A significant association between physical restraint and the development of venous thromboembolism in psychiatric patients

Recently, the systematic review about venous thromboembolism (VTE) prophylaxis in hospitalized adult nonsurgical patients has been reported [1], bringing lively and controversial discussions. The prophylaxis of VTE is a very important subject for also hospitalized psychiatric patients. We have certified that we comply with the Principles of Ethical Publishing in the International Journal of Cardiology [2]. To elucidate the risk factors for the development of VTE in hospitalized psychiatric patients, we analyzed patients who developed VTE which was confirmed by ultrasound and/or contrast enhanced computed tomography during recent five years (from April 2007 to September 2011) in our hospital, using the inpatient medical records. We studied age, sex, and frequency of the existence of reported risk factors for VTE [3] and physical restraint in VTE patients with and without psychiatric diseases. We detected 48 VTE patients. There were 31 patients with psychiatric diseases and 17 patients without psychiatric diseases. The differences in age, sex, and frequency of the existence of reported risk factors for VTE and physical restraint in VTE patients with and without psychiatric diseases were shown in Table 1 [3]. Age of VTE patients with psychiatric diseases was significantly lower than that of VTE patients without psychiatric diseases. There were no significant differences in frequency of reported risk factors for VTE between patients with and without psychiatric diseases. The frequencyof physical restraintwas significantly higher in VTE patients with psychiatric diseases than patients without psychiatric diseases. A number of studies have suggested a significant association between increasing age and elevated incidence of VTE [3]. Risk for VTE approximately doubles with each subsequent decade. In our study, VTE patients with psychiatric diseases were significantly younger than VTE patients without psychiatric diseases, suggesting that an association between aging and the development of VTE is weaker in patients with psychiatric diseases than patients without psychiatric diseases. Present study demonstrated a significantly higher frequency of physical restraint in patients with psychiatric diseases as compared with patients without psychiatric diseases, indicating a significant association between physical restraint and the development of VTE in psychiatric patients. Virchow R proposed that thrombosis was the result of at least 1 of 3 underlying etiologic factors: vascular endothelial damage, stasis of blood flow, and hypercoagulability. According to his description, there has been interest in the development of animal models of thrombosis to mimic the human condition. Therefore, the inferior vena cava (IVC) ligationmodel and the IVC stenosis model have been developed as the mouse models of VTE [4]. Studies in the IVC ligation rats suggest that after IVC ligation a combination of stasisinduced vein wall injury and enhanced tissue factor expression in endothelial cells and leukocytes produce thrombosis, and the IVC stenosis model combined external compression with a reduction in blood flow to produce laminar thrombosis [5,6]. Physical restraint may induce external compression and a reduction in blood flow of vein, and also a stasis-induced vein wall injury and enhanced tissue factor expression in endothelial cells, resulting in thrombosis formation. Physical restraint also leads to immobility strongly associated with the development of VTE [3]. In conclusion, physical restraint is significantly associated with the development of VTE in psychiatric patients.