Lovich Mark A, Peterfreund Gregory L, Sims Nathaniel M, Peterfreund Robert A
Department of Anesthesia and Pain Medicine, Caritas St. Elizabeth's Medical Center, Brighton, MA, USA.
Crit Care Med. 2007 Dec;35(12):2792-8. doi: 10.1097/01.ccm.0000295587.04882.4f.
Central venous catheters (CVCs) are conduits for drug infusions. Dead volumes of different CVC lumens vary considerably. This study quantitatively evaluated drug delivery dynamics of CVCs in a laboratory model of continuous drug infusion.
CVCs studied included a triple-lumen catheter (16-gauge and 18-gauge lumens), the proximal infusion port of a pulmonary artery catheter, and a 9-Fr introducer sheath, with and without a pulmonary artery catheter in the lumen. One syringe pump infused a carrier. A second pump infused the model drug methylene blue (3 mL/hr), joining the carrier immediately upstream of the CVC. Samples were collected every minute for quantitative analysis.
Laboratory model.
None.
At low fixed flow rates, experiments characterized drug delivery kinetics of different CVCs. Data collection then assessed effects of increased carrier flow.
The time to steady-state delivery after initiation of methylene blue infusion differed between CVCs. At a carrier flow of 10 mL/hr, the fastest achievement of steady-state delivery was with the 18-gauge lumen of a triple-lumen catheter. The 9-Fr introducer had the slowest time to achieve steady-state delivery. Other CVCs had intermediate kinetics. Reducing drug delivery from steady state to zero after cessation of methylene blue infusion was fastest with the 18-gauge lumen and slowest with the 9-Fr introducer. Increasing carrier flow rates from 10 to 60 mL/hr hastened the time to target for initiation and cessation of methylene blue delivery.
Experiments demonstrate large differences between CVCs in the dynamics for delivery of model drug methylene blue. Achieving targeted steady-state delivery, and termination of a planned continuous drug infusion, may be far slower than typically appreciated. Delivery kinetics depend on the dead volume and the rate of carrier flow. Safe and effective management of continuous drug infusions depends on understanding the dynamics of the delivery system.
中心静脉导管（CVC）是药物输注的管道。不同CVC管腔的死腔量差异很大。本研究在持续药物输注的实验室模型中对CVC的药物输送动力学进行了定量评估。
所研究的CVC包括三腔导管（16号和18号管腔）、肺动脉导管的近端输注端口以及9F引导鞘管，管腔内有无肺动脉导管。一个注射泵输注载体。另一个泵输注模型药物亚甲蓝（3 mL/小时），在CVC上游紧邻载体处注入。每分钟采集样本进行定量分析。
实验室模型。
无。
在低固定流速下，实验对不同CVC的药物输送动力学进行了表征。然后收集数据评估载体流速增加的影响。
亚甲蓝输注开始后达到稳态输送的时间在不同CVC之间有所不同。在载体流速为10 mL/小时时，三腔导管18号管腔达到稳态输送最快。9F引导鞘管达到稳态输送的时间最慢。其他CVC的动力学处于中间水平。亚甲蓝输注停止后，将药物输送从稳态降至零，18号管腔最快，9F引导鞘管最慢。将载体流速从10 mL/小时增加到60 mL/小时加快了亚甲蓝输送开始和停止达到目标的时间。
实验表明不同CVC在模型药物亚甲蓝输送动力学方面存在很大差异。实现目标稳态输送以及终止计划好的持续药物输注可能比通常认为的要慢得多。输送动力学取决于死腔量和载体流速。持续药物输注的安全有效管理取决于对输送系统动力学的理解。
