In vivo quantitative assessment of catheter patency in rats

Abstract

Formation of fibrin sleeves around catheter tips is a central factor in catheter failure during chronic implantation, and such tissue growth can occur despite administration of anticoagulants. We developed a novel method for monitoring catheter patency. This method recognizes the progressive nature of catheter occlusion, and tracks this process over time through measurement of changes in catheter resistance to a standardized 1 mL bolus infusion from a pressurized reservoir. Two indirect measures of catheter patency were used: (a) reservoir residual pressure and (b) reservoir discharge time. This method was applied to the study of catheter patency in rats comparing the effect of catheter material (silastic, polyurethane, Microrenathanetrade mark), lock solution (heparin, heparin/dexamethasone) and two different cannulation sites (superior vena cava via the external jugular vein, inferior vena cava via the femoral vein). Our findings reveal that application of flexible smaller-size silastic catheters and a dexamethasone lock solution resulted in prolonged catheter patency. Patency could be maintained over nine weeks with the femoral vein catheters, compared with five weeks with the external jugular vein catheters. The current method for measuring catheter patency provides a useful index for the assessment of tissue growth around the catheter tip. The method also provides an objective and quantitative way of comparing changes in catheter patency for different surgical methods and catheter types. Our method improves on the conventional method of assessing catheter occlusion by judging the ability to aspirate from the catheter.

Menadione (Vitamin K3) Is a Catabolic Product of Oral Phylloquinone (Vitamin K1) in the Intestine and a Circulating Precursor of Tissue Menaquinone-4 (Vitamin K2) in Rats

“…Unlike PK and MK-4, accurate measurement of MD in biological fluids by physicochemical means is difficult because of its high volatility. Thus, we developed a novel method for the measurement of MD (putative MD-d 7 ) using rhUBIAD1 as a source of converting enzyme and deuterium-labeled geranylgeranyl pyrophosphate (GGPP-d 5 ) as a source of the side chain in the final product (putative MK-4-d 12 ). In this method, MD-d 7 in the lymph and serum was converted to MK-4-d 12 , which was quantitatively detected by atmospheric pressure chemical ionization-liquid chromatography-tandem mass spectrometry (APCI-LC-MS/MS).…”

“…(9). PK-d 7 , MK-4-d 7 , MK-4-d 12 , their respective epoxides, and GGPP-d 5 were also synthesized in our laboratory as reported previously (10,11). The synthesis and unambiguous physicochemical assignments of these deuteriumlabeled vitamin K compounds have been described elsewhere (10,11).…”

A novel system allowing long-term simultaneous video-electroencephalography recording, drug infusion and blood sampling in rats

“…A study carried out in rats by (Yang et al, 2005) assessed catheter patency for up to 63 days using two routes of infusion: jugular vein and femoral vein in combination with two different infusion fluids, heparinised saline or heparinised saline containing dexamethasone and several types of catheter tubing. The authors found that the combination of heparinised saline containing dexamethasone, infused via the femoral vein and the use of silastic tubing resulted in a useful infusion over 9 weeks (Yang et al, 2005). It is conceivable that their methods could have been combined with our vEEG/infusion system to further enhance the success of chronic infusions.…”

Antisense inhibition of secretory and cytosolic phospholipase A2 reduces the mortality in rats with sepsis*

“…All animal experiments in this study were performed with the approval of the Animal Care and Use Committee of Saint Louis University School of Medicine, and in accordance with the National Institutes of Health Guidelines for ethical animal treatment. Three days prior to the induction of sepsis, a femoral vein catheter was inserted into the animal (25) to serve as an access port for intravenous injection of ODNs and saline. Sepsis was induced by cecal ligation and puncture (CLP) as described by Wichterman et al (26) except that buprenorphine HCl, 0.5 mL/kg subcutaneous, was administered for added postoperative pain control three times at 12-hr intervals.…”