Preferred display size and visual distance for ultrasound-guided radial artery cannulation

Introduction: In-line positioning of an ultrasound image provides higher success rates and less time to completion for radial arterial cannulation. But preferable size and distance of ultrasound display has not been previously discussed. Objective: To assess the ideal visual distance and display size when using a smart phone or tablet as the ultrasound image display. Methods: Four smart phones or tablets were used as ultrasound displays in six different configurations in a simulated radial artery puncture. In a questionnaire, 116 anaesthesiologists working in Ibaraki Prefecture, Japan, were asked which of the six configurations was preferable for radial artery cannulation. Results: Sixty anaesthesiologists answered the questionnaire. About half (53%) preferred the smaller display (4- or 5.5-inch) fixed at a distance of 30 to 40 cm, and most of the rest (44%) preferred the larger display (7.9- or 9.7-inch) placed posterior to the probe with a visual distance of 45 to 60 cm. Conclusions: Among the anaesthesiologists, the preferable size and visual distance for ultrasound-guided radial artery cannulation varied using a smart phone or tablet for in-line display.