Table 2.

Types of disposable mechanical pumps.

	Positive Pressure	Negative Pressure	Elastomeric
Mode of action	As the drug reservoir of the pump gets filled with the solution, it compresses the spring contained within, which in turn exerts pressure on the infusion bag driving the solution out through the tubing	The vacuum or area of very low pressure in one chamber of the pump becomes aggravated as the opposite chamber gets filled with the solution. The significant difference in pressure between the two chambers causes the movable wall plunger to push the fluid out through the tubing	A stretchable elastomer intended to hold the solution is contained within an outer protective shell made of hard plastic or a softer material. Once filled with the drug solution, the membranes of the elastomer exert pressure on the solution driving it out through the tubing
Disposable parts	Entirely disposable, or reusable	Entirely disposable	Entirely disposable
Accuracy	+/- 10 to +/- 20	+/- 10%	+/- 15%