Controlled comparison of intrathecal cinchocaine with intrathecal cinchocaine and morphine. Clinical effects and plasma morphine concentrations.

Twenty patients scheduled for elective total hip replacement were given either intrathecal cinchocaine with morphine hydrochloride 2.5 mg or intrathecal cinchocaine alone before general anaesthesia. Arterial plasma morphine concentrations were measured and analgesic, respiratory and biochemical effects compared. Plasma morphine concentrations increased to 19.3 nmol litre-1 at 210 min. PaCO2 concentrations increased significantly only in those patients who received morphine as well as cinchocaine. Patients receiving cinchocaine alone, but not those given cinchocaine and morphine, had significant (P less than 0.01) increases in plasma cortisol concentrations' in the period after operation. Median time to next analgesic in patients receiving cinchocaine with intrathecal morphine was 22 h, significantly (P less than 0.01) longer than in patients receiving intrathecal cinchocaine alone (7.8 h).