Detection of early anastomotic leakage by intraperitoneal microdialysis after low anterior resection for rectal cancer: a prospective cohort study.

AIM: Anastomotic leakage (AL) is a common and serious complication following sphincter-preserving surgery for rectal cancer. Early detection and intervention can improve clinical outcomes. The aim of this prospective cohort study was to compare intraperitoneal microdialysis with a clinical scoring system for early detection of AL. METHOD: A microdialysis catheter was anchored near the anastomosis at low anterior resection (LAR) for rectal cancer. Peritoneal fluid samples were analysed (lactate, pyruvate, glucose and glycerol concentration) 4-hourly and compared with a daily clinical leak score (DULK = Dutch leakage). At day 7 a pelvic CT with rectal contrast enema was performed to establish if there had been a radiological leak. RESULTS: In this two-centre study, 129 patients [median age 65 (26-82) years; 60.5% male] underwent LAR. The leak rate was 27% (grade A, n = 11; grade B, n = 12; grade C, n = 12). Receiver operator characteristic analysis demonstrated a lactate cut-off value of 9.8 mm and had 77% sensitivity, 82% specificity, 78% accuracy, a positive predictive value (PPV) of 58, a negative predictive value (NPV) of 88 (CI 79-94) and an area under the curve (AUC) of 0.9 for AL. This compared with a clinical score ≥ 4, which had 57% sensitivity, 79% specificity, 71% accuracy, a PPV of 46, a NPV of 82 and an AUC of 0.7 for AL. The mean day for a positive test when using delta lactate ≥ 6.3 mm was 1.6 days and for leak score ≥ 4 it was 3.3 days (NS). CONCLUSION: When AL occurs, intraperitoneal lactate concentration increases over time, and at a certain cut-off has a higher sensitivity, specificity, accuracy, PPV and NPV than a clinical scoring system.

Assessment of changes in blood glucose concentration with intravascular microdialysis.

Blood glucose and its variability of is a major prognostic factor associated with morbidity. We hypothesized that intravenous microdialysis incorporated in a central venous catheter (CVC) would be interchangeable with changes in blood glucose measured by the reference method using a blood gas analyzer. Microdialysis and central venous blood glucose measurements were simultaneously recorded in high-risk cardiac surgical patients. The correlation between absolute values was determined by linear regression and the Bland-Altman test for repeated measurements was used to compare bias, precision, and limits of agreement. Changes in blood glucose measurement were evaluated by four-quadrant plot and trend interchangeability methods (TIM). In the 23 patients analyzed, the CVC was used as part of standard care with no complications. The correlation coefficient for absolute values (N = 99) was R = 0.91 (P < 0.001). The bias, precision and limits of agreement were - 9.1, 17.4 and - 43.2 to 24.9 mg/dL, respectively. The concordance rate for changes in blood glucose measurements (N = 77) was 85% with the four-quadrant plot. The TIM showed that 14 (18%) changes of blood glucose measurements were uninterpretable. Among the remaining 63 (82%) interpretable changes, 23 (37%) were interchangeable, 13 (20%) were in the gray zone, and 27 (43%) were not interchangeable. Microdialysis using a CVC appears to provide imprecise absolute blood glucose values with risk of insulin misuse. Moreover, only one third of changes in blood glucose measurements were interchangeable with the reference method using the TIM.