**4. Ultrasound access**

Ultrasound (US) for radial access from several smaller studies implied a benefit in time to access [13, 14]. The RAUST trial included 698 patients and showed that an ultrasound-guided approach decreased the number of attempts (mean 1.65 ± 1.2 vs. 3.05 3.4, p < 0.0001) and the time to getting access (88 ± 78 seconds vs. 108 ± 112 seconds, p = 0.006) [15]. In another randomized controlled trial performed in Australia that enrolled 1388 patients, ultrasound use decreased time to getting access (93 vs. 11 seconds, p = 0.009), the number of attempts (1.47 vs. 1.9, p < 0.0001) with increased chances of success from the first try (73% vs. 59.7%, p < 0.0001) [16]. Besides the faster and higher success rate, pre-puncture ultrasound can prevent vascular complications by properly sizing the radial artery to sheath diameter [17].
