Association between temporal patterns of baroreflex sensitivity after traumatic brain injury and prognosis: a preliminary study

Early Autonomic Dysfunction in Traumatic Brain Injury: An Article Review on the Impact on Multiple Organ Dysfunction

Background/Objectives: Traumatic brain injury (TBI) is a complex condition and a leading cause of injury-related disability and death, with significant impacts on patient outcomes. Extracranial organ involvement plays a critical role in the outcome of patients following TBI. Method: This review aims to provide a comprehensive overview of the pathophysiology, clinical presentation, and challenges in diagnosing patients with autonomic dysfunction after TBI. The databases used in this review include PubMed/MEDLINE, Cochrane Central Register, and Scopus. Results: Of 172 articles identified for screening, 98 were ultimately included in the review. Conclusion: This review summarized the current evidence on the pathophysiology, clinical presentation, and diagnosis of early autonomic dysfunction. It also emphasizes the effects of autonomic dysfunction on end-organ damage. These insights aim to guide clinicians and researchers toward improving the care for and understanding of autonomic dysfunction in TBI patients, while underscoring the need for further research in this area.

Exploration of simultaneous transients between cerebral hemodynamics and the autonomic nervous system using windowed time-lagged cross-correlation matrices: a CENTER-TBI study

BACKGROUND

Traumatic brain injury (TBI) can significantly disrupt autonomic nervous system (ANS) regulation, increasing the risk for secondary complications, hemodynamic instability, and adverse outcome. This retrospective study evaluated windowed time-lagged cross-correlation (WTLCC) matrices for describing cerebral hemodynamics-ANS interactions to predict outcome, enabling identifying high-risk patients who may benefit from enhanced monitoring to prevent complications.

METHODS

The first experiment aimed to predict short-term outcome using WTLCC-based convolution neural network models on the Wroclaw University Hospital (WUH) database (Ptraining = 31 with 1,079 matrices, Pval = 16 with 573 matrices). The second experiment predicted long-term outcome, training on the CENTER-TBI database (Ptraining = 100 with 17,062 matrices) and validating on WUH (Pval = 47 with 6,220 matrices). Cerebral hemodynamics was characterized using intracranial pressure (ICP), cerebral perfusion pressure (CPP), pressure reactivity index (PRx), while ANS metrics included low-to-high-frequency heart rate variability (LF/HF) and baroreflex sensitivity (BRS) over 72 h. Short-term outcome at WUH was assessed using the Glasgow Outcome Scale (GOS) at discharge. Long-term outcome was evaluated at 3 months at WUH and 6 months at CENTER-TBI using GOS and GOS-Extended, respectively. The XGBoost model was used to compare performance of WTLCC-based model and averaged neuromonitoring parameters, adjusted for age, Glasgow Coma Scale, major extracranial injury, and pupil reactivity in outcome prediction.

RESULTS

For short-term outcome prediction, the best-performing WTLCC-based model used ICP-LF/HF matrices. It had an area under the curve (AUC) of 0.80, vs. 0.71 for averages of ANS and cerebral hemodynamics metrics, adjusted for clinical metadata. For long-term outcome prediction, the best-score WTLCC-based model used ICP-LF/HF matrices. It had an AUC of 0.63, vs. 0.66 for adjusted neuromonitoring parameters.

CONCLUSIONS

Among all neuromonitoring parameters, ICP and LF/HF signals were the most effective in generating the WTLCC matrices. WTLCC-based model outperformed adjusted neuromonitoring parameters in short-term but had moderate utility in long-term outcome prediction.

Heart Rate Variability and Cerebral Autoregulation in Patients with Traumatic Brain Injury with Paroxysmal Sympathetic Hyperactivity Syndrome

BACKGROUND

Severe traumatic brain injury (TBI) can lead to transient changes in autonomic nervous system (ANS) functioning and development of paroxysmal sympathetic hyperactivity (PSH) syndrome. Clinical manifestation of ANS disorders may be obscured by therapeutic interventions in TBI. This study aims to analyze ANS metrics and cerebral autoregulation in patients with PSH syndrome to determine their significance in early prognostication.

