Venous thromboembolism in intensive care patients

Point-of-care contrast enhanced lung ultrasound and COVID-19

OBJECTIVES

Bedside lung ultrasound has been indispensable during the coronavirus disease 2019 (COVID-19) pandemic, allowing us to rapidly assess critically unwell patients. We demonstrate the unique application of contrast-enhanced ultrasound with the aim of further understanding this disease.

METHODS

Patient demographics were recorded alongside recent cross-sectional imaging and inflammatory markers. Ultrasound was conducted by experienced operators in a portable setting. Conventional six-point lung ultrasound method was used to evaluate B-lines, small (subpleural) consolidation and the pleura. Areas of small consolidation were targeted after intravenous administration of ultrasound contrast.

RESULTS

The areas of small consolidations, a potential sign of pneumonia on B-mode lung ultrasound, usually enhance on contrast-enhanced ultrasound. Our study revealed these areas to be avascular, indicating an underlying thrombotic/infarction process. Findings were present in 100% of the patients we examined. We have also shown that the degree of infarction correlates with CT severity (r = 0.4) and inflammatory markers, and that these areas improve as patients recover.

CONCLUSIONS

We confirmed the theory of immune thrombus by identifying the presence of microthrombi in the lungs of 100% of our patients, despite 79% having had a recent negative CT pulmonary angiogram study. contrast-enhanced ultrasound can be utilised to add confidence to an uncertain COVID-19 diagnosis and for prognosticating and monitoring progress in confirmed COVID-19 patients. Contrast-enhanced ultrasound is clearly very different to CT, the gold standard, and while there are specific pathologies that can only be detected on CT, contrast-enhanced ultrasound has many advantages, most notability the ability to pick up microthrombi at the periphery of the lungs.

Deep Venous Thrombosis in COVID-19 Patients: A Cohort Analysis

Deep venous thrombosis (DVT) is a severe complication of coronavirus disease 2019 (COVID-19). The purpose of this study was to study the prevalence, risk factors, anticoagulant therapy and sex differences of DVT in patients with COVID-19. The enrolled 121 hospitalized non-ventilator patients were confirmed positive for COVID-19. All suspected patients received color Doppler ultrasound (US) to screen for DVT in both lower extremities. Multivariate logistic regression was performed to identify risk factors related to DVT in COVID-19 patients. DVT was found in 48% of the asymptomatic COVID-19 patients with an increased PADUA or Caprini index using US scanning. The multivariate logistic regression determined that age (OR, 1.05; p = .0306), C-reactive protein (CRP) (OR, 1.02; p = .0040), and baseline D-dimer (OR, 1.42; p = .0010) were risk factors among COVID-19 patients. Although the most common DVT location was infrapopliteal (classes I and II), higher mortality in DVT-COVID-19 patients was confirmed. DVT-COVID-19 patients presented significant increases in CRP, neutrophil count, and D-dimer throughout the whole inpatient period compared to non-DVT-COVID-19 patients. Although anticoagulation therapy accelerated the recovery of lymphocytopenia in DVT patients, men DVT-COVID-19 patients with anticoagulant therapy showed significant higher CRP and neutrophil count vs. lymphocyte count (N/L) ratio, but showed lower lymphocyte counts compared to women DVT-COVID-19 patients. DVT is common in COVID-19 patients with high-risk factors, especially for older age and higher CRP and baseline D-dimer populations. It is important to consider sex differences in anticoagulant therapy among DVT-COVID-19 patients.

Pulmonary Embolism in the Mechanically-Ventilated Critically Ill Patient: Is it Different?

