Ultrasound-image Guided Versus Doppler Guided Versus Palpation Technique for Arterial Cannulation in Adults

Radial arterial cannulation is a common invasive procedure for real-time measurement of arterial blood pressure. Placement of the arterial catheter using conventional palpation is often relatively easy and quick, but this is not always true. A relatively new method for direct visualization of the artery is the use of two-dimensional ultrasound. This technique allows cannulation of the artery to take place under real-time visualization and may increase the success rate of first time pass of the needle. Another technique utilizing Doppler has also proven to be effective in cannulating the radial artery. This technique utilizes changes in acoustic pitch as the probe passes directly over the artery. The primary objective of this study is to compare the first attempt success rate for radial artery cannulation among the palpation, Doppler and U/S guided technique when applied by trainees. Secondary outcomes include: success rate within 5 minutes, successful, number of attempts required, and correlation between success rate and operator experience for successful cannulation of the radial artery.