Comparison of Supraclavicular Anterior Out-of-plane Approach with Infraclavicular Out-of-plane Approach for Ultrasound guided Subclavian Vein Cannulation: A Prospective Randomized Control Trial

Preoperative anaesthetic check-up will be done one day prior to the planned elective procedure. After the anaesthetic plan is made to include central venous catheterization, patients satisfying the inclusion and exclusion criteria will be enrolled in the study after obtaining written informed consent from the patient. Randomization into either group will be done at this point using SNOSE technique. Once the patient is shifted inside the operation theatre, standard monitoring devices including pulse oximeter, non-invasive blood pressure cuff, ECG leads will be attached and continuous monitoring of vitals will be done. General anaesthesia and Intubation will be carried out by the attending anaesthesiologists. With patient lying supine and arm adducted by side, neck will be extended and head turned to the opposite side at an angle of 30 degrees. A wedge will be placed in between the shoulder blades. Linear Ultrasound probe of frequency 8-15MHz will be used for this procedure. Under sterile precautions required for the placement of a central venous catheter, the procedure will be started. The procedure will be done by a member of the anaesthesia team with an experience of at least 20 successful cannulations with both approaches. A screening ultrasound will be done before starting the procedure. In the supraclavicular anterior out-of-plane approach ultrasound probe will be held with the left hand and the needle with the right hand. The probe will be placed on the right side of the neck, at the level of cricoid cartilage so as to visualize the internal jugular vein (IJV) in short axis. Once IJV is identified, the probe will be moved caudally down the neck, tracing the course of IJV. Once the superior border of the clavicle is reached, the probe will be angulated to visualize the confluence of IJV with subclavian vein as they form the brachiocephalic vein. The probe will then be adjusted so as to bring the vein to the centre of ultrasound screen. Pleura will also be visualized in the same frame. The depth of vein from skin surface will be noted. The needle will be inserted 0.5 -1 cm lateral to the centre of the footprint of the ultra sound probe, in between clavicle and probe at an angle of 5 to 10 degrees to the axis of the probe, directing the needle towards the vein and parallel to the pleura, under vision. Keeping the depth from skin noted earlier in mind, the skin will be pierced with a central vein catheter needle. Care will be taken to ensure that needle will not be inserted more than the measured depth in ultrasound. Its entry into the vein is visualized in ultrasound view and until there is flashback or free aspiration of blood in the syringe attached to the needle. Once free flow of venous blood is confirmed, the ultrasound probe is kept aside and with the left hand, needle is stabilized at the skin entry point by resting the hypothenar eminence against the chest to prevent inadvertent insertion into deeper structures. After successful venous puncture, catheterization will be done using the seldinger technique. Aspiration of blood from each of the three lumens will be confirmed before suturing the catheter onto the skin. A sterile dressing will be applied over the catheter. In the infraclavicular out-of-plane approach, with similar aseptic precautions, and the patient lying in supine position and the neck in neutral position, the USG probe will be placed in the craniocaudal direction with the orientation marker pointing cephalad at the level of the coracoid process. The Axillary artery and vein will be visualized. Then the probe will be moved medially tracing both the vessel to visualize the subclavian vein and artery. On going more medially first the subclavian artery will become invisible by becoming infraclavicular. Then the probe will be moved medially to visualize clavicle and major part of subclavian vein. Once the optimal view is obtained, the distance of the vein from the skin will be noted to guide needle insertion. The needle will be inserted via the out- of -plane approach to enter the subclavian vein and at an angle of 45-60 degrees to the skin and its insertion will be approached step-by-step by moving the probe to visualize the needle tip. Once successful puncture is noted by visualizing the needle tip within the vein and by observing back-flow of blood into the syringe on aspiration, catheterization of the vein will proceed using seldinger technique. Once free flow of blood is confirmed in all three ports, the catheter will be sutured to the skin and sterile dressing will be applied. An observer will note the following parameters- first pass success, number of attempts, number of redirections, time taken for venous puncture, time taken for getting an optimal view of structures in ultrasound, time taken for successful cannulation, and complications like arterial puncture or pneumothorax. In both groups, the observer will set a timer to note the various timelines along the procedures. The timer will start with visualization of structures in ultrasound and then the time of needle insertion will be noted. The time at which flashback occurs in the syringe will be noted next. Finally, once the aspiration of blood from each of the three lumens of the catheter is confirmed, the final time reading will be taken. Position of the catheter tip will be checked using ultrasound. Presence of catheter tip in the ipsilateral internal jugular vein or contralateral subclavian vein will be considered as catheter misplacement. After completion of the procedure, the operator will grade the ease of the technique using a five-point Likert’s scale. A chest radiograph will be taken in the postoperative day one to confirm position of the catheter tip and identify pneumothorax and haemothorax.  All data will be documented using a standard proforma.