Pulmonary embolism (PE) confers significant in-hospital morbidity and mortality, and critically ill patients remain at risk for venous thromboembolism despite thromboprophylaxis. Recognition of the clinical manifestations and immediate management of PE are of paramount importance. Despite diagnostic advances, PE is often undiagnosed and untreated in patients receiving mechanical ventilation, as these patients do not exhibit the common clinical features of the condition, making the diagnosis very challenging. Computed tomographic pulmonary angiography is probably the reference standard for the diagnosis of acute PE in the haemodynamically stable, ventilated patient. In the setting of circulatory collapse, bedside echocardiography may be used to risk stratify these patients, based on the presence or absence of right ventricular dysfunction, and guide further management. Treatment options include anticoagulation alone, anticoagulation plus thrombolysis, surgical or catheter embolectomy. Inotropes, vasopressors and pulmonary artery vasodilators may be considered after initial resuscitation of the right ventricle. Few studies have focused on estimating the prevalence of PE among mechanically-ventilated intensive care unit (ICU) patients and there is notable lack of data assessing predictive factors, prevention, diagnostic strategy and management of PE in the ICU setting.

Pulmonary embolism in intensive care unit: Predictive factors, clinical manifestations and outcome

OBJECTIVE:

To determine predictive factors, clinical and demographics characteristics of patients with pulmonary embolism (PE) in ICU, and to identify factors associated with poor outcome in the hospital and in the ICU.

METHODS:

During a four-year prospective study, a medical committee of six ICU physicians prospectively examined all available data for each patient in order to classify patients according to the level of clinical suspicion of pulmonary thromboembolism. During the study periods, all patients admitted to our ICU were classified into four groups. The first group includes all patients with confirmed PE; the second group includes some patients without clinical manifestations of PE; the third group includes patients with suspected and not confirmed PE and the fourth group includes all patients with only deep vein thromboses (DVTs) without suspicion of PE. The diagnosis of PE was confirmed either by a high-probability ventilation/perfusion (V/Q) scan or by a spiral computed tomography (CT) scan showing one or more filling defects in the pulmonary artery or in its branches. The diagnosis was also confirmed by echocardiography when a thrombus in the pulmonary artery was observed.

RESULTS:

During the study periods, 4408 patients were admitted in our ICU. The diagnosis of PE was confirmed in 87 patients (1.9%). The mean delay of development of PE was 7.8 ± 9.5 days. On the day of PE diagnosis, clinical examination showed that 50 patients (57.5%) were hypotensive, 63 (72.4%) have SIRS, 15 (17.2%) have clinical manifestations of DVT and 71 (81.6%) have respiratory distress requiring mechanical ventilation. In our study, intravenous unfractionated heparin was used in 81 cases (93.1%) and low molecular weight heparins were used in 4 cases (4.6%). The mean ICU stay was 20.2 ± 25.3 days and the mean hospital stay was 25.5 ± 25 days. The mortality rate in ICU was 47.1% and the in-hospital mortality rate was 52.9%. Multivariate analysis showed that factors associated with a poor prognosis in ICU are the use of norepinephrine and epinephrine. Furthermore, factors associated with in-hospital poor outcome in multivariate analysis were a number of organ failure associated with PE ≥ 3.

Moreover, comparison between patients with and without pe showed that predictive factors of pe are: acute medical illness, the presence of meningeal hemorrhage, the presence of spine fracture, hypoxemia with PaO₂/FiO₂ ratio <300 and the absence of pharmacological prevention of venous thromboembolism.

CONCLUSION:

Despite the high frequency of DVT in critically ill patients, symptomatic PE remains not frequently observed, because systematic screening is not performed. Pulmonary embolism is associated with a high ICU and in-hospital mortality rate. Predictive factors of PE are acute medical illness, the presence of meningeal hemorrhage, the presence of spine fracture, hypoxemia with PaO₂/FiO₂ < 300 and the absence of pharmacological prevention of venous thromboembolism.

Acquired thrombotic risk factors in the critical care setting

Acquired thrombotic risk factors include a variety of noninherited clinical conditions that can predispose an individual to an increased risk for venous thromboembolism. For patients in a critical care setting, certain acquired risk factors represent chronic conditions that the patients may have had before the current acute illness (e.g., malignancy, various cardiovascular risk factors, certain medications), whereas others may be directly related to the reason the patient is in an intensive care unit or the patient's management there (e.g., postoperative state, trauma, indwelling vascular access, certain medications). Optimal thromboprophylactic strategies depend on individual patient risk profiles including an assessment of the specific clinical setting. Treatment for patients with acquired thrombotic risk factors includes anticoagulant therapy and, if possible, resolution of the acquired risk factor(s). Heparin-induced thrombocytopenia represents a unique clinical situation in which all sources of heparin must be discontinued and the patient started on an alternative anticoagulant (e.g., a direct thrombin inhibitor) in the acute setting. The duration of anticoagulant therapy would vary depending on the specific clinical setting.

