Dehydration with Bowel Purgatives

Abstract

Purpose: Dehydration-related complications from colon preparation have recently emerged as a vital issue in colonoscopy screening. Signs of dehydration include weight loss, postural changes in blood pressure (BP) and pulse rate (PR), dizziness, and headaches. To assess whether multiple classes of purgatives may lead to dehydration, signs were monitored in patients (pts) undergoing colonoscopy in 2 identically designed, randomized, multicenter, investigator-blinded studies. Methods: Pts scheduled for colonoscopy received either 4-L PEG solution (Cherry Flavor NuLYTELY®; Braintree Laboratories Inc, Braintree, Mass; n = 432) or NaP tablets (Visicol® Tablets; Salix Pharmaceuticals, Inc, Morrisville, NC; n = 427) for bowel preparation. Weight, postural changes in BP and PR, and adverse events (AEs) were recorded up to 7 days before colonoscopy (baseline), on the day of colonoscopy, and 48 to 72 hours postcolonoscopy. Postural hypotension was defined as a symptom-associated orthostatic increase of 30 beats/min in PR or an orthostatic decrease in systolic (≥25 mm Hg) or diastolic (≥20 mm Hg) BP. Results: On the day of colonoscopy, weight loss was evident in pts treated with 4-L PEG (2.4 ± 2.8 lb) and 40 NaP tablets (2.1 ± 3.3 lb). Pts regained the majority of lost weight within 3 days postcolonoscopy, but weights were still reduced compared with baseline levels (−0.7 ± 3.0 lb, PEG group; −0.3 ± 3.1 lb, NaP group). Fourteen (3.2%) pts in the PEG group and 21 (4.9%) pts taking NaP tablets reported light-headedness or dizziness. Similarly, 2.8% (n = 12) and 3.3% (n = 14) of pts treated with PEG and NaP, respectively, experienced headaches. Seven pts (4 and 3 pts in PEG and NaP groups, respectively) reported symptoms suggestive of postural hypotension but did not reach the predefined criteria. In both groups, slight changes in plasma electrolytes resolved by end of study. Conclusions: Mean weight loss after purgation with either PEG solution or NaP tablets was ∼2 lb. Return to baseline weight was not fully achieved 2 to 3 days postcolonoscopy. Data suggest that pts lose a similar amount of stool and fluid during purgation, regardless of the bowel preparation. The prolonged weight reduction, along with AEs such as light-headedness, dizziness, and headaches, suggests that dehydration may be a risk even several days postcolonoscopy. Thus, pts who are scheduling a colonoscopy should be advised of the importance of proper hydration prior to, during, and after bowel preparation. Complications of dehydration can be avoided.