Clinical Research On Induction With Inhalation Sevoflurane In Elderly Patients

Objective:To estimate the efficiency and safety of induction with inhalation sevoflurane in elderly patients ,compared with routine intravenous (IV) anesthesia induction.Methods:60 elderly patients with aged 63-75yr and ASA physical status I or II undergoing selective abdominal operations were allocated randomly to one of three groups.Intravenous induction group(group V) patients were bolus injected with midazolm(0.05mg.kg~-1),propofol (1.0mg.kg~-1),sulfentanly(0.5ug.kg~-1) and vecuronium (0.1 mg.kg~-1) orderly.Intravenous-inhalation co-induction group(group I+V) patients inhalated 8% sevoflurane and followed by bolus injection of sulfentanly(0.5ug.kg~-1) and vecuronium (0.1 mg.kg~-1) when they lost consciousness.Inhalation induction group(group I) patients were administered surface anesthesia with 2% lidocaine for pars laryngea about 10 minutes preinduction,then inhalated 8% sevoflurane alone.At loss of consciousness (LOC), ventilation was assisted to establish PetCO2 between 20–30 mmHg. The trachea was intubated if the depth of anesthesia was adequate possiblely(which meant that the BIS value achieved a steady state of the minimal value as soon as possible). Group I and group I+V patients continued to inhaleted 1% sevoflurane for maintenance after intubation. Then heart rate(HR), mean arterial pressure(MAP),pulse oxgen saturation (SpO2),bispectral index (BIS) value,concentration of inspired and end-tidal sevoflurane were recorded every minute until 5 minutes after intubation.Also the time to LOC,the induction-intubation time,assessment of intubation conditions, frequency of successful intubation for the first attempt and adverse events during induction were documented.Results:1.There were no statistically significant differences in gender ,body weight ,BMI ,history of hypertension and diabetes mellitus among the groups. 2.The average time to LOC in group V was 65.8 seconds , about ten seconds shorter than the other groups. But there were no significant differences with that among the groups.The BIS decreased gradually with the initiation of induction , increased transiently at the moment of intubation,and maintained between 40 to 65 at last.It decreased significantly lower in group V than the other groups (P <0.05).And the minimal value of BIS was significantly different between group V(35.7±8.6) and group I (41.2±7.8) (P <0.05).No significant difference was found in the time to reach to the minimal value of BIS among the groups.3.The average induction-intubation time was approximately 5 minutes, which was not significantly different among the groups. The assessment of intubation conditions were considered as acceptable in all groups.However,60% in group I were judged to have excellent intubation conditions ,signifantly differed with groupV(90%) and group I+V(95%)(P<0.05).There was also no significant difference with respect to successful intubation for the first attempt among the groups.4.The percentage decreases in MAP compared with baseline in group I ranged from 2.30% to 21.31% during induction ,which was significantly lower than group V(P<0.05). It was similar with group V and group I+V.Futher more,the three groups had proximity in the percentage decreases at 1 min after intubation,but at 5 min after intubation it was significantly less in group I than the others(P<0.05).No significant difference was observed in the change of HR among the groups.But at the moment of intubation, HR increased to exceed baseline in group I more significantly highly than the other groups(P <0.05). The increase of SpO2 wasn't statistically different in all groups.5.There were 8 patients keeping weak breathing before intubation in GroupI(40%) ,and the rest recovered spontaneously respiration after placement of endotracheal tube(ETT).There was no statistically significant difference with sevoflurane concentration between group I and group I+V. 6.No serious adverse events occured before intubation in all groups.The incidence of breathholding was significantly more in group I (30%)than group V ,but not significantly different with group I+V(15%).Conclusion:This study of induction with different methods in elderly patients suggests that induction anesthesia with 8% sevoflurane inhalation is an acceptable alternative to routine IV induction. It is associated with similar time of LOC,but more stable hemodynamics and less incidence of apnea than routine IV induction.And it also can offer acceptable intubation conditions without muscle relaxant and is well tolerated by the eldly patients. Of course, a little dose of sulfentanyl added can inhabited cardiovascular responses better.