Dynamic Needle Tip Positioning Modification Technique in Short Axis Approach

Ultrasound guided radial artery cannulation by Dynamic Needle Tip Positioning Technique in Short Axis Approach (DNTP - SA) will be performed by an experienced anesthesiologist who has no subsequent role in the study. The ultrasound transducer is oriented transversely to the radial artery at the wrist, and the vessel appears as a circular anechoic structure in the ultrasound screen with gradual advancing of the needle till reaching the radial artery. Meanwhile, the ultrasound probe is being moved proximally in advance of the needle tip until it disappears from the ultrasound image. The cannula then advanced in the direction of the artery.

Ultrasound guided radial artery cannulation in Long Axis Approach (LA) will be performed by an experienced anesthesiologist who has no subsequent role in the study. In the LA-IP approach, an ultrasound probe is placed parallel to the radial artery and the artery appears as a tubular anechoic structure in ultrasound.