The inclusion criterion was patients in the ICU who required central venous vascular access. The exclusion criteria were refusal to participate in this study by patient or their legal representative and patient with known history of difficult central venous access at internal jugular vein (IJV). The procedure operators were doctors in anaesthesia residency program with various level of experiences classified into 3 groups: 1 to < 2 years, 2 to < 3years, 3 years and above. Simply speaking all the operators have had previous training in ultrasound guided vascular access procedure. This would ensure that patient's safety is not compromised.