A Comparison of Proximal Tibia, Distal Femur, and Proximal Humerus Infusion Rates Using the EZ-IO Intraosseous Device on the Adult Swine (Sus scrofa) Model

Abstract

Objective. We sought to compare the flow rates of the proximal tibia, the distal femur, and the proximal humerus using high pressure (greater than 300 mmHg) through an intraosseous (IO) infusion needle in an adult swine model. Methods. We performed a prospective interventional study in 11 swine. After placement of central vein and arterial lines, blood was removed via the central line until the animal's mean arterial pressure decreased 25% from the recorded baseline. We inserted a 25-mm IO needle into the proximal tibia and 45-mm needles into the distal femur and proximal humerus. All extremities were utilized in each study animal. We infused normal saline at each site for 10 minutes with a pressure bag inflated to the highest achievable pressure (greater than 300 mmHg) as measured at the infusion site with a calibrated portable inline pressure gauge. We measured the volume of normal saline remaining and we calculated infusion rates for each site. We then compared infusion flow rates between the three locations. Statistical analysis and comparison of the infusion rates of all three study arms were as performed using analysis of variance (ANOVA). Results. The average weight of the swine was 71 kg (range 64–84 kg). Successful placement of the IO needle was confirmed at all three sites. The mean infusion flow rate was 213 mL/min (standard deviation [SD] 53.2 mL/min) for the proximal humerus, 138 mL/min (SD 65.3 mL/min) for the distal femur, and 103 mL/min (SD 48.1 mL/min) for the proximal tibia (p < 0.001). The flow rate through the proximal humerus was statistically greater than that for the proximal tibia and the distal femur (p < 0.001). The flow rates through the proximal tibia and distal femur were similar. Conclusion. The humerus is a suitable alternative site for IO placement, with a potential for higher flow rates than the proximal tibia and distal femur when resuscitating a patient. Key words: intraosseous; prehospital; resuscitation; tactical combat casualty care; emergency medical services