Effect of Preoperative Oral Rehydration on the Hypotension during Spinal Anesthesia.

BACKGROUND: Preoperative dehydration is one of risk factors of hypotension during spinal anesthesia (SA). We hypothesized that preoperative oral rehy- dration (POR) may help prevent hypotension during SA. METHODS: After obtaining approval from the ethics committee, patients who underwent surgery twice (urological surgery or orthopedic surgery) within 6 months were enrolled in the study. For the first sur- gery, the patients fasted after midnight and were given an intravenous infusion (100 ml - hr-1) on the morning before the surgery (fasting group). During the second surgery, the patients underwent POR (1,200 ml) from the night prior to the surgery to 2 hr before the surgery (POR group). The same amount of anes- thetic drug was administered during both surgeries. The delta systolic blood pressure (ASBP) was mea- sured between the pre-anesthetic condition and the early phase (0-5 min after SA induction) or secondary phase (10-15 min after SA induction). A P value<0.05 in the t-test was considered to indicate statistical sig- nificance. RESULTS: The ASBP was lower in the POR group compared to the fasting group during both the early and secondary phases; however, only the ASBP during the early phase was significantly different (P=0.019). There was no difference in the total amount of fluid infusion, heart rate, and levels of anesthesia between both groups during the study. CONCLUSIONS: POR prevented hypotension immedi- ately after SA induction.