A critical review of thromboembolic complications associated with central venous catheters

PURPOSE

Central venous catheters (CVC) are commonly used in critical care. While thrombosis is a well-recognized and frequent complication associated with their use, CVC-related thromboembolic complications, including pulmonary embolism (PE) and right heart thromboembolism (RHTE), occur less frequently and often evade diagnosis. Little information exists to guide clinicians in the diagnosis and management of CVC-related thromboembolic complications.

SOURCE

We critically review and synthesize the literature highlighting the incidence of CVC-related thrombosis. We highlight the risk for developing thromboembolic complications and provide approaches to diagnosing and managing RHTE.

PRINCIPLE FINDINGS

The incidence of CVC-related thrombosis varies depending on patient, site, instrument, and infusate-related factors. Central venous catheters-related thrombosis represents an important source of morbidity and mortality for affected patients. Pulmonary embolism occurs in approximately 15% of patients with CVC-related upper extremity deep venous thrombosis (UEDVT). More frequent use of transesophageal echocardiography, in patients with suspected and confirmed PE, has resulted in increased detection of RHTE. While it is recognized that the occurrence of RHTE, in association with PE, increases mortality, the optimal strategy for their management has not been established in a clinical trial.

CONCLUSION

Central venous catheter-related thrombosis occurs frequently and represents an important source of morbidity and mortality for affected patients. Our review supports that surgery and thrombolysis have both been demonstrated to enhance survival in patients with RHTE and PE. However, important patient, clot, and institutional considerations mandate that treatment for patients with RHTE and PE be individualized.

A survey of thromboprophylaxis management in patients with major trauma

BACKGROUND

Venous thromboembolism (VTE) is a common life-threatening complication of major trauma. Although clinical guidelines clearly suggest routine VTE prevention with low-molecular-weight heparin (LMWH) in this specific group of patients, there is still a lack of strong recommendations regarding the timing and the modality of heparin administration and the role of mechanical prophylaxis. We tested the hypothesis that there is significant practice variation in thromboprophylaxis management of patients with major trauma among intensive care unit (ICU) specialists.

METHODS

Two hundred Italian ICU specialists, representing 200 ICU throughout the country, were contacted by telephone and were asked (1) whether they routinely prescribe pharmacological antithrombotic prophylaxis in patients with major trauma, whether prophylaxis is prescribed to all patients or to selected patients, and the type of prophylaxis and the timing of administration and (2) whether they recommend physical prevention, whether this is prescribed to all patients or to selected patients, and the type of physical prophylaxis.

RESULTS

In patients with major trauma, 85% of the interviewed ICU specialists answered that they prescribe pharmacological prophylaxis for VTE. 37.6% of them prescribe prophylaxis only to selected patients based on the level of risk, 87.7% prescribe low-molecular-weight heparin, and 42.4% start prophylaxis immediately after hospitalization. Only 61% of the interviewed specialists prescribe physical prophylaxis; 82.8% of them use elastic stockings, 9.8% intermittent pneumatic compression, and 7.4% other mechanical devices. Physical prophylaxis is prescribed to all patients by 41%, and by 59% only in case of contraindication to pharmacological prevention. Inferior vena cava (IVC) filter insertion is considered by 47% when anticoagulation is contraindicated; 91.4% of them recommend the IVC filter only if deep vein thrombosis (DVT) has been diagnosed.

CONCLUSIONS

Even when there are clinical guidelines, prescription of VTE prevention in patients with major trauma is underused and timing and modality of prophylaxis are rather heterogeneous. When anticoagulation is contraindicated, IVC filters are commonly recommended only in the presence of DVT.