Abstract

The presence of autonomic neuropathy can potentially blunt the reflex sympathetic response of vasoconstriction to prone positioning, thus possibly influencing changes in pulse pressure variation and its ability to predict fluid responsiveness. A hypothesis that in the presence of co-existing autonomic dysfunction, a fluid challenge in mechanically ventilated patients undergoing surgery in the prone position would fail to produce significant changes in pulse pressure variation was formed and tested. Methods: An initial preoperative screening for autonomic dysfunction was performed on 60 ASA grade 1 and 2 adult, consenting volunteers who were electively posted for surgery in the prone position using a battery of 5 bedside clinical tests (0-2 tests positive). A fluid challenge of 6% hydroxyl-ethyl starch, 6ml/kg over 10 minutes, was given to patients in both the groups, 15 minutes after surgical incision. Pulse Pressure Variation was monitored after induction, 5 minutes after induction, 5 minute after prone positioning, on initiation of fluid bolus and 15 minutes after starting the bolus. The observer was blinded to the findings of the preoperative screening. Results: A significant decrease in PPV was seen 15 minutes after starting the bolus (17.72±3.78 vs. 9.80±1.65 and 17.36±2.05 vs. 8.32±1.67) in both the groups, which was comparable between the two groups. Conclusion: It was determined, in the end, that autonomic dysfunction does not affect the predictive power of PPV for fluid responsiveness in anaesthetized prone individuals.

Description