Background Ambulatory anorectal surgery requires an anesthetic of short duration but profound depth. Saddle block anesthesia (SBA) can provide dense sacral anesthesia with minimal motor blockade, but the ideal local anesthetic agent remains undefined. This systematic review aims to identify the optimal SBA regimen for ambulatory anorectal surgery.
Methods We sought randomized trials examining SBA for ambulatory anorectal surgery and stratified patients into four subgroups according to local anesthetic type and dose: (1) longer acting, higher dose; (2) longer acting, lower dose; (3) shorter acting, higher dose; and (4) shorter acting, lower dose. Longer acting agents included bupivacaine and levobupivacaine; shorter acting agents included chloroprocaine, mepivacaine, and prilocaine. Lower dose was defined as ≤5 mg and ≤20 mg for longer and shorter acting local anesthetics, respectively. The primary outcome was time to discharge; secondary outcomes included times to sensory and motor block regression, urine voiding, and ambulation, as well as block success.
Results A total of 11 trials (1063 patients) were included. Overall study quality and reporting consistency was poor. Doses ranged from 1.5–7.5 mg to 3–30 mg of longer and shorter acting local anesthetics, respectively. Hyperbaric local anesthetics were used in eight trials (953 patients, 86%). The median time to discharge appeared similar across all subgroups with an overall time of 182 (IQR 102) min. The use of long-acting, lower dose regimens was associated with a faster median time to motor block regression. Block success approached 99% among all trials.
Conclusions There is presently insufficient qualitative and quantitative evidence to identify an optimal SBA regimen for ambulatory anorectal surgery. Nonetheless, we found that doses as low as 1.5 and 3 mg of longer and shorter acting hyperbaric local anesthetics, respectively, can achieve effective and reliable SBA with timely hospital discharge. Despite similar discharge times, longer acting, lower dose local anesthetics may produce faster motor block regression following SBA for ambulatory anorectal surgery.
- ambulatory care
- anesthesia, conduction
- injections, spinal
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Contributors EMY helped perform the literature search, title and abstract screening, data abstraction, data analysis and interpretation, and drafting and review of the manuscript. FWA and RB helped perform the literature search, data analysis and interpretation, and drafting and review of the manuscript. CT helped perform the literature search, title and abstract screening, data abstraction, data analysis and interpretation, and review of the manuscript. AG and ES helped perform the literature search, title and abstract screening, data abstraction, and review of the manuscript.
Funding RB receives research time support from the Evelyn Bateman Cara Operations Endowed Chair in Ambulatory Anesthesia and Women’s Health, Women’s College Hospital, Toronto. FWA receives research time support from the Department of Anesthesiology and Pain Medicine and the Ottawa Hospital Research Institute, University of Ottawa.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.