Comparison of BPAP S/T and Average Volume-Assured Pressure Support Modes for Hypercapnic Respiratory Failure in the Emergency Department: A Randomized Controlled Trial

Background There is limited research into the utility of average volume- assured pressure support (AVAPS), a volume-assured pressure-controlled mode, especially in patients with hypercapnic respiratory failure. Aims This study aimed at a randomized comparison of AVAPS and bilevel positive airway pressure spontaneous/timed (BPAP S/T) modes in non-invasive mechanical ventilation application with hypercapnic respiratory failure patients in the emergency department. Study design Randomized controlled study. Methods Eighty of 140 patients admitted to the emergency department with hypercapnic respiratory failure requiring non-invasive mechanical ventilation were randomly assigned to the AVAPS or S/T groups (33 patients in the S/T group, 47 patients in the AVAPS group) using the sealed envelope method. Data of arterial blood gas, vital parameters, Glasgow Coma Score, additional treatment needs, and clinical outcomes were evaluated, and the treatment success rates of both groups were compared. Results A total of 80 patients, 33 in the S/T and 47 in the AVAPS group, were analyzed in the study. The pH values improved in the AVAPS group compared to the baseline (0.07 [0.04-0.10] vs 0.03 [0.00-0.11]). PaCO2 (partial pressure of carbon dioxide) excretion was faster in the AVAPS group than in the S/T group in the first hour (10.20 mmHg [6.20-19.20] vs. 4.75 ([-] 0.83-16.88)). The comparison of blood gas measurements showed no significant differences between the groups regarding the changes in PaCO2 and pH values over time (P = .141 and P = .271, respectively). During the emergency department follow-up, 3 (6.4%) patients in the AVAPS group and 5 (15.2%) patients in the S/T group needed intubation [Relative risk: 0.42 (95% CI: 0.11 to 1.64), P = .21]. Conclusion The AVAPS mode is as effective and safe as BPAP S/T in treating patients with hypercapnic respiratory failure in the emergency department.