a mylab 30 gold ( esaote , genova , italy ) and a linear probe ( la435 : 6 - 18 mhz , esaote , genova , italy ) were used as the ultrasonographic equipment . performed in the intensive care unit ( icu ) , a blanket was placed under the calf of the patient in order to maintain dorsosacral position . a pad was placed beneath the shoulders for support in order to maintain a neutral position of the head or to prevent extension or flexion of the head . 1 mg / kg of ketamine was injected before the procedure for sedation , and after confirming sedation , the patient 's head was rotated to the side opposite to the site of the procedure . a linear probe applied with non - sterilized ultrasonographic gel ( aquasonic , parker , new jersey , usa ) was placed in the cricothyroid membrane area to transectionally scan and confirm the anatomic structures of the internal jugular vein and carotid arteries before the procedure . the probe was then moved towards the patient 's legs to confirm the merging of the internal jugular vein and the subclavian vein , clavicle , and pleural line . after confirmation of these anatomic structures , the site of the procedure was sterilely draped with 2% povidone iodine and covered with a sterile spread . 1 to 2 ml of 2% lidocaine was locally injected into the site of the procedure . a sterilized gel ( aquasonic , parker , new jersey , usa ) was applied to the probe and covered with a sterilized ultrasonographic drape . if the size of the subclavian vein identified through the probe was smaller than 2 mm , a 4 french catheter was used . if larger , a 5 french catheter ( pediatric two - lumen central venous catheterization set , arrow international , pennsylvania , usa ) was used ( fig . the internal jugular vein , carotid artery , subclavian vein , the clavicle and its shadow were identified by transectionally scanning , as done previously before sterile draping . the needle was inserted while targeting the confluence of the internal jugular vein and the subclavian vein . after positioning the needle tip within the vessel , blood was aspirated in order to confirm its location , and a guide wire was inserted following typical catheterization procedures ( fig . the internal carotid area was checked with the probe to see whether the catheter entered the internal jugular vein . after confirming no entry into the internal jugular vein , the catheter was fixed to the skin ( fig . catheterization was carried out in the operating room ( or ) , and the patient was first put under general anesthesia and placed in a trendelenburg position . an identical method was used in a total of 11 pediatric patients . demographic and procedural information ages ranged from 2 days to 24 months , weighing 1,120 g to 12.4 kg , with height ranging from 34.2 cm to 91.7 cm . 3 procedures were carried out in the icu , 5 in the or , 2 in the neonatal intensive care unit ( nicu ) , and 1 in the ward . most were successful at the first attempt , although one patient carried out in the or was successful upon the second attempt . a single attempt was defined as introducer - needle insertion into the skin , advancement into the vein , and blood aspiration . the number of attempts was increased if blood was not aspirated or the catheter insertion was unsuccessful despite aspiration , such that the introducer needle needed to be reinserted . complications such as incorrect catheter location , arterial puncture , pneumothorax , or hemothorax did not occur in any patients . the first patient in whom we ultrasonographically placed a subclavian vein catheter was a female pediatric patient weighing 5,150 g , born premature and being treated for a respiratory - related disease for over twelve months in the nicu and icu . anesthesiology was consulted because many attempts of subclavian vein catheterization by cardiovascular and pediatric surgeons were unsuccessful , causing multiple hematomas and making of the anatomic landmark difficult . there are a considerably large number of reports on ultrasound - guided central line placement in adult patients , but few on pediatric patients , for whom most procedures are carried out on the internal jugular vein . the only successful report of pediatric ultrasonographic - guided subclavian approach is by pirotte et al . . the success rates of central venous catheterization through anatomic landmarks are high in adult and pediatric patients , but failure rates are as high as 35% , along with delayed management of complications such as arterial puncture , formation of arteriovenous fistula , pneumothorax , and nerve injury , thus encouraging the use of an ultrasonograph during internal jugular vein catheterization . however , because there is no definite evidence on the efficacy of ultrasound - guided subclavian vein catheterization , it is difficult to make a positive conclusion . there are barely any cases considering ultrasound - guided subclavian vein catheterization in pediatric patients , although one case using a 25 mm linear probe through the supraclavicular fossa to access the axillary vein , or supraclavicularly to access the venous confluence   has been reported . however , for this particular case , it is difficult to say that a genuine central venous line was placed because the axillary vein was accessed . also , a prolonged period of catheter placement in the supraclavicular fossa is prone to infection , because the catheter insertion point is close to the patients ' mouth , thus causing management issues . it is possible for the procedure to be carried out not only on the right side but also the left side , but a right - handed practitioner may be prone to difficulties , thus making handedness a problem . pirotte and veyckemans   are the only ones to report a case of ultrasound - guided subclavian vein catheterization through an infraclavicular approach in pediatric patients . however , because a 25 mm hockey stick probe ( hsp ) was used , anatomical structures were detectable in real - time in small children . however , in larger children , this is not possible , and the needle has to be inserted after confirming the subclavian vein is limited to the clavicular area by marking the skin , making it difficult to observe the entire process . on the other hand , a 40 mm linear probe was used in the current cases rather than the 25 mm hsp that pirotte et al . used , making it possible to precisely observe not only the subclavian vein but other surrounding structures in children weighing over 10 kg , as well as premature infants weighing approximately 1 kg , while being able to observe the entire process of central venous catheterization . this method was successful on its first attempt in 10 out of 11 patients , and resulted in no complications regarding insertion . due to its larger scanning range than the 25 mm hsp , the 40 mm probe provided more accurate scanning images of the surrounding structures , despite the posterior acoustic shadowing due to the clavicle . in conclusion , if the method proposed here is carried out by a skilled anesthesiologist who is familiar with subclavian vein catheterization in pediatric central venous catheterization , ultrasound - guided central venous catheter insertion can be useful for premature infants , whose anatomical structures are difficult to identify , as well as relatively larger infants weighing over 10 kg , without any major complications . however , because this case was not a planned prospective study , more research is needed to prove its superiority to catheterization by anatomical indications .