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Lessons learned from airway pressure release ventilation

BACKGROUND: The aim of this article is to review a single institution's experience with airway pressure release ventilation (APRV) with respect to safety, complications, and efficacy at correcting hypercarbia and hypoxemia. METHODS: Patients transitioned from either volume- or pressure-targeted ventilation to APRV in a university hospital surgical intensive care unit were retrospectively reviewed. Patients whose ventilator strategy started with APRV were excluded. Abstracted data included age, sex, diagnosis, ventilation parameters, indication for altering the ventilator strategy, laboratory values, and ventilator-associated complications. Data before and after transitioning to APRV were compared using a two-tailed unpaired t test or &khgr;2 test as appropriate; significance assumed for p ⩽ 0.05. RESULTS: Patient mix (n = 38) was 43% trauma, 32% sepsis, 8% cardiac surgery, 12% vascular surgery, and 5% other. Transitioning to APRV was undertaken most often for hypoxemia (88%) and less frequently for hypercarbia (12%). The mean time to correct hypoxemia (SAO2 >92%) was 7 minutes ± 4 minutes, while the mean time to correct PCO2 (PCO2 ⩽40 mm Hg) was 42 minutes ± 7 minutes. The mean time to maximal CO2 clearance was 66 minutes ± 12 minutes. The mean minute ventilation decreased on APRV by 3.3 L/min ± 0.9 L/min but achieved superior CO2 clearance and oxygenation. The mean time to FIO2 ⩽0.6 was 5.2 hours ± 0.9 hours. Four of the 38 patients developed a pneumothorax. Ninety-seven percent of patients on APRV who were transported out of the intensive care unit using bag-valve ventilation (with appropriate positive end-expiratory pressure valve settings) with Phigh ≥20 cm H2O developed hypoxemia within 5 minutes. Hundred percent of patients with a Phigh ⩽20 cm H2O were safely hand ventilated during transport without developing hypoxemia. CONCLUSIONS: APRV is a safe mode of ventilation for hypoxemic or hypercarbic respiratory failure. Improvements in PO2 and PCO2 are achieved at lower minute ventilations than with volume- or pressure-targeted modes. LEVEL OF EVIDENCE: III.