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Gut mucosal ischemia during cardiac surgery
1Department of Surgery, University of Massachusetts Medical Center, Worcester 01605.
Abstract:
Transient episodes of gut mucosal ischemia occur in many patients having cardiac surgery. Ischemic mucosal injury increases mucosal permeability and promotes the translocation of bacterial toxins and bacteria and, hence, the release of mediators. Collectively these substances are the putative cause of LOS, nosocomial infections, and MSOF. Circumstantial evidence suggests that the morbidity and mortality from cardiac surgery might be greatly reduced by preventing or limiting in duration the episodes of gut mucosal ischemia. This objective is unlikely to be reliably achieved in clinical practice without monitoring the adequacy of gut mucosal oxygenation. The adequacy of gut mucosal oxygenation can be conveniently monitored in the stomach with a Tonomitor incorporated into a nasogastric tube, because changes induced in this organ by disturbances in DO2 reflect changes occurring in other parts of the gut. Preventative measures currently possible in routine clinical practice include maintaining an intramucosal pH at normal levels by optimizing DO2, preventing the release of splanchnic vasoconstrictors and the formation of cellular aggregates by the use of pulsatile perfusion during bypass, and minimizing oxygen requirements with cooling and muscle relaxation. The translocation of bacterial toxins and bacteria across injured mucosa may be minimized by gut lavage before surgery. Therapeutic measures for gut mucosal ischemia currently possible in routine clinical practice include, in addition to the preventative measures outlined above, the prevention of free radical-induced mucosal injury during resuscitation, parenteral antibiotics, the treatment of sepsis, and the resection of infarcted gut.
Insights
Monitoring gut mucosal oxygenation during cardiac surgery can reduce complications. This approach helps prevent gut injury, potentially lowering mortality and improving patient outcomes by managing ischemia.
Area of Science:
- Gastroenterology
- Cardiology
- Critical Care Medicine
Background:
- Cardiac surgery can cause transient gut mucosal ischemia, increasing permeability and bacterial translocation.
- This injury is linked to systemic inflammatory response syndrome (SIRS), nosocomial infections, and multiple organ failure (MOF).
- Reducing cardiac surgery morbidity and mortality may depend on preventing or limiting gut mucosal ischemia duration.
Purpose of the Study:
- To highlight the importance of monitoring gut mucosal oxygenation during cardiac surgery.
- To discuss methods for monitoring gut mucosal oxygenation.
- To outline current preventative and therapeutic strategies for gut mucosal ischemia.
Main Methods:
- Monitoring gut mucosal oxygenation using a Tonomitor in a nasogastric tube.
- Optimizing oxygen delivery (DO2) to maintain intramucosal pH.
- Utilizing pulsatile perfusion during bypass to prevent splanchnic vasoconstriction and aggregate formation.
- Minimizing oxygen demand through cooling and muscle relaxation.
- Employing gut lavage before surgery to reduce bacterial translocation.
- Preventing free radical injury during resuscitation and using parenteral antibiotics.
Main Results:
- Monitoring gut mucosal oxygenation in the stomach reflects changes in other gut areas.
- Optimizing DO2, pulsatile perfusion, and cooling can help maintain intramucosal pH.
- Gut lavage, specific resuscitation techniques, antibiotics, and surgery can mitigate ischemic injury and its consequences.
Conclusions:
- Monitoring gut mucosal oxygenation is crucial for managing ischemia during cardiac surgery.
- A combination of preventative and therapeutic measures can reduce the incidence and severity of gut mucosal injury.
- Effective management of gut mucosal ischemia may significantly decrease morbidity and mortality associated with cardiac surgery.