Minimum Alveolar Concentration-Awake of Sevoflurane is Decreased in Patients with Parkinson's Disease: An Up-and-Down Sequential Allocation Trial

Effects of mild cognitive impairment and sleep disorders on the minimum alveolar concentration value of sevoflurane

OBJECTIVES

To explore the effect of mild cognitive impairment (MCI) and MCI with sleep disorders on the potency of sevoflurane anesthesia in the elderly.

DESIGN

Prospective study methods. Dixon up-and-down methods.

SETTING

Comprehensive public tertiary hospital, Cangzhou City, Hebei Province, China.

PARTICIPANTS

70 elderly patients scheduled for elective unilateral breast cancer surgery and finally analyzed 58 patients, including 30 patients with MCI (group M) and 28 patients with MCI with sleep disorders (group MS).

OUTCOME MEASURES

The required minimum alveolar concentration (MAC) value of sevoflurane in the two groups was determined using the Dixon up-and-down method. The MAC value of sevoflurane and its 95% confidence interval (CI) were calculated using the logistic regression method. Serum melanin-concentrating hormone concentrations were determined by Elisa kits.

RESULTS

The MAC value of sevoflurane in group M was 1.43 (95% CI 1.05-1.61%), and the MAC value of sevoflurane in group MS was 1.93 (95% CI 1.78-2.08%), There were notable differences between the two groups (P < 0.0001). The level of melanin-concentrating hormone (MCH) in the MS group was significantly lower than that in the M group (21.52 ± 3.82 vs. 37.17 ± 3.66 pg/ml, P < 0.0001). There was a significant negative correlation between MCH levels and the probability of body movement during skin incision (OR = 0.844, 95% CI: 0.715-0.996, P = 0.045).

CONCLUSIONS

Patients with MCI with sleep disorders required higher doses of sevoflurane than those with MCI alone. Changes in anesthetic requirements may be related to changes in MCH levels.

Median Effective Concentration of Ropivacaine for Femoral Nerve Block Maintaining Motor Function During Knee Arthroscopy in Two Age Groups

BACKGROUND

Femoral nerve block combined with general anesthesia is commonly used for patients undergoing knee arthroscopy in ambulatory care centers. An ideal analgesic agent would selectively (differentially) block sensory fibers, with little or no effect on motor nerves. Ropivacaine is considered to cause less motor block than others. This study investigated the median effective concentration (EC50) of ropivacaine for differential femoral nerve block in adults either younger or older than 60 years.

METHODS

Patients with American Society of Anesthesiologists physical status I-III and scheduled for knee arthroscopy were categorized as 18- to 60-years-old (Group 1), or older than 60 years (Group 2). Surgeries were performed under general anesthesia combined with femoral nerve block via 22 mL ropivacaine. The EC50 of ropivacaine for differential femoral nerve block was determined using the up-and-down method and probit regression. The primary outcome was the EC50 (95% confidence interval [CI]) of the 2 groups. Data on the sensory block, analgesic effect, complications, and hemodynamics during surgery were also recorded.

RESULTS

The EC50 of 22 mL ropivacaine for differential femoral nerve block of Group 1 (0.124%, 95% CI 0.097-0.143%) was significantly higher than that of Group 2 (0.088%, 95% CI 0.076-0.103%). The sensory block and hemodynamic data of the 2 groups were comparable. None of the patients experienced neurological complications.

CONCLUSION

The EC50 of ropivacaine administered for differential femoral nerve block during knee arthroscopy was lower in patients older than 60 years, relative to younger adults.