Intraabdominal microdialysis – methodological challenges

Development and validation of an LC-ESI-QTOF-MS method to measure cefepime in the plasma and peritoneal fluid of rats using microdialysis: application in a pilot pharmacokinetic study

Cefepime (CEF) is a cephalosporin and can be administered in secondary peritonitis together with metronidazole to treat sepsis. This study aimed to develop and validate a method of LC-ESI-QTOF-MS for the quantification of cefepime in the plasma and peritoneal microdialysate of healthy Wistar rats. Chromatographic separation was performed using a CLC-ODS C₁₈ column (250 mm x 4.6 mm), a C₁₈ pre-column (4 mm, 5 μm) and isocratic elution. Gallic acid was used as the internal standard (IS). The mobile phase consisted of (A) ultrapure water (pH adjusted to 3.5) and (B) acetonitrile (80:20, v/v) at 0.8 mL/min. Quantification was performed using a mass spectrometer with electrospray ionization in positive mode to monitor ions with m/z 481.1322 (CEF) and m/z 171.0288 (IS). The method was validated for selectivity, precision, accuracy, linearity, stability, lower limit of quantification, carryover, recovery, and matrix effect. Calibration was done in the range of 1-40 μg/mL and 1-100 μg/mL for the peritoneal microdialysate and plasma, respectively. Plasma extraction recovery ranged from 93.9% to 99.9%. The technique was validated and successfully applied in a pilot pharmacokinetic study for estimating the free concentration of CEF in the peritoneal microdialysate of rats for the first time.

Early detection of anastomotic leakage after pancreatoduodenectomy with microdialysis catheters: an observational Study

BACKGROUND

Microdialysis catheters can detect focal inflammation and ischemia, and thereby have a potential for early detection of anastomotic leakages after pancreatoduodenectomy. The aim was to investigate whether microdialysis catheters placed near the pancreaticojejunostomy can detect leakage earlier than the current standard of care.

METHODS

Thirty-five patients with a median age 69 years were included. Two microdialysis catheters were placed at the end of surgery; one at the pancreaticojejunostomy, and one at the hepaticojejunostomy. Concentrations of glucose, lactate, pyruvate, and glycerol were analyzed hourly in the microdialysate during the first 24 h, and every 2-4 h thereafter.

RESULTS

Seven patients with postoperative pancreatic fistulae (POPF) had significantly higher glycerol levels (P < 0.01) in the microdialysate already in the first postoperative samples. Glycerol concentrations >400 μmol/L during the first 12 postoperative hours detected patients with POPF with a sensitivity of 100% and a specificity of 93% (P < 0.001). After 24 h, lactate and lactate-to-pyruvate ratio were significantly higher (P < 0.05) and glucose was significantly lower (P < 0.05) in patients with POPF.

CONCLUSION

High levels of glycerol in microdialysate was an early detector of POPF. The subsequent inflammation was detected as increase in lactate and lactate-to-pyruvate ratio and a decrease in glucose (NCT03627559).

Monitoring of patients with microdialysis following pancreaticoduodenectomy-the MINIMUM study: study protocol for a randomized controlled trial

BACKGROUND

Postoperative pancreatic fistula after pancreatoduodenectomy is a much-feared complication associated with substantial mortality and morbidity. The current standard for diagnosing postoperative pancreatic fistula, besides routine clinical examination, include radiological examinations, analysis of pancreatic drain amylase activity, and routine blood samples. Another promising method is by intraperitoneal microdialysis to monitor intraperitoneal metabolites measured at the pancreaticojejunostomy, thereby detecting what occurs locally, before chemical events can be reflected as measurable changes in systemic blood levels.

