Effect of outpatient bowel preparation on preoperative electrolytes

Abstract

Study Objective: With the shift to outpatient and same-day admit surgery, preoperative bowel preparation is now also performed on an outpatient basis. This practise has the potential to cause electrolyte disturbances and for this reason, patients have their electrolytes re-measured on the day of surgery in order to detect and rectify any abnormalities. Though the ability to do this on an outpatient basis has been studied, to our knowledge the effect on preoperative bloodwork has not been documented and was our goal. Design: A retrospective observational analysis of charts of patients 18 years of age and older, who underwent outpatient bowel preparation for an elective bowel resection in 2006. Setting: The Perioperative services of two sites of a tertiary care institution. Patients: Medical records identified 119 patients who met the specified inclusion criteria. Interventions: Patients that had both preadmission (PAC) and day of surgery (DOS) bloodwork obtained (standard practise) were reviewed and regression analysis performed. Measurements: Serum chemistry (sodium, potassium, chloride, bicarbonate, creatinine, blood, urea, nitrogen and haemoglobin) were noted in the PAC and on DOS as well as their demographic data including comorbidities. Main Results: There was a statistically significant decrease in chloride, bicarbonate, potassium (K+) and blood urea nitrogen (BUN) and an increase of creatinine (Cr). There were 9 patients whose K+ was < 3.0 on DOS that had been > 3.0 in PAC and 13 patients whose creatinine was >100 on DOS that had been <100 in PAC. No correlation between demographic factors (including age, gender, type of bowel preparation or comorbidity) and day of surgery hypokalemia or elevated creatinine were noted. Conclusions: We documented statistically significant but clinically insignificant changes in potassium, chloride, bicarbonate, BUN and creatinine. There were no predictive factors for either hypokalemia or elevated creatinine. No changes in patient management occurred. There appears to be no value in repeating serum chemistries after bowel preparation performed at home.