RESPIRATORY DEPRESSION FOLLOWING ADMINISTRATION OF INTRATHECAL BUPIVACAINE TO AN OPIOID-DEPENDENT PATIENT

OBJECTIVE: To document two cases of respiratory depression in patients receiving morphine once the stimulating effect of pain on respiration was removed by bupivacaine. CASE SUMMARIES: Case 1: A 72-year-old 84- kg white man with cancer of the bladder and bone metastases had intens e back and leg pain that was treated with intrathecal morphine for 6 m onths at an increasing dosage up to 10 mg twice daily. The intrathecal route was avoided for 4 days because of a suspected local infection a t the site of the intrathecal catheter. During this 4-day period the p atient received extended-release morphine and subcutaneous morphine da ily. When the intrathecal route was used again, he received an identic al dose of morphine plus bupivacaine and epinephrine. Ten minutes afte r the injection, fatal respiratory distress occurred. Case 2: A 92-yea r-old white woman was admitted for revascularization of arteritis on h er left leg. To treat a painful sacrum and heel bedsores, she received extended-release oral morphine for 8 days. Induction of the intrathec al anesthesia was performed with bupivacaine. After 10 minutes, the pa tient became subcomatose, with miosis and apnea. Intravenous naloxone restored spontaneous respiration and normal consciousness. CONCLUSIONS : Pain is a physiologic antagonist of the respiratory depressant effec ts of opioid analgesics. By reducing pain stimulation, bupivacaine may make patients more susceptible to opioid respiratory depression. Such situations require titration of bupivacaine and other analgesics as w ell as increased monitoring of the patient.