A Study into the Feasibility of Using HRV Variables to Guide Treatment in Patients with Paroxystic Sympathetic Hyperactivity in a Neurointensive Step-Down Unit

BACKGROUND: Patients suffering brain injury may experience paroxystic sympathetic hyperactivity, presenting diagnostic and therapeutic challenges in neurointensive rehabilitation. The syndrome has been modelled as peripheral and central excitatory:inhibitory ratios of autonomous nervous activity. Another model represents the symptoms as oscillations of the two components of the autonomous nervous system. In therapeutic framework, the syndrome is perceived as the patient misconstruing sensory input relating to body positioning. OBJECTIVE: To investigate whether changes in frequency domain of heart rate variability reflect pharmacological and/or therapeutic measures in rehabilitation. METHODS: ECG was recorded before and after pharmacological and therapeutic interventions in eight patients with high probability of the syndrome in a neurointensive step-down unit. Recordings were analysed off-line in frequency parameters. Appropriate statistical methods were applied. RESULTS: Low, high frequency and the LF/HF ratio changed significantly following therapeutic as well as pharmacological interventions. DISCUSSION: The cohort was small, the setting the immediate postictal period of intensive care with multidisciplinary rehabilitation. Still, changes in frequency domain were detected following therapeutic efforts. This opens up the venue of on-line monitoring of the intended therapeutic effect.