USE OF HAND-HELD DOPPLER TO IDENTIFY DIFFICULT FOREARM VEINS FOR CANNULATION

Intravenous cannulation is a necessary procedure in many hospital pati ents. Some patients are regarded as having 'impossible' veins that are invisible and impalpable despite venous tourniquet. We investigated t he use of a hand-held Doppler to identify veins suitable for percutane ous cannulation in such patients. A total of 24 arms in 12 patient vol unteers with invisible and impalpable forearm veins was studied by squ eezing the ipsilateral hand and using a hand-held 8 MHz Doppler probe on the forearm. Each venous signal was noted and the loudest chosen. C lassification as 'good' or 'poor' was made on signal strength. The bes t signal was then mapped and the direction was indicated by a line on the skin. Each forearm was examined using a colour-flow Duplex. All ve ins were noted and diameters measured with and without tourniquet. The se results were compared with the best veins found by hand-held Dopple r. In all, 23 (96%) arms had the largest vein correctly identified by the hand-held Doppler. All 19 (100%) described as 'good' on signal had a diameter of 2.0-4.2 mm (mean 3.2 mm). All 4 (100%) described as 'po or' on Doppler signal had diameters of 1.4-1.7 mm (mean 1.6 mm). Hand- held Doppler, used as described, can accurately identify forearm veins larger than 2.0 mm in diameter in patients with invisible and impalpa ble veins with venous tourinquet. These veins should be amenable to pe rcutaneous cannulation.