Propofol-Bispectral Index (BIS) Electroencephalography (EEG) Pharmacokinetic-Pharmacodynamic Model in Patients With Post-Cerebral Hemorrhage Hydrocephalus

Background. Titrating hypnotic agents for patients who suffer from a cerebral insult is a challenging task. To date there is no real gold standard to precisely quantify electroencephalography (EEG) response in a fashion that could be utilized for patients with post-cerebral hemorrhage hydrocephaly. While we must administer as per usual analgesics for noxious stimuli, we have to administer the hypnotic agents more sparingly due to lack of objective monitoring.Methods. We compared 15 adult post-cerebral hemorrhage hydrocephalus patients undergoing ventriculo-peritoneal shunt placement with 15 controls matched for gender and approximate age. We set propofol target controlled infusion estimated plasma concentrations (C-p) to gradually reach 4 mu g/mL over 4 minutes. To precisely quantify post-cerebral hemorrhage mental dysfunction, we used electronically retrieved bispectral index (BIS) and propofol C(p)data points to create individual inhibitory monophasic mathematical model for each patient that incorporates an independent hysteresis lag function.Results. In post-cerebral hemorrhage patients C-p-BIS curve, C-50(propofol concentration associated with inhibitory 50% BIS response) cutoff point was significantly shifted to the left by 39%. Whereas before infusion and at stable propofol 4 mu g/mL aneurismal surgical sides ipsilateral (75 +/- 13, 25 +/- 9) and contralateral (73 +/- 15, 27 +/- 9) mean +/- SD BIS values were significantly lower than ipsilateral (95 +/- 3, 46 +/- 12) and contralateral (94 +/- 3, 46 +/- 12) matched controls.Conclusions. Using BIS as surrogate marker of propofol hypnotic effect, BIS monitoring in patients with post-cerebral hemorrhage hydrocephaly showed a pattern of change and trend that was similar albeit 39% significantly lower than subjects without.

Automated summary

The study investigated the sensitivity of post-cerebral hemorrhage hydrocephalus patients to hypnotic agents and the use of BIS as a surrogate marker for their hypnotic effect, showing a pattern of response that was similar but significantly lower compared to healthy subjects.