Perioperative Outcomes of Hyperlactatemia during Craniotomy: A Systematic Review and Meta-Analysis of 1,832 Patients

Background Hyperlactatemia, is common in patients undergoing neurosurgical procedures. Several studies have identified potential risk factors for developing hyperlactatemia in neurosurgical patients, including body mass index, surgery duration, tumour volume, and certain drugs such as volatile anesthetic agents and corticosteroids. This systematic review and meta-analysis examined the evidence of the association between perioperative lactate levels in patients undergoing brain surgery and postoperative morbidity and mortality. Methods Using PubMed, Scopus, Web of Science, Embase, CINAHL, Medline, Google Scholar, and the Cochrane Central Register of Controlled Trials databases, a systematic literature search was conducted for studies examining the association between perioperative hyperlactatemia and postoperative outcomes in patients undergoing brain surgery. Two authors independently evaluated the full-text papers for eligibility, and then data extraction and meta-analyses of similar studies were conducted (using a random effect model for each outcome measure). The Newcastle Ottawa Scale was used to evaluate the risk of bias (NOS scale). Results Seven observational studies were included, and a total of 1,832 patients were assessed in the systematic review and meta-analysis. The quality of the included studies ranged from poor to high quality according to the NOS quality assessment tool. Meta-analysis results revealed no significant association between perioperative hyperlactatemia and postoperative new neurological deficits (five studies: odds ratio [OR] = 0.97, 95% confidence interval [CI] [0.50–1.87], p = 0.92; heterogeneity: I 2 = 38%, p = 0.18). Similarly, perioperative hyperlactatemia was neither significantly associated with increased 30-day postoperative mortality (two studies; OR = 0.20, 95% CI [0.02–2.00], p = 0.17; heterogeneity: I 2 = 0%, p = 0.59) nor 6 months survival rate (three studies; OR = 1.05, 95% CI [0.75–1.47], p = 0.79; heterogeneity: I 2 = 0%, p = 0.51). Moreover, there was no difference in the length of hospital stay between the two groups (four studies: mean difference = –0.85, 95% CI [–1.73 to 0.03], p = 0.06). Pooled studies were not homogenous (I 2 = 68%, p = 0.03). Conclusion Perioperative hyperlactatemia is benign in neurosurgical patients and is not associated with significant postoperative outcomes, such as developing new postoperative neurological deficit, 30-day mortality, 6-month survival, or prolonged hospital stay.