Background: Intubation using direct laryngoscopy is a risky and painful procedure that is associated with undesirable hemodynamic changes such as tachycardia, hypertension, and arrhythmia. Recently, intravenous oxycodone was introduced and used for the control of acute postoperative pain and to attenuate intubation-related hemodynamic responses (IRHRs), but there is insufficient information regarding its proper dosage. We investigated the attenuating effects of different doses of oxycodone and fentanyl on IRHRs.
Methods: For calculating oxycodone effective dose (ED95), which attenuated all IRHR changes to less than 20% over baseline values in 95% of male patients at 1 minute after intubation, oxycodone 0.1 mg/kg was injected for the first patient 1 hour before intubation, and the next dose for each subsequent patient was determined by the response of the previous patient using Dixon up-and-down method with an interval of 0.01 mg/kg. After obtaining the predictive oxycodone ED95, 148 patients were randomly allocated to groups receiving normal saline (group C), oxycodone ED95 (group O1), oxycodone 2 × ED95 (group O2), or fentanyl 2 μg/kg (group F). We recorded the incidence of "success" as a less than 20% change from baseline values in all IRHRs 1 minute after intubation.
Results: The predictive oxycodone ED95 was 0.091 (0.081-0.149) mg/kg. The incidence of "success" was highest in group O2 (75.7%), followed by group O1 (62.2%) and group F (45.9%) with significant differences between the groups (P < .001). The systolic, diastolic, mean arterial pressure, and heart rate were not significantly different among groups after administration of either oxycodone or fentanyl. The percentage hemodynamic changes of the group O2 were significantly lower than those of groups F and O1, but the absolute percentage hemodynamic changes were not significantly different among groups F, O1, and O2. The recalculated oxycodone ED95 with probit analysis (0.269 mg/kg) was needed to prevent any arterial pressure and heart rate changes.
Conclusions: Oxycodone 0.182 mg/kg is more effective in attenuating all IRHRs than fentanyl 2 μg/kg with safe hemodynamic changes. Further research is required to determine if the recalculated oxycodone ED95 (0.269 mg/kg) is also effective and hemodynamically safe for preventing all IRHRs.