[0.5 mg intrathecal morphine in spinal anesthesia. A double blind study on sensory block, postoperative analgesia and...

In a randomized double-blind study the influence of morphine 0.5 mg on the development and regression of spinal anaesthesia, the postoperative analgesia and the side effects were investigated. Forty-two patients received an isobaric spinal anaesthesia with tetracaine 20 mg without morphine (n = 19) or with morphine 0.5 mg (n = 23). The sensory blockade was tested by pinprick; the patients evaluated their postoperative pain with an analogue scale. Arterial blood gases, respiratory rate, blood pressure and heart rate were measured and side effects determined. In the test group the cranial level of anaesthesia was during the development (p greater than 0.05) and regression (p less than 0.05) half to three segments higher than in the control group. The postoperative analgesia was more intense and longer lasting with morphine than without (p less than 0.05). Following morphine, P art CO2 was higher (p less than 0.05), the respiratory rate lower (p less than 0.05). Pruritus, nausea, vomiting and disturbances of micturition were more frequent. Following spinal anaesthesia with a deeper level of anaesthesia at T8-T11 the postoperative analgesia was superior than following spinal anaesthesia with a higher level of anaesthesia at T3-T4 (p less than 0.05). Only following higher levels of anaesthesia there was evidence of respiratory depression (p less than 0.05). This is why the level of spinal anaesthesia with the addition of morphine must not be higher than necessary for surgery.