COMPARISON OF CHANGE IN LUNG COMPLIANCE ON PRESSURE CONTROL AND AIRWAY PRESSURE RELEASE VENTILATION – A RANDOMIZED CROSS-OVER TRIAL

Background: Mechanical ventilation is a critical intervention in intensive care units, particularly for patients with impaired lung compliance. Optimizing ventilation requires careful adjustment of modes to preserve alveolar integrity, improve oxygenation, and minimize ventilator-associated injury. Airway Pressure Release Ventilation (APRV) and Pressure Control Ventilation (PCV) are widely used pressure-based strategies, yet their effects on lung compliance and oxygenation remain debated. Comparative evidence is limited, especially in crossover designs allowing within-patient evaluation of these modes. Objective: The study aimed to assess changes in lung compliance and oxygenation indices following mechanical ventilation with APRV and PCV, using a randomized cross-over design. Methods: This randomized cross-over trial was conducted in the Department of Anaesthesiology, Surgical ICU, Dr. Ruth K.M. Pfau Civil Hospital Karachi, Pakistan, from May to December 2021. A total of 70 patients aged 18–85 years requiring mechanical ventilation for >6 hours were included. Ventilation was initiated with Assist-Control Volume Control (AC-VC) mode for baseline measurements, followed by randomization to APRV or PCV in Phase I and cross-over to the alternate mode in Phase II. Data collected included dynamic lung compliance, oxygen index (OI), arterial blood gases, peak inspiratory pressure (PIP), mean airway pressure (MAP), and airway resistance. Results: Baseline compliance in AC-VC mode was 45.5 mL/cmH₂O/kg (IQR: 32.8–64.2). In Phase I, compliance was significantly higher with APRV at 89.6 mL/cmH₂O/kg (IQR: 62.4–124.7) compared to PCV at 48.2 mL/cmH₂O/kg (IQR: 34.6–68.9). In Phase II, APRV maintained higher compliance at 76.4 mL/cmH₂O/kg (IQR: 55.2–108.6) compared with PCV at 68.3 mL/cmH₂O/kg (IQR: 49.5–92.1). Correlation analysis showed APRV weakly positive in Phase I (r = 0.173, p = 0.322) and Phase II (r = 0.261, p = 0.131), while PCV was moderately negative in Phase I (r = -0.311, p = 0.069) and very weakly negative in Phase II (r = -0.065, p = 0.712). Regression revealed a significant negative association for PCV in Phase I (B = -1.998, p = 0.025). Oxygen index analysis indicated significant improvements with both modes in Phase I, but only APRV sustained improvement in Phase II. Conclusion: APRV demonstrated more consistent benefits in preserving lung compliance and sustaining oxygenation compared with PCV. These findings support the role of APRV in critically ill patients; however, larger multicenter studies are needed to confirm long-term outcomes and guide individualized ventilation strategies.