Comparison of adaptive support ventilation and synchronized intermittent mandatory ventilation in patients with acute respiratory distress syndrome: A randomized clinical trial

Background: Suitable mechanical ventilation strategies can reduce the incidence and severity of ventilator‑associated lung injury in patients with acute respiratory distress syndrome (ARDS). In this study, the effects of adaptive support ventilation (ASV) and synchronized intermittent mandatory ventilation (SIMV) on respiratory parameters and arterial blood gases (ABGs) parameters were compared in ARDS patients. Materials and Methods: Twenty‑four patients were randomly divided into two groups of ASV and SIMV. Patients were followed up for 3 days, and respiratory parameters including rapid shallow breathing index (RSBI), spontaneous breathing rate (SBR), minute volume, and peak inspiratory pressure (PIP) as the primary outcomes and ABG parameters including PaO2 , FiO2 , PaCO2 , HCO3 , and PaO2 /FiO2 ratio as the secondary outcomes were measured. Results: PIP in patients in the SIMV group on the 1st day (P = 0.013), 2nd day (P = 0.001), and 3rd day (P = 0.004) was statistically significantly more compared to those in patients in the ASV group. RSBI, SBR, and minute volume between the ASV and SIMV groups during the 3 days were not statistically significantly different (P > 0.05). The mean arterial blood pressure, heart rate, PaO2 , and PH between both groups were similar (P > 0.05). At the end of the 2nd and 3rd days, the level of FiO2 and PaCO2 in ASV was significantly lower than those in ASV group. HCO3 in each of the 3 days in the ASV group was statistically significantly lower than that in the SIMV group (P < 0.050). PaO2 /FiO2 ratio in patients in the ASV group in the 3 days was statistically significantly higher than that in the SIMV group (P < 0.050). Conclusion: By reducing PIP and improving oxygenation and ABG parameters, ASV mode may be a safe and feasible mode during mechanical ventilation in patients with ARDS.