Infusion pumps problems with

Mechanical complications of PN are related to catheter placement and the system and equipment used to administer PN. A central venous catheter must be placed by a trained professional, and risks associated with placement include pneumothorax, arterial puncture, bleeding, hematoma formation, venous thrombosis, and air embolism.1,20 Over time, the catheter may require replacement. Problems with the equipment include malfunctions of the infusion pump, intravenous tubing sets, and filters. 

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. 

Mechanical or technical comphcations include malfunctions in the system used for intravenous dehvery of the solution. Examples of such malfunctions include infusion pump failure, problems with administration sets or tubing, and problems with the catheter. Catheter-related comphcations are potentially life-threatening. 

Insulin fibril formation is particularly important with the advent of infusion pumps to deliver insulin. In these devices, insulin is exposed to elevated temperatures, the presence of hydrophobic surfaces, and shear forces, all factors that increase insulin s tendency to aggregate. These problems can be overcome if the insulin is prepared with phosphate buffer or other additives. Another physical stability problem associated with insulin is adsorption to tubing and other surfaces. This normally occurs if the insulin concentration is less than 5 lU/mL (0.03 mM), and it can be prevented by adding albumin to the dosage form if a dilute insulin solution must be used (34). 

IV-PCA systems are also prone to patient errors and system malfunctions. In some cases these issues occur at a frequency great enough to cause the US Food and Drug Administration (FDA) to take action by issuing a recall due to a design defect that caused some of the infusion pumps to disrupt analgesic therapy [ 11 ]. Furthermore, the complexity of the IV-PCA system may increase the risk of SREs, due to problems with the infusion pump, IV line, or other components of the system. 

The former small unit infusion pumps are pressured by human blood pressure using a blood pressure cuff. However, this mechanism leads to serious problems, such as sudden change of the flow rate because the infusion flow rate is only dependent on the patient s blood pressure. Thus, recently, small volume pumps have been usually operated by an automatically controlled motor or a small embedded system. In addition, for the portable infusion pump, other possible pump power sources have been developed, such as osmotic pressure and spring-powered systems. However, with osmotic power needs it is necessary to change a salt solution bag after finishing infusion and with spring power it is necessary to overcome the limitation of the flow rate for use in various conditions. 

Repeated episodes of catheter obstruction by fibrin clots or omental encapsulation can be a problem during continuous peritoneal insulin infusion from implanted pumps (SEDA 20, 397). In the encapsulated tissue, collagen fibrosis, inflammatory reactions with lymphocytes, and amyloid-like deposits reacting to anti-insulin antibodies can occur higher macrophage chemotaxis may also promote these processes. 

Continuous intraperitoneal insulin infusion with implantable pumps has been assessed in 34 patients with poorly controlled diabetes (231). In two patients, the pump was explanted in one patient with Werner s syndrome (no subcutaneous fat) the pump was explanted because of infection in the pocket, and one pump was explanted because the patient had local complaints and psychological problems. One patient refused to be included. Patients were followed for 58 months. HbAic fell from 10.0 to 9.0% in the first year and remained there. Median days in hospital fell from 45 to 13 after 1 year. The quality of life was relatively low and many had psychiatric problems. Although long-term glycemic control improved and lengths of hospital stay were reduced, normal glucose control and normal quality of life could not be achieved. 

Complications have been described after the insertion of 157 intrathecal catheters in 142 patients (15). In most cases problems were related to the placement procedure, with subsequent neurological complications. Clinically unsuspected degeneration of the posterior columns, perhaps related to intraspinal infusion of morphine or to a paraneoplastic effect, has been observed postmortem in two patients with implanted pumps (16). 

No single infusion system is ideal for delivery of all drugs in all institutions for all patients. For example, a syringe pump with microbore tubing may be preferred for the infusion of vancomycin to neonates. Each facility must be cognizant of problems of drug delivery and develop specific guidelines for intravenous infusions. 

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