Bacteriology, Drug Stability and Exchange of Percutaneous Delivery Systems and Antibacterial Filters in Long‐Term Intrathecal Infusion of Opioid Drugs and Bupivacaine in “Refractory” Pain

ObjectiveTo provide a basis for recommendations on the exchange of containers (syringes and cassettes) and antibacterial filters, and for choice of administration device in patients with “refractory” pain treated with long-term percutaneous intrathecal (IT) infusions of opioid (morphine or buprenorphine) and bupivacaine mixtures. DesignProspective, cohort, nonrandomized control trial-case series, with consecutive sample, no standard criterion, and cost-benefit analysis. SettingTertiary care center, institutional practice as well as hospitalized and ambulatory care. PatientsEighty-nine (51 women and 38 men); 81 with malignant pain and 8 with benign “refractory” pain. Interventions(a) The chemical stability of the drugs in the containers during 30 days, (b) The results of bacteriologic culture of the residual volumes of the analgesic mixtures from used and reused (1–16 times) syringes (n = 135) and cassettes (n = 258), and of 5 ml of sterile isotonic saline filtered through the used Millipore filters (n = 149). The bacteriologic samples from the 89 patients were taken after 1–40 (median = 7), 1–86 (median = 20), and 5–78 (median =31) days of IT treatment, respectively. Main Outcome MeasuresChemical stability: buprenorphine and bupivacaine concentrations-liquid chromatography; morphine concentrations-gas chromatography. Bacteriologic cultures: standard laboratory procedures. The hypothesis (repeated use of the infusion systems and their exchange once a month does not significantly affect drug concentrations or increase the infection risk) was elaborated before data collection began. ResultsThe bupivacaine-opioid mixtures were found to be chemically stable within 3–10% of the original doses up to 30 days. Seventeen cultures (from five syringes, six cassettes, and six filters) in 13 patients (having no signs of meningeal infection) were found to be colonized with Staphylococcus.