The properties of an improvised piston pump for the rapid delivery of intravenous fluids

Abstract

SummaryTo maximise the effect of a small fluid load, it is occasionally desirable to bolus manually with multiple depressions of a large-capacity syringe. This is usually achieved by placing the syringe on the side port of a three-way tap. We modified this technique by placing two-one-way valves in line with the three-way tap, effectively creating a piston pump, the infusion rates via which we compared with those achieved by an inflatable pressure-infuser in a simulated resuscitation. Fluid flow was faster using the piston pump than with the pressure-infuser (mean (SD) time to infuse 2000 ml saline 0.9% via a 16-G cannula 352 (10) s vs 495 (19) s, respectively, p < 0.0001). The piston pump appears to have potential for both tight control of fluid delivery and major high-volume resuscitation. The lightweight nature of the pump and its lack of reliance on gravity may also make it suitable for the pre-hospital setting.

Is flow really laminar in a piston pump infusion?

“…The piston pump assembly described by O'Callaghan and Singh [1] is indeed exactly the same as ours [2]. We were unaware of their earlier description of this technique and have not accredited them with its prior publication.…”

“…Smart, Primrose, Peters and Speirits [1] are to be commended on a useful invention that may, as they state, facilitate the easy rapid infusion of fluids in resource-poor settings. However, there is nothing new under the sun.…”

A reply

“…The piston pump assembly described by O'Callaghan and Singh [1] is indeed exactly the same as ours [2]. We were unaware of their earlier description of this technique and have not accredited them with its prior publication.…”

“…To clarify, we would like to point out that first, our observations about the nature of flow through the cannula are based on Experiment 3 in our paper [2] (Fig. 5), and second, each of the four individual lines within each group in Fig.…”

“…It has been brought to our attention that the number of patients (65 535) included in our recent observational audit of operative repair of hip fracture [2] is close to a very specific number, well known in computer circles as the largest 16-bit binary integer, or 2…”