Objectives: Blood lactate is frequently used to guide management in critically ill patients. In patients undergoing mitral valve surgery, an elevated lactate level is frequently observed; however, overall mortality is low. The authors hypothesized that hyperlactemia is not a useful predictor of poor outcomes in this patient population. The main aim of this study was to explore how blood lactate level and lactate clearance are associated with 30-day mortality and major adverse events in patients undergoing mitral valve surgery.
Design: This was a retrospective database review. Logistic regression analysis was performed to assess the associations of perioperative factors with blood lactate in the intensive care unit (ICU).
Setting: Tertiary-care teaching hospital.
Participants: The study comprised 917 patients undergoing mitral valve surgery.
Interventions: None.
Measurements and main results: The majority of patients (71.8%) had elevated blood lactate ≥2 mmol/L on ICU admission; however, within 24 hours, 85.1% of all patients had normal lactate values. Overall 30-day mortality was 2.29% (n = 21). The combination of lactate ≥7 mmol/L on ICU admission and a persistent elevated blood lactate level 24 hours after ICU admission provides an excellent prediction of 30-day mortality (C statistic = 0.85). However, even a significantly elevated lactate level on ICU admission was well-tolerated in the majority of patients as long as lactate values normalized within 24 hours. Male sex, longer cardiopulmonary bypass time, blood transfusion in the ICU, and an elevated blood lactate level on ICU admission and 12 hours after ICU admission all were independent risk factors of clearance failure.
Conclusions: An elevated blood lactate level is common after mitral valve surgery and is well-tolerated in the majority of patients. Adding lactate clearance improved the predictive value of the blood lactate level.
Keywords: blood lactate; cardiopulmonary bypass; critically ill; heart surgery; lactate clearance; postoperative care.
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