The Minimal Effective Dose of Hyperbaric Spinal Bupivacaine for Successful Reliable Saddle Block for Minor Perianal Surgeries

Following approval of the Research and Ethics Committee of the University of Dammam and written informed consent, patients with American Society of Anesthesiologists physical Status I and II, aged 20-55 years, scheduled for outpatient elective perianal surgery in the lithotomy position ( hemorrhoidectomy, fistulectomy), were prospectively enrolled in this study. Patients unwilling to participate, those with contraindications to regional anesthesia, morbid obesity, bleeding disorders, mental health problems or language barriers, taking psychotropic or analgesic medication, or a known history of allergic reactions to amide local anesthetics, were excluded from the study.

Actually, 35 patients were enrolled. However; after they have signed the informed consent; 7 patients were excluded because they have received analgesics in the morning of surgery, and 4 patients refused to receive the saddle block on the operating room. So actually 24 patients out of 35 participants underwent intervention

All patients were fasted for over 6 hours and were premedicated with 0.2 mg/kg oral diazepam 60 min before spinal anesthesia.

In the operating room (OR), an intravenous (IV) 18-20G catheter was placed, and standard monitoring [electrocardiogram (ECG), heart rate (HR), oxygen saturation (SpO2), and noninvasive blood pressure (NIBP)] were started.

Under aseptic conditions, the dural puncture was performed by staff-grade anesthesiologists, using a standard midline approach in the sitting position at the L3-L4 or L4-L5 intervertebral space, using a 25-gauge Whitacre needle with its orifice directed caudally. A predetermined small dose of hyperbaric bupivacaine (Marcaine Spinal Heavy; Astra Zeneca, Lund, Sweden) which was prepared in1 mL tuberculin syringe was injected. All patients remained in the sitting position for 10 min. the patient was asked if he/she perceived any change in motor power.