Cerebral Oximetry for Detecting High-mortality Risk Patients with Cryptococcal Meningitis

Abstract

Background: Cryptococcus is the commonest cause of adult meningitis in Africa, with 50%-70% experiencing increased intracranial pressure. Cerebral oximetry is a noninvasive near-infrared spectroscopy technology to monitor percent regional cerebral tissue oxygenation (rSO₂). We assessed if cerebral oximetry predicts meningitis mortality.

Methods: We performed cerebral oximetry within 14 days of cryptococcal meningitis diagnosis on 121 Ugandans from April 2016 to September 2017. We evaluated baseline rSO₂ association with mortality by multivariable logistic regression and correlation with other clinical factors. We compared groups formed by initial rSO₂ <30% vs ≥30% for longitudinal change with mixed effects models. We measured change in %rSO₂ before and after lumbar puncture (LP).

Results: The median initial rSO₂ (interquartile range) was 36% (29%-42%), and it was <30% in 29% (35/121). For 30-day mortality, the unadjusted odds ratio (per 5% increase in rSO₂) was 0.73 (95% confidence interval [CI], 0.58 to 0.91; P = .005). Those with initial rSO₂ <30% had 3.4 (95% CI, 1.5 to 8.0) higher odds of 30-day mortality than those with initial rSO₂ ≥30%. Hemoglobin correlated with initial rSO₂ (rho = .54; P < .001), but rSO₂ did not correlate with pulse oximetry, intracranial pressure, cerebral perfusion pressure, or quantitative cerebrospinal fluid culture, and rSO₂ was unchanged pre/post-lumbar punctures. The longitudinal rSO₂ measurements change was 15% (95% CI, 12% to 18%) lower in the group with initial rSO₂ <30%.

Conclusions: Individuals with cryptococcal meningitis and low cerebral oximetry (rSO₂ < 30%) have high mortality. Cerebral oximetry may be useful as a prognostic marker of mortality. Targeted interventions to improve rSO₂ should be tested in trials to try to decrease mortality in meningitis.

Keywords: cerebrovascular circulation; cryptococcal meningitis; hemodynamic monitoring; mortality; oximetry; physiologic monitoring.

Figure 1.

Baseline regional cerebral tissue oxygenation (rSO2) measurements by vital status at day 30. Initial rSO₂ measurements grouped according to early death (days 1–14), late death (days 15–30), or survivor at day 30. The median rSO₂ values were 30%, 36%, and 37%, respectively.

Figure 2.

Longitudinal changes in regional cerebral tissue oxygenation (rSO₂) readings over time for 51 participants who had multiple cerebral oximetry measurements during the first 30 days after meningitis diagnosis. Generally, survivors improved their cerebral oximetry readings over time. The red squares represent patients who died after the last measurement. The top graph shows 16 of 51 participants with initial rSO₂ <30%, and the bottom graph includes 35 participants with initial rSO₂ ≥30%. From longitudinal mixed models, the change over time in rSO₂ was 15% (95% confidence interval, 12% to 18%) lower in the group with initial rSO₂ <30%.