Forty-five degree wrist angulation is optimal for ultrasound guided long axis radial artery cannulation in patients over 60 years old: a randomized study.

Arterial cannulation is a common anaesthetic procedure that might be challenging and time-consuming in elderly patients. To establish an appropriate wrist joint position for arterial cannulation is crucial for ultrasound (US)-guided cannulation success. This study aimed to find out the optimal wrist joint angle for long axis in-plane (LA-IP) US-guided approach in radial artery cannulation in elderly patients. One hundred patients over 60 years old, who were assumed to require an arterial catheter for continuous blood pressure monitoring or frequent blood gas analysis in the intensive care unit or in the operating room were included in this prospective randomized study. Patients were randomized to five groups according to the wrist positions (0°, 15°, 30° 45° and 60° groups) for LA-IP approach for radial artery cannulation. Cannulation time (s), number of attempts, total success rate (%), first attempt success rate were recorded in all patients. Mean radial artery height was increased in 45° group compared to other groups (p < 0.05). Distance between skin and radial artery in 45° and 60° groups were statistically significantly decreased compared to 0° group (p < 0.05 for all comparisons). Mean cannulation time of 45° group was statistically decreased compared to other groups (p < 0.05). Number of attempts and total success rate were similar among groups, whereas first attempt success rate was significantly increased in 45° group compared to other groups (p < 0.05). Mean arterial height of the first attempt successful group was statistically increased compared to the first attempt failed group (p < 0.001) and mean cannulation time and mean number of attempts were also negatively correlated with arterial height (p < 0.001; for all comparisons). The 45° wrist angle increment might be advantageous in US-guided LA-IP radial artery cannulation in elderly patients in view of cannulation time and first attempt success rate.