Effect of preoperative volume loading on the intraoperative variability of blood pressure and postoperative nausea and vomiting.

INTRODUCTION Preoperative volume loading (PVL) in addition to counteract the decreases in blood pressure during intraoperative period, also may decrease postoperative nausea and vomiting (PONV). This study was designed to investigate the effect of preoperative volume loading on the intraoperative blood pressure variability and postoperative nausea and vomiting. METHODS Thirty subjects scheduled for elective orthopedic procedures randomly divided into case and control groups. The patients in the case group received lactated Ringer 10 ml/kg before induction of general anesthesia. Mean arterial blood pressure (MAP) and heart rate were recorded in two groups every 3 minutes from induction of anesthesia until five minutes after extubation. Variability of mean arterial blood pressure and heart rate were defined as the standard deviation (SD) of the measured values for each patient. Means of these individual SD values were compared between two groups using Mann-Whitney U test. RESULTS The mean variability of mean arterial blood pressure and heart rate ware significantly lower in case group (8.3 +/- 3 mmHg and 8.4 +/- 2.5 bpm vs. 13 +/- 6 mmHg and 11 +/- 2.6 bpm in control group; p < 0.5). The severity of nausea (measured as a ten-point visual analog scale) was significantly lower in case group (1.2 +/- 0.9 vs. 3.9 +/- 1.8 in control group; p < 0.05). No patients in case group developed postoperative vomiting (compared to 5 patients in control group). CONCLUSIONS The results of this study shows that preoperative volume loading is associated with lower variability of blood pressure and heart rate during operative period and also reduces the severity and incidence of postoperative nausea and vomiting.