a 74-year - old man with diabetes mellitus ( dm ) , hypertension ( htn ) , and atrial fibrillation ( af ) presented to the emergency room with sudden onset of left leg pain due to superficial femoral artery ( sfa ) thrombosis . soon after arrival , he was scheduled to undergo emergency thrombectomy . he had been receiving metformin ( 850 mg / day ) for dm , olmesartan ( 40 mg / day ) for htn , and warfarin ( 3 mg / day ) and digoxin ( 0.25 mg / day ) for af . in the preoperative evaluation , chest radiography showed cardiomegaly , while electrocardiogram showed the presence of atrial fibrillation . prothrombin time ( pt ) and international normalized ratio ( inr ) were within the normal range ( pt , 10.5 sec ; inr , 0.92 ) , even though the patient was on warfarin therapy . a central venous catheter ( cvc , 7-fr double lumen catheter ) was inserted via the left subclavian vein using the landmark technique under general anesthesia . in the first attempt , the needle was passaged twice without aspiration of blood . in the second attempt , after positioning the needle tip , blood was successfully aspirated through the needle in the third passage to confirm its location , followed by successful insertion of the cvc . subsequently , 5,000 u of heparin was administered 5 minutes before incision of the femoral artery for thrombectomy . the thrombectomy was performed uneventfully with an operative time of 90 minutes . the arterial blood gas analysis ( abga ) during surgery showed the following : ph , 7.337 ; paco2 , 43.4 mmhg ; pao2 , 112 mmhg ; and oxygen saturation , 98% . the estimated blood loss and urine output were approximately 100 ml and 300 ml , respectively . the patient was then transferred to intensive care unit ( icu ) for close monitoring . postoperatively , continuous infusion of heparin ( 1,000 u / hr ) via cvc was maintained . the infusion rate was adjusted under the activated partial thromboplastin time of 80 - 120 sec . a portable chest radiograph showed proper position of the cvc in the superior vena cava and no interval changes ( fig . consequently , cvc was removed and compressed for 30 minutes . at 15 hr postoperation , when the patient 's hemodynamic values were stable and the dorsalis pedis artery was palpable , he was transferred to the general ward . on the first postoperative day ( pod ) , the patient was started on warfarin ( 4 mg / day ) . a chest radiograph at this point showed no remarkable findings except a slightly increased opacity in the left anterior chest wall ( fig . however , 10 mg of furosemide was administered when the urine output decreased , even though the fluid intake was adequate . on pod 2 , the patient experienced syncope on his way to bathroom , possibly due to orthostatic hypotension . his vital signs were as follows : blood pressure ( bp ) , 80/50 mmhg ; heart rate ( hr ) , 142 bpm ; and spo2 , 85% . subsequently , the patient was transferred to the icu and a diagnostic workup was performed . the abga revealed severe metabolic acidosis ( ph , 6.93 ; paco2 , 28 mmhg ; pao2 , 164 mmhg ; hco3 , 5.9 mm ; oxygen saturation , 98% ) , and the patient received 15 l / min oxygen via a reservoir mask . his hb level decreased from 14.3 g / dl to 9.6 g / dl . after transferring him to the icu , volume resuscitation was initiated with normal saline and packed red blood cells ( rbcs ) . however , inotropes were not administered to the patient , because his bp increased to 90/50 mmhg after volume resuscitation . his hemodynamic values returned to normal with fluid therapy ( 4,300 ml of normal saline ) and transfusion ( 3 units of packed rbc ) . a computed tomography ( ct ) revealed a huge hematoma between the pectoralis major and minor muscles on the left chest wall ( fig . however , an angiogram showed no detectable extravasations from the branches of the left subclavian artery . laboratory tests revealed multiple organ dysfunction syndrome including respiratory failure , ischemic hepatitis , and acute kidney injury due to hemorrhagic shock . the levels of serum aspartate aminotransferase ( ast ) , alanine aminotransferase ( alt ) , lactate dehydrogenase ( ldh ) , and creatinine ( cr ) were remarkably elevated : ast , 2,800 iu / l ; alt , 2,100 iu / l ; ldh , 6,000 iu / l ; cr , 3.40 mg / dl . continuous renal replacement therapy ( crrt ) was started on pod 2 , and tracheal intubation was performed on pod 3 when an ineffective breathing pattern was observed and the spo2 decreased to 90% . mechanical ventilation was applied without any intervention to the hematoma , such as insertion of the wound , use of a suction tube , or surgical removal . the patient was extubated on pod 12 , and crrt was stopped on pod 13 . the patient was transferred to the general ward on pod 20 , and the hospital course was uneventful thereafter . central venous catheterization can be life saving , but can also cause complications such as pneumothorax , inadvertent puncture or perforation of great vessels , air embolism , catheter malposition , infection , and thrombus formation . in this report , we describe a case of hemorrhagic shock caused by a huge hematoma after insertion of a cvc without apparent arterial puncture in a patient on anticoagulation therapy . signs such as the decrease in urine output , orthostatic hypotension , compensatory increase of hr , and aggravation of af were associated with hypovolemia caused by hemorrhage , which was the cause of shock . however , we could not entirely rule out the possibility of obstructive shock due to the mass effect of the huge hematoma . complication rates during central venous catheterization have been significantly associated with the number of needle passes . successful catheterization at the first attempt limits the risk of immediate complications such as arterial puncture and pneumothorax , to less than 1% . in our case , however , we did not note any signs associated with complications , such as pulsatile flow or air bubbles , during the procedure . similarly , there were no abnormal findings such as extravasations of subclavian artery on the angiogram . nonetheless , we could not completely rule out the possibility of arterial puncture around the subclavian region , because ct showed that the chest wall was severely compressed by the huge hematoma . furthermore , small swelling and oozing were also observed at the insertion site after surgery . therefore , the possibility of arterial puncture influenced the treatment decision for the hematoma in our case . however , we did not use a suction device or surgical removal for hematoma management because we assumed that an undetectable vessel injury might have caused the hematoma , leading to compression of the chest wall . in addition , we believed that respiratory failure might result from multiorgan dysfunction syndrome caused by hemorrhagic shock , and not from compression of chest wall due to the huge hematoma . therefore , to reduce the complications associated with insertion of a cvc , ultrasound - guided central venous catheterization is strongly recommended . it could result in an initial high success rate with fewer needle passage attempts , faster access , and a reduction in mechanical complications . internal jugular vein ( ijv ) and subclavian vein ( scv ) catheterization have a similar overall risk of mechanical complications such as arterial puncture , hematoma , and pneumothorax . however , scv catheterization is more likely to be complicated by pneumothorax or hemothorax , whereas ijv catheterization is mostly associated with arterial puncture . in contrast , femoral vein ( fv ) catheterization has a higher incidence of mechanical complications than scv or ijv . the policy for central venous catheterization in our department advocates the scv approach , because it is associated with a lower infection rate and better compliance than other approaches . however , it is difficult to apply pressure around the scv as compared to the ijv or fv , which are easily compressible access sites that can be used when an arterial puncture or hematoma occurs . therefore , the scv catheterization technique should be particularly avoided , especially for patients on anticoagulation therapy or with coagulation disorders . arterial puncture , hematoma , and pneumothorax are the most common complications during central venous catheterization . the incidences of arterial puncture and hematoma are 3.1 - 4.9% and 1.2 - 2.1% , respectively , in patients undergoing central venous catheterization . this technique can lead to substantial morbidity , although these complications are usually self - limiting . furthermore , other serious complications , including hemothorax requiring closed thoracostomy or hemorrhage requiring transfusion , show evident symptoms such as dyspnea and severe hypotension , and their progression is rapid ; therefore , they are easily identified at the early stage . in our case , bleeding did not spread into the pleural space but between the pectoralis major and minor muscles in the left chest wall , and a huge hematoma was formed . in addition , the hematoma was too deep to cause an evident change in skin color or swelling , and the patient did not present any symptoms that could be considered serious complications . the abnormal finding of a small increased opacity in the left chest wall was dismissed as inconsequential , because the patient did not have any remarkable changes in hemodynamic values or laboratory findings . anticoagulation therapy during the perioperative period might also have influenced the formation of a huge hematoma . reported that hemorrhagic shock is associated with a huge hematoma after catheterization in patients with anticoagulant therapy . in our case , there was a minor association between warfarin therapy , which was administered preoperatively , and formation of the hematoma , as the value of pt ( inr ) was within the normal range . however , administration of heparin during the intraoperative and postoperative period might also be linked closely to the formation of a huge hematoma , especially if vessel injury occurs during insertion of cvc . in conclusion , it is often difficult to detect serious complication such as concealed hematoma after central venous catheterization . therefore , when insertion of a cvc is performed in patients requiring anticoagulant therapy , the possibility of massive bleeding must be considered and particular attention must be given to the care of such patients . additionally , it might be helpful to prevent complications by choosing a proper site of insertion and ultrasound - guided technique .
a 74-year - old man who had been receiving warfarin for atrial fibrillation , underwent emergency thrombectomy . a central venous catheter ( cvc ) was inserted via the left subclavian vein , and heparin was administered to prevent preoperative and postoperative thrombotic events . 
 after an uneventful thrombectomy , the patient was transferred to the intensive care unit ( icu ) . on the second postoperative day , 
 the patient developed syncope and his blood pressure and oxygen saturation decreased . 
 a computed tomography ( ct ) revealed a huge hematoma under the pectoralis major muscle . 
 the patient was then treated with continuous renal replacement therapy and mechanical ventilation for multiorgan dysfunction syndrome , which developed due to hemorrhagic shock in the icu . 
 these findings suggest that when a cvc is inserted in patients requiring anticoagulant therapy , the possible risk of excessive bleeding must be carefully considered . 
 further , choosing a proper insertion site and performing an ultrasound - guided aspiration may be helpful in preventing these complications .