Patient Controlled Intrathecal Analgesia With Bupivacaine for Chronic Low Back Pain

Methodology /Technical Approach: Seventeen patients who are already using SynchroMed II pump containing an admixture of bupivacaine and an opioid and using PTM doses will receive Solution A during the first week of the study and will be crossed over to Solution B during the second week of the study. Solution A and Solution B would consist of either the patient's usual intrathecal opioid with bupivacaine at the same concentrations or the usual patient's intrathecal opioid at the same concentration but without bupivacaine. Only the Investigational Pharmacy at University Hospitals Case Medical Center (UHCMC) would be aware of the contents of Solution A and Solution B. Patients and study personnel in the Pain Medicine Division would be blinded to the solution content. The sequence of pump refills will be as follows: * Week I: Patients will have the intrathecal pumps refilled with 10 milliliters of a Solution A or B, after removal of residual volume of baseline solution. * Week II: IT pump will be filled with 10 ml of Solution A or B (whichever solution subject did not receive Week 1), after removal of residual volume from Week I. Both patients and the evaluating physician will be blinded. In order to accomplish this, only the central compounding (investigational) pharmacy at UHCMC would make two solutions labeled: A or B respectively. Study subjects will be randomized and randomization order will be held at the pharmacy that will supply the medication. Patients will be kept on each solution for one week. Data will be collected daily Primary outcome measures will include 0-10 numerical rating scale (NRS) or Visual Analogue Scale (VAS) both immediately before and within 30 minutes after a PTM bolus. Patients will be provided with a diary to record pain scores just before a PTM bolus and the lowest pain score within half an hour after a PTM bolus. Only 5 recording per day on days 3-7 and 10-14 will be available on the diary-thus patients would record pain scores only before and after the first 5 PTM boluses. Only the scores before and after the first 3 successful PTM boluses would be considered. Successful PTM activations would be determined by review of the patient PTM diary and the internal log from the intrathecal drug delivery system. Each recording on the PTM diary would be time matched to the successful PTM activation code in the internal log. This will obviate any potential mis-administered bolus whereby the patient does not activate the bolus device appropriately. Secondary outcome measures will include average NRS pain scores for the week, functional capacity as evaluated by the Oswestry disability index (ODI) scores, Global Impression of Change and painDETECT. Other relevant data such as number of boluses used and paresthetic sensation post bolus (if felt)/patient guess of blinding arm would be recorded.