Arterial to jugular-bulb lactate difference in patients undergoing elective brain tumor craniotomy

Abstract

Hyperlactatemia is common during tumor craniotomy, but the underlying pathophysiology is unclear. This study measured simultaneous arterial and jugular-bulb lactate concentrations in patients undergoing brain tumor craniotomy to investigate the hypothesis that hyperlactatemia was associated with a net cerebrovascular lactate input. In 20 patients, arterial and jugular-bulb blood was collected hourly from the start of surgery to 6 h postoperatively for measurement of lactate, glucose, and oxygen concentration. For each marker, data were analyzed using a linear mixed-effects model with jugular-bulb concentration as dependent variable, arterial concentration as fixed effect, and patient as random effect. Furthermore, we generated regression lines between arterial and jugular-bulb concentrations. The slope of the regression line between arterial and jugular-bulb lactate was 0.95 (95% CI 0.93-0.97, R² = 0.98), indicating that increasing arterial lactate levels were associated with an increasingly positive net cerebrovascular balance (net input). The line crossed the identity line at 2.86 (95% CI 0.57-5.16) mmol/L, indicating that lower levels of lactate were associated with a negative net cerebrovascular balance (net output). This suggests a switch from net lactate output during normolactatemia towards net input during hyperlactatemia. Hyperlactatemia in tumor-craniotomy patients probably does not originate from the brain.

Keywords: brain tumor; cancer; craniotomy; hyperlactatemia; lactate; neurosurgery.

FIGURE 1

Participant flow diagram. Twenty‐one patients initially consented to participate in the study. One patient was excluded due to the absence of a brain tumor. All 20 patients were included in the data analysis, although two patients had incomplete datasets.

FIGURE 2

The time‐course of (a) lactate, (b) glucose, and (c) oxygen concentration, (d) arterial carbon dioxide tension (PaCO₂), (e) mean arterial pressure (MAP), and (f) body temperature for all patients. Values are mean and 95% confidence intervals. Arterial measurements in red, jugular‐bulb measurements in blue, and MAP and body temperature measurements in black.

FIGURE 3

Linear mixed‐effects model of arterial to jugular‐bulb lactate, glucose, and oxygen content. Each point corresponds to a unique patient at a specific timepoint. The stippled red line is the identity line, with a slope of one. The full blue line is the linear regression line. The table in the upper left corner of each graph summarizes the results of a linear mixed‐effects model, where jugular‐bulb values are the outcome variable, arterial values are considered as fixed effects and individual patients are treated as random effects.