[Effect of gender factor on the effective dose of oxycodone for inhibiting responses to laryngeal mask airway insertion in elderly patients undergoing ophthalmic surgery].

ABSTRACT

Objective: To evaluate the effect of gender factor on the effective dose of oxycodone for inhibiting responses to laryngeal mask airway (LMA) insertion in elderly patients undergoing ophthalmic surgery. Methods: From June to October 2021, 56 elderly patients, including 26 females and 30 males, aged from 65 to 80 (72±5) years, with a body mass index (BMI) of 18.5-24.9 kg/m2 and American Society of Anesthesiologists (ASA) physical status of Ⅰ or Ⅱ, who underwent elective ophthalmic surgery requiring LMA insertion in the Beijing Tongren Hospital affiliated to Capital Medical University were selected. Patients were divided into two groups according to gender elderly female group and elderly male group. The modified Dixon sequential method was used. Oxycodone 0.10 mg/kg was injected intravenously in the first patient. Etomidate 0.2 mg/kg and cisatracurium 0.1 mg/kg were administrated 5 min later. After 3 min, the laryngeal mask was placed when the bispectral index (BIS) ≤60. The positive response to LMA insertion was defined as an increase in the maximum mean arterial pressure or the maximum heart rate>20% of the baseline value within 2 min after insertion. When the response to LMA insertion was positive, the dose of oxycodone was increased in the next patient, otherwise the dose was decreased, and the ratio of adjacent dose was 1.1. This process was repeated until the 7th turning point occurred. The half-maximal effective doses (ED50) and 95% confidence intervals (CI) of oxycodone for inhibiting laryngeal mask insertion were calculated and compared between the two groups. Meanwhile, the adverse reactions during anesthesia induction were observed. Results: All 26 patients in the elderly female group completed the test, but one patient in the elderly male group withdrew due to poor alignment of laryngeal mask, and finally 29 patients completed the study. There were 13 cases and 14 cases who had positive response to LMA insertion in the elderly female and male groups, respectively. The ED50 (95%CI) of oxycodone for inhibiting laryngeal mask insertion in the elderly male group was 0.096 (0.083-0.112) mg/kg, which was higher than that in the elderly female group [0.081 (0.073-0.098) mg/kg, P=0.008]. No adverse reactions such as choking cough, muscle tremor, hypoxemia, nausea, vomiting, reflux and aspiration occurred in 55 patients, except that one patient in the elderly female group had transient hypotension after induction, which improved after symptomatic treatment. Conclusion: The ED50 of oxycodone for inhibiting laryngeal mask insertion reaction in ophthalmic surgery is different in patients with different genders, which is 0.096 (0.083-0.112) mg/kg in the elderly male group and 0.081 (0.073-0.098) mg/kg in the elderly female group.