Drip as you trip

Patients hooked on to intravenous drug delivery systems have so far had to confine themselves to their beds. But a new portable infusion pump brings relief to them as they can now be mobile and continue with their routine tasks even as drugs get administered into their bodies

Published: Wednesday 31 January 1996

-- A PORTABLE infusion pump that allows patients to carry their 'drip' around, is certainly a boon for them. This electronic pump developed by the UK medical equipment company, Smith and Nephew Industry, will enable patients to undergo treatment in the comfort of their homes while they go about their normal activities. Approximately, the size of a personal stereo, the pump is attached to the patient at all times. This ensures a continuous supply of the medication to the patient.

Intravenous or IV drug delivery enables a direct flow of drugs and other fluids into the patient's blood stream. In addition, it releases a reduced dose of the drug, which in turn lowers the side effects produced. The iv drug delivery renders instant relief to the patient.

The portable infusion equipment operates by a suction pump action. A camshaft is turned via a set of gears by a motor. The motor in turn is driven by a nine volt battery' An inlet valve positioned on the camshaft opens and the fluid is drawn from the drug cassette into the pumping area. The closing of the inlet valve is immediately followed by the opening of the outlet valve. The medicine is then squeezed out through the tube into the patient's body by an expulsor. Since a vaccum has been created in the system, the medicine gushes in to fill the pumping area when the expulsor lifts off the medication tube. A drug reservoir can release upto 100 ml of the medicine into the blood stream. Patients stocking their drug supplies in their fridges can replace the drug cassette themselves.

But what is it that regulates the flow of the liquid? A microprocessor inside the pump. A nurse or a doctor programmes the quantity and timings of doses into the microprocessor. The micro processor activates the pump when a dose is due or keeps the flow regulated when a continuous dose is required.

The mode by which the system asks for the drug cassette is quite fascinating. There are sensors to monitor the working of the PUMP. An alarm is set off to indicate that the battery has gone down or that the drug in the cassette has run out. In case of a blockade or a back-flow of the medicine, safety sensors do their job. These activate the alarm and stop the pump under such circumstances.

But for those occasional alarms, the friendly pump sends life-supporting drugs and fluids into the patient's body efficiently while he or she goes around as actively as ever.

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