Carlson, Dorothy S. DEd, RN; Pfadt, Ellen MSN, RN
Because of the number of inpatient surgeries (4,100 per 100,000 population) performed yearly in the United States, perioperative nurses play an important role in assessment, prevention, and early recognition of deep vein thrombosis (DVT).1 This article focuses on the scope of the problem, pathophysiology of DVT, risks in surgery, perioperative considerations, and nursing interventions.
Scope of the problem
The umbrella term venous thromboembolism (VTE) covers DVT and pulmonary embolism (PE). In the United States, the annual incidence of VTE may be as high as 1 per 1,000 persons.2
A DVT typically forms in the deep veins of the lower extremities and pelvis, but can rarely occur in the deep veins of the upper extremities.3 The true incidence of DVT is unknown because clinical manifestations may not always be apparent if the vein isn't completely occluded and significant magnifications of inflammation are absent.4–6 An estimated two-thirds of patients with VTE present with DVT; the remaining one-third present with PE.7 VTE can be present in surgical and nonsurgical patients.8
When a DVT dislodges, it becomes an embolus that travels to the lung and becomes a PE, lodging in the pulmonary artery or its branches. The patient's presentation depends on the size and location of the embolus and degree of compromised pulmonary circulation. The incidence of a DVT dislodging and becoming a PE may be as high as 60% to 80%, but statistics can vary because more than 50% of patients have no clinical manifestations.2 For this reason, data regarding the percentage of deaths due to PE are not definitive; some PEs may only be discovered during autopsy.2
Although the exact cause of DVT is unknown, three factors, known as Virchow triad, are responsible: venous stasis, hypercoagulability, and endothelial or vessel wall injury.4,9 For a DVT to form, at least two of the three factors must be present.10
Venous stasis leads to platelet and thrombin aggregation, impeding unidirectional blood flow in the extremity and ultimately affecting flow to the right side of the heart when a PE is involved. Causes of stasis include inactivity of muscles in the extremities through immobilization, paralysis, or lack of exercise resulting in venous pooling; incompetent venous valves in the extremities; reduced venous flow; and impaired cardiac function.6,11
Hypercoagulability increases blood viscosity and encourages thrombus formation. Coagulation factors are altered and contribute to thrombus formation and subsequent growth, diminishing the body's natural anticoagulant and fibrinolytic activity. Abnormalities of these factors can be inherited or acquired. Even in patients with normal coagulation, dehydration reduces fluid volume and concentrates existing clotting factors, leading to a hypercoagulable state.2,6,12 Patients who are prone to hypercoagulation include those who are septic, who smoke, and those taking corticosteroids.
Endothelial or vessel wall injury stimulates the intrinsic coagulation pathway resulting in platelet aggregation and release of clotting factors.11 Damage to the vessel can be direct or indirect and decreases fibrinolytic capabilities, thus promoting localized clot formation and growth.11 Direct endothelial damage can result from surgery or fracture, while indirect endothelial damage occurs from sepsis or diabetes (see Factors that promote DVT).
A venous thrombus contains red blood cells, white blood cells, and platelets that are held together by fibrin (see How a thrombus forms). Thrombi often form on the cusps of venous valves.13 As additional blood cells and fibrin collect to create a larger thrombus with a tail, the vessel lumen ultimately can be obstructed.11
A thrombus causes inflammation of the vein (thrombophlebitis).6,14 Inflammation or occlusion is responsible for the clinical manifestations of DVT: swelling, warmth, pain, redness, low-grade fever, tenderness, and cyanosis in the affected extremity. Homans sign is no longer considered definitive for the presence or absence of a DVT.15
Blood turbulence in the vessel can dislodge a thrombus, leading to PE. Signs and symptoms of a PE can be dramatic or silent depending on the size of the embolism and the amount of obstructed pulmonary circulation.2 Clinical signs and symptoms may mimic other cardiovascular diseases or appear weeks after the event. Anxiety, pleuritic chest pain, and dyspnea are the classic manifestations.15
Risks in surgery
Patients undergoing orthopedic surgeries, particularly older patients having total hip arthroplasty (THA), total knee arthroplasty (TKA), or hip fracture surgery are at a higher risk for DVT than younger patients who have diagnostic arthroscopy.8 One factor contributing to the formation of DVT in orthopedic cases is the positioning of the extremity during surgery. Also, retracting soft tissue and femoral and iliac vein compression can damage vessel walls.16 Finally, reaming the bone for a prosthesis can release antigens that promote clotting, and thermal damage caused by the chemical reaction to cement used in THA or TKA can cause vessel damage.6,16 Prolonged pneumatic tourniquet time during a TKA may increase the risk of DVT due to venous stasis.8
Neurologic surgery also carries a higher DVT risk than general surgery. Predisposing factors for DVT include surgical removal of supratentorial tumor in the brain, length of surgery greater than 4 hours, preoperative leg weakness, long ICU stay, and delayed ambulation postoperatively.10
Laparoscopic surgeries may require longer surgical times than open procedures, increasing DVT risk. Pneumoperitoneum, which occurs when carbon dioxide gas is introduced in the abdominal cavity, and the use of reverse Trendelenburg position (for example, for laparoscopic cholecystectomy) reduce venous return from the legs. Both of these actions promote venous stasis and increase DVT risk. 8
Other surgical procedures that carry a high risk for DVT include genitourologic and obstetric surgery.9 These procedures can require any of the following, which place the patient at risk: using an abdominal approach during surgery, surgery for removal of malignancy, advanced patient age, or lithotomy positioning during surgery.8
Let's look at specific considerations and nursing actions to prevent VTE.
Before surgery, conduct a thorough physical assessment, including a complete patient history to detect risk factors and provide a baseline for comparison to intraoperative and postoperative outcomes. Assess for risk factors that would predispose the patient to DVT development, and use the Wells criteria for probability of DVT to determine the patient's risk. The Wells criteria consist of 10 yes-or-no questions including whether the patient has active cancer, paralysis or limb immobilization, is bedridden, has leg tenderness, has swelling of the entire extremity, has measurable calf edema compared to the other extremity, and has a history of DVT: a score of 0 is low risk, 1 or 2 is moderate risk, and 3 or greater is high risk of DVT.5
Incorporate the mnemonic “A, B, C, D, E” into the nursing assessment: Allergies, especially to medications and latex; Bleeding tendencies, anticoagulant use, over-the-counter medications, and herbal preparations that can cause bleeding; Corticosteroids; Diabetes; Emboli and a previous history of VTE.15
Assess the patient's use of tobacco products and history of pack years. Tell the patient who smokes to refrain from the use of all nicotine products for at least a week before surgery, and advise the patient on the importance of smoking cessation.
Preoperative teaching is an important component of the nursing role, and can relieve patient anxiety, help prevent complications, and improve outcomes. Give the patient instructions in simple and understandable terms in a time frame that's neither too long before nor too close to the surgery. Although you may have little time for preoperative instruction before emergency surgeries.
Tell patients about the surgical procedure and what to expect after surgery. Discuss the specific measures to prevent DVT, including turning and positioning at least every 1 to 2 hours and performing foot and ankle exercises.15 The most common exercises are flexion, extension, and rotation of the ankