Determinants of immediate failure of noninvasive mechanical ventilation outside the intensive care unit.

Background: This study aimed to characterize which are the early determinants of immediate failure of the use of noninvasive mechanical ventilation (NIMV) outside the ICU.

Methods: This prospective study included patients who were admitted to the Military Hospital in Guayaquil, Ecuador. Each variable was analyzed independently by using a multiple logistic regression model toward establishing an association with the event.

Results: A total of 249 cases of NIMV over a 10 year period of its application outside the ICU was included in the study. Fifty-five (22.10%) patients were transferred to the ICU, A multivariate analysis showed that the determinants of immediate NIMV failure outside the ICU were the following: age (OR: 1.12; P = 0.03); SBP (OR: 1.04; P = 0.001); HR (OR: 1.66; P < 0.0001); pCO₂ (OR: 1.16; P = 0.007); pO2 (OR: 1.35; P = 0.003); levels of IPAP (OR: 1.35; P < 0.0001); and the number of quadrants affected, as shown in a chest X-ray (OR: 1.40; P < 0.0001).

Conclusions: The number of affected quadrants in a chest X-ray, tachyarrhythmia and hypoxemia may be useful in the initial decision in the use of NIMV outside the ICU. High values of IPAP, the persistence of elevated pCO₂, arterial hypotension, and age could be useful as a second screening associated with immediate NIMV failure outside the ICU.