Intracranial Pressure Monitoring, Heart Rate Variability, Baroreflex Sensitivity, and Signal Complexity During Neurointensive Care after Decompressive Craniectomy in Malignant Middle Cerebral Artery Infarction.

BACKGROUND

Malignant middle cerebral artery infarction (MMI) is generally treated with decompressive craniectomy (DC) followed by neurointensive care (NIC). However, prognostic values of autonomic and complexity indices remain unclear. We aimed to explore heart rate variability (HRV), baroreflex sensitivity (BRS), and signal complexity (SC) in patients with MMI during post-DC NIC in relation to demographics, stroke severity, NIC variables [intracranial pressure (ICP), cerebral perfusion pressure (CPP), and Pressure Reactivity index (PRx)], and outcome.

METHODS

This single-center, retrospective study analyzed 70 ICP-monitored, typically sedated, and mechanically ventilated patients with MMI, during NIC after DC (2008-2022). HRV, BRS, and SC [multiscale entropy (MSE)] of heart rate, mean arterial pressure (MAP), ICP, and amplitude of ICP (AMP) were analyzed for the first seven NIC days post-DC. Correlations (Spearman) were explored for HRV, BRS, and SC with demographics, stroke severity, and NIC variables. Associations (multivariable ordinal logistic regression) were evaluated for HRV, BRS, and SC variables in relation to six-month modified Rankin Scale (mRS). Combinations of SC and NIC variables were explored in relation to mRS in heatmaps.

RESULTS

Median age was 57 years and 79% were male. At 6 months, median mRS was 4, and 7% died. HRV and BRS were reduced post-DC, but not associated with demographics, stroke severity, NIC variables, and mRS. Higher SC correlated (Spearman) with lower burden of secondary insults (NIC variables beyond pathological thresholds). Higher SC of MAP, ICP, and AMP correlated independently with lower six-month mRS in multivariable ordinal logistic regression. Low SC combined with pathological NIC variables correlated particularly with worse outcome in heatmaps.

CONCLUSIONS

Lower systemic and cerebral SC correlated with greater burden of secondary insults and worse long-term outcome in MMI post-DC. Low SC may indicate overloaded systemic and cerebral compensatory mechanisms, resulting in reduced tolerance for secondary insults. SC may aid prognostication and fine-tune NIC to identify and prevent autoregulatory insults.