METHODS

This single-center retrospective study investigated the relationship between changes in ANS metrics, cerebral autoregulation, and PSH syndrome. Arterial blood pressure and intracranial pressure signals were monitored for 5 days post TBI. ANS metrics included time and frequency domain heart rate variability (HRV) metrics. Cerebral autoregulation was assessed using the pressure reactivity index.

RESULTS

Sixty-six patients with severe TBI (median age 33 [interquartile range 26-50] years) were analyzed, and PSH was confirmed in nine cases. Impairment of cerebral autoregulation was observed in 67% of patients with PSH and 72% without the syndrome. Patients with PSH had higher HRV in the low-frequency range (LF; 253 ± 178 vs. 176 ± 227 ms2; p = 0.035) and lower heart rates (HRs; 70 ± 7 vs. 78 ± 19 bpm; p = 0.027) compared to those without PSH. A receiver operating characteristic curve analysis indicated that HR (area under the curve (AUC) = 0.73, p = 0.006) and HRV in the LF (AUC = 0.70, p = 0.009) are moderate predictors of PSH. In the multiple logistic regression model for PSH, diffuse axonal trauma (odds ratio (OR) = 10.82, 95% confidence interval (CI) = 1.70-68.98, p = 0.012) and HR (OR = 0.91, 95%  CI 0.84-0.98, p = 0.021) were significant factors.

CONCLUSIONS

Elevated HRV in the LF and decreased HR may serve as early predictors of PSH syndrome development, particularly in patients with diffuse axonal trauma. Further research is needed to investigate the utility of the cerebral autoregulation-ANS relationship in PSH prognostication.

Nursing Interventions and Intracranial Pressure Change in Pediatric Patients With Severe Traumatic Brain Injury

BACKGROUND

Nursing interventions in the care of pediatric patients with severe traumatic brain injury (TBI) can have a direct effect on intracranial pressure (ICP), yet they have been largely underexplored. Early evidence is therefore needed to describe these relationships and to determine intervention that promotes neuroprotection and recovery.

OBJECTIVES

The aim of this study was to examine nursing interventions within the first 72 hours of pediatric severe TBI and their effects on ICP.

METHOD

This is a retrospective review of pediatric patients admitted for severe TBI using a quasi-experimental approach to assess nursing interventions and their association with the patients' ICP values prior to and after each intervention.

RESULTS

Of the 56 patients who met the inclusion criteria, 3392 intervention events (range, 31-138 events per patient) were reported. Paired t tests conducted for each intervention type found a statistically significant relationship with suctioning and percent change in ICP values (P = .045). All other interventions showed no significant differences.

DISCUSSION

Standard nursing interventions, specifically suctioning, in pediatric severe TBI may affect ICP and therefore neuroprotection. Further work is needed to better understand the role and timing of nursing interventions and their influence on cerebral hemodynamics so that future TBI guidelines consider nursing care and their impact on brain injury recovery.

Synergistic dynamics of heart rate variability and systolic blood pressure revealed by dual Poincaré plot analysis

Cardiac arrest (CA) survivors often suffer secondary brain injury due to impaired autonomic nervous system (reflected by heart rate HR) and hemodynamic function (reflected by blood pressure BP and baroreflex regulation). This study proposes a Dual Poincaré Plot, a novel method analyzing coupled variability in HR - BP dynamics to assess these impairments. Ten rats were categorized into good and poor neurological outcome groups in a rat model of CA. Dual Poincaré plot analysis, squared partial directed coherence, and sequence method were used to characterize the outcome. Results revealed differences in variability of HR, BP, and baroreflex, as well as coupling strength, between groups. Good outcome subjects exhibited 1) increased variability in both BP and HR, 2) enhanced baroreflex regulation, and 3) weakened cardiovascular coupling. Conversely, subjects with poor outcomes displayed 1) decreased HR-BP variability, 2) impaired baroreflex, and 3) stronger coupling. The Baroreflex Index from the Dual Poincaré plot showed a high correlation with the traditional sequence method (R2 = 0.91). These results imply that Dual Poincaré offers a real-time assessment of autonomic-hemodynamic interaction, effectively stratifying post-CA neurological recovery and potentially enhancing prognostic accuracy for timely interventions.

