A new mechanical device for subcutaneous infusion

Continuous subcutaneous infusion of opiates is an important alternative to other routes for management of cancer pain. For patients unable to take oral medication, administration via continuous subcutaneous infusion is less traumatic than other methods, such as IV, IM and PR and avoids the peaks and troughs associated with bolus doses. Several studies of patients receiving continuous subcutaneous infusion have reported decreased side-effects and increased pain control (1,2,3). This method of administration decreases nursing time required for drug administration and is suitable both in the hospital and home environment. Infusion devices chosen should be accurate, economical, and practical both for patients and nursing staff.

The Daw Park Hospice offers patients with chronic cancer pain continuous subcutaneous infusion. The infusion pump currently in use is the Graseby pump MS26. The Graseby MS26 is powered by a battery with a screw driving the syringe plunger at an adjustable and predetermined rate in mm/h. Using lOmL, 20mL or 30mL syringes the pump allows a range of volumes up to 22mL. The pump is calibrated with speed settings of 0-99 mm/h and accuracy of ±5%. To set the Graseby MS26, the syringe is filled with the required volume and then inserted in the syringe trough of the syringe driver. If required, bolus doses of drug can be delivered by pressing the boost button. The approximate cost of the Graseby MS26 is $1400.(4)

The purpose of the current study is to trial a new pump, the Paragon Drug Delivery System® (Figure 1) manufactured by I-Flow Corporation. The major advantage of the Paragon is the large volumes it can accommodate and a greater infusion time, allowing a continuous infusion for up to 8 days, 18 hours, and a maximum fill volume of llOmL.

The Paragon system is a mechanical device designed for continuous drug delivery at a constant rate. It consists of a mechanical infuser and an administration set and operates by a multi-spring mechanism.. The infuser is a container made from acetyl and polycarbonate plastics that houses four springs and a floating pressure plate. The administration set is a single piece of equipment, comprising a PVC medication bag, flow control tubing and twoway valved filling port. When loaded, the springs within the infuser drive the pressure plate, which squeezes the medication bag and forces medication through the flow control tubing. The flow rate is determined by a glass orifice at the end of the flow control tubing.