Significantly shorter anesthesia time for surgery of the lumbar spine. Process analytical comparison of spinal anesthesia and intubation narcosis

Most surgery of the lumbar spine is performed with the patient under general anesthesia (GA); however, qualitative benefits of spinal anesthesia (SA) have been reported. The goal of this study was to compare time efficiency between these two anesthesia methods in lumbar spine surgery. To test the hypothesis that the use of SA leads to significant time saving compared to GA for lumbar spine surgery, key points in the preoperative, intraoperative and postoperative anesthesiology care times were analyzed. The focus was on anesthesia time excluding surgery time. Electronically based data of 473 anesthesia procedures (368 SA, 105 GA) for lumbar spine interventions performed in the prone position (i. e. decompression, discectomy and transpedicular instrumentation) were analyzed retrospectively. Patient population data including gender, age, American Society of Anesthesiologists (ASA) classification and body mass index (BMI) were analyzed. The focus was on the documented perioperative key time points which are defined as follows: (1) induction, (2) positioning (turning into prone position), (3) scrubbing and covering, (4) surgery time (knife to skin closure), (5) closing (end of surgery until leaving operating room) and (6) handing over to recovery. Differences in the amount of time for each perioperative period were calculated for SA and GA. In 7 out of the 368 SA patients SA failed and had to be converted to GA. There were no significant differences in BMI, ASA prevalence and gender between SA and GA patients but SA patients were significantly older (median 61.7 +/- 15.4 years) than GA patients (median 56.1 +/- 14.6 years). However, SA required significantly less time for induction (SA: 17.7 +/- 7.0 min, GA: 21.6 +/- 7.2 min), preoperative preparation (SA: 9.7 +/- 3.6 min, GA: 13.3 +/- 5.4 min) and closing period (SA: 4.9 +/- 1.1 min, GA: 15.3 +/- 5.7 min) compared to GA. Total anesthesia time with exclusion of the surgery time revealed a significant time reduction using SA of 19 min (95 % confidence interval: range 13.6-24.4 min, median in SA: 56.7 min, median in GA: 75.7 min, p < 0.0001). This study showed that in lumbar spine surgery 19 min of anesthesia time can be saved using SA compared to GA which could have an impact on economic aspects. Gender, BMI and ASA had no statistically detectable influence on the choice between the two anesthesia methods. The fact that time-intensive complex instrumentation is mainly performed in younger patients may explain why GA patients were younger than SA patients.