Infusion Pump

Infusion Pump

An infusion pump is a device used to deliver fluids, medication, or nutrients into a patient's circulatory system, primarily through intravenous means, although subcutaneous, arterial, and epidural infusions are also occasionally employed.

These pumps offer precise delivery mechanisms that would be impractical or unreliable if carried out manually by healthcare staff. For instance, they can administer minute injections as small as 0.1 mL per hour (too minute for traditional drips), injections at regular intervals or on-demand, and fluids with variable volumes dictated by specific times of the day.

Infusion pumps are typically operated through a user interface that requires input from technicians or nurses during setup:

- Continuous infusion involves small pulses of fluid delivered at a rate determined by the programmed speed.
- Intermittent infusion alternates between high and low infusion rates to prevent cannula blockages, commonly used for administering antibiotics.
- Patient-controlled infusion allows patients to control the rate of infusion within preset limits, often used in patient-controlled analgesia.
- Total parenteral nutrition requires an infusion pattern similar to regular mealtimes.

Certain pumps offer functionalities allowing adjustment of infusion rates based on circadian rhythms, crucial for certain medication regimens.

There are two primary types of infusion pumps: large volume pumps, capable of delivering substantial amounts of nutrient solutions, and small volume pumps, which administer hormones or medicines like opiates.

Large volume pumps typically utilize peristaltic pump mechanisms, employing computer-controlled rollers or finger-like components to compress a silicone-rubber tube through which the fluid flows. Small volume pumps, on the other hand, use computer-controlled motors to drive a screw that pushes the plunger of a syringe.

In makeshift medical scenarios, a common improvisation for an infusion pump involves using a blood pressure cuff around a fluid bag or placing the bag beneath the patient to regulate infusion pressure. However, this method is not without risks, as flow rates can fluctuate significantly based on the patient's blood pressure or weight.

In resource-limited settings, pressurized infusion systems are often used, employing purpose-designed plastic pressure bottles pressurized with disposable syringes. While less sophisticated than electronically controlled pumps, these systems require more nursing attention but offer improved flow control.

Infusion pumps may also utilize osmotic power, where a salt solution absorbs water, expanding its volume and pressing medicine out at a controlled rate. Additionally, spring-powered clockwork infusion pumps are utilized in veterinary and ambulatory settings.

For battlefield applications requiring rapid and large-volume fluid perfusion, specialized infusion pumps have been developed. These pumps are meticulously designed to mitigate various failure modes that could pose risks to patients, such as overdose, underdose, reverse flow, and air embolism.