Postoperative circadian disruptions in moderate to severe traumatic brain injury

Background and objectives We conducted this study to examine postoperative changes in brain temperature and heart rate rhythms in moderate to severe traumatic brain injury (TBI) and their association with one-year functional outcomes and mortality. Methods In this inpatient retrospective study, we analysed 102 patients with TBI who underwent surgery. Hourly brain temperature and heart rate were recorded for 120 h after surgery, and circadian rhythmicity was assessed using a 24-h cosinor model. Associations between rhythm parameters and outcomes were examined using multivariable analyses. Results The percentages of patients exhibiting brain temperature rhythm at 1–60 h (period A) and 61–120 h (period B) after surgery were 63.7% (65/102) and 64.7% (66/102), respectively; the corresponding percentages for heart rate rhythm were 32.3% (33/102) and 41.1% (42/102), respectively. We found that 40.2% (41/102) and 36.2% (37/102) of patients experienced changes in brain temperature and heart rate rhythmic patterns, respectively, transitioning between presence and absence of rhythm. Multivariate analysis demonstrated that age [Odds ratio (OR) 0.933, 95% confidence interval (CI) 0.890–0.978, P =0.004], initial Glasgow Coma Scale score (OR 1.699, 95% CI 1.195–2.417, P =0.003), blood glucose level (OR 0.955, 95% CI 0.925–0.985, P =0.003), brain temperature mesor in period A (OR 45.658, 95% CI 2.483–839.398, P =0.010), presence of brain temperature rhythm in period B (OR 0.018, 95% CI 0.002–0.150, P <0.001), and presence of heart rate rhythm in period B (OR 0.185, 95% CI 0.039–0.884, P =0.035) were independently associated with 1-y functional outcomes. Age (OR 1.128, 95% CI 1.036–1.229, P =0.006) and mean intracranial pressure in the first 24 h (OR 1.168, 95% CI 1.005–1.257, P =0.043) were independent predictors of one-year mortality. Interpretation and conclusions Postoperative brain temperature and heart rate rhythms provide clinically meaningful information regarding neurological recovery after TBI. The reappearance or preservation of rhythmicity in the acute postoperative period indicates greater long-term improvement potential and enhances prognostication and rehabilitation planning.