Key result
Brain injury linked to ~83% lower respiratory HRV amplitude and an inverted phase.
Why the study?
The characteristics and determinants of respiratory heart rate variability in brain-injured patients in the neuro-ICU are poorly understood.
Does severe brain injury alter respiratory heart rate variability amplitude and phase compared to healthy controls?
Case-Control (n=86)
No
Does severe brain injury alter respiratory heart rate variability amplitude and phase compared to healthy controls?
Answers are grounded in this paper and cite their sources.
Brain-injured patients demonstrate markedly impaired central generation of respiratory heart rate variability, which is further altered by mechanical ventilation and sedation.
Background Respiratory heart rate variability (RespHRV), the physiological variation in heart rate in phase with breathing, is mainly generated by central brainstem mechanisms. Its characteristics and determinants in brain-injured patients in the neuro-intensive care unit (neuro-ICU) are poorly understood. Objective To characterize RespHRV amplitude and phase in brain-injured patients compared to healthy participants, and to explore clinical variables influencing RespHRV in the neuro-ICU. Methods We analyzed 55 brain-injured patients (traumatic brain injury, aneurysmal subarachnoid hemorrhage, or other causes) and 31 healthy controls. ECG and respiratory signals were recorded and processed to extract cycle-by-cycle RespHRV amplitude and phase. Group differences were assessed using Mann–Whitney and Watson–Williams tests. In an additional analysis, 55 patients’ RespHRV amplitude and phase were modeled using generalized linear mixed-effects models to evaluate the impact of sedation, mechanical ventilation mode, vasoactive and analgesic drugs, and time, including random intercepts and slopes for subjects. Results Compared to controls, brain-injured patients exhibited a significantly lower RespHRV amplitude (1.04 [0.45, 1.96] vs. 6.21 [4.08, 9.34] bpm; p < 0.001) and an inverted RespHRV phase, with peak heart rate occurring during expiration rather than inspiration. Mixed-effects modeling revealed that machine-triggered ventilation and high level of sedation induced a significant reduction in RespHRV amplitude. Conclusions Brain-injured patients demonstrate markedly impaired central generation of RespHRV, with peripheral contributors likely accounting for the remaining variability. Ventilation mode and pharmacological interventions strongly alter RespHRV. Restoration of normal RespHRV patterns may serve as a physiological marker of autonomic and brainstem recovery, warranting further investigation in longitudinal studies.
No takes yet. Share an insight, caveat, or question.
Ghibaudo et al. (2025) conducted a case-control in Severe acute brain injury (n=86). Severe acute brain injury (Neuro-ICU admission) vs. Healthy controls was evaluated on Respiratory Heart Rate Variability (RespHRV) amplitude (p=<0.001). Brain-injured patients exhibited a significantly lower respiratory heart rate variability amplitude (1.04 bpm vs. 6.21 bpm) and an inverted phase compared to healthy controls.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: