Analgesia Effects of Nalbuphine vs Sulfentanil in Patient-controlled Intravenous Analgesia After Cesarean Section

Cesarean section may result in great trauma and postoperative pain. Besides incision pain, uterine contraction pain is another source of postoperative pain after cesarean section. In clinical practice, a large amount of uterine contraction agent is routinely applied after cesarean section so as to promote involution of uterus and reduce postoperative hemorrhage, which also causes great uterine contraction pain. Acute pain is the risk factor of chronic pain, and may postpone the recovery from labour and influence the quality of life of parturient. Though various analgesia modules have been attempted, more than 20% parturients still experience severe postoperative pain, and pain management after cesarean section remains a challenge to anesthesiologists.

Opiate drugs constitute the baseline medication for postoperative analgesia. However, pure μ opioid receptor agonist like morphine and fentanyl may induce adverse effects such as nausea, vomiting, dizziness, drowsiness and respiratory depression. Nalbuphine hydrochloride is an opiate-like substance structure-related oxymorphone, which is a κ receptor agonist/μ receptor partial antagonistic type analgesia drug. Specific κ receptor agonist and gene knockout experiment reveals that κ receptor agonist depresses the visceral pain induced by chemical stimulation, the effect of which outperforms pure μ opioid receptor agonist. Studies have discovered that some κ receptor agonists can reduce or inhibit the side effects of μ receptor agonist such as tolerance or dependence. The adverse effects of μ receptor agonist such as pruritus, nausea, vomiting, delayed gastric emptying are caused by the drug on peripheral opioid receptor, and can be relieved by opioid receptor agonist. The structure of nalbuphine hydrochloride is related to naloxone, an opioid receptor antagonist, therefore, the incidence of adverse effects of nalbuphine hydrochloride is lower than that of μ receptor agonist. In recent years, nalbuphine hydrochloride has become more and more popular in postoperative analgesia. There has been reports on intrathecal administration of nalbuphine hydrochloride for analgesia after cesarean section, while the effect of intravenous administration of nalbuphine hydrochloride on analgesia after cesarean section remains undetermined. This study aim to compare the effects of nalbuphine hydrochloride vs sufentanil citrate on patient-controlled intravenous analgesia after cesarean section.