Pharmacodynamic Estimate of Propofol-Induced Sedation and Airway Obstruction Effects in Obstructive Sleep Apnea-Hypopnea Syndrome

ABSTRACT

PURPOSE: Sedatives must be carefully titrated for patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) as oversedation may lead to disastrous respiratory outcomes. This study aimed to investigate the relations between the effect-site concentration (Ce) of propofol and sedation and airway obstruction levels in patients with OSAHS. MATERIALS AND METHODS: In 25 patients with OSAHS, sedation was induced by 2% propofol using target-controlled infusion. Sedation and airway obstruction levels were assessed using the Observer's Assessment of Alertness/Sedation Scale and a four-category scale, respectively. The relationships between propofol Ce and sedation and airway obstruction were evaluated using a sigmoid Emax model. Pharmacodynamic modeling incorporating covariates was performed using the Nonlinear Mixed Effects Modeling VII software. RESULTS: Increased propofol Ce correlated with the depth of sedation and the severity of airway obstruction. Predicted Ce50(m) (Ce associated with 50% probability of an effect> or =m) for sedation scores (m> or =2, 3, 4, and 5) and airway-obstruction scores (m> or =2, 3, and 4) were 1.61, 1.78, 1.91, and 2.17 microg/mL and 1.53, 1.64, and 2.09 microg/mL, respectively. Including the apnea-hypopnea index (AHI) as a covariate in the analysis of Ce50(4) for airway obstruction significantly improved the performance of the basic model (p<0.05). CONCLUSION: The probability of each sedation and airway obstruction score was properly described using a sigmoid Emax model with a narrow therapeutic range of propofol Ce in OSAHS patients. Patients with high AHI values need close monitoring to ensure that airway patency is maintained during propofol sedation.