Anesthetic outcomes
Epidural anesthesia was used in 120 (41.4 %) patients, and spinal anesthesia in the remaining 170 (58.6 %). Data regarding morphine use are shown in Table 3. In 225 patients (77.6 %) morphine was used, of which 124 (72,9 %) was intradural and 101 (84.9 %) was epidural. Mean morphine dose was 58.0 µg (SD 16.6) in spinal anesthesia and 3 mg (SD 0.7) in epidural anesthesia. The use of morphine did not significantly change the time to first micturition (10.9 h [IC95% 9.4 – 12.4] vs 12.2 h [IC95% 11.3 – 13.2], p = 0.170), the time to mobilization (11.2 h [IC95% 9.8 – 12.6] vs 11.1 h [IC95% 8.8 – 13.3], p = 0.944) and the time to oral intake (7.5 h [IC95% 6.2 – 8.7] vs 7.4 h [IC95% 6.6 – 8.2], p = 0.949) compared to when no morphine was administered. This effect remained unchanged when adjusting by modality of anesthesia, spinal or epidural.
Regarding morphine adverse effects, the use of morphine did not increase the incidence of nausea and vomiting (10.9 % [IC95% 3.3 – 18.6] vs 8.5 % [IC95% 4.8 – 12.1], p = 0.546), pruritus (3.1 % [IC95% 0 – 7.34] vs 3.1 % [IC95% 0.8 – 5.4], p = 1.000) and urine retention (16.9 % [IC95% 7.8 – 26.0] vs 26.2 % [IC95% 20.5 – 32.0], p = 0.123).
When adjusting for the modality of neuraxial anesthesia, urinary retention was significantly higher when morphine was used in spinal anesthesia (8.7 % [IC95% 0.5 – 16.8] vs 21.8 % [IC95% 14.5 – 29.0], p = 0.049), but no differences were found with the use of morphine when epidural anesthesia was performed (36.8 % [IC95% 15.2 – 58.5] vs 31.7 % [IC95% 22.6 – 40.8], p = 0.660). The incidence of nausea, vomiting and pruritus was not significantly different when adjusting for the modality of neuraxial anesthesia.
Finally, the administration of morphine was significantly associated with a better pain control at 6 and 12 h at rest: NRS 3.0 [IC95% 2.4 – 3.6] vs 2.3 [IC95% 2.1 – 2.5] (p = 0.013) and NRS 2.5 [IC95% 2.0 – 3.0] vs 2,0 [IC95% 1.7 – 2.2], (p = 0.043), respectively. Regarding pain at mobilization, we found no difference at 6 nor at 12 h: NRS 3.5 [IC95% 2.6 – 4.4] vs 3.3 [IC95% 3.0 – 3.5], (p = 0.540) and NRS 3.8 [IC95% 3.2 – 4.3] vs 3.4 [IC95% 3.1 – 3.7], (p = 0.308), respectively. When assessing pain control according the type of neuraxial anesthesia, spinal anesthesia showed better control both at 6 h at rest and at movement (p < 0.001 and p = 0.031 respectively) (Figure 2).