Effect of Mild Sedation and Analgesia on Radial Artery Cannulation in Novice Residents

Inclusion Criteria: * Patients who required arterial cannulation for continuous blood pressure monitoring * Aged \>20years * ASA physical status of 1-3 * BMI 18-28kg/m2 * All patients agreed to participate in this study at the time of recruitment and signed an informed consent form. Exclusion Criteria: * a positive Allen's test * infection at the puncture site * coagulation disorders; arterial diseases (such as Raynaud's disease or thromboangiitis obliterans) * use of vasoactive drugs within 30 minutes before measurement during the study * patients with arterial abnormalities and bends; hemorrhagic shock * arterial atherosclerosis; radial artery puncture within the past 30 days * chronic use of opioid or benzodiazepine drugs * and known allergies or adverse reactions to benzodiazepines or opioids.