NONINVASIVE POSITIVE PRESSURE VENTILATION VIA FACE MASK - FIRST-LINE INTERVENTION IN PATIENTS WITH ACUTE HYPERCAPNIC AND HYPOXEMIC RESPIRATORY-FAILURE

Objectives: We have previously reported our experience with noninvasiv e positive pressure ventilation (NPPV) via face mask in a small group of selected patients with acute respiratory failure (ARF). NPPV was fr equently effective (70% success rate) in correcting gas exchange abnor malities and in avoiding endotracheal intubation (ETI); NPPV also had a low rate of complications. We have evaluated the clinical applicatio n of NPPV as first-line intervention in patients with hypercapnic and short-term hypoxemic ARF. A dedicated respiratory therapist conducted an educational program with physicians-in-training rotating through th e medical ICUs of a university medical center and supervised implement ation of a simplified management protocol. Over 24 months, 164 patient s with heterogeneous forms of ARF received NPPV. We report on the effe ctiveness of NPPV in correcting gas exchange abnormalities, in avoidin g ETI, and associated complications, in different conditions precipita ting ARF. Patient population: One hundred fifty-eight patients complet ed the study. Forty-one had hypoxemic ARF, 52 had hypercapnic ARF, 22 had hypercapnic acute respiratory insufficiency (ARI), 17 had other fo rms of ARF, and 26 with advanced illness had ARF and refused intubatio n. Twenty-five percent of the patients developed ARF after extubation. Intervention: Mechanical ventilation was delivered via a face mask. I nitial ventilatory settings were continuous positive airway pressure ( CPAP) mode, 5 cm H2O, with pressure support ventilation of 10 to 20 cm H2O titrated to achieve a respiratory rate less than 25 breaths/min a nd an exhaled tidal volume of 7 mL/kg or more. Ventilator settings wer e adjusted following arterial blood gases (ABG) results. Results: The mean duration of NPPV was 25+/-24 h. When the 26 patients with advance d illness are excluded, NPPV was effective in improving or correcting gas exchange abnormalities in 105 patients (80%) and avoiding ETI in 8 6 (65%). Failure to improve ABG values was the reason for ETI in 20 of 46 (43%). The overall average predicted and actual mortality were 32% and 16%, respectively. Survival was 93% in non-intubated patients and 79% in intubated patients. NPPV was effective in lessening dyspnea th roughout treatment in all but seven patients. Complications developed in 24 patients (16%). In patients with hypercapnic ARF, nonresponders had a higher PaCO2 at entrance (91.5+/-4.2 vs 80+/-1.5; p<0.01). In pa tients with hypercapnic ARF and ARI, arterial blood gases response (pH and PaCO2) within 2 h of NPPV predicted success (p<0.0001). None of t he entrance parameters predicted need for ETI. Conclusions: We conclud e that application of NPPV in clinical practice is an effective and sa fe alternative to ETI in many hemodynamically stable patients with hyp ercapnic ARF and in those with hypoxemic ARF in whom the clinical cond ition can be readily reversed in 48 to 72 h. An educational and superv ision program is essential to successfully implement this form of ther apy.