Elsevier

Air Medical Journal

Volume 36, Issue 5, September–October 2017, Pages 248-257
Air Medical Journal

Original Research
Infusion Pump in UH60L/M Flight in Afghanistan: Why Failures Occur

https://doi.org/10.1016/j.amj.2017.04.007Get rights and content

Highlights

  • It is assumed that ambient pressure changes cause air emboli that lead to pump failure despite adequate evidence.

  • Although unproven, it is more likely that these alarms are usually caused by loosening of the tubing within the collar; this disjointing of the tubing and the ultrasonic sensor can be perceived as an air embolus.

  • Problems such as this may have been related to at least 1 reported patient death.

  • Manufacturers should design an override that allows the pump to function even with air emboli.

Abstract

The ALARIS MSIII Infusion Pump (CareFusion, San Diego, CA) uses 3 separate alarms designed to prevent air emboli: “check air sensor,” “air in lower tubing,” and “air in line.” It is assumed that ambient pressure changes cause air emboli that lead to pump failure although evidence to support this is limited. In this small study, the MSIII proved to be highly resilient and able to maintain function even after large repetitive emboli. Although unproven, it is more likely that these alarms are usually caused by loosening of the intravenous tubing within the pump’s collar. This disjointing of the tubing and the ultrasonic sensor can be perceived as an air embolus leading to severe consequences. If the user attempts the clear air function, the pump will not resume function. Problems such as this may have been related to at least 1 reported patient death. More research is needed to determine the cause of these alarms and determine the exact cause. Patient safety can potentially be improved at all levels including manufacturer modifications and operator training. It seems reasonable that the manufacturer should design a mode (“transport mode”) that allows the pump to function even with air emboli.

Section snippets

Methods

This study has the following objectives: quantify the volume of AIL in milliliters for user reference, determine the volume of air that can be trapped within the cassette, evaluate pump function in a controlled setting, determine the volume of air required to cause an AIL alarm, determine the effectiveness of the ClrAir function, determine at what volume pumps reach refractory failure caused by air emboli (which is defined as an AIL alarm that does not resolve after pressing the ClrAir button 5

Results

The results for the study objectives are provided in Table 3, Table 4, Table 5, Table 6, Table 7 and Figure 4, Figure 5, Figure 6, Figure 7. Results from Aerial trial #3 are shown in Figure 7; this trial was aborted after the third bolus due to operational restrains during that particular mission.

Discussion

When looking at the IV tubing, the user should appreciate that 2 cm air is roughly 0.1 mL air emboli. No pumps failed with emboli smaller than 0.9 mL; this is the equivalent of 18 cm air in typical IV tubing.

Cassettes were able to retain up to 0.55 mL air without allowing any air emboli to pass through the pump. This is protective in the sense that the cassette can “absorb” emboli to prevent pump failure or patient harm. It is also detrimental because if the cassette is not flushed properly the

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    The views expressed are those of the authors and do not represent the official position of the Department of Defense.

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