Randomized clinical trial of intravenous fluid replacement during bowel preparation for surgery

Background: Bowel preparation using purgatives has previously been shown si gnificantly to increase haemoglobin concentration and decrease weight. This prospective randomized study assessed the effects of administering intrave nous fluid during bowel preparation. Methods: Patients having bowel preparation with Picolax(R) for colonic proc edures were randomized prospectively to receive no intravenous fluid (group 1) or calculated intravenous crystalloid based on body-weight (group 2) du ring preparation. Physiological, haematological and biochemical variables w ere measured before and after bowel preparation. Results: Forty-one patients were recruited with a median age of 69 (range 2 9-86) years, 22 in group 1 and 19 in group 2. There was no difference betwe en groups in any of the variables measured before bowel preparation. On com pletion, there was a significant difference between groups in mean weight l oss (P = 0.01), postural change in systolic pressure (P = 0.015) and serum creatinine concentration (P = 0.008). In addition there was a significant f all in erect blood pressure after bowel preparation in group 1 (P = 0.02). The mean urine output in group 1 was 982 ml and in group 2 was 1808 ml (P = 0.004). The faeces weight between groups was not significantly different. Conclusion: Picolax(R) bowel preparation has a significant dehydrating effe ct, which can be minimized by administering a simultaneous volume of intrav enous fluid (mean 2 litres in this study).