Comparative ultrasonographic anatomy of medial-oblique probe position with classic short axis probe position for ultrasound guided axillary vein cannulation: A cross-over study

Study objectiveSubclavian vein cannulation in the infraclavicular region may be a preferred approach as it is associated with less infection than internal jugular or femoral venous access in critically ill patients. Short-axis view" has a problem that shaft of the puncture needle is not visualized and tip of the needle is only seen as dot; hence posterior wall of the vein puncture is always possible with short-axis approach. We have designed this study to know the ultrasonographic anatomy of subclavian vein in short axis and medial oblique view. DesignProspective randomized, cross-over. SettingOperating room. PatientsOne hundred consecutive patients aged between 18-50yrs of either sex, ASA PS I-III undergoing elective surgery under general anesthesia. InterventionThe ultrasonographic anatomy of axillary vein cannulation in infraclavicular region in one hundred patients was assessed as per randomization sequence in medial oblique probe position and short-axis probe position. MeasurementsAntero-posterior and transverse diameter of axillary vein, pleural line visibility. Main ResultsTransverse diameter of subclavian vein was higher in medial-oblique view [mean difference (95% confidence interval) 0.12 cm (0.09-0.16) cm; p<0.0001]. However, mean (standard deviation) antero-posterior diameter was similar in two views [0.72(0.15) cm in short axis versus 0.68 (0.16) cm in medial oblique; p=0.07]. Visibility of pleural line was similar in both the view (p=0.84, Chi-square test). ConclusionMedial-oblique view may be useful in axillary approach of subclavian vein cannulation. Further clinical studies are required to know whether medial oblique view can reduce complications and increase success rate of ultrasound guided subclavian vein cannulation over short axis view.