Mortality is directly related to the duration of mechanical ventilation before the initiation of extracorporeal life support for severe respiratory failure.

Objective: To investigate the relationship between the period of mechanical ventilation before extracorporeal life support and survival in patients with respiratory failure.
Design: Retrospective review.
Setting: Surgical intensive care unit at a university medical center.
Patients: Thirty-six consecutive adult patients with severe respiratory failure managed with extracorporeal life support.
Interventions: Extracorporeal life support was utilized in 36 acute respiratory failure adult patients with a variety of diagnoses and an estimated mortality rate of > 90%. Management protocols were followed before and during extracorporeal life support. The 36 patients were physiologically similar before extracorporeal life support was initiated: shunt of 48 +/- 17%; F10(2) of 1.0 +/- 0.1; peak inspiratory pressure of 56 +/- 16 cm H2O; positive end-expiratory pressure of 14 +/- 6 cm H2O; and respiratory rate of 23 +/- 10 breaths/ min. Ventilation was utilized for 1 to 17 days before extracorporeal life support. Typical lung rest settings during extracorporeal life support were F10(2) of 0.40, peak inspiratory pressure of 30 cm H2O, positive end-expiratory pressure of 10 cm H2O, and respiratory rate of 6 breaths/min. Death was almost always secondary to end-stage pulmonary failure.
Measurements and Main Results: Survival (hospital discharge) in these 36 patients was inversely associated with the number of days of preextracorporeal life support ventilation, with a 50% mortality rate predicted by logistic regression after 5 days of mechanical ventilation. The overall survival rate was 18 (50.0%) of 36 patients.
Conclusions: In severe acute respiratory failure treated with lung rest and extracorporeal life support, a predicted 50% mortality rate was associated with 5 days of preextracorporeal life support mechanical ventilation.