ObjectiveTo determine if ultrasound guidance can be safely performed and improve success rates for subclavian venous catheterization performed by less experienced operators.DesignProspective, randomized study.SettingTwenty-bed trauma-surgical-medical intensive care unit in a 524-bed, community, tertiary care, teaching hospital.PatientsAfter the decision for central venous cannulation was made, informed consent was obtained, and less experienced operators then attempted to insert subclavian catheters in 33 critical care patients.InterventionsCatheter placements were attempted, either by landmark technique, ultrasound technique, or by landmark attempts with ultrasound salvage. Catheterization techniques to be used were randomized using a random number table.Measurements and Main ResultsFifty-three placement procedures were attempted in 33 patients. One procedure was excluded from data analysis. Successful catheterizations, occurrence rates of complications, number of attempts, and number of catheter kits used were recorded. In the analysis, 52 catheterization procedures were studied. Twelve (44%) catheters were successfully placed from 27 attempts using the landmark technique vs. 23 (92%) successful catheterizations during 25 ultrasound procedures (p = .0003). Fifteen failed landmark technique attempts had ultrasound salvage attempted, with 12 (80%) catheters successfully inserted. Eleven complications (minor) occurred in 27 attempts of subclavian venous catheterization using conventional landmark technique vs. one complication (minor) in 25 attempts of subclavian venous catheterization with ultrasound guidance (p = .002). There were no major complications in either group. The landmark group required an average of 2.5 venipunctures and 1.4 catheter kits per attempted catheterization. The ultrasound group required an average of 1.4 venipuncture attempts and 1.0 inserition kit. The statistical significance in differences in groups for the average number of venipunctures was p = .0007 and average number of kits used was p = .0003.ConclusionsUltrasound guidance improves the success rate of subclavian venous catheterization performed by less experienced operators. There were no major complications in either group. Ultrasound guidance is usually successful in allowing performance of subclavian venous catheterizations when landmark techniques fail.(Crit Care Med 1995; 23:692-697)