Morphine spinal administration

The spinal administration of morphine, with or without a local anesthetic, has been advocated for producing a sustained period of postoperative analgesia. However, adverse side effects from such analgesia include ventilatory depression, itching, and urinary retention. Morphine depresses all phases of respiration (respiratory rate, tidal volume, and minute volume) when given in subhypnotic and subanalgesic... 

For pediatric patients undergoing posterior spinal fusion and segmental spinal administration for idiopathic scoliosis, a dose of pre-operative intrathecal morphine ranging from 9 to 19 (xg/kg with a mean of 14 (Xg/kg provided effective analgesia with a low frequency of respiratory depression and intensive care unit admission [5]. Another report of pediatric spinal fusion patients showed no advantage of 15 pg/kg intrathecal morphine over a dose of 5 pg/kg [6]. 

After epidural injection, an opioid may transfer into the cerebrospinal fluid (CSF), into the blood or bind to epidural fat, the extent depending on their lipophilicity. After epidural administration, morphine passes slowly into the CSF. Sufentanil, which is highly lipid soluble, can be detected in the plasma within 2-5 minutes after epidural injection and part of the analgesic effect of the more lipid soluble opioids may be due to a supraspinal action amplifying the direct spinal action. Epidural fentanyl and sufentanil produce a more consistent and intense analgesia than morphine, with a faster onset. Flowever, the duration is short but this can be overcome by giving them by continuous epidural infusions. 

In addition to the development of tolerance, persistent administration of opioid analgesics has been observed to increase the sensation of pain leading to a state of hyperalgesia. This phenomenon has been observed with several opioid analgesics, including morphine, fentanyl, and remifentanil. Spinal dynorphin and activation of the bradykinin receptor have emerged as important candidates for the mediation of opioid-induced hyperalgesia. 

Honore, P., Chapman, V., Buritova, J., Besson, J.-M.. Concomitant administration of morphine and an N-methyl-D-aspartate receptor antagonist profoundly reduces inflammatory evoked spinal c-Fos expression, Anaesthesiology 1996, 85, 150-160. 

Miosis is a characteristic symptom of opiate administration, and while tolerance develops to many of the pharmacological effects of this class of drugs, tolerance to the miotic effects occurs at a much slower rate. Miosis is due to an excitatory action of the autonomic segment of the nucleus of the oculomotor nerve, an effect attributed to the stimulation of the mu receptors. In general, it would appear that the actions of morphine and its analogues on the brain, spinal cord and gastrointestinal tract are due to stimulation of the mu receptors. 

The fact that 6-opioid receptors act at spinal and supraspinal sites increases the possibility that, like morphine, 6-opioid agonists may exhibit a synergistic interaction between the spinal and supraspinal sites of action. It has been clearly established that the concurrent administration of ICV and ITH morphine results in a multiplicative antinociceptive interaction [130,131]. It is this supraspinal/spinal multiplicative nature of morphine and its clinical analgesic utility at tolerable doses. Early studies with mice indicated only... 

A 26-year-old woman with a history of multiple substance abuse required emergency caesarean section at 30 weeks of gestation as a result of crack cocaine-induced placental abruption and fetal distress (251). Her admission blood pressure was 145/95 mmHg, heart rate 95/minute and respiratory rate 20/minute. The fetal heart rate was 130/minute and non-reactive, with late and variable decelerations and no response to maternal oxygen administration. Spinal block with bupivacaine, fentanyl, and morphine was performed with the patient in a sitting position. No maternal or neonatal postoperative complications were reported. 

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