Abstract
BackgroundIntrathecal morphine is commonly used for post caesarean analgesia. However, their use is frequently associated with the incidence of troublesome side effects such as nausea, vomiting and pruritus. Various mechanisms have been postulated for the opioid-induced pruritus, with a variety of medications with different mechanisms of actions formulated for the prevention and treatment. But, the results are inconsistent and hence the prevention and treatment of opioid-induced pruritus still remains a challenge. Ondansetron which is antiemetic, non-sedative and has no antianalgesic effect is an antagonist to 5-HT3 receptor, the receptor with which opioids interacts and imparts its effects. Ondansetron, thus, would be an attractive treatment strategy for both opioid-induced pruritus and post-operative nausea and vomiting.MethodsAfter the approval from institutional review committee and written consent received from the patient, 50 healthy parturients of ASA I and II physical status undergoing caesarean section under spinal anaesthesia were enrolled for the study. They were randomly categorized into placebo group (2 ml normal saline) and treatment group (2 ml of 4 mg ondansetron), each group containing 25 patients. Pruritus and post-operative nausea and vomiting scores were recorded up to 24 hours after the administration of intrathecal morphine. Statistical analysis was performed using chi-square test.ResultsThe incidence, severity and necessity of treatment for pruritus in the treatment group was significantly reduced compared to the placebo group (16% vs 88%). Similarly, the risk of post-operative nausea and vomiting in the treatment group was less compared to the placebo group (8% vs 56%).ConclusionProphylactic administration of ondansetron to parturients receiving intrathecal morphine for post-operative analgesia provides a significant reduction of intrathecal morphine-induced pruritus and nausea and vomiting.Trial registrationCTRI/2015/01/005362 registered on 07/01/2015 in Clinical Trials Registry – India (ctri.nic.in).
Highlights
Intrathecal morphine is commonly used for post caesarean analgesia
Neuraxial administration of morphine - an opioid, which is considered as a gold standard for analgesia, has been associated with a frequent incidence of pruritus and post-operative nausea and vomiting (PONV) [1,2,3]
The exact mechanism of neuraxial opioid-induced pruritus is unclear, the postulated mechanisms include the presence of an “itch centre” in the central nervous system (CNS), medullary dorsal horn activation, antagonism of inhibitory transmitters, modulation of 5-hydroxytryptamine subtype 3 (5-HT3) or serotonergic pathways and the involvement of prostaglandins [3,8]
Summary
Intrathecal morphine is commonly used for post caesarean analgesia Their use is frequently associated with the incidence of troublesome side effects such as nausea, vomiting and pruritus. Neuraxial administration of morphine - an opioid, which is considered as a gold standard for analgesia, has been associated with a frequent incidence of pruritus and post-operative nausea and vomiting (PONV) [1,2,3]. There is dense concentration of opioid receptors and 5-HT3 receptors in the dorsal part of the spinal cord and the nucleus of the spinal tract of the trigeminal nerve in the medulla [8] Activation of these receptors by neuraxial opioid administration or by circulating oestrogen in the parturients results in neuraxial opioid-induced pruritus which is usually localized to the face, neck, or upper thorax [7]. We undertook a prospective, randomized, double-blinded and placebo controlled study to assess the effectiveness of prophylactic intravenous (IV) administration of ondansetron in the prevention of intrathecal morphine-induced pruritus and PONV
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