Ultrasound-guided radial artery catheterisation increases the success rate among anaesthesiology residents: a randomised study.

INTRODUCTION: The palpation technique is generally used for radial artery catheterisation, but is associated with a high rate of failure and complications. Dynamic needle tip positioning (DNTP) is a new ultrasound-guided technique. We aimed to compare the traditional palpation technique with DNTP performed by four anaesthesiology residents. METHODS: The study was a randomised, controlled, patient-blinded, crossover study. Fourty patients underwent bilateral radial artery catheterisation using both techniques. The primary endpoint was the first attempt success rate. The secondary endpoints were: 1) number of skin perforations, 2) number of needle retractions, 3) needle manipulation time, 4) total time, 5) attempts lasting >180 seconds, 6) number of catheters used, 7) frequency of aborted attempts or crossovers, and 8) pain scores (VAS). RESULTS: The first attempt success rate was significantly higher in the DNTP group compared with the palpation group (36/40 vs. 28/40, p = 0.022).The palpation technique group required a higher number of skin perforations (44 vs. 60, p = 0.016), needle retractions (p = 0.001) and catheters (42 vs. 52, p = 0.011) compared with the DNTP group. Neither the total time required for arterial catheterisation, the needle manipulation time nor the VAS scores were significantly different between the groups (all p>0.407). Aborted attempts were only seen in the palpation group (7/40, p = 0.016). CONCLUSIONS: Ultrasound-guided arterial catheterisation using the DNTP technique is superior to the standard palpation technique. This study favours the ultrasound-guided DNTP technique as the first choice rather than merely being viewed as a rescue procedure.

Guidance markers increase the accuracy of simulated ultrasound-guided vascular access: an observational cohort study in a phantom.

INTRODUCTION: Peripheral ultrasound (US)-guided vascular access is gaining popularity. Though studies have demonstrated that US-guided vascular access has several advantages, the procedure is challenging to even the most experienced operator. The aim of this observational cohort study was to investigate whether adding guidance markers on a US system would increase the accuracy of US-guided needle tip placement compared to no guidance markers. METHODS: A total of 18 physicians and 12 nurses familiar with US-guided vascular access volunteered to participate. Two identical US systems were used. System A was as manufactured. System B included three guide markers drawn on the transducer and screen. The participants performed six needle insertions in a gelatin phantom with three imbedded targets. First participants used US system A and then US system B. Primary endpoint was horizontal distance between needle tip and target. Secondary endpoint was participant's subjective feeling of advantage of the guidance markers measured on a Likert scale. RESULTS: Guidance markers on the US system significantly increased the accuracy of needle placement on all three targets individually (p = 0.00) and on overall placement, (inter-quartile range 3.21 mm vs. 0.49 mm, p = 0.00). In addition, the use of guidance markers eliminated the difference in accuracy between physicians and nurses, respectively. All participants evaluated the guidance markers to be helpful during the needle insertions. CONCLUSIONS: Adding guidance markers to the US system significantly increased the accuracy of needle placement in the horizontal plane during simulated US-guided vascular access using a phantom.

A technique for ultrasound-guided blood sampling from a dry and gel-free puncture area.

PURPOSE: Vein punctures are performed daily to sample blood. Ultrasound (US) offers an alternative to the blind landmark technique for difficult vascular access. A challenge for this procedure is the presence of US gel in the puncture area. We present a technique for US-guided puncture from extremity veins not palpable or visible to the human eye, while keeping the puncture area dry and gel-free. METHODS: Ten healthy volunteers underwent two US-guided vein punctures from veins that were neither palpable nor visible. One was drawn from an antebrachial vein and another from a brachial vein. A sterile barrier drape was made from a commercially available dressing and a piece of transparent sterile plastic. The barrier drape consists of an adhesive part placed on the skin designed for sonography and a free transparent flap constituting the barrier between the unsterile sonographic site and the sterile gel-free puncture site. RESULTS: The success rate for vein puncture was 100% in both locations. A total of 22 skin punctures were performed (11 antebrachial and 11 brachial). Gain output was increased 7% (4-12%), and 8% (4-15%), respectively, to compensate for attenuation of the US signal due to the drape. Alignment of the centre of the transducer with the long-axis of the target vein during the procedure was reported as a challenge. CONCLUSIONS: US-guided blood sampling from a brachial and antebrachial vein was possible with a 100% success rate, while ensuring a dry and gel-free venipuncture area on one side and the transducer on the other side of a sterile barrier.