Ultrasound Screening for Thrombus in a Previously Cannulated Vein – A Sine Qua Non in All Trauma Patients!

INTRODUCTION

Catheter-related thrombosis (CRT) is a relatively common complication of central venous catheter (CVC) insertion, with reported incidence varying from 5% to 18%.¹ Many factors contribute to the development of CRT, which include the presence of polytrauma, immobilisation, multiple surgical procedures, and the presence of CVC, including the type of infusions administered, location of the tip, frequency of blood withdrawal and flushing of the line. Current data show that CVC placement carries the highest risk, followed by malignancy, ovarian hyperstimulation syndrome, sepsis, polytrauma, especially head and neck trauma, IV drug abuse, and pacemaker placement.¹ CVC insertion is frequent in polytrauma patients. The majority of CRT patients are asymptomatic, which can make their identification difficult.

CASE REPORT

We present an image of a 36-year-old female with a history of road traffic accidents who sustained blunt trauma to the abdomen and chest. Due to difficult peripheral intravenous access, central venous access was placed in the right internal jugular vein (IJV) under ultrasound (US) guidance for exploratory laparotomy. One month later, the patient was scheduled for an exploration of the sinus tract over the abdomen. The patient had left the IJV CVC in situ. All three ports of the CVC were aspirated to check the backflow of blood, but none were functioning. Subsequently, US scanning was done on the right IJV for placing the CVC, which revealed the presence of a thrombus [Figure 1 and Video 1]. Since peripheral intravenous access was difficult, the left femoral vein was cannulated. The procedure was uneventful.

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Figure 1:

Red arrow showing the presence of thrombus in the right internal jugular vein.

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DISCUSSION

Polytrauma patients experience harsh shifts in their physiologic milieu with the presence of all components of the Virchow triad for thrombosis – venous stasis, endothelial injury, and a hypercoagulable state. The sluggish blood flow during shock and immobilisation, vessel trauma associated with CVC placement, and hypercoagulability due to tissue injury predispose them to thrombus formation. Patients with an injury severity score of 9 reported deep vein thrombosis (DVT) even while on prophylactic anticoagulation. CRT is common in the intensive care unit (ICU), and the presence of trauma leading to frequent surgeries contributes further.²

Vascular ultrasonography (USG) helps in the non-invasive bedside diagnosis of CVC-related thrombosis. USG detects thrombus in the lumen in axial view and, when scanned longitudinally, reveals the extent of the thrombus through the length of the vein. In the absence of a visible thrombus, vein compressibility should be checked, which is 96% sensitive for IJV thrombus and approaches 100% if colour flow Doppler is used.³

When a thrombus is suspected or seen, checks on the subclavian and brachiocephalic veins should be performed because they are in continuity. In this regard, it is important to note that the subclavian and brachiocephalic veins are incompressible; hence, diagnosis by USG relies solely on visualisation of a hyperechoic thrombus intraluminally or indirectly by observing the absence of flow. When USG is inconclusive, computed tomography or magnetic resonance imaging helps in the diagnosis of thrombus in these veins, which are intra-thoracic and associated with a high likelihood of venous thromboembolism.

Pulmonary embolism (PE) is the most common and dreaded complication of an IJV thrombus, with an estimated occurrence ranging up to 36%.⁴ Hence, upper extremity DVTs (UEDVTs) or an isolated IJV thrombus are not benign findings and require anticoagulant therapy as with lower extremity DVTs (LEDVTs). Often, IJV thrombi do not cause symptoms and may go unscreened and untreated, resulting in sudden death from a ‘silent’ PE. Mortality rates are similar to those of LEDVTs.⁵ Another important complication, which is not as common, is when the thrombus is infected and travels as a septic embolus to the lungs.

CRT in polytrauma patients who are subjected to multiple surgeries is not entirely preventable, but practices that reduce the odds should be employed wherever possible. Pre-procedure scanning of large central veins before placing a CVC in the operating room when time permits is essential. Infection prevention is of paramount importance to avoid thrombus infection. The CVC tip should be placed at the cavoatrial junction to avoid turbulent flow that may result in thrombosis. Saline flushing of lines at regular intervals, using the minimum number of lumens as necessary, and limiting the number of blood withdrawals through the catheter are some of the other measures. The routine use of low-molecular-weight heparin to prevent CRT in a patient with CVC is not recommended since it does not reduce thrombosis rates.

CONCLUSION

With better ICU care and increased accessibility to CVCs, the incidence of CRT is also increasing. Rather than dismissing it as a known complication not calling for treatment, we recommend that trauma patients be screened for UEDVTs and LEDVTs alike, especially during ICU stays and operations, even when receiving thromboprophylaxis.