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

Bowel preparation using purgatives has previously been shown significantly to increase haemoglobin concentration and decrease weight. This prospective randomized study assessed the effects of administering intravenous fluid during bowel preparation.

Patients having bowel preparation with Picolax for colonic procedures were randomized prospectively to receive no intravenous fluid (group 1) or calculated intravenous crystalloid based on body-weight (group 2) during preparation. Physiological, haematological and biochemical variables were measured before and after bowel preparation.

Forty-one patients were recruited with a median age of 69 (range 29-86) years, 22 in group 1 and 19 in group 2. There was no difference between groups in any of the variables measured before bowel preparation. On completion, there was a significant difference between groups in mean weight loss (P = 0.01), postural change in systolic pressure (P = 0.015) and serum creatinine concentration (P = 0.008). In addition there was a significant fall 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.

Picolax bowel preparation has a significant dehydrating effect, which can be minimized by administering a simultaneous volume of intravenous fluid (mean 2 litres in this study).