Monitoring Intraoperative Blood Lactate Levels: Implications for Cardiopulmonary Bypass Maggie Savelberg B.Sc.(H), Perfusionist Fellow London Health Sciences, London, Ontario

Objective: Marker for Adequate Perfusion Solution: Lactic Acidosis Study: Patient Selection/Methods Outline: Study: Results/Conclusion

Objective: Appropriate Marker for Adequate Perfusion Objective: Appropriate Marker for Adequate Perfusion Cardiopulmonary Bypass Solution Challenge Function Allow adequate systemic oxygenation and perfusion during cardiac surgical procedure. Periods of acute tissue hypoperfusion: - Poor venous return - Low volumes/flows - Patient anatomy - Surgical technique - Circulatory arrest - Hemodilution Monitoring of intraoperative lactate levels & acid/base status leading to therapeutic intervention to improve post- operative course.

Lab Abnormalities ↑ Lactate > 2.0mmol/L ↓ HCO 3 - / BE ↓ Arterial pH ↑ Anion gap Solution: Clinical Definitions & Significance? Lab Abnormalities ↑ Lactate >2.0 mmol/L Hyperlactatemia vs Lactic Acidosis Metabolic Acidosis Lee et al., Emerg Med J 2008;25: Mild pH ≥ 7.35 La Severe pH ≥ 7.35 La - > 5.0 -Difficult to identify - Lactic acidosis better correlated with in-hospital mortality Demers et al., Ann of Thorac Surg 2000;70: Easily identified -Chart & Monitor -Substitute marker

Study: Patient Selection & Methods Study: Patient Selection & Methods 1,376 patients 18% Lactate >4.0mmol/L 28 % ♀ 72% ♂ 82% Lactate <4.0mmol/L 1,259 patients 79% CABG 17% Valve - Exclusions - Exclusions

Identification ? Normal Range pH normal Lactate (mmol/L) ↓ pH - upregulation anaerobic metabolism ↓ vascular removal 3 Demers et al., Ann of Thorac Surg 2000;70: It is here – intraoperatively where patient outcome can be improved by determining the cause and correcting hypoperfused states. Correction Zone

Tissue Hypoxia ↑ Flow rate ↑ Mechanical Ventilation ↑ F i O 2 ↑ Hgb NaHCO 3 Net Effect ↑ tissue perfusion ↑ Blood pH ↑ Tissue Oxygenation ↓ Oxygen Demand Prevention & Treatment of Lactic Acidosis Cause CHEST 2000; 117:

- Communicate our difficulties - Changes - Understanding - Willingness to accommodate Anesthesia Perfusion Surgeon Summary: Intercollaborative Team Effort Taken From: Google Imagies at