Monitoring oxygenation and ventilation during magnetic resonance imaging: a pictorial essay

Effect of distance and infusion rate on operation of Medfusion 2010 infusion pump during magnetic resonance imaging

STUDY OBJECTIVES

To determine the accuracy and reliability of intravenous infusion, as well as magnetic resonance image effect of the Medfusion 2010 infusion pump (Medex Medical Supplies, Inc., Duluth, GA) at distances of 2, 4, 8, 12, and 16 feet from a 1.5 Tesla MRI magnet over a four-week time interval, using infusion rates that would correspond to those of propofol administration.

DESIGN

Prospective, open-label study.

SETTING

Radiology department MRI in an American academic medical center.

INTERVENTIONS

Five infusion pumps, including one outside the MRI suite as control, were tested. Pumps were evaluated at distances of 2, 4, 8, 12, and 16 feet from a 1.5 Tesla magnet. One pump at distances of 2 and 16 feet was tested during 30 and 90 hours of operation, respectively. Three pumps at distances of 4, 8, and 12 feet were tested during 120 hours of operation. Pump batteries were recharged for 18 hours outside the MRI suite between the 6-hour test periods. Distilled, deionized water was infused from a 30-mL or 60-mL syringe via a 36-inch Medex small-bore extension set into a graduated collection cylinder at rates of 5, 10.5, 21, or 42 mL/hr. Each rate was increased to the next infusion rate level at 30-hour weekly intervals. The collection cylinder with infused water was weighed on an electronic scale accurate to within +/-0.001 g. Analysis of variance and regression analysis were used to analyze data. A p < 0.05 value was considered statistically significant.

MEASUREMENTS AND MAIN RESULTS

There was no significant difference comparing the grams weight of volume measured and the mL volume visualized within and between groups at varying distances from the magnet. Increasing infusion rates resulted in corresponding increases in volume delivered irrespective of the distance from the magnet.

CONCLUSIONS

The Medfusion 2010 infusion pumps were found to be reliable and accurate, without causing failure or any significant degradation of MRI images compared to control at infusion rate of 42 mL/hr at a distance of 2 feet for 30 hours; and a rate of 5.0, 10.5, 21, and 42 mL/hr at 16 feet for 90 hours; and at 4, 8, and 12 feet for 120 hours of operation.