Spinal anaesthesia with 4 mg versus 3 mg of hyperbaric bupivacaine plus 10 µg of fentanyl for adult anorectal surgery: faster recovery with prolonged analgesia

Abstract

The goal of study was to test the hypothesis that addition of fentanyl to low-dose spinal hyperbaric bupivacaine reduces the effective dose of bupivacaine with faster recovery and similar quality of anaesthesia for anorectal surgery. 132 adult consecutive American Society of Anaesthesiology (ASA) 1–3 patients were randomized to receive spinal anaesthesia (SA) in the sitting position at L3-4 or L4-5 with hyperbaric bupivacaine (Marcaine Spinal Heavy 0.5%) injected over 2 minutes: Group S4 (n = 66) 0.8 mL, Group S3F (n = 66) 0.6 mL + fentanyl 10 µg to 0.8 mL. After sitting for 10 minutes, surgery was started. The rate of success, level and duration of sensory and motor block, time to voiding and ambulation, complications, consumption of analgesics, quality of anaesthesia according to the patient and medical staff (0–2 score) were assessed. Student’s t, Mann-Whitney, Analysis of variance (ANOVA), Kruskall-Wallis and χ 2 tests were used. Characteristics of SA are presented as mean ± standard deviation (SD), no of cases (%), median (range), p < 0.05* regarded as statistically significant. Maximum level of sensory block was 7.7 ± 1.4 vs. 7.0 ± 1.8 dermatomes in Group S3F vs. Group S4. Level of motor block was 0 Bromage score in >85% of cases in both groups. Mean duration of sensory block was 212.7 ± 35.1* vs. 229.5 ± 36.5 minutes in Group S3F vs. Group S4. Median time to urinate was 260 (120–960)* vs. 315 (160–1140) minutes in Group S4 vs. Group S3F. Quality of anaesthesia was comparable among groups. Pruritus was recorded in 4 cases vs. 0, Group S3F vs. Group S4 (p < 0.05). In conclusion, a combination of 3 mg of spinal hyperbaric bupivacaine with fentanyl produces an adequate level of anaesthesia similar to a dose of 4 mg but with faster recovery and prolonged analgesia for adult anorectal surgery. The trial was registered retrospectively in ISRCTN registry as ISRCTN84658134 and can be viewed at https://www.isrctn.com/ISRCTN84658134.