The study confirmed that the incidence of symptomatic CRVT among SICU inpatients was 9.89% and revealed that the independent risk factors of symptomatic CRVT included trauma, major surgery, and heart failure based on the SICU primary disease risk model (AUROC = 0.610).
Given the high risk of developing venous thromboembolism, hospital-acquired VTE is extremely high in ICU patients, but its incidence has been reported differently by various medical institutions. One study analyzed SICU patients with duplex sonography performed during CVC placement or within 7 days after CVC removal and found that fifty-nine CRVTs were diagnosed in 28% of patients15. Gibson, C. D. et al. retrospectively analyzed the occurrence of vein thrombosis among hospitalized patients in the medical ICU, and selected patients with suspected limb thrombosis for ultrasound examination. The incidence of thrombosis was 16%, and the catheter usage rate of patients with thrombosis was 55.26%. However, the incidence of symptomatic CRVT was not further analyzed16. Chen, Y. et al. studied symptomatic thrombosis associated with peripherally inserted CVC in cancer patients and found that the incidence of symptomatic CRVT was 6.7%17. The incidence of symptomatic CRVT in our study was 9.89%. The difference may be related to the study population and statistical methods.
The traumatically injured are at an especially high risk for VTE18-21. In the absence of pharmacologic prophylaxis, those with severe injuries have a risk of VTE that surpasses 50%22. Immediately after the injury, the delicate homeostasis balance of coagulation in the system is disturbed by the reduction of functional protein C, the reduction of antithrombin and the cessation of acute fibrinolysis, leading to the state of hypercoagulability23-25. The combination of endothelial and tissue injury, vascular stasis and hypercoagulability 26 represents a high risk factor for early VTE in this population, especially in patients with severe multiple trauma27,28. Hamada, S. R. et al. prospectively studied 153 patients with severe trauma from a SICU of a university level 1 trauma center and found that the prevalence of VTE was 30.7%. CVC was an independent risk factor for VTE occurrence in this group of cases (OR 4.39, 95% CI [1.1-29])27. Most of the wounds in the population in our study involved multiple injuries, including major compound injuries of head, neck, chest and/or abdomen. The incidence of symptomatic CRVT was 16.1%, which did not seem high. However, the VTE here did not include thrombosis unrelated to CVC.
Given that major surgery may result in unstable respiratory, circulatory and other organ functions, patients need to be admitted to SICU for life support after surgery. The major operations of the center mainly include abdominal surgery, cardiac surgery, open brain surgery and multiple injury repair surgery. These types of operations are characterized by long operation time, a large amount of blood loss, need for blood transfusion, and the need to be performed under general anesthesia, and all of these parameters contribute to the risk of venous thrombosis formation29,30. At present, clinical researchers in different surgical specialties, including general surgery31, orthopedics32, thoracic surgery33, urology34, tumor surgery35 and neurosurgery36, found that the incidence of VTE after major surgery is relatively high, ranging from 3.6% 31 to 21.3%36. They believe that major surgery is a risk factor for VTE and that active prevention is needed8. The current study population included 255 patients admitted to the SICU due to major surgery, among which 41 patients (13.9%) had SCRVT. Major surgery was an independent risk factor for symptomatic CRVT in this group.
Heart failure accounts for a high proportion of SICU inpatients, and symptomatic CRVT was noted in 16.2% (47/290) in patients admitted to ICU due to heart failure in this study. Basnet, S. et al. found that the incidence of heart failure associated with VTE increased yearly by analyzing inpatient with heart failure from 2000 to 201337. Wilson, T. J. et al. analyzed the risk factors for thrombosis associated with peripherally inserted CVC in inpatients and found that heart failure (OR, 2.62; 95% CI, 1.01-6.83) was associated with the occurrence of a CRVT38. Heart failure is characterized by a prothrombotic state, which not only increases the risk for cardioembolic events and ischemic stroke 39 but also increases the risk for deep venous thrombosis (DVT) and pulmonary embolism (PE), which together constitute VTE40. In a study of 13,728 subjects, Fanola, C. L. et al. reported that over a 22-year period, heart failure occurred in 2,696 (20%) patients, and 729 VTE events were identified. Heart failure was associated with an increased long-term risk of VTE (OR 4.39, 95% CI [2.58-3.80]) that was independent of multiple risk factors for venous thromboembolism41.
This study also noted that a long duration of CVC intubation42 and long endotracheal intubation16,18 could increase symptomatic CRVT occurrence in SICU patients. In this study population, anticoagulation therapy was insufficient due to anticoagulation contraindication, and the comparison of anticoagulation therapy between the two groups was statistically significant (P = 0.005), which may also increase the occurrence of symptomatic CRVT. Therefore, especially after major surgery8 or trauma26, patients should undergo active measures to prevent thrombosis, and anticoagulation drugs should be given if there is no anticoagulation contraindication. Otherwise, mechanical prophylaxis to prevent thrombus should be performed. In addition, this study also suggested that age, BMI, APACHE II score, length of ICU stay and other factors were significantly different in the comparison between the two groups, which was basically consistent with the results of previous studies12,16,17,43.
Our study has several limitations. First, it involved a single center and a relatively small number of patients. Second, this was a retrospective study performed using electronic medical records, and the study population was quite heterogeneous, which possibly introduced the potential for information bias. In addition, only symptomatic CRVT was analyzed in this study. Nonsymptomatic CRVT was not included in the analysis, which potentially resulted in the incidence of CRVT being greatly underestimated. Therefore, a multicenter, prospective randomized controlled study is necessary to further evaluate the risk factors associated with CRVT in patients in the SICU catheter-related thrombi disease.