
The largest published series to date of ECLS in trauma patients
is from the University of Michigan.[273]
Thirty
patients suffering from traumatic injuries over an 8-year period were treated with
venovenous or venoarterial extracorporeal circulation. Entry criteria included an
estimated mortality risk greater than 80%, which was defined as a PaO2
/FIO2
ratio less than 100 despite 100% FIO2
,
pressure-controlled inverse ratio ventilation, optimal PEEP, and prone positioning
therapy. Pulmonary recovery sufficient to wean the patient from ECLS occurred in
56%, and 50% survived to discharge. As with previous studies, early
institution of extracorporeal support was associated with improved survival (<5
vent days).
