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.