Impaired cerebral autoregulation detected in early prevasospasm period is associated with unfavorable outcome after spontaneous subarachnoid hemorrhage: an observational prospective pilot study

BACKGROUND

Subarachnoid hemorrhage (SAH) patients with cerebral autoregulation (CA) impairment at an early post-SAH period are at high risk of unfavorable outcomes due to delayed cerebral ischemia (DCI) or other complications. Limited evidence exists for an association between early-stage CA impairments and SAH patient outcomes. The objective of this prospective study was to explore associations between CA impairments detected in early post-SAH snapshot examinations and patient outcomes.

METHODS

The pilot observational study included 29 SAH patients whose CA status was estimated 2-3 days after spontaneous aneurysm rupture and a control group of 15 healthy volunteers for comparison. Inflatable leg recovery boots (reboots.com, Germany) were used for the safe controlled generation of arterial blood pressure (ABP) changes necessary for reliable CA examination. At least 5 inflation‒deflation cycles of leg recovery boots with a 2-3 min period were used during examinations. CA status was assessed according to the delay time (∆TCBFV) measured between ABP(t) and cerebral blood flow velocity (CBFV(t)) signals during artificially induced ABP changes at boot deflation cycle. CBFV was measured in middle cerebral artery by using transcranial Doppler device.

RESULTS

Statistically significant differences in ∆TCBFV were found between SAH patients with unfavorable outcomes (∆TCBFV = 1.37 ± 1.23 s) and those with favorable outcomes (∆TCBFV = 2.86 ± 0.99 s) (p < 0.001). Early assessment of baroreflex sensitivity (BRS) during the deflation cycle showed statistically significant differences between the DCI and non-DCI patient groups (p = 0.039).

CONCLUSIONS

A relatively small delay of ∆TCBFV <1.6 s between CBFV(t) and ABP(t) waves could be an early warning sign associated with unfavorable outcomes in SAH patients. The BRS during boot deflation can be used as a biomarker for the prediction of DCI.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT06028906. Registered 31 August 2023 - Retrospectively registered, https://www.

CLINICALTRIALS

gov/study/NCT06028906 .

Hypertension at the nexus of veteran status, psychiatric disorders, and traumatic brain injury: Insights from the 2011 Behavioral Risk Factor Surveillance System

Variable military service-related experiences, such as combat exposure, psychiatric disorders (PD), and traumatic brain injuries (TBI), may differentially affect the likelihood of having health care professional-identified high blood pressure (i.e., hypertension).

PURPOSE

Compare the odds of self-reported hypertension among non-combat and combat veterans with and without PD/TBI to non-veterans and each other.

METHODS

We used data from men from the 2011 Behavioral Risk Factor Surveillance System and distinguished: non-veterans (n = 21,076); non-combat veterans with no PD/TBI (n = 3,150); combat veterans with no PD/TBI (n = 1,979); and veterans (combat and non-combat) with PD and/or TBI (n = 805). Multivariable, hierarchical logistic regression models included exogenous demographic, socioeconomic attainment and family structure, health behavior and conditions, and methodological control variables.

RESULTS

One-third of men reported having been told at least once by a medical professional that they had high blood pressure. Bivariate analyses indicated that each veteran group had a higher prevalence of self-reported hypertension than non-veterans (design-based F = 45.2, p<0.001). In the fully adjusted model, no statistically significant differences in the odds of self-reported hypertension were observed between non-veterans and: non-combat veterans without PD/TBI (odds ratio [OR] = 0.92); combat veterans without PD/TBI (OR = 0.87); veterans with PD and/or TBI (OR = 1.35). However, veterans with PD and/or TBI had greater odds of reporting hypertension than both combat and non-combat veterans without PD/TBI (p<0.05).

DISCUSSION

Military service-related experiences were differentially associated with a survey-based measure of hypertension. Specifically, veterans self-reporting PD and/or TBI had significantly higher odds of self-reporting hypertension (i.e., medical provider-identified high blood pressure).