Effect Of β₂ Agonist Salbutamol Aerosol On The Uptake Of Sevoflurane In Elderly Patients

Objective:To study whetherβ₂ agonist salbutamol has an effect on the uptake of sevoflurane in elderly patients.Methods:It is a prospective randomized double-blind study.With Ethical Committee approval and written informed consent,30 patients aged 65～75 years,ASAⅠ～Ⅱ, BMI 18～30 kg/m²,undergoing general anesthesia were randomly received either salbutamol(n=15) or control sample(n=15) 200μg per-person.General anesthesia was induced with fentanil 3μg/kg,propofol 2mg/kg and rocuronium 0.9 mg/kg 30 min later.When the trachea was intubated,Intermittent positive pressure ventilation(IPPV) was applied with 2%sevoflurane and a 2 L/min fresh gas flow(tidal volume:of 8～10 ml/kg;respiratory rate:10 breaths/min;inspiratory to expiratory time ratio of 1:2; to maintain EtCO₂ 30～35mmHg)via a nonrebreathing circuit.HR,IBP,S_PO₂,EtCO₂, Insevo and Etsevo were recorded 1,2,3,5,10,15 min after intubation.We expose the two groups after the whole trial,and get the conclusion whether there is a different speed on the uptake of sevoflurane between the two groups.Results:There is no statistical difference in height,age,weight,BMI,base HR and base MAP between the salbutamol group and the control group(P＞0.05).The inhaled concentration of sevoflurane(Fi) at 1,2,3,5,10,15 min of the salbutamol group and the control group are 0.71±0.11,0.95±0.10,1.12±0.13,1.36±0.11, 1.62±0.09,1.71±0.07 and 0.61±0.14,0.93±0.12,1.10±0.11,1.34±0.14,1.61±0.13, 1.74±0.09 respectively.There is significant statistical difference for Fi within each group(P＜0.05);with the increase of Fi by time,the result is different:there is significant statistical difference for Fi between the salbutamol group and the control group at 1 min after intubation(P＜0.05),but there is no significant statistical difference for Fi between the groups at 2,3,5,10,15 min after intubation(P＞0.05). The concentration of sevoflurane in pulmonary alveoli(Fa) on 1,2,3,5,10,15 min of the salbutamol group and the control group are 0.35±0.10,0.58±0.07,0.71±0.09, 0.93±0.11,1.20±0.08,1.36±0.10 and 0.29±0.11,0.55±0.07,0.70±0.10,0.93±0.11, 1.23±0.12,1.39±0.08 respectively.There is significant statistical difference for Fa within each group(P＜0.05);however,with the increase of Fa by time,there is no significant statistical difference for Fa between the groups at each time after intubation(P＞0.05).The statistics of the salbutamol group and the control group shows that,within each group,HR increases within 1 min after intubation,decreases within 2 min and 3 min(P＜0.05) and becomes stable after 10 min(P＞0.05);MAP decreases within 5 min after intubation(P＜0.05) and becomes stable after 10 min(P＞0.05).There is no significant statistical difference for HR and MAP between the salbutamol group and the control group at 1,2,3,5,10,15 min after intubation(P＞0.05).Conclusion:β₂ agonist salbutamol may not have effect on the uptake of sevoflurane by the elderly patients.