Cerebrospinal Fluid and Spinal Cord Distribution of Hyperbaric Bupivacaine and Baclofen during Slow Intrathecal Infusion in Pigs

被引:67
作者
Flack, Sean H. [1 ]
Bernards, Christopher M. [1 ]
机构
[1] Univ Washington, Dept Anesthesiol, Virginia Mason Med Ctr, Seattle, WA 98101 USA
关键词
CLEARANCE IN-VIVO; PLASMA PHARMACOKINETICS; EPIDURAL OPIOIDS; MICRODIALYSIS; EPINEPHRINE; RELEASE; HUMANS; MODEL;
D O I
10.1097/ALN.0b013e3181c38da5
中图分类号
R614 [麻醉学];
学科分类号
100217 ;
摘要
Background: Despite the widespread use of implanted pumps for continuous intrathecal drug delivery, there have been no studies aimed at defining the effect of baricity and posture on drug distribution in the cerebrospinal fluid and spinal cord during the very slow infusion rates typically used for chronic intrathecal drug administration. Methods: Intrathecal microdialysis probes were placed at six points along the neuraxis in both the anterior and posterior intrathecal space of anesthetized pigs to permit cerebrospinal fluid sampling. Animals were then positioned either vertically or horizontally (prone), and a hyperbaric solution containing bupivacaine (7.5 mg/ml) and baclofen (2 mg/ml) was infused at 20 mu l/h for 6 h, while the cerebrospinal fluid was collected for measurement of drug concentration. At the end of the experiment, the animals were killed, and the spinal cord was removed and divided into 1-cm sections that were further divided into anterior and posterior portions for measurement of drug concentration. Results: Bupivacaine and baclofen distribution was biased caudally in the vertical group and cephalad in the horizontal group. Drug concentration decreased rapidly in the cerebrospinal fluid and spinal cord as a function of distance from the site of administration in both groups, resulting in most drugs being located in very close proximity to the site of infusion. Conclusion: Even at very slow infusion rates, drug distribution within the cerebral spinal fluid and spinal cord are affected by baricty/posture. These findings suggest that patient position and solution baricity may be important clinical factors determining the distribution and ultimate efficacy of chronic intrathecal drug infusions.
引用
收藏
页码:165 / 173
页数:9
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