A PT’s Guide to Preventing Deep Vein Thrombosis

A PT’s Guide to Preventing Deep Vein Thrombosis

Physical therapists play a critical role in identifying and preventing deep vein thrombosis in at-risk patients.

A 36-year-old female patient receives treatment at a physical therapy clinic for lymphedema management of her right upper extremity secondary to a recent mastectomy. One morning, she presents with complaints of sudden swelling and tenderness in her upper left extremity. She denies any incident of injury and just returned from a flight the previous day.

Across town, a physical therapist working in acute rehabilitation notes calf swelling and significant pitting edema in the left lower extremity of a patient who recently underwent a total hip replacement. Should the therapist continue with the PT treatment? Is it appropriate to refer patients to their attending physicians?

These patients were correctly referred to physicians who ordered duplex doppler ultrasounds for the involved extremities. Both patients were diagnosed with deep vein thrombosis and started on appropriate treatment. Without suitable PT intervention and referral to another provider, these patients may have faced potential morbidity or mortality.

What is deep vein thrombosis?

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are both considered venous thromboembolism (VTE).

DVT is defined as "blood clots in the pelvic, leg or major upper-extremity veins." These clots can dislodge from the veins, travel through the heart and settle in the lung arteries, causing potentially deadly PEs. This disorder is often "silent" and can imitate other common conditions such as heart attack, pneumonia and anxiety. Their effects encompass a wide spectrum, from minor to fatal.

An estimated 300,000 people are hospitalized annually in the United States for DVT. This is especially significant, as up to 75 percent of cases of DVT remain obscure and do not come to medical attention.

What causes a DVT?

Thrombosis is a naturally occurring physiologic process. Normally, a physiologic balance is present between factors that promote and delay coagulation, or blood clotting. A disruption in this equilibrium may result in the coagulation process occurring at an inopportune time, location or in an excessive manner. Conversely, failure of the normal coagulation mechanism may lead to hemorrhage.

The nature of orthopedic illnesses and diseases, trauma and surgical repair, or replacement of hip and knee joints predisposes patients to the incidence of VTE disease. These complications are predictable and are the result of modifications to the natural equilibrium mechanisms in various disease states. Risk factors for VTE include patients with diagnoses such as cardiac disease, respiratory distress, irritable bowel syndrome, kidney disease, inherited/acquired thrombophilia or a recent cerebrovascular accident.

However, DVT may also occur in patients with malignancy and those undergoing treatment, individuals on estrogen-based birth control, and those who have experienced prolonged immobilization from surgery or a recent flight. Additionally, women during pregnancy or in the postpartum period are at greater risk.

Pulmonary embolism is estimated to be responsible for about 150,000 deaths per year, representing 5 percent of all perioperative mortality. DVT is hypothesized to be the source of 90 percent of acute pulmonary emboli. Experts estimate that 2 to 3 percent of patients undergoing total hip arthroplasty and 4 to 7 percent of patients undergoing surgery for hip fracture suffer nonfatal PEs.

Recommended course: Pulmonary Conditions – Pathophysiology, Diagnostic Tests and Procedures, and Treatment

Prevention and awareness are the best strategies to combat VTE. Until recently, only half of Americans had adequate education about the disease. Without the vital knowledge of DVT as a medical problem, the public was unable to engage health care providers to discuss lifestyle changes and comprehensive measures that usually succeed in preventing this illness.

Preventing deep vein thrombosis and other VTEs

Lifestyle changes. The most prevalent lifestyle risk factors for this disease are the same challenges that permeate Western society: obesity, inactivity and smoking. The first line of defense in DVT prevention is educating patients about the importance of these lifestyle changes. Encouraging patients to participate in structured weight loss programs, educating on available resources for smoking cessation, and reviewing the benefits of 30 minutes of moderate activity daily will empower patients to prevent this disease.

Mechanical measures. Graduated elastic compression stockings are adequate for patients at low risk for DVT. Vascular compression stockings maintain their elasticity for three months. Patients should change these stockings regularly. Pneumatic compression boots also help patients who are hospitalized or homebound.

