Dexmedetomidine versus fentanyl as adjunct to ropivacaine-dexamethasone for labor analgesia: a randomized control study

Abstract

Background and aims Although intrathecal analgesia is an effective option during labor, there is a need to establish sustainable and assured analgesia during the entire labor process. We aimed to compare the effect of dexmedetomidine versus fentanyl as an adjuvant to low-dose ropivacaine-dexamethasone for intrathecal labor analgesia in primigravida women.Patients and methods The study was conducted after approval of ethical committee of Al Azhar University Hospital. A total of 60 primiparous women classified in American Society of Anesthesiologists classes II with a singleton pregnancy in active labor were given combined spinal epidural analgesia. This was a double-blind randomized controlled trial that allocated them in two groups of 30 patients each. Group I received intrathecal 2.5 mg of 0.1% ropivacaine (diluted to 2.5 ml with normal saline)+5 μg dexmedetomidine+4 mg dexamethasone. Occurrence of any adverse reaction was observed for ten min. Group II received 25 μg of fentanyl instead of 5 μg dexmedetomidine. For both groups, epidural top-ups of 10 ml of 1% ropivacaine were given when parturients complained of two painful contractions (visual analog scale ≥4), after epidural test dose of 3 ml of 0.5% ropivacaine was slowly injected via epidural catheter and no occurrence of adverse reaction was observed 10 min later. Data collected were demographic profile of the patients, intrathecal block characteristics, needs for epidural activation before delivery, and maternal and fetal adverse effects. The primary study goal was to prove the analgesic efficacy and safety of intrathecal selective sensory block on both mother and fetus, whereas the study secondary goal was to prove that intrathecal single dose injection could be used as an effective alternative option in labor analgesia as well as epidural analgesia. Catecholamine level (epinephrine and norepinephrine) was measured using enzyme-linked immunosorbent assay technique.Results The mean age (years), weight (kg), height (cm), and BMI (kg/m2) in group I were 24.3±3.30, 65.4±16.2, 161.3±4.6, and 22.3±3.4, respectively, whereas in group II were 25.23±4.44, 66.3±15.6, 160.4±4.3, and 22.2±3.1, respectively, with insignificant difference (P>0.05). Mean visual analog scale score before onset of analgesia in group I and group II was 8.59±1.22 and 8.7±1.14, respectively. The time to full cervical dilatation was 120.14±10.2 in group I and 120.0±10.6 in group II, and the mean duration of second stage of labor was 12.02±1.37 min in group I and 11.83±0.93 min in group II. The mean duration of analgesia was statistically significant (lower) in group II (221.83±22.26) as compared with group I (296.33±44.83) (P<0.001). The mean analgesia in group I (12.3±1.8) and group II (12.1±1.7) was statistically insignificant (P>0.05). The mean highest sensory levels in group I and group II were statistically insignificant, that is, T5 (T4–T8) versus T6 (T4–T7) (P>0.05). The sensory region time in group II was greater (241.83±22.26 min) as compared with group I (329.83±44.10), with P value less than 0.001. Neither maternal nor fetal adverse events were statistically significant different between both groups (P>0.05). The mean basal norepinephrine level in pg/ml in group I was 130.30±27.6 and in group II was 103.50±20.6, with P value more than 0.05. At 2 h, norepinephrine level in pg/ml was 119.90±24.1 in group I and 90.50±13.6 in group II, with P value more than 0.05. At baseline, the epinephrine level in pg/ml in group I and group II was 59.20±11.3 and 53.20±10.3, respectively, whereas at 2 h, the epinephrine level in pg/ml was 57.90±9.1 in group I and 49.20±8.6 in group II, with P value more than 0.05.Conclusion Ropivacaine-dexamethasone combined with dexmedetomidine for intrathecal block achieved a potent selective sensory block with prolonged duration of analgesia, delayed S1 regression time, and limited maternal and fetal adverse effects than intrathecal ropivacaine-dexamethasone combined with fentanyl. However, dexmedetomidine or fentanyl provides a safe and efficacious adjuvant to intrathecal ropivacaine-dexamethasone in primigravida women with rapid onset, profound analgesia, and hemodynamic stability throughout the labor.