Trans-Esophageal Doppler Assessment of Acute Hemodynamic Changes Due to Prone Positioning in Acute Respiratory Distress Syndrome Patients.

BACKGROUND: Effect of prone positioning on acute hemodynamic changes (within 10 min) in acute respiratory distress syndrome (ARDS) has not been studied. METHODS: In this prospective observational study, hemodynamic assessment by trans-esophageal Doppler (TED) was done with the primary aim of measuring early changes in cardiac index (CI), if any, after prone positioning in moderate to severe ARDS patients. A subgroup analysis was also done based on the response to passive leg raise (PLR). RESULTS: The baseline hemodynamic variables of 26 included patients were: CI 3.5 (3.1-4.3) L/min/m, peak velocity (PV) 83.2 (60.9-99.3) cm/s, flow time corrected (FTc) 341 (283-377) ms, mean acceleration (MA) 9.0 (7.04-11.7) m/s. After prone position, there were no statistically significant changes in CI, 3.5 (P=0.83), 3.75 (P = 0.96), 3.7 (P = 0.34), and 3.9 (P = 0.95) at 5, 10, 20, and 30 min respectively. FTc, mainly indicator of preload, showed decreasing trend to 315 (275-367) ms at 30 min post prone (P = 0.06). On the basis of PLR test also, CI did not change significantly in both PLR+ and PLR- groups. In PLR+ group, PV increased from 72.4 to 83 (P = 0.01), 74.9 (P = 0.03), 82 (P = 0.02), and 82 (P = 0.03) cm/s; while in PLR- group, MA increased from 8.8 to 9.7 (P = 0.03), 10.1 (P = 0.03), 9.3 (P = 0.04), and 10.6 (P = 0.01) m/s at 5, 10, 20, and 30 min respectively. CONCLUSIONS: In moderate to severe ARDS patients, there were no significant changes in CI during first 30 min after prone positioning, even in the subgroups on the basis of PLR response.