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INFUSION PUMP

Typical Number in Hospital: 100 Cost Bands: 2,3,4 References: 4

Infusion pumps and controllers are used extensively for delivering intravenous fluids and drugs as part of the care of patients in hospital. These are usually pumps but the term is often used loosely to describe an infusion controller which relies on the head of the fluid reservoir for its motive force, and merely controls the rate at which the fluid is dispensed.

Infusion pumps may be motorized syringes used for the slow delivery of small quantities of fluid or drugs or they may operate from a reservoir bag pumping and regulating the rate of passage of fluid along the giving set.

There are two main types which work from a reservoir. There are those which pump by applying peristaltic pressures to the outside of the giving set and measure the rate of flow by counting the drops passing through an optical gate clipped on to the drip chamber. Other types employ a disposable double syringe unit (cassette) connected into the giving set which draws in measured quantities of fluid according to the required infusion rate, and simultaneously dispenses from the other side of the syringe plunger. These are usually called volumetric pumps.

The drop-counting infusion pumps and controllers may produce erroneous rates of infusion if the drop counting mechanism is confused by incorrect placement or extraneous light input. Most modern pumps have adequate protection circuitry and alarms to prevent the common hazards, but operator problems are still common. The so-called volumetric pumps employing the bi- directional syringe units (cassettes) involve relatively high costs for the disposable cassettes but are more reliable and accurate. Basic syringe pumps may cause trouble if unsuitable syringes are used, or if they must work against a high back pressure. Small battery operated and clockwork types exist which can be carried on the person where long-term infusion at very slow flow rates is required.

Content and Design Copyright 2000 Dr. Malcolm C Brown.  See Title Page for more details