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Saddle Block Anesthetic Technique For Benign Outpatient Anorectal Surgery
*Kent J Peterson, *Paul A Dyrud, *Colin M Johnson, Carrie Y Peterson, Kirk A Ludwig, Timothy J Ridolfi
Medical College of Wisconsin, Wauwatosa, WI

Objective:Current American Society of Colorectal Surgery Clinical Practice Guidelines for Ambulatory Anorectal Surgery endorse use of monitored anesthesia care (MAC), general anesthesia (GA), or spinal anesthesia (SA) based on physician and patient preference. Although several studies support the use of MAC over GA, the literature regarding SA is limited and heterogenous due to small sample sizes and disparate SA techniques. Saddle block anesthesia (SBA) is a form of SA that localizes to the lowermost sacral spinal segments allowing for preservation of lower extremity motor function and faster recovery. We accrued the largest reported cohort of anorectal procedures using SBA, as such, we sought to evaluate our institutional 12-year experience.
Methods:Patients who underwent a benign anorectal procedure at our outpatient surgery center between July 2008-2020 were retrospectively reviewed. Demographics, surgical factors, peri-operative times, and adverse events were collected from the electronic medical records. SBA was generally performed in the pre-operative area using a spinal needle (22-25 gauge) and a single injection technique with a 1:1 ratio local anesthetic mixed with 10% dextrose solution. Between 1-1.5 mL of the hyperbaric mixture was injected intrathecally in the sitting position and the patient remained upright for 3-10 minutes. This technique of SBA provides analgesia for approximately 1-3 hours.
Results:859 SBA patients were identified with a median age of 44 and ASA score of 2. 609 (70.9%) were male. Surgical indications included lesion removal (27.1%), anal fistula (25.8%), hemorrhoidectomy (24.7%), combination (10.2%), pilonidal disease (6.3%), and anal fissure (5.8%). Prone jackknife positioning was used in 91.6% of procedures. SBA most often was performed with bupivacaine (48.9%) or ropivacaine (41.7%). The median procedural SBA time was 11 minutes, surgery time was 17 minutes, anesthesia time was 42 minutes, and recovery time was 91 minutes. Patients spent a median of 3 hours and 53 minutes in the facility. Adverse events included conversion to GA (2.1%), urinary retention (1.9%), spinal headache (1.5%), hemodynamic instability (0.9%), and injection site reaction (0.3%).
Conclusion:Demonstrated using the largest known cohort of anorectal SBA patients, SBA provides analgesia with a low rate of adverse events and may provide an effective alternative to GA.


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