A Randomized Controlled Trial Comparing the Effects of Conventional, Bar-shaped, and V-shaped Local Infiltration Anesthesia on Pain Relief and Cannulation Success Rate in Patients Requiring Radial Artery Cannulation.

The purpose of the study, as well as the necessity, benefits, and risks of arterial cannulation, and the purpose of the study, were explained in detail to all participants screened by inclusion and exclusion criteria, and signed informed consent was obtained on the day before the operation.

Upon entering the operating room, participants will be connected to a pulse oximeter, noninvasive blood pressure monitor, and electrocardiograph and will record baseline heart rate, blood pressure, depth of the radial artery at the first wrist stripe before local anesthesia, and PVDF capacitance difference.

The arterial pressure transducer and tubing will be flushed with 25 U/mL of heparin saline and kept in a ready state.

Anesthesiologists not participating in the study will then be asked to open an opaque sealed envelope to determine the type of local anesthesia to be used during intubation. The conventional approach is to complete a 2 cm subcutaneous injection with 2% lidocaine directly above the artery in the direction of the palpable beat; the bar-blocking is to complete a 2 cm subcutaneous injection perpendicular to the arterial beat line 2 cm from the proximal segment of the puncture site, and the V-blocking is to complete a subcutaneous injection at a 90-degree angle with a 2-cm margin toward the distal end at 2 cm proximal to the puncture site. Heart rate, blood pressure, depth of the radial artery at the first wrist stripe, and PVDF capacitance difference were recorded at the end of local anesthesia.

The radial artery cannula will be placed with a 20 gauge radial artery catheter by palpation under the supervision of an anesthesia consultant in the operating room by another anesthesiology resident not involved in the study.