Very small air bubbles (10 - 70 microl) cause clinically significant variability in syringe pump fluid delivery.

AIM

The goal of this study was to analyse flow disturbances resulting from the presence of small air bubbles in syringe pump delivery lines incorporating pressure-sensing discs.

METHODS

Laboratory based gravimetric measurement of syringe pump flow rate with concurrent fluid pressure monitoring.

RESULTS

Small air bubbles can become lodged in the pressure-sensing disc part of syringe pump delivery lines. This can give rise to serious disturbances in fluid delivery from minute to minute, but does not trigger pump alarms. Small air bubbles being delivered through non-horizontal sections of delivery line can also cause significant transient disturbances to fluid delivery.

CONCLUSIONS

The demonstrated disruptions to fluid delivery could be sufficient to cause adverse effects on patients, particularly in the case of a vulnerable patient receiving a potent fast-acting drug at a low flow rate. The prevalence of these effects in clinical settings would be difficult to establish, but careful efforts to remove air from syringe delivery lines before starting infusions would be recommended to minimize the risks.