Background and Goal of Study: Laryngoscopy and endotracheal intubation lead essentially to undesirable hemodynamic changes, which most anesthesiologists have attenuated by pharmaceutical intervention such as opioid and non-opioid analgesics. Intravenous oxycodone also can be used for this purpose, but it has different effective dose according to gender as well as age. However, there are no references on the optimal dose to attenuate these hemodynamic changes. Therefore, we investigated the half maximal effective dose (ED50) of intravenous oxycodone to blunt the hemodynamic responses to laryngoscopy and endotracheal intubation by the Dixon´s up-and-down method in male patients.

Materials and methods: After institutional review board approval, thirty three male patients, aged between 20 and 65 years, were finally enrolled. First patients were slowly injected with intravenous oxycodone 0.1 mg/kg 20 minutes before anesthesia. The induction of anesthesia and neuromuscular block was started with propofol and rocuronium. And then, 2 minutes later, endotracheal intubation was performed. The dose of intravenous oxycodone for each subsequent patient was determined by the response of the previous patient by the Dixon´s up-and-down method (DUDM) with an interval of 0.01 mg/kg according to the degree of hemodynamics changes with 20% limitation 1 min after intubation. The ED50 of intravenous oxycodone was determined by using Dixon up-and-down method which calculating the mean of midpoint dose of all independent pairs of patients who manifested crossover from “response” to “no response” after eight crossover points. Probit regression model was used to calculate dose response curve and confidence intervals and estimated ED50 and ED95 were calculated. 

Results and discussion: TheED50of intravenous oxycodone was 0.074 ± 0.008 mg/kg in male patients by DUDM. From probit regression model, the ED50 and ED95 of intravenous oxycodone were 0.069 [95% confidence interval (CI), 0.06-0.077] and 0.091 (CI, 0.077-0.129) mg/kg in male patients, respectively.

Conclusion(s): The intravenous oxycodone showed the narrow preventive dosage for blunting hemodynamic response to laryngoscopy and endotracheal intubation, and the additional study will be needed to confirm the actual blunting effect of hemodynamic responses to laryngoscopy and endotracheal intubation using the ED50 and ED95 of intravenous oxycodone.

The half maximal effective dose of intravenous oxycodone for blunting the hemodynamic responses to laryngoscopy and endotracheal intubation