A Comparative Study of the Ease of Radial Artery Cannulation Using the Palpation Method in Patients Undergoing Surgery Under General Anaesthesia: Pre-induction Versus Post-induction.

Introduction Radial artery cannulation is performed for continuous blood pressure monitoring and blood gas measurements in the operating room, critical care unit, and postoperative period. Various factors determine the artery used for cannulation, including accessibility, ease of placement, collateral flow, risk of infection, and embolic phenomena. Most anaesthesiologists consider anaesthesia induction the most likely timing of hemodynamic instability. These hemodynamic changes may affect the blood vessels in terms of their lumen and pulsation, thus posing a challenge to the anaesthesiologist for successful arterial cannulation. In the present study, we aim to assess whether these hemodynamic changes, consequent to the induction of general anaesthesia, significantly affect the success rate of radial artery cannulation compared to the success rate if performed before the induction of general anaesthesia using the palpation method. Materials and methods A total of 60 eligible and consenting ASA-PS I & II (American Society of Anaesthesiologists Physical Status I & II) patients undergoing elective surgery (which requires invasive blood pressure monitoring) under general anaesthesia were prospectively randomized into two groups, Pre-I (Pre-induction) and Post-I (Post-induction), using a random selection method. In the Pre-I group, radial artery cannulation was performed before induction of anaesthesia, while in the Post-I group, radial artery cannulation was performed after induction of anaesthesia. The data, including the success rate of arterial cannulation, the number of attempts required to cannulate the radial artery successfully, and the time taken to successfully cannulate the radial artery, were obtained and analysed. Results Demographic variables such as mean age, weight, height, BMI (body mass index), and the ASA-PS were comparable across the groups, and the differences were not statistically significant. In the Pre-I group, of 30 patients, 28 were in ASA class I, and two were in ASA class II; the respective numbers in the Post-I group were 27 and 3. Of all 60 patients, the radial artery was successfully cannulated in 54 patients - 26 in the Post-I group and 28 in the Pre-I group. The number of attempts for cannulation was one attempt in 23 patients and two attempts in three patients in the Post-I group; the respective numbers for the Pre-I group were 26 and 2. The mean time for cannulation was 14.38 seconds in the Post-I group and 12.67 seconds in the Pre-I group. The complications (hematoma at the site of cannulation) related to radial cannulation were noted in three patients - two in the Post-I group and one in the Pre-I group. Conclusion Radial artery cannulation can be performed with comparable ease, before and after the induction of anaesthesia, in patients belonging to ASA-PS I & II.