Phosphate salt bowel preparation regimens alter perioperative acid-base and electrolyte balance

Abstract

Background: Hyperphosphatemic acidosis and severe electrolyte disturbances caused by phosphate salts (PO) used for mechanical bowel preparation have been described in occasional case reports prior to bowel resection surgery. We hypothesized that PO used preoperatively for bowel preparation may cause more pronounced acid base and electrolyte changes than polyethylene glycol (PG).Methods: Forty American Society of Anesthesiologists physical status II-III patients were randomly allocated to receive either PO or PG for bowel preparation before intra-abdominal surgery (bowel resection or other major elective intra-abdominal surgeries). Measurements of pH, base deficit, blood gases, lactate, hemoglobin, calcium, magnesium, potassium and phosphorus were undertaken before the laxative administration, intraoperatively, and postoperatively.Results: Preoperative demographic, hemodynamic and laboratory data were similar in the two groups. Intraoperative calcium (8.4 [0.6] Conclusions: Calcium and magnesium changes were more pronounced in patients who received PO for bowel preparation. Objectif : L'acidose hyperphosphatémique et des troubles sévères des électrolytes causés par les sels phosphatés (PO) utilisés pour la préparation intestinale mécanique ont été décrits à l'occasion dans des présentations de cas avant la résection de l'intestin. Nous avons supposé que les PO utilisés avant l'opération pour la prépara-tion intestinale pouvaient causer plus de changements acide base et électrolytiques que le polyéthylèneglycol (PG). Méthode : Quarante patients d'état physique ASA II-III ont reçu au hasard soit des PO, soit du PG pour la préparation de l'intestin à la chirurgie intra-abdominale comme la résection de l'intestin ou d'autres opérations majeures réglées. Les mesures du pH, du déficit basique, des gaz sanguins, du lactate, de l'hémoglobine, du calcium, du magnésium, du potassium et du phosphore ont été faites avant l'administration du laxatif, pendant et après l'opération.Résultats : Les données démographiques, hémodynamiques et de laboratoire étaient similaires dans les deux groupes. Le calcium (8,4 [0,6] vs 9 [0,5] mg·dL -1 ) et le pH (7,35 [0,04] vs 7,41 [0,03]) peropératoires étaient plus bas, mais le lactate (1,3 [0,4] vs 0,9 [0,3] (8 [0,5] vs 8,9 [0,2] mg·dL -1 , 1,68 [0,3] vs 1,8 [0,4] et 3,5 [0,36] vs 3,7 [0,33] mEq·L -1 ) tandis que le phosphore (4,1 [0,3] vs 3,3 [0,2]

The Prevention of Surgical Site Infection in Elective Colon Surgery

“…Most investigators do not believe that there is benefit to the choice of the mechanical preparation, but one study identified lower SSI rates when a phosphate-based preparation was used [108]. Experimental studies have indicated that phosphate may module the virulence of gram negative bacteria [109], but hyperphosphatemia may attend the use of this mechanical preparation [110]. …”

Impact of mechanical bowel preparation in elective colorectal surgery: A meta-analysis

“…However, MBP is not without its own complications and the process is both time-consuming and unpleasant for patients[ 20 ]. It has been shown to cause clinically significant dehydration[ 21 ] and electrolyte disturbances, particularly hypocalcaemia and hypokalaemia to which the elderly are especially vulnerable[ 22 - 24 ]. Patient satisfaction is poor for undergoing bowel preparation prior to surgery and colonoscopy, and this may necessitate an additional day preoperatively in hospital, particularly for frail elderly patients.…”

Reply

“…First, as we stated in our manuscript, the drug was not used in cases where it was contraindicated. 1 Secondly, although we did use 90 mL of solution, we prescribed the medication in two doses, separated by an eight-hour interval. While the time interval between the administration of doses varies amongst studies, a 90 mL volume, administered in two separate doses is recommended in the drug leaflet (Soffodex by Dexxon Ltd, Or-Akiva, Hadera, Israel) and several recently published studies.…”