Extended Out-of-hospital Low-molecular-weight Heparin Prophylaxis Against DVT and PE in Patients Undergoing Major Lung Resection

Postoperative venous thromboembolism (VTE) is a significant health-care problem, resulting in significant morbidity, mortality and resource utilization. The true incidence is unknown, and may range from 1% to 15%. The latest American College of Chest Physicians (ACCP) guidelines on VTE prevention clearly outlines the perioperative thromboprophylaxis regiments for specific surgical populations. Specifically for patients undergoing orthopaedic procedures, such as total hip replacement, there is strong Grade 1A evidence for the use of extended thromboprophylaxis. For other surgical subgroups such as vascular and thoracic surgery, the evidence is less clear.

Therefore at the current time, the clinical practice of VTE prophylaxis in thoracic surgery includes administration of unfractionated or low molecular weight heparin starting at the perioperative period and finishing at the time of patients' discharge. Prolonged thromboprophylaxis in orthopaedic surgery beyond 10 days and up to 35 days has become the standard of care and has Grade 1A recommendations from ACCP. This approach has never been tested or validated in thoracic surgery, where major lung resection exposes the patient to an increased VTE risk not only due to the surgical stress and existence of malignancy, but also due to direct in-situ vascular injury secondary to resection of pulmonary arterial branches during the lung resection. Hence, there is a clear need to systematically evaluate the incidence of VTE after resection of lung malignancies and to evaluate the role of extended VTE prophylaxis in preventing DVT and pulmonary embolus (PE) after those major lung resections.

The study will involve patients undergoing sub-lobar resection, lobectomy, bilobectomy or pneumonectomy for lung cancer or metastatic lung disease at St. Joseph's Healthcare Hamilton, a regional tertiary thoracic surgery program with more than 350 major lung resections performed within the institution annually, as well as the University Health Network's Toronto General Hospital. The study will evaluate the incidence of post-operative venous thromboembolism (VTE) and will include 150 consecutively recruited patients. Study interventions will include Computed Tomography with pulmonary embolus (PE) protocol and bilateral extended leg Doppler Ultrasound for the detection of Deep Vein Thrombosis 30 days post-surgery.

In summary, this study is aimed at evaluating, for the first time in a prospective manner, the actual incidence of DVT and PE in patients undergoing major lung resections for malignancies. The knowledge gained in this study will be used to inform a future investigation involving an RCT to compare current post-operative thromboprophylaxis with an extended 30-day prophylaxis protocol with the hope of providing an evidence-based practice change in VTE prophylaxis care for this high risk population.

Patient Inclusion Criteria

• At least 18 years of age
• Either gender
• Diagnosed with resectable lung cancer or metastatic lung disease eligible to complete metastasectomy
• Undergoing one of the following surgeries: Segmentectomy, wedge resection, lobectomy, bilobectomy or pneumonectomy
• Competent to understand and sign consent documents

Patient Exclusion Criteria

• Known allergic or anaphylactic reaction to contrast dye, heparin or low molecular weight heparin (LMWH)
• Under current anticoagulation for venous thromboembolism or other medical conditions
• Known renal impairment, defined as creatinine clearance value of less than 55ml/min/m2 as calculated by the Cockroft-Gault method
• History of, or ongoing liver disease, manifested as ascites or previous peritoneal tapping for ascites
• Pregnant or planning to become pregnant
• Diagnosed or treated for VTE in the past 3 months prior to surgery
• Present or previous increase risk of haemorrhage
• History of previous HIT (heparin induced thrombocytopenia)
• Platelet count must be below 75,000
• Previously inserted Inferior Vena Cava Filter (IVC) filter.