Catheter-associated thrombosis (CRT) is a frequent complication of central venous catheterization. It is often assessed by point of care ultrasound in critically ill patients.

A multicenter clinical study led by Prof. LU Qin, academic chair, and Prof. ZHANG Mao, chair of SAHZU Emergency Medicine, has looked into the occurrence and evolution of venous catheter-related thrombosis in critically ill patients using point-of-care ultrasound. The study was recently published in Intensive Care Medicine entitled Daily Point-of-Care Ultrasound-Assessment of Central Venous Catheter-related Thrombosis in Critically Ill Patients: A Prospective Multicenter Study.

The study result shows that CRT can occur as soon as the central venous catheter (CVC) is placed and mostly during the first week following catheterization. Fifty percent of the thromboses are small (<5 mm in diameter), and nearly one-third are greater than 7 mm in diameter. The thromboses are usually stable, and some may gradually become smaller and disappear after catheter removal.

CVC placement is one of the routine procedures for critically ill patients. Catheter-related complications have thus received much attention, including the most common one --- central venous catheter-associated thrombosis (CRT) which could lead to serious consequences such as pulmonary embolism. However, current researches on CRT are either single-center or retrospective, centering around cancer or pediatric patients, or mainly focusing on the central venous catheters placed through peripheral veins. Less studies examine the clinical significance of CRT in critically ill patients.

Moreover, in clinical setting or according to related researches, CRT tends to be evaluated only before CVC removal or after the onset of symptoms is observed, which could result in a delay in the diagnosis of CRT. Venous thrombosis is the result of blood stasis, endothelial injury, or a hypercoagulable state of blood, and the presence of these risk factors at the time of CVC insertion may cause CRT to happen earlier than expected. The timing of CRT onset remain unknown yet, and there is a lack of studies evaluating the change in size of CRT over time before and after CVC removal. Therefore, the goal of this prospective multicenter study is to evaluate the occurrence and evolution of CRT from CVC insertion to removal with daily point-of-care ultrasound assessment.

The study was conducted in 28 intensive care units (ICUs). Duplex ultrasound was performed daily from CVC insertion until at least 3 days after CVC removal or before patient discharge from the ICU to detect CRT and to follow its progression. CRT diameter and length were measured and diameter > 7 mm was considered extensive.

The study included 1262 patients. The incidence of CRT was 16.9% (95% confidence interval 14.8-18.9%). CRT was most commonly found in the internal jugular vein. The median time from CVC insertion to CRT onset was 4 (2-7) days, and 12% of CRTs occurred on the first day and 82% within 7 days of CVC insertion. CRT diameters > 5 mm and > 7 mm were found in 48% and 30% of thromboses. Over a 7-day follow-up, CRT diameter remained stable when the CVC was in place, whereas it gradually decreased after CVC removal. The ICU length of stay was longer in patients with CRT than in those without CRT, and the mortality was not different.

In conclusion, CRT is a frequent complication. It can occur as soon as the CVC is placed and mostly during the first week following catheterization. Half of the thromboses are small but one-third are extensive. They are often non-progressive and may be resolved after CVC removal.     

More about SAHZU Emergency Medicine:

1984: One of the first Emergency Medicine Departments in China

1987: Founder of Chinese Society of Emergency Medicine

1987: Established the first Emergency Intensive Care Unit

1990: Founder of Chinese Journal of Emergency Medicine

1994: One of the first to establish a hospital-wide trauma treatment model led by the emergency department with efficient multidisciplinary collaboration

2005: Officially launched air medical services

2010: Founder of the SCI-indexed World Journal of Emergency Medicine

2012: Recognized as the National Key Clinical Specialty

2017: First in China to carry out a series of research on the application of 5G in emergency medicine

2018: First in China to formally propose and build a resuscitation center

2019: Recognized as the State-level regional center of excellence of trauma

2021: Recognized as Key national emergency medicine residency training program

2022: Recognized as National Emergency Medical Rescue Base

Source: The Second Affiliated Hospital, Zhejiang University School of Medicine (SAHZU)