Cannulation of a internal jugular vein (IJV) is commonly performed procedure in perioperative period and in intensive care for monitoring central venous pressure and for providing secure vascular access for the administration of vasoactive drugs or to initiate rapid fluid resuscitation.1 The usual practice of using surface anatomy and palpation to identify IJV before cannulation (landmark technique) is based on the presumed location of the vessel, the identification of surface or skin anatomic landmarks, and blind insertion of the needle until blood is aspirated. Confirmation of successful cannulation of IJV relies on blood aspiration of a certain character and color (lack of pulsation and dark color). Depending on the site and patient population, landmark techniques for vascular cannulation are associated with a 60–95% success rate.2 Although frequently performed, the insertion of vascular catheters is not free of complications. The complications may occur more often with less experienced operators, challenging patient anatomy (obesity, cachexia, distorted, tortuous or thrombosed vascular anatomy, congenital anomalies such as persistent left superior vena cava), compromised procedural settings (mechanical ventilation or emergency), and the presence of comorbidity (coagulopathy, emphysema).2 The most common complications are bleeding, haematoma, arterial puncture, pneumothorax3,4. Less commonly damage to neural structures such as the stellate ganglion, phrenic nerve and the brachial plexus has been reported.5 The incidence of mechanical complications increases sixfold when more than three attempts are made by the same operator.10 Ultrasound techniques were first reported for IJV cannulation in 1984. 6 The development of portable lightweight ultrasound machines, designed specifically for central venous cannulation has made ultrasound guidance practical for routine clinical use. Ultrasound facilitates direct visualisation of the internal jugular vein, its dimensions, orientation, and surrounding structures resulting in improved first pass success rates, reduced number of needle passes and less inadvertent injury to surrounding structures. The Agency for Healthcare Research and Quality, in its 2001 report Making Health Care Safer: A Critical Analysis of Patient Safety Practices, recommended the use of ultrasound for the placement of all central venous catheters as one of its 11 practices aimed at improving patient care.12 The National Institute for Clinical Excellence (NICE) also published guidelines supporting the routine use of ultrasound guidance for internal jugular vein cannulation .7

Using ultrasound, IJV can be imaged in short axis(SAX),long axis( LAX), or oblique-view ( OAX) orientation..The advantage of the SAX view is better visualization of surrounding structures and their relative positions to the needle (especially the carotid artery during internal jugular line placement) so that it is easier to direct the cannulating needle toward the target vessel and away from surrounding structures when both(artery vs. vein) are clearly imaged simultaneously. The disadvantage of SAX view is that this view does not image the entire needle pathway or provide an appreciation of insertion depth. The advantage of the LAX view is better visualization of the needle throughout its course and depth of insertion, because more of the needle shaft and tip are imaged within the ultrasound image plane throughout its advancement, thereby avoiding insertion of the needle beyond the target vessel. The disadvantage of LAX view is that surrounding structures are not visualized so that it is difficult to discern if the needle is overlying the artery or vein.and also limited by anatomic considerations such as room on the neck with the probe in vertical orientation. The OAX view allow better visualization of the needle shaft and tip and also offers the safety of imaging surrounding structures in the same view, thus capitalizing on the strengths of both the SAX and LAX approaches.11 Numerous studies have shown significant benefits of using real-time ultrasonography for IJV cannulation . Prevoius studies designed to compare between USG-guided and landmark-guided techniques for IJV access have preferentially used the short-axis (SAX) technique as the preferred approach for cannulation. Whereas the long-axis (LAX) approach to vessel access also has been used successfully. Studies comparing SA and LA approach for IJV cannulation have shown conflicting results. Chittoodan et al 8 reported higher first pass success rate and less carotid artery puncture when a short axis, rather than a long axis, approach is employed. Shrestha et al 9 concluded that LA and SA techniques for ultrasound-guided cannulation of IJV are comparable in terms of number of skin puncture, number of needle redirections, first pass success, and carotid puncture. In literature, there are no studies comparing SAX, LAX and OAX approach using real time ultrasound for cannulating IJV in terms of ease of cannulation and immediate complications. Hence, we have planned a study to compare between the SAX, LAX and OAX approach for IJV cannulation in terms of scan time, puncture time, number of skin punctures, quality of needle visualisation, success of cannulation, and any immediate complications.

HYPOTHESIS We hypothesize that there is no difference in the three approaches for ultrasound guided IJV cannulation with respect to scan time, puncture time and complications.