Comparison of Hemodynamics during Prone vs Supine Position in Mechanically Ventilated Adult ARDS Patients

The hemodynamic effects of the prone position have not been well studied in patients with severe acute respiratory distress syndrome (ARDS). This study aimed to evaluate the effects of pronation on hemodynamics in mechanically ventilated adult patients with severe ARDS. METHODOLOGY: A prospective observational study was conducted in a tertiary care ICU. The study included mechanically ventilated severe ARDS patients who received prone positioning, had a pulse contour-based cardiac output monitor attached, had a clear echocardiographic window, and completed at least one prone session. Hemodynamic parameters (HR, MAP, CI, CO, SVV, MAPSE, TAPSE) were recorded one hour before and one hour after pronation, one hour after 16 hours of prone positioning, and one hour after the completion of the prone session. During the study period, uniform sedation and neuromuscular blockade protocols were implemented. Patients who required premature termination of the prone position before completing a 16-hour session were excluded. Statistical analysis was performed using an independent sample t-test to compare normally distributed two groups. For non-normally distributed data, appropriate non-parametric tests, such as the Wilcoxon test, were used. A chi-squared test was used for group comparisons for categorical data.(1–3) RESULTS: The average hemodynamic variables of three consecutive supine-prone sessions were as follows (Fig. 1). Improvement in CO (6.5 L/min to 6.8 L/min), CI (3.9 L/min/m(2) to 4.3 L/min/m(2)), TAPSE (1.9 cm to 2.36 cm), and MAPSE (1.4 cm to 1.42 cm) were observed (Fig. 1). Right ventricular function variables, such as CI (3.9 to 4.58 L/min/m(2), p < 0.001) and TAPSE (1.9 cm to 2.31 cm, p = 0.010), showed significant improvement during the first prone session. No significant differences were observed in the changes in HR (95.36/min to 72.67/min, p = 0.897), MAP (86.82 to 85.33 mmHg, p = 0.849), and SVV (8.6 to 5.67, p = 0.226) between the prone and supine positions (Fig. 2). CONCLUSION: Prone positioning in severe ARDS is associated with improvement in hemodynamic parameters, namely CO, CI, TAPSE, and MAPSE. Prone positioning is also associated with improvement in right ventricular dysfunction.(4,5)