S0545 Impact of Colonoscopy Bowel Preparation and Intra-Procedural Volume of Colonic Irrigation (VOCI) on Serum Electrolytes

Abstract

INTRODUCTION: A safe and effective bowel preparation (BP) is key to the performance of high-quality colonoscopy. Colonic irrigation is often used to clear stool and improve mucosal visualization. Procedures involving high volume water irrigation in other organs (e.g. TURP syndrome) have been associated with complications due to fluid shifts and electrolyte imbalance (nausea, emesis, hypotension, altered consciousness, mortality rate 0.2-0.8%). The effect of BP and volume of colonic irrigation (VOCI) on serum electrolytes requires further investigation. METHODS: An institutionally approved quality improvement prospective cohort study was undertaken at a large VA Medical Center. Veterans scheduled for outpatient colonoscopy between 03/2019 and 03/2020 were included. Data collected included demographics, baseline electrolyte levels (within prior 6 months), BP type, volume of clear liquid diet consumed (CLD) prior to colonoscopy, procedure details including VOCI, and complications. Serum chemistry panels were obtained from the intravenous catheter placed for sedation. After 8 weeks, data for 110 patients (pilot cohort) were analyzed. To confirm findings of significant electrolyte changes, observed rates of change and missing data were used to determine a validation cohort (n = 89). A +/-10% change in serum electrolyte level AND outside the normal range was considered significant. RESULTS: There was little variation among demographics and colonoscopy characteristic between the two cohorts (Table 1). Significantly more veterans had serum electrolyte abnormalities pre-colonoscopy compared to baseline in both cohorts (56.4% vs. 32.1% in pilot cohort, P < 0.001 and 53.9% vs. 28.9% in validation cohort, P < 0.001,Figure 1), with hypokalemia being the most common (12-16%). Rates of significant electrolyte changes (> 10%) were similar between cohorts with hypokalemia and hypocalcemia being the most common. Changes in Cr, Ca, and Phos were more pronounced in the validation cohort (Table 2). CONCLUSION: Significant pre-procedure serum electrolyte changes occurred following BP, especially hypokalemia. Post-procedure hypokalemia and, the increased incidences of post-colonoscopy hypocalcemia and hypophosphatemia in the validation cohort (cohort with higher average VOCI) suggest that VOCI is associated with electrolyte shifts. Further studies are required to assess the clinical impact of these electrolyte shifts and measures to avoid them.Figure 1.: Number of Unique Patients with Abnormal Labs at Given Times.Table 1Table 2