Retrospective cohort of 24,974 surgical cases under spinal anesthesia: Bupivacaine dose and failure rate
Alexander Avidan, MD, Charles Weissman, MD, Carolyn F. Weiniger, MD
Department of Anesthesiology and Critical Care Medicine, Hadassah – Hebrew University Medical Center, Jerusalem Israel.
Background and Goals
Per text books and current literature, bupivacaine is the preferred local anesthetic for spinal anesthesia. Recommended doses range from low (up to 5mg) to high (up to 15-20mg). There is a debate about the selection of hyperbaric, hypobaric or plain bupivacaine. The goal of this study was to investigate the selected bupivacaine dose used for spinal anesthesia for common lower body surgery and to examine the failure rates.
Material and Methods
This study was approved by the Hadassah Institutional Review Board (IRB). Data from anesthetics with spinal anesthesia for various types of surgery of the lower body (obstetric, gynecologic, proctologic, orthopedic, urologic, inguinal hernia and bone marrow aspiration) were retrieved from the anesthesia information management system (Metavision, iMDsoft, Israel) of the Hadassah – Hebrew University Medical Center from February 2007 to December 2016. 
Results and Discussion
Data from 24,974 anesthesia records were retrieved and are summarized in Table 1. Hyperbaric bupivacaine was the most frequent choice for all surgeries, and most frequently reported sensory levels were appropriate to cover for the surgical innervation. The sensory level was not reported in 57% of cases. Overall, 2.2% of the spinals were reported as failures.
Table 1
		Duration (minutes)	Dose Bupivacaine (mg)	Failure Rate
		Anesthesia	Surgery	Hyperbaric	Hyporbaric	Plain	
Type of Surgery	N %	Mean SD	Mean SD	N (%)	Mean SD	N (%)	Mean, SD	N %	Mean SD	N (%)
Orthopedic	9742 (39.0%)	100 ±178	59 ±173	7613 (82.2%	9.2 ±2.9	756 (8.2%)	9.4 ±4.1	820 (8.9%)	6.6 ±3.6	205 (2.1%)
Cesarean delivery	8814 (35.3%)	73 ±165	31 ±23	7937 (92.9%)	9.0 ±2.3	13 (0.2%)	9.2 ±1.9	598 (7.0%)	7.9 ±3.3	147 (1.7%)
Inguinal hernia repair	1886 (7.6%)	76 ±55	48±22	1703 (93.1%)	9.6 ±4.1	9 (0.5%)	9.1 ±1.5	118 (6.4%)	7.8 ±1.8	98 (5.2%)
Urology	2253 (9.0%)	73 ± 43	43 ±26	2105 (97.1%)	9.6 ±2.6	5 (0.2%)	8.8 ±1.1	57 (2.6%)	8.2 ±1.8	68 (3.0%)
Proctology	1701 (6.8%)	49±110	19 ±12	1590 (98.7%)	8.5 ±2.3	4 (0.2%)	7.9 ±1.7	17 (1.1%)	7.7 ±1.8	21 (1.2%)
Gynecology	508 (2.0%)	63 ±25	37 ±20	458 (96.2%)	8.6 ±2.0	0		18 (3.8%)	9.0 ±2.6	15 (3.0%)
Bone marrow aspiration	70 (0.3%)	85 ±28	45 ±22	67 (95.7%)	10.2 ±1.7	0		3 (4.3%)	8.3 ±3.2	6 (8.6%)
Total	24974	74 ±35	42 ±26	21473 (98.7%)	9.1 ±2.7	787 (0.2%)	9.4 ±4.0	1631 (1.1%)	7.2 ±3.4	560 (2.2%)
	Missing 1083 (4.3%)	
Conclusions
The selection and dose of spinal anesthesia were suitable for the duration of surgery. Hyperbaric bupivacaine was the most common choice. Doses were between the recommended low and high doses. The failure rate was like that reported in the literature.

Retrospective cohort of 24,974 surgical cases under spinal anesthesia: bupivacaine dose and failure rate