Can intravenous lidocaine before extubation in the elderly undergoing noncardiac surgeries improve postoperative cognitive impairments?

Postoperative cognitive impairment is common in the elderly. Multiple factors such as anesthetic drugs are effective on postoperative cognitive function. Lidocaine is a drug used for different therapeutic targets in anesthesia. One of its indications is reducing airway irritations before extubation. This study is designed to evaluate the effect of bollous intravenous lidocaine at the end of surgery on postoperative cognitive function in the elderly undergoing urologic and orthopedic surgery with general anesthesia. In this double blinded clinical trial, after permission from research committee and having obtained written consent, patients older than 65yr were devided in two equal groups (each group comparising of 35 patients). In case group, we used intravenous lidocaine 1.5mg/kg before extubation and in control group, normal saline was used. Cognitive state was evaluated by MMSE questionnaire at four stages: preoperative, at discharge time from recovery, 6hours and 24hours after surgery. Finally, data were analysed with ANOVA, T-test and Mann-Whiteny test. Two groups had no significant differences in demographic factors, surgery status, past history of HTN, DM and smoking. Mean of MMSE at the time of discharge from recovery was 22.4±4.5(SD) and 22.1±4.4(SD) in lidocaine and normal saline group respectively. It showed significant differences with MMSE at the time of before surgery and 24 hours after surgery within two groups, but there was no significant differences in MMSE before surgery, at discharge time from recovery,6hours and 24hours after surgery between two groups. Frequency of severe cognition impairments in lidocaine group before surgery, at discharge from recovery room, 6hours and 24 hours after surgery was 8%, 17%, 9%, 6% respecttively. This frequency was 0%, 20%, 17%, 3% respectively in normal saline group. Two groups showed no significant differences in cognitive impairments at before and after surgery.Conclusion and Administration of bolous intravenous lidocaine before extubation didnot improve cognition state in elderly undergoing noncardiac surgeries under general anesthesia. The effect of lidocaine on cognitive function following cardiac surgeries in which the brain is at potential risk is clear, but in noncardiac surgeries where the brain is not at risk of ischemic events, lidocaine showed no clinical effects. Thus further studies with different doses of lidocaine and different assessment methods are recommended.