Relationship between intracranial pressure pulse morphology and baroreflex sensitivity during intracranial hypertension after traumatic brain injury: a CENTER-TBI study

Purpose In traumatic brain injury (TBI), reduced pressure–volume compensatory reserve, which is reflected in intracranial pressure (ICP) pulse morphology, may lead to intracranial hypertension (IH), a state independently linked to altered autonomic function. Whether baroreflex sensitivity (BRS) contributes to pulse morphology changes remains unclear. We aimed to evaluate this association during IH episodes and periods of non-elevated ICP. Methods Data from 186 TBI patients from the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study were analyzed. IH was defined as a 5-min moving average of ICP exceeding 20 mmHg. ICP waveform morphology was assessed using the pulse shape index (PSI), and BRS was calculated using the time-domain cross-correlation method. Results On admission, most patients presented with severe TBI (62%), and 144 (77%) experienced IH. In the mixed-effects analysis of 5,418 episodes from 129 patients with IH, within-patient BRS was independently associated with PSI ( b = 0.26, 95% CI [0.18; 0.35], p < 0.001), indicating that for a given patient, episodes with higher BRS were accompanied by higher PSI. This within-patient association did not differ between IH episodes and non-elevated ICP periods (interaction p = 0.483), indicating a consistent coupling across both conditions. Age showed a comparably strong, independent association with PSI ( b = 0.36, 95% CI [0.21; 0.50], p < 0.001). Conclusions Within individual patients, episode-to-episode fluctuations in BRS were associated with ICP pulse morphology, regardless of whether ICP was elevated, indicating that this association is not specific to IH episodes. Age showed an independent association with PSI, suggesting a combined contribution of age-related and autonomic regulation factors to ICP pulse morphology in patients with TBI.