This study was a prospective, single-center, single-arm clinical trial with a historical control. This study was approved by institutional ethics committee in Mahidol University (046125) and was registered on Thai Clinical Trials Registry (TCTR20200601004). All patients signed a written consent form before their participation in the study that was conducted from February 2019 to September 2019 at Ramathibodi Hospital, Mahidol University. The reporting in this manuscript followed the recommendations in the STROBE guideline.
All patients underwent elective hepatobiliary and pancreatic surgery under general anaesthesia, had an American Society of Anesthesiologists (ASA) physical status of I to III, were older than 18 years, and required radial artery cannulation for intraoperative monitoring. We excluded patients who required insertion of an arterial line before induction of anaesthesia, had previously undergone radial artery cannulation during the same hospital admission, had unstable vital signs, or had peripheral vascular disease. The patients were assigned into two groups; direct arterial puncture group (DP group) and guidewire-assisted cannulation group (GW group). The study was separated to two periods. The DP group was conducted when our new first-year anesthesiology residency trainees started working at the operating room after orientation program. The GW group was conducted in surgical residency trainees who rotated into division of hepatobiliary and pancreatic surgery.
In the direct arterial puncture group, the cannulation procedures were performed by first-year anesthesiology residents who had performed either zero or one radial artery cannulation. They had attended simulator training of radial artery cannulation by direct arterial puncture on a manikin-based training and watched a video demonstrating this cannulation technique on the orientation day of our training program. In the guidewire-assisted cannulation group, radial artery cannulation was performed by inexperienced surgical residents who had only performed arterial blood gas sampling and had never performed radial artery cannulation. The study assigned only one anesthesiologist who did not involve with the patient care processes to show the video demonstrating steps of guidewire-assisted cannulation technique to surgical residents on the morning of procedure. After watching video that was approximately seven minutes in length, the surgical residents were able to ask any question before the procedure. The nurse anesthetists prepared radial artery cannulation equipment for our trainees.
Both techniques started with the patient’s arm secured on an arm board, the wrist extended, and the fingers fixed. In the DP group, after cleaning the cannulation site with antiseptic solution, the direct arterial puncture began with manual palpation to identify the site of maximal pulsation. After the point of puncture had been identified, a 20-gauge fluorinated ethylene propylene polymer catheter (Jelco; Smiths Medical, Minneapolis, MN, USA) was used to puncture the skin at an angle of 30° to 45°. After arterial blood was seen in the hub of the catheter, the catheter was dropped to 5° to 10° and slightly advanced to ensure cannulation of the artery. Finally, the needle was held in place while the catheter was advanced into the radial artery. In the GW group, after arterial blood was seen in the hub of catheter, the arterial catheter was advanced through the posterior wall of the radial artery. The needle was removed and the catheter withdrawn until arterial blood pulsation was seen. Half of the guidewire (0.018” × 9¾”) (Arrow; Teleflex, Wayne, PA, USA) was inserted, and the arterial cannula was then advanced into the radial artery.
Intraoperatively, all patients were maintained under general anaesthesia with an endotracheal tube. After induction of anaesthesia, radial artery cannulation was performed. All residents performed their radial artery cannulation technique without any suggestions from the attending anesthesiologists. When the residents had completed their procedure, the catheter was connected to the pressure transducer to obtain the arterial waveform.
Successful cannulation of the radial artery was defined as the appearance of an arterial waveform on the monitor after connection to the transducer. The insertion time was measured from the first needle puncture of the patient’s skin to placement of the catheter into the radial artery. The number of attempts was counted as the number of needle advances through a skin puncture until the patient’s blood was seen in the hub. Failure of cannulation was defined as no achievement of radial artery cannulation within two attempts or a procedural time of more than 15 minutes. In cases of failure, the arterial cannulation was performed by the attending anesthesiologist. The number of attempts and the cannulation time were recorded by nurse anesthetists who were not involved in this study. The record of procedural time was stopped when the arterial waveform was seen on the monitor or failure of cannulation. Other collected data were the patients’ characteristics, ASA physical status, underlying diseases, vital signs before cannulation, and local haematoma formation after cannulation.
The sample size was calculated by the success rate of the direct puncture and guidewire-assisted techniques in a previous study[9] with a type I error of 0.05 and power of 0.8. The result indicated that 29 patients were required in each group.
Statistical analysis was performed using SPSS version 20.0 software (IBM Corp., Armonk, NY, USA). Continuous data are presented as mean ± standard deviation or median (interquartile range). Categorical data are presented as number (percentage). The chi-square test or Fisher’s exact test was performed to compare categorical variables, and Student’s t-test or the Mann–Whitney U test was performed to compare continuous variables in each group. Kaplan–Meier curves of the cumulative success of cannulation and the procedural performance time were plotted. The log-rank test was performed for statistical comparison of the two groups. A P-value of < 0.05 was considered statistically significant.