Abstract
AimProlonged postoperative ileus (PPOI) occurs in around 15% of patients after major abdominal surgery, posing a significant clinical and economic burden. Significant fluid and electrolyte changes may occur peri‐operatively, potentially contributing to PPOI; however, this association has not been clearly elucidated. A joint clinical‐theoretical study was undertaken to evaluate peri‐operative electrolyte concentration trends, their association with ileus, and predicted impact on bioelectrical slow waves in interstitial cells of Cajal (ICC) and smooth muscle cells (SMC).MethodsData were prospectively collected from 327 patients undergoing elective colorectal surgery. Analyses were performed to determine associations between peri‐operative electrolyte concentrations and prolonged ileus. Biophysically based ICC and SMC mathematical models were adapted to evaluate the theoretical impacts of extracellular electrolyte concentrations on cellular function.ResultsPostoperative day (POD) 1 calcium and POD 3 chloride, sodium were lower in the PPOI group (p < 0.05), and POD3 potassium was higher in the PPOI group (p < 0.05). Deficits beyond the reference range in PPOI patients were most notable for sodium (Day 3: 29.5% ileus vs. 18.5% no ileus, p = 0.04). Models demonstrated an 8.6% reduction in slow‐wave frequency following the measured reduction in extracellular NaCl on POD5, with associated changes in cellular slow‐wave morphology and amplitude.ConclusionLow serum sodium and chloride concentrations are associated with PPOI. Electrolyte abnormalities are unlikely to be a primary mechanism of ileus, but their pronounced effects on cellular electrophysiology predicted by modeling suggest these abnormalities may adversely impact motility recovery. Resolution and correction of electrolyte abnormalities in ileus may be clinically relevant.
Highlights
Delayed GI transit after surgery is common, occurring in 15%–25% of patients undergoing major abdominal surgery, and results in distressing symptoms, prolonged length of hospital stay, and a considerable economic burden (Iyer et al, 2009; Madl & Druml, 2003; Peters et al, 2017)
The relationship between serum electrolyte concentrations and interstitial cells of Cajal (ICC)/smooth muscle cell (SMC) function, which contributes directly to GI motility, has not been clearly defined, and the extent that electrolyte abnormalities contribute to ileus is still unclear
This joint clinical and theoretical study has evaluated postoperative electrolyte derangements associated with ileus
Summary
Delayed GI transit after surgery (postoperative ileus; POI) is common, occurring in 15%–25% of patients undergoing major abdominal surgery, and results in distressing symptoms, prolonged length of hospital stay, and a considerable economic burden (Iyer et al, 2009; Madl & Druml, 2003; Peters et al, 2017). Serum electrolyte derangements are common postoperatively, potentially impairing GI motility by their effect on ion channels and cellular membrane potentials, as well as intra-cellular functions and inter-cellular co-ordination. These abnormalities have previously been proposed as a possible factor contributing to prolonged POI (PPOI; Vather et al, 2014). The relationship between serum electrolyte concentrations and ICC/smooth muscle cell (SMC) function, which contributes directly to GI motility, has not been clearly defined, and the extent that electrolyte abnormalities contribute to ileus is still unclear. Extracellular chloride concentrations may be important, given the recently discovered role of the calcium-activated chloride channel, Anoctamin-1 (Ano1) in slow-wave pacemaking, and the role of the chloride equilibrium potential in modulating slow-wave morphology (Gomez-Pinilla et al, 2009; Lees-Green et al, 2014; Singh et al, 2014)
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