Rectal lactate levels in endoluminal microdialysate during routine coronary surgery

Area of Science:

• Gastroenterology
• Surgical Monitoring
• Critical Care Medicine

Background:

• Assessing splanchnic perfusion during cardiopulmonary bypass (CPB) is crucial for patient outcomes.
• Current methods for monitoring intestinal perfusion and metabolism are limited.
• Lactate accumulation in the gut can indicate compromised oxygen delivery.

Purpose of the Study:

• To evaluate the feasibility of intestinal endoluminal microdialysis for monitoring splanchnic perfusion.
• To assess the utility of microdialysis in measuring luminal metabolites in the large bowel.
• To correlate intestinal metabolic changes with systemic and muscular parameters during CPB.

Main Methods:

• Prospective study involving 13 patients undergoing elective cardiac surgery with CPB.
• Placement of an endoluminal microdialysis catheter in the recto-sigmoid junction for continuous metabolite measurement.
• Simultaneous measurement of lactate in blood and muscle tissue.
• Use of a tonometric catheter alongside the microdialysis catheter.

Main Results:

• Luminal lactate in the large bowel increased significantly (10-fold) during CPB.
• Arterial lactate showed a slight but significant increase during CPB.
• Muscular lactate also increased during CPB, but the lactate-pyruvate ratio remained stable.
• Elevated luminal lactate suggests local production due to impaired oxygen delivery.

Conclusions:

• Intestinal endoluminal microdialysis is a feasible method for monitoring intestinal metabolism.
• This technique, combined with tonometry, offers a way to assess both circulation and metabolism in the rectal mucosa.
• The findings support the potential clinical application of endoluminal microdialysis for monitoring splanchnic perfusion adequacy.