Cellular Potassium Depletion Predisposes to Hypokalaemia After Oral Sodium Phosphate

Abstract

Background: Oral sodium phosphate has become an attractive alternative to polyethylene glycol for colonic cleansing preparatory to elective colorectal surgery. Its use, however, has been associated with hypokalaemia. The authors of the present study tested the hypothesis that patients with cellular depletion of potassium are at significant risk for hypokalaemia with oral sodium phosphate bowel preparation. Methods: In 23 patients, total body potassium was measured by whole-body counting and intracellular water volume was measured by bioimpedance analysis before oral sodium phosphate bowel preparation. Patients were divided into those whose serum potassium fell to 3.5 mmoVL or lower (Group 1) and those whose did not after sodium phosphate treatment (Group 2). Results: The fall in serum potassium concentration over the period of oral sodium phosphate administration was significantly negatively correlated with intracellular potassium concentration measured prior to administration (r = -0.65, P = O.ooo9). In Group 1, serum potassium concentration fell from 4.1 * 0.1 (standard emor of the mean (SEM)) mmoVL to 3.2 * 0.1 mmoVL (P c 0.OOOl) while in Group 2 there was no significant change in this concentration (4.0 f 0.1 vs 3.9 * 0.1 mmoVL) as a result of sodium phosphate treatment. Intracellular potassium concentration prior to administration of sodium phosphate was significantly lower in Group 1 (1 17 * 9 mmoVL vs 143 ~t 7 mmoVL, P c 0.05). Conclusions: Caution should be exercised when treating patients with oral sodium phosphate who are considered to be cellularly depleted of potassium. These patients are at risk of hypokalaemia after this treatment.

Postoperative arrhythmias in colorectal surgical patients: incidence and clinical correlates

“…Hypokalaemia (serum potassium < 3.5mmol ⁄ dl) was more common in the arrhythmia group (9 ⁄ 13 vs 9 ⁄ 38; P ¼ 0.005), although in seven cases the hypokalemia developed after the arrhythmia. These patients may have had intracellular potassium depletion at the time of the arrhythmia [21]. Potassium deficiency may precipitate arrhythmias [22].…”

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

“…In a prospective randomized study Lawrance et al 6 studied ®ve different oral¯uid regimens in 197 patients and found no difference in any of the groups with regard to adverse events. Hill et al 7 demonstrated that patients with cellular potassium depletion were at risk of hypokalaemia after bowel preparation with sodium phosphate. The present study con®rms the dehydrating effect of Picolax â bowel preparation as measured by the decrease in weight, erect systolic, erect diastolic and supine diastolic pressures in group 1, and the signi®cant difference in postural pressure change between groups.…”

Enhanced recovery after surgery fact or fiction?

“…Finally, the question remains how to implement such evidence based perioperative care programmes on a broader basis in the Netherlands. Future studies should investigate the added benefit of laparoscopic surgery within a fast track perioperative care programme 12,55 .…”

“…A proportion of patients who undergo bowel preparation with purgative laxatives and who are subject to conventional preoperative fasting protocols are subject to dehydration and electrolyte imbalance. [53][54][55] Avoidance of bowel preparation, the use of preoperative oral carbohydrate loading and free access to fluids until 2 h before induction of anaesthsia are potential methods to reduce this problem. There is good evidence to support the safety of allowing access to fluids up to 2 h before surgery.…”