Pharmacological options. For patients at a greater risk of developing DVT, a daily self-injection of a low fixed dose of low-molecular weight heparin or fondaparinux is efficient and safe. Oral anticoagulation with warfarin is used primarily for patients undergoing orthopedic surgery. Warfarin requires careful management and constant collaboration between the patient and the health care provider. Warfarin is administered once daily. The dose varies in order to maintain within a target range. Clinicians can use a blood test, the International Normalized Ratio (INR), to assess the appropriate dosage for the patient.

One baby aspirin daily for patients not on anticoagulants is occasionally recommended to prevent DVT. However, aspirin on its own, although effective for reducing the risk of heart attack or stroke, is not very effective for preventing deep vein thrombosis.

Treating a DVT

Screening for DVT includes the D-dimer assay test, compression ultrasonography, duplex doppler ultrasonography, venography and MR venography. Clinicians can diagnose a PE on subjective symptoms and physical examination results. Complaints may include shortness of breath, persistent tachycardia and chest pain.

Exams to confirm PE may include electrocardiography, pulse oximetry, ventilation/perfusion lung scanning, arterial blood gases, spiral CT scans, and pulmonary angiography. Clinicians consider the latter to be the gold standard.

The failure rate of prevention strategies is less than 10 percent. If preventive efforts are not successful, the cornerstone of treatment is intensive anticoagulation, administered in doses higher than those used for prevention. Clinicians can place an inferior vena cava filter on a temporary or permanent basis in order to prevent emboli from reaching the lungs.

PT interventions for patients with DVTs

Historically, clinicians placed patients with active DVTs on bedrest from 7 to 10 days. The theory was that limb movements may provoke a PE. Research indicates that early ambulation with appropriate anticoagulation medication and compression garments appears to be effective in preventing deep vein thrombosis (DVT) and pulmonary embolism (PE)

Those patients who walk early may experience decreased pain and edema, improved muscle strength, and less deleterious effects of bedrest. However, the physician and PT must evaluate and assess the patient's medical history and symptoms to determine when safe ambulation should occur.

The physical therapist's role

In acute and sub-acute settings, PTs treat patients diagnosed with conditions that predispose them to VTE. Because PTs in this environment treat patients daily, they may be more sensitive to subtle changes that occur with the edema or tenderness in a patient's lower extremity. These PTs have greater access to nurses, surgeons and attending physicians who can order diagnostic tests to rule out DVT.

However, it may be more difficult to identify and assess DVT in patients while treating in the outpatient setting. Research demonstrates that PTs may not properly identify the signs and symptoms of DVT and refer the patient back to the physician as indicated.

Outpatient PTs function as more autonomous practitioners. They need to listen to a patient's subjective complaints, review their past medical history, and analyze physical examination findings. At this stage of healing, patients may see a PT several times a week and visit a physician intermittently for follow-up care. This places a greater responsibility on PTs to accurately assess the possibility of DVT and refer to the physician.

The clinician's decision rule

One valuable tool that PTs can use is the clinical decision rule (CDR) for DVT probability devised by Wells and colleagues. The CDR assists PTs in determining the likelihood of a patient having a DVT with appropriate clinical symptoms. The score of the CDR helps classify patients into low-, moderate- and high-risk categories.

The tool analyzes a patient's medical history and PT examination findings. If a patient scores a zero with the CDR, there is less than a 3-percent chance of DVT. A score of one or two indicates a 17-percent probability of DVT. Those who score a three or above have a 75-percent chance of having a DVT.

Most experts agree that patients they suspect have a DVT should participate in formal diagnostic testing, even if the risk of DVT is low. For PTs, the CDR serves two important functions. First, the PT has a greater awareness of the significant evidence-based variables that raise a patient's risk for DVT. Secondly, the PT can direct the urgency of a referral to the physician. For example, if a patient presents with a moderate risk for DVT, the PT should speak to the physician and advocate for a diagnostic evaluation that same day.

Physical therapists are uniquely qualified to evaluate and assess the early signs and symptoms of VTE disease in patients in acute, home care and outpatient settings. By accurately identifying and referring patients who demonstrate symptoms of these diseases to physicians, therapists can prevent morbidity and mortality. It is important that PTs remain current with the literature and improve their knowledge base of DVT and PE prevention and management.

This article was written by Mehreen Rizvi

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