Noninvasive Positive-Pressure Ventilation With Different Interfaces in Patients With Respiratory Failure After Abdominal Surgery: a Matched-Control Study

BACKGROUND: Acute respiratory failure (ARF) is a relatively common complication after abdominal surgery.

METHODS: We compared the efficacy of noninvasive positive-pressure ventilation (NPPV) delivered via helmet versus via face mask in patients with ARF after abdominal surgery in 2 intensive care units (31 beds) in the hospital affiliated with the Catholic University of Rome. Twenty-five patients with ARF after abdominal surgery were treated with NPPV via helmet, and the data from those patients were matched with 25 controls chosen from a historical group of 151 patients treated with face mask during the previous 2 years for respiratory complications after abdominal surgery. The matching was done according to age, Simplified Acute Physiology Score II, and the ratio of P_aO2 to fraction of inspired oxygen (P_aO2/F_IO2). NPPV was delivered in pressure support, starting with 10 cm H₂O, and positive end-expiratory pressure (PEEP) was increased in steps of 2-3 cm H₂O, up to a maximum of 12 cm H₂O, in order to maintain an arterial oxygen saturation over 90% with the lowest possible F_IO2.

RESULTS: NPPV significantly improved P_aO2/F_IO2 in both groups. Five of 25 helmet patients (20%) and 12 of 25 mask patients (48%) were intubated (p < 0.036). The main cause for NPPV failure in both groups was intolerance (mask 32% vs helmet 12%, p = 0.6). Heart rate, systolic blood pressure, respiratory rate, duration of NPPV, level of pressure support, and PEEP presented no differences between the 2 groups, nor did intensive-care-unit or hospital mortality. Both the helmet and mask interfaces were effective in improving gas exchange and respiratory rate. The global rate of NPPV complications (mask intolerance, major leaks that caused ventilator malfunction, and ventilator-associated pneumonia) was significantly higher in the mask group than in the helmet group (19 patients vs 4 patients, p < 0.03).

CONCLUSIONS: NPPV can be an alternative to conventional ventilation in patients with ARF after major abdominal surgery, and helmet use is associated with a better tolerance and a lower rate of complications.