ĐẶC ĐIỂM CƠ HỌC VÀ PHÂN BỐ KHÍ VÙNG PHỔI TRONG THÔNG KHÍ NHÂN TẠO TƯ THẾ NẰM SẤP Ở BỆNH NHÂN CÓ HỘI CHỨNG SUY HÔ HẤP CẤP TIẾN TRIỂN

Abstract

Objective: Assessment of changes in lung mechanics and regional lung ventilation distribution using Electrical Impedance Tomography (EIT) during prone position mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). Subjects and Methods: This was a descriptive observational study including all ARDS patients indicated for prone mechanical ventilation and monitored by EIT at the Center for Critical Care Medicine, Bach Mai Hospital from May 2024 to September 2025. Measurements of lung mechanics done by ventilators and TVP, TVROI4, and the A/P ratio were performed by EIT machines at specified study time points. Data were analyzed and processed using SPSS software. Results: The study included 17 ARDS patients who underwent prone positioning with 24 EIT measurements. The mean age was 51.88 ± 22.34 years; 64.7% were male; mean BMI was 23.31 ± 3.92 kg/m². The most common comorbidities were hypertension (41.2%) and heart failure (23.5%). The mean SOFA score was 11.76 ± 3.01; APACHE II 21.2 ± 5.99; and Lung Injury Score (LIS) 2.85 ± 0.34. Most patients had disease onset >3 days (70.6%); the time from onset to initiation of prone ventilation was 2.7 ± 0.44 days. Before prone positioning, mean Cstat was 24.06 ± 1.68 mL/cmH₂O; median Pplat was 25 cmH₂O; and median driving pressure was 15.5 cmH₂O. Arterial blood gas analysis indicated severe respiratory failure with a mean P/F ratio of 93.23 ± 22.58; median PaCO₂ 49 mmHg; pH 7.31; and HCO₃⁻ 26.94 mmol/L. EIT demonstrated heterogeneous ventilation distribution, predominantly in the anterior lung region (56%) compared to the posterior region (44%), with an A/P ratio of 1.49. Ventilation between the left and right lungs was relatively balanced (48% vs. 52%); however, ventilation in the most dependent region was markedly reduced (mean TVROI4 7.5%). After prone positioning, Cstat increased, while Pplat and Pdriv decreased; PaO₂/FiO₂ improved significantly. Ventilation distribution became more homogeneous, as reflected by a reduced A/P ratio and increased ventilation in the dependent lung regions. Conclusion: The lung mechanics and EIT parameters improve during prone mechanical ventilation in patients with ARDS.