A prospective evaluation of the utility of ultrasound guided radial artery cannulation versus the traditional blind palpation technique in adult cardiac surgical patients. The ULTRA-ART Study.

Research Plan Synopsis and Design: This is a prospective, randomized study design comparing the use of out-of-plane ultrasound guidance to the traditional palpation method for placement of radial arterial lines in the adult elective cardiothoracic surgical population at a large academic single centre in Australia. All eligible patients undergoing cardiac or thoracic surgery at TPCH will be included to reach the total number of 328 patients. Either senior trainees in anaesthesia or the consultant anaesthetist for each case will place the arterial lines. All registrars and faculty are familiar with the ultrasound for use in vascular access (both central and peripheral venous cannulation). However for completeness - prior to study initiation - all senior registrars and anaesthetic consultants involved in arterial line placement will be given a short (10 minute) didactic instruction on ultrasound use for arterial line placement, and it will be assured that all persons undertaking the procedure have completed greater than 25 total arterial line placements in the past, 5 of which must have been done under ultrasound guidance. Currently, arterial lines are not routinely placed under ultrasound guidance in the operating theatre. Intervention and Procedures: Study anaesthetists will use a Sonosite M-turbo ultrasound system (Bothell, WA, USA) with an HFL-38E 6-13 MHz linear array transducer. An observer with a stopwatch will time how long the physician took to achieve successful placement. In the ultrasound group, time zero will be defined as the time the ultrasound machine is turned on (before gel is applied to the transducer and before a sterile cover is applied). For the blind palpation group time zero will be defined as the time the operator’s fingers are placed on the wrist to palpate the radial pulse to guide needle placement. In addition, for both techniques, a second time record will be started at the point the needle enters skin. The time of placement will end when the catheter has successfully been placed into the vessel with appropriate pulsatile blood return and waveform presence. Data will be collected on a standardized data sheet. Patients will be randomly assigned to either the ultrasound guided or blind palpation group by using a randomly generated list of allocations. The random allocations will be kept in sequentially numbered sealed envelopes in a locked / secure area, and will be removed one at a time. A standard 20 gauge arterial leader-cath (Vygon Corporation, Montgomeryville, PA, USA) arterial access catheter will be used for all access procedures. The palpation technique will be performed in the classic and standard manner by using the radial artery pulsation as a guide. The ultrasound technique will consist of applying the ultrasound transducer to the skin and using the ultrasound image to locate the target vessel in the short axis – the artery being identified by lack of compression compared to the surrounding veins, pulsatility, and use of colour Doppler if necessary. The ultrasound will be covered with a large tegaderm in a sterile manner, sterile gel will be used to maintain infectious precautions, and the arterial line will be placed with an in-plane ultrasound approach. As a number of the patients in this population can be difficult arterial access, we will limit the number of attempts to three completely new attempts per patient (defined as a distinctly new and purposeful penetration of the skin with the needle, followed by unlimited needle redirections in the skin). A new kit will not be needed for each separate attempt. A new site is defined as moving to the other wrist or another backup location. If failure occurs using the technique to which the patient is randomized (3 attempts without success), either technique can be used as a rescue technique. Data Collection: The data will be prospectively collected on structured forms to avoid the obvious concerns with retrospective analysis or database assessment. A trained research assistant will be present in the operating theatre during the placement of the arterial catheter, and will obtain all the measurements in a controlled and consistent manner. Demographic data will be collected on all patients. Additionally, all patients will be followed up for 24 hours to assess the secondary endpoints mentioned above (such as swelling, bruising, dressing changes, satisfaction, etc). Project Schedule: This project will begin once ethical approval is obtained, and will continue for approximately 9 months. It will take 3 months for ethical approval and study set up, 7 months to carry out the study, and 2 months for statistical analysis.