Infusion devices

Infusion devices have been used for diabetes, cancer chemotherapy, pain control (patient-controUed analgesia, ie, PGA), infection, Alzheimer s disease, Parkinson s, nausea, thalassemia, thromboembolism, and to treat severe spasms resulting from spiaal cord iajury (140—143). 

Electronic infusion devices are classided as either infusion controllers or infusion pumps. The primary difference between die two is diat an infusion pump adds pressure to die infusion, whereas an infusion controller does not. An infusion pump may be used to deliver the desired number of drops per minute. An alarm is set to sound if the IV is more than or less dian the preset rate... 

When oxytocin is prescribed, the primary health care provider orders the type and amount of IV fluid, the number of units of oxytocin added to the IV solution, and the IV infusion rate An electronic infusion device is used to control the infusion rate. The primary health care provider establishes guidelines for the administration of the oxytocin solution and for increasing or decreasing the flow rate or discontinuing the administration of oxytocin based on standards established by the Association of Women s Health, Obstetric, and Neonatal Nurses (AWHONN). Usually, the flow rate is increased every 20 to 30 minutes, but this may vary according to the patient s response. The strength, frequency, and duration of contractions and the FHR are monitored closely. 

Insulin pump therapy consists of a programmable infusion device that allows for basal infusion of insulin 24 hours daily, as well as bolus administration following meals. As seen in Fig. 40-3, an insulin pump consists of a programmable infusion device with an insulin reservoir. This pump is attached to an infusion set with a small needle that is inserted in subcutaneous tissue in the patient s abdomen, thigh, or arm. Most patients prefer insertion in abdominal tissue because this site provides optimal insulin absorption. Patients should avoid insertion sites along belt lines or in other areas where clothing may cause undue irritation. Infusion sets should be changed every 2 to 3 days to reduce the possibility of infection. 

Aggregation of proteins is a microscopic process of protein molecule association. The aggregates may be dimers or larger oligomers that remain in solution, yet may alfect the observed biological activity. Precipitation refers to the formation of visible proteinaceous particles, which may reduce potency in addition to altering the appearance of a formulation and its performance in various infusion devices. 

Insulin aggregation and precipitation was an impediment to the development of implantable devices for insulin delivery as noted by several investigators working with conventional insulin infusion devices [51-54]. The potential causes of the observed aggregation and precipitation are thermal effects, mechanical stress, the nature of the materials in contact with the insulin solution, formulation factors, and the purity of the insulin preparation. 

The closed-loop system (often termed the artificial pancreas ) is essentially a more sophisticated version of the system described above. It consists not only of a pump and infusion device, but also of an integral glucose sensor and computer that analyses the blood glucose data obtained and adjusts the flow rate accordingly. The true potential of such systems remains to be assessed. 

Heparin is an anticoagulant that prevents the formation of blood clots. Like insulin, it is also measured in units of activity. IV heparin may be administered by standard gravity flow or electronic infusion devices. The normal adult heparinizing dosage is 20,000-40,000 units per 24 hours. In general, IV heparin is ordered in units per hour. Heparin may also be ordered by the physician to infuse at a predetermined flow rate in mL per hour. 

Administer continuous infusions of remifentanil only by an infusion device. The injection site should be close to the venous cannula. Clear all IV tubing at the time of discontinuation of infusion. 

Fungal infection, empirical Administer 3 mg/kg/day of liposomal amphotericin B using a controlled infusion device over 120 minutes infusion time may be reduced to 60 minutes if well tolerated or increased if patient experiences discomfort. 

Controlled release can be achieved using infusion devices in hospital and chn-ical settings. Advances in miniaturization of these devices is beginning to provide portability. Ftowever, these devices are not ideal for most applications due to their cost and complex training requirements. 

Controlled-rate infusion devices, as well as feedback-regulated drug delivery devices, have the potential to improve drug safety and efficacy. With advancement in computer technology and miniaturization of precision motors, highly compact computer-controlled infusion pumps are now available for insulin delivery. These pumps, weighing about 3 to 4 ounces, can be... 

Figure 13.13. Schematic representation of a physically driven based portable infusion device.

CONTINUOUS SUBCUTANEOUS INSULIN INFUSION DEVICES (CSII, INSULIN PUMPS)... 

Blanco and Samadani37 obtained a patent for the construction of a microprosessor-based insulin pump that works in a similar fashion to the Biostator. The implantable infusion device consists of a catheter, an information-transmitting sensor located in the catheter, a microprocessor, a pump, the drug reservoir, and a power source. The pump, the sensor, and the valves are connected by appropriate leads to the microprocessor. The device is implanted in the subcutaneous tissue in the chest area, and the infusion catheter is tethered intravenously to a central location, such as the right atrium. The device is inserted with the inlet port facing outward so that it may be refilled periodically by a physician. 

Continuous Subcutaneous Insulin Infusion Devices (Csii, Insulin Pumps)... 

K. Davis, A. McDaniel, and D. Scott, Stability of heroin hydrochloride in infusion devices and containers for IV administration, Am. J. Hosp. Pharm., 47 211 (1990). 

Aldesleukin adsorbs to infusion devices and is incompatible with a loss of its potency when mixed with ganciclovir sodium, lorazepam, pentamidine isethion-ate, prochlorperazine edisylate, and promethazine hydrochloride. Suitable analytical methods should be selected for testing.223... 

Fabrication of the Infusion Device. The external rigid casing of the compression device was made from 2.5 mm thick plastic sheets, preferably optically clear. The leak-proof inflatable sacs were made by heat sealing of heavy-duty polyethylene sheets which also had good optical clarity and at the same time were resistant to swelling when in contact with an aerosol propellant. 

Infusion Device Flow Rate. The example given in Table II shows that the flow rate with 4 aligned nylon fibre flow moderators in series is essentially constant up to 200 mL of... 

In Vivo Test of the Infusion Device. Before the infusion device was used to deliver micro-volume of a heparin solution, the amount of the anticoagulant required to delay the normal clotting time from 1.02 min to > 15 min was determined. An intraperitoneal silicone catheter was inserted by way of a trocar needle into an anesthetized Wistar rat, and the external catheter end was connected to the flow rate testing assembly. With a glass hollow fibre flow moderator having a flow rate of 50 plitre/hr at 48 kPa driving pressure, it was found to require about 25 IU/kg/hr to obtain a Lee-White... 

Their pumping mechanism is the roller peristaltic action which is also used for flow control. But the power consumption is high and the battery in some of these pumps needs to be replaced practically every day (6). The clinical infusion devices aforementioned are much too expensive for research purposes in laboratory animals, which are used because their inbreeding helps to avoid variations in pharmacological action due to genetic factors. Thus, there is a need to devise a simple and low cost infusion pump that can readily be modified in size or flow rate to accommodate different research requirements. 

The infusion device described in this report can be fabricated in a few hours with materials usually available in a laboratory. For high flow, the aligned nylon fibre flow moderator can be used. When microvolume delivery is required, the use of the hollow fibre flow moderator can be considered. As for the infusion enclosures, the transparent material was specially chosen to allow visualization of the internal contents of the drug solution bag, which is always inspected at regualr intervals during use for the presence of particulate suspension or air bubbles that may develop and be harmful. 

The steady flow rate observed in the heparin infusion study with the corresponding delay in clotting time indicates that the infusion device can provide dependable controlled release. Since the service life, size and flow rate of the device may be varied depending on the requirements of an experiment, these features should make it readily adaptable to the infusion of many other drugs. 

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