Catheter failure

Thermoplastic elastomers (TPEs) are a relatively new class of polymer which offer a wide range of stiffness because their microstructure ean be controlled during polymerization. They are often block copolymers, made by reacting 

4 Microstructure of amorphous styrene-butadiene block copolymer. 

5 Microstructure of block copolyester with crystalline domains. 

However, a problem occurred in 1990 when a Mrs K was giving birth to her first child. Following safe delivery of the baby boy, when the needle was withdrawn the catheter tip was foimd to be absent. Inspection of the remaining catheter showed that the tip had broken away across the proximal (or nearest) infusion hole and remained in the patient s spinal fluid. Any operation to extract the small piece of plastic was out of the question, because surgical 

6 Tip of thermoplastic nylon catheter showing bleed holes and plastic deformation above distal bleed hole. 

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Thrombosis associated with hemodialysis most commonly occurs in patients with venous catheter access for dialysis and is a common cause of catheter failure. However, thrombosis can occur in synthetic grafts and less frequently in AV fistulas. 

In another catheter failure study, two samples of multi-layer catheters were tested. One catheter was breaking while the other was known to be a "good" sample. The catheters were freeze-fractured in order to obtain a cross-section view for SEM analysis, which was used to determine the construction of the catheter layers. ATR-FTIR spectroscopy was undertaken to identify the polymers used in the multi-layer catheter samples. 

Reeves RK, Stolp-Smith KA, Christopherson MW. Hyperthermia, rhabdomyolysis, and disseminated intravascular coagulation associated with baclofen pump catheter failure. Arch Phys Med Rehabil 1998 79(3) 353-6. 

With double-lumen intravenous catheters for acute hemodialysis, hemperfusion, and plasma exchange, the most common complications are bleeding, hematomas, catheter failure, risk of infection, central vein thrombosis and stenoses, and rarely, air embohsm. Femoral placement is the site associated with the fewest non-in-fectious comphcations [16]. Comphcations of treatment will be discussed below. 

Upon stabilization, placement of a pulmonary artery (PA) catheter may be indicated based on the need for more extensive cardiovascular monitoring than is available from non-invasive measurements such as vital signs, cardiac rhythm, and urine output.9,10 Key measured parameters that can be obtained from a PA catheter are the pulmonary artery occlusion pressure, which is a measure of preload, and CO. From these values and simultaneous measurement of HR and blood pressure (BP), one can calculate the left ventricular SV and SVR.10 Placement of a PA catheter should be reserved for patients at high risk of death due to the severity of shock or preexisting medical conditions such as heart failure.11 Use of PA catheters in broad populations of critically ill patients is somewhat controversial because clinical trials have not shown consistent benefits with their use.12-14 However, critically ill patients with a high severity of illness may have improved outcomes from PA catheter placement. It is not clear why this was... 

Parenteral nutrition can be a lifesaving therapy in patients with intestinal failure, but the oral or enteral route is preferred when providing nutrition support ( when the gut works, use it ). Compared with PN, enteral nutrition generally is associated with fewer infectious complications (e.g., pneumonia, intraabdominal abscess, and catheter-related infections) and potentially improved outcomes.1-3 However, if used in appropriate patients (i.e., patients with questionable intestinal function or when the intestine cannot be used), PN can be used safely and effectively and may improve nutrient delivery.4 Indications for PN are listed in Table 97-1.1... 

Myocardial ischemia and infarction cause abnorma myocardial metabolism, decreased left ventricular (LV) systolic function, diastolic dysfunction, congestive heart failure, and decreased survival. Consequently, revascularization techniques, either surgical or catheter based, have become integral to treatment of severe ischemic heart disease. 

Smits PC, van Geuns RJ, Poldermans D, Bountioukos M, Onderwater EE, Lee CH, Maat AP, Serruys PW. Catheter-based intramyocardial injection of autologous skeletal myoblasts as a primary treatment of ischemic heart failure chnical experience with six-month follow-up. J Am Coll Cardiol 2003 42 2063-2069. 

