Intrathecal Bupivacaine and Effect on Blood Pressure Over Time in Intrathecal Drug Delivery Systems: a Retrospective Review
Matthew McEwan, DO; Salim Hayek, MD, PhD; Elias Veizi, MD; Ryan Galica, MD; Omar Ali, MD;
Sivakanth Katta, MD
Bupivacaine is a common adjuvant medication used in addition to opioids in intrathecal drug delivery systems (IDDSs). While the short-term effects of larger dose intrathecal bupivacaine on blood pressure have been studied, there is a dearth of data regarding long-term effects of continuous intrathecal bupivacaine infusion in IDDSs.
Materials & Methods:
Following IRB approval, a review of all patients with bupivacaine infusing through IDDSs in patients with non-cancer pain from January 2013 to January 2017 is performed. Patient demographics, hypertension status, antihypertensive medications, and catheter tip level are documented. Bupivacaine doses are documented at implantation, three months after implant, six months after implant, and one year after implant. Blood pressure values before implantation, one week after implant, three months after implant, six months after implant, and one year after implant are recorded as available. The effect of intrathecal bupivacaine on mean arterial blood pressure, systolic blood pressure, and diastolic blood pressure is reported at these time intervals in IDDSs.
Eighty-seven patients were identified who met criteria for inclusion in the study. This group consisted of 49 female patients (56.32%) and 38 male patients (43.68%). 77 of the patients were classified as Caucasian (88.51%). 9 patients identified as African-American (10.34%). Median patient age was 65 years. The median baseline mean arterial blood pressure was 97.67 mmHg. The median baseline mean arterial blood pressure (MAP) was 97.33 mmHg. The median baseline systolic blood pressure (SBP) was 134.5 mmHg. The median baseline diastolic blood pressure (DBP) was 78 mmHg. Catheter tip levels were between T7 and T12. The mean starting bupivacaine dose was 6.88 mg, and the mean dose at one year was 9.43 mg. There was a significant decrease in SBP from the baseline overall in all patients at 1 week, six months, and one year post-implant. There were no significant decreases in DBP at any point. No correlation between mean arterial pressure, systolic blood pressure, or disastolic blood pressure as compared to bupivacaine dose was detected at any point.
From the data that was gathered, it can be inferred that long-term bupivacaine administration in IDDSs likely exerts a lowering effect on systolic blood pressure. While there were significant decreases in systolic pressure in this group of chronic non-cancer pain patients, diastolic pressures and mean arterial pressures were largely unaffected. This effect is likely due to efferent sympathetic blockade by bupivacaine. Larger, randomized, double-blinded studies examining specifically the effect of bupivacaine on blood pressure at various points in the thoracic spine and using varied delivery paradigms would likely provide valuable input on the potential role of targeted intrathecal sympatholysis using bupivacaine and its effects on blood pressure control.