Date of Award

January 2015

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Shamsuddin Akhtar

Subject Area(s)

Medicine

Abstract

Introduction: Previous studies have demonstrated that elderly patients have decreased anesthetic requirements due to age related pharmacokinetic and pharmacodynamic changes. It was our impression that anesthetic dosages are inconsistently corrected for age in routine practice. We hypothesized that common induction anesthetics (midazolam, fentanyl, propofol) are not rigorously corrected for age, thus leading to potential overdosing.

Methods: We retrospectively reviewed the intraoperative electronic anesthetic records of 796 patients (≥18 yrs) undergoing gynecological-oncology surgeries. We conducted analyses of weight-adjusted dosing differences and hemodynamic outcomes (first 10 mins after induction) between young patients (18-64 yrs, n=575) and elderly patients (≥65 yrs, n=221). Data was also analyzed across different age groups and ASA classes. To analyze whether anesthetic administration varied by provider, we abstracted records in which a provider administered anesthesia for at least 5 young and elderly cases. Statistical analyses were conducted using t-test and ANOVA, with p<0.05 considered significant. RESULTS: For fentanyl, we did not observe any significant difference in average doses between young and elderly patients within ASA classes I & II, as well as within ASA classes III & IV (p=0.33; 0.37). However, we noted a significant difference in average doses between them for midazolam and propofol.

There was a statistically significant decline in the amount of midazolam and propofol administered with increasing age (p-values <0.01). However, there was no significant difference in the doses of fentanyl received across all age groups (p=0.78).

Irrespective of ASA class, the elderly group experienced significantly increased post-induction hypotension compared to their younger counterparts (p < 0.01).

16.0% of elderly cases were administered vasopressors shortly after induction, and before incision, compared to 6.3% of their younger counterparts (p<0.01). We observed that for all providers, there was no age correction for the dosage of fentanyl, or propofol, or both. In many individual cases, the dose of propofol given is far more than what is recommended. In addition, we observed wide variability in dosing among providers.

Conclusion: Our findings confirm that anesthetic dosing of fentanyl is not being rigorously corrected for age. Although propofol and midazolam are corrected for age, increased frequency of hypotension in the elderly population is still observed. Significantly increased vasopressor use in the elderly compared to their younger counterparts was recorded. High variability in anesthetic administration among providers was also observed. The results of this observational study suggest that there is room for improvement in anesthetic administration for elderly undergoing non-cardiac surgeries.

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