Intravenous epoprostenol increases exercise tolerance, improves pulmonary hemodynamics, and improves survival in patients with primary pulmonary hypertension. However, there are limitations to intravenous administration, and a significant proportion of patients develop catheter-related problems, such as thrombosis, pump failure, and catheter-related sepsis. In an attempt to improve delivery, several trials of aerosolized prostacyclin have been undertaken, primarily in patients with primary pulmonary hypertension. 

Urine samples were taken from a urinary catheter from living-related and cadaveric renal transplant donors at the time of procurement surgery. TAC was found to be significantly lower in urine from poor cadaveric donors when compared with either good cadaveric or living donors. Therefore, TAC of urine may be a good marker of preoperative oxidant stress in the kidney and may have a predictive value with respect to the clinical outcome of transplantation (S17). Patients with acute renal failure showed higher urine TAC (K5). 

In parallel to catheter-based delivery, stent-based approaches, such as passive stent coatings (diamond-like carbon, phosphorylcholine, and silicon carbide coatings) and immobilized drug coatings (heparin-coated stents), were evaluated for their ability to inhibit restenosis. Although animal studies demonstrated some promise, none of these technologies were clinically successful for restenosis prevention. The failure of these surface modification technologies further added to the need for the development of DES based on the principles of sustained CDD,... 

Gruberg L, Mehran R, Dangas G, et al. Acute renal failure requiring dialysis after percutaneous coronary interventions. Catheter Cardiovasc Interv 2001 52 409-416. 

Endpoints measured included death, ongoing or recurrent ischemia, major amputation, and major morbidity. The trial was halted early after first interim analysis. This was driven by the failure of catheter-directed lysis in patients with chronic native artery occlusions,... 

Side effects, such as headache and jaw pain, are observed, but the major drawbacks with epoprostenol therapy relate to its delivery. Epoprostenol has an extremely short half-life in the blood (2-3 min) and therefore must be administered by continuous intravenous infusion via a surgically implanted central vein catheter. This can lead to complications such as local infections, sepsis, or catheter-associated thrombosis. In addition, interruption of therapy due, for example, to pump failure can lead to a life-threatening rebound of symptoms. The compound itself is unstable at room temperature and must be stored in the refrigerator. Despite these severe drawbacks, i.v. epoprosenol remains a useful treatment for patients presenting with WHO class IV PAH. The problems with epoprostenol have led to the development of alternative agents. 

Metabolic acidosis involves a build-up of hydrogen ions in the blood, thus lowering blood pH. Under normal physiological conditions, the kidneys excrete excess hydrogen ions, and release more bicarbonate ions into the bloodstream to buffer the excess acid. However, in renal failure, or in diabetic ketoacidosis, this mechanism either fails, or is unable to compensate to an adequate extent. Hence, metabolic acidosis is usually treated with sodium bicarbonate, either intravenously (1.26% or 8.4% i.v. solution) or orally (typically 1 g three times a day). Sodium bicarbonate 1.26% intravenous solution is isotonic with plasma (and with sodium chloride 0.9%), so may be given in large volumes (1-2 L) by peripheral venous catheter to correct metabolic acidosis and provide fluid replacement at the same time. Sodium bicarbonate 8.4% may only be given by central venous catheter. 

Because of the ease of introducing intravenous and intra-arterial catheters and measuring blood flow and blood pressure, dogs are commonly used to conduct hemodynamic studies. These studies evaluate the effect of the test compound on systolic and diastolic blood pressure, heart rate, cardiac output, dp/dt, respiration, ECG, and ventricular pressure. From these data, effects desirable for treating angina pectoris, congestive heart failure, coronary vasospasm, and myocardial infarction can be detected. 

A 14-year-old child receiving continuous intrathecal baclofen treatment developed a fever of up to 40°C and painful muscle spasms, attributed to baclofen withdrawal due to failure of the intrathecal catheter. The symptoms resolved promptly after reintroduction of intrathecal baclofen (25). 

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