Spinal anesthesia for lumbar spine surgery correlates with fewer total medications and less frequent use of vasoactive agents: A single center experience

Abstract

Study objective: Anesthesiologists at our hospital commonly administer spinal anesthesia for routine lumbar spine surgeries. Anecdotal impressions suggested that patients received fewer anesthesia-administered intravenous medications, including vasopressors, during spinal versus general anesthesia. We hypothesized that data review would confirm these impressions. The objective was to test this hypothesis by comparing specific elements of spinal versus general anesthesia for 1-2 level open lumbar spine procedures.

Design: Retrospective single institutional study.

Setting: Academic medical center, operating rooms.

Patients: Consecutive patients (144 spinal and 619 general anesthesia) identified by automatic structured query of our electronic anesthesia record undergoing lumbar decompression, foraminotomy or microdiscectomy by one surgeon under general or spinal anesthesia.

Interventions: Spinal or general anesthesia.

Measurements: Numbers of medications administered during the case.

Main results: Anesthesiologists administered in the operating room a total of 10 ± 2 intravenous medications for general anesthetics and 5 ± 2 medications for spinal anesthetics (-5, 95% CI -5 to -4, p<0.001, univariate analysis). Multivariable analysis supported this finding (spinal versus general anesthesia: -4, 95% CI -5 to -4, p<0.001). Spinal anesthesia patients were less likely to receive ephedrine, or phenylephrine (by bolus or by infusion) (all p<0.001, Chi-squared test). Spinal anesthesia patients were also less likely to receive labetolol or esmolol (both p = 0.002, Fishers' Exact test). No neurologic injuries were attributed to, or masked by, spinal anesthesia. Three spinal anesthetics failed.

Conclusions: For routine lumbar surgery in our cohort, spinal compared to general anesthesia was associated with significantly fewer drugs administered during a case and less frequent use of vasoactive agents. Safety implications include greater hemodynamic stability with spinal anesthesia along with reduced risks for medication error and transmission of pathogens associated with medication administration.

Fig 1. Number of drugs administered by group.

Total number of drugs administered for each type of anesthetic. For each group the plot shows all data points, median, Interquartile Range (IQR) and outliers (black circles).

Fig 2. Number of drugs over time.

—Panel A Number of drugs administered by year (median, quantiles as error bars).—Panel B Number of drugs administered for the first and second halves of each cohort. There was no statistically significant difference between the first half and second half for SA cases. There was a statistically significant difference between the first half and second half GA cases, p <0.001 (Wilcoxon rank sum test). Error bars represent Q1 and Q3.

Fig 3. Bupivacaine spinal anesthetic dose.

Bupivacaine, 0.5% solution without any adjuvant agents. Median dose (milliliters) by year. The apparent downward trend in dose over time was not statistically significant (p = 0.132, linear regression).