METHODS

The MINIMUM study is a prospective, randomized, controlled, single center enrolling 200 patients scheduled for open pancreatoduodenectomy comparing the microdialysis method to the "standard of care." Half of the included patients will be randomized to receive an intraperitoneal microdialysis catheter implanted at the end of surgery and will be monitored by microdialysis as an additional monitoring tool. The other half of the patients will not receive a microdialysis catheter and will be monitored according to the current standard of care. The primary objective is to evaluate if the microdialysis method can reduce the total length of stay at the hospital. Secondary endpoints are the frequency of complications, length of stay at the hospital at our institution, catheter malfunction, number of infections and bleeding episodes caused by the microdialysis catheter, patient-reported quality of life and pain, and cost per patient undergoing pancreatoduodenectomy. The patients will be randomized in a 1:1 ratio.

DISCUSSION

Intraabdominal microdialysis could potentially reduce morbidity and mortality after pancreatoduodenectomy. Furthermore, there is a great potential for shortening the in-hospital length of stay and reducing the financial aspect considerably. This study may potentially open the possibility for using microdialysis as standard monitoring in patients undergoing pancreatoduodenectomy. The hypothesis is that the microdialysis method compared to "standard care" will reduce the total length of hospital stay.

TRIAL REGISTRATION

Clinicaltrials.gov ( NCT03631173 ). Registered on 7 September 2018 under the name: "Monitoring of patients With Microdialysis Following Pancreaticoduodenectomy". Based on protocol version 19-1, dated 15th January 2019.

Intraperitoneal microdialysis detects intestinal leakage earlier than hemodynamic surveillance and systemic inflammation in a pig model

OBJECTIVE

Anastomotic leakage is a common complication following large abdominal surgery, often developing to life-threatening abdominal sepsis due to late diagnosis. Currently, diagnostics rely on systemic hemodynamic and infection monitoring. We hypothesized that intraperitoneal microdialysis allows detection of peritonitis prior to changes in standard clinical parameters in a pig model.

MATERIALS AND METHODS

We included six pigs; five underwent intraperitoneal fecal contamination, one had sham surgery for a total of 10 h. Microdialysis was established in four intraabdominal quadrants and two hepatic lobes. All pigs were hemodynamically monitored with pulmonary artery and femoral artery catheters. Blood samples were assessed for inflammatory markers, terminal complement complex (TCC), interleukin (IL)-6, IL-10, and plasminogen activator inhibitor-1 (PAI-1).

RESULTS

Microdialysis showed intraperitoneal lactate increase during the first two hours after fecal contamination, which remained elevated throughout the observation time with concurrent decrease of glucose. Arterial lactate remained within reference range (<1,6mM). Systemic inflammatory markers TCC, IL-6, IL-10 and PAI-1 increased significantly after minimum four hours. Mean arterial pressure, stroke volume variation and cardiac output were not compromised the first five hours. Sham surgery did not influence any of the parameters.

CONCLUSION

Intraperitoneal fecal contamination leads to a rapid and pronounced intraperitoneal increase in lactate, decrease in glucose while pyruvate and glycerol levels remain unchanged. This distinct metabolic pattern of peritoneal inflammation can be easily detected by microdialysis. Observation of this pattern may minimize time to safe diagnosis of intestinal perforations after intraperitoneal fecal contamination.

Perioperative intraperitoneal metabolic markers in patients undergoing cardiac surgery with cardiopulmonary bypass: an exploratory pilot study

Background:

Cardiopulmonary bypass and postoperative cardiac dysfunction cause splanchnic hypoperfusion resulting in intra-abdominal anaerobic metabolism and risk for gastrointestinal complications. The intra-abdominal metabolism can be monitored by intraperitoneal measurement of relevant metabolites using microdialysis. The aim of this study was to investigate the intraperitoneal metabolism using microdialysis during and after cardiopulmonary bypass at 34°C.

Methods:

In six patients undergoing elective coronary artery bypass grafting or aortic valve replacement under cardiopulmonary bypass, microdialysis was used to measure intraperitoneal and subcutaneous glucose, lactate, pyruvate, glycerol and glutamate concentrations, intraoperatively and up to 36 hours postoperatively. Arterial and central venous blood gases were analysed as were haemodynamics and the development of complications.

Results:

All patients had an ordinary perioperative course and did not develop gastrointestinal complications. The arterial, intraperitoneal and subcutaneous lactate concentrations changed during the perioperative course with differences between compartments. The highest median (interquartile range) concentration was recorded in the intraperitoneal compartment at 1 hour after the end of cardiopulmonary bypass (2.1 (1.9–2.5) mM compared to 1.3 (1.2–1.7) mM and 1.5 (1.0–2.2) mM in the arterial and subcutaneous compartments, respectively). In parallel with the peak increase in lactate concentration, the intraperitoneal lactate/pyruvate ratio was elevated to 33.4 (12.9–54.1).

Conclusion:

In cardiac surgery, intraperitoneal microdialysis detected changes in the abdominal metabolic state, which were more pronounced than could be shown by arterial blood gas analysis. Despite an uneventful perioperative course, patients undergoing low-risk surgery under cardiopulmonary bypass might be subjected to a limited and subclinical intra-abdominal anaerobic state.

Peritoneal microdialysis as a tool for detecting anastomotic leakage in patients after left-side colon and rectal resection. A systematic review

OBJECTIVE

The objective was to evaluate peritoneal microdialysis in the detection of clinical anastomotic leakage after left-sided colon and rectal resection through a systematic review.

METHODS

A systematic review (PRISMA guidelines) based on a systematic search through PubMed, Cochrane Library, and EMBASE (1 February 2017) was performed. Methodological index of non-randomised studies score was selected to assess the methodological quality. Patient demographics and raw data for intraperitoneal microdialysis concentrations of glucose, lactate, glycerol and pyruvate for 5 d postoperative were obtained from the respective study groups.

RESULTS

Ten studies with a total of 128 patients were included. Thirty (23%) patients developed clinical anastomotic leakage. The area under the curve for intraperitoneal lactate concentration was significant higher in patients with anastomotic leakage (58.2; 95% CI 39.2, 77.2) compared with the no leakage group (41.0; 95% CI 35.2, 46.1; p = .007). Receiver operating characteristic curve analysis of the maximum measured lactate concentration demonstrated 25% sensitivity, 88% specificity and 74% accuracy for AL at a cut-off value of 9.8 mmol/L. The odds ratio for a 5 mmol/L increase in lactate in relation to the risk of AL was 2.9 (CI 1.1, 8.0).

CONCLUSIONS

Increased intraperitoneal lactate concentration within the first 5 d postoperative was significantly associated with clinical anastomotic leakage, but with low predictive values. The microdialysis method is not yet ready for clinical implication before large prospective studies have defined cut off values for a biologic marker in the setting of a clear definitions of leakage.

Microdialysis in Postoperative Monitoring of Gastrointestinal Organ Viability: A Systematic Review

BACKGROUND

Microdialysis is a technique for continuous measurement of extracellular substances. It may be used to monitor tissue viability. The clinical implications of using microdialysis as a tool in gastrointestinal surgery have yet to be defined. The aim of the present study was to evaluate the clinical significance of microdialysis with special attention to different markers measured to predict the clinical outcome of surgical patients.

METHODS

Embase, MEDLINE, and the Cochrane Library were searched systematically for human studies written in English. Study selection, data extraction, and quality assessment were performed independently by two authors. We included studies in which the microdialysis technique was used for postoperative monitoring of patients undergoing gastrointestinal surgery. To be eligible, studies had to compare patients with and without postoperative complications.

RESULTS

Twenty-six studies were included in this review. MINORS score ranged from 3 to 12 (median 10.5). Most studies showed that levels of biomarkers obtained by microdialysis correlated with the postoperative clinical course. Lactate, pyruvate, glucose, and glycerol were the most frequently measured biomarkers. Several studies found that changes in biomarkers in complicated patients preceded symptoms of complications and/or changes in conventional paraclinical methods of postoperative monitoring.

CONCLUSIONS

Studies show that microdialysis may have the potential to become a tool in postoperative surveillance of surgical patients. Larger randomized studies are needed to define the clinical implications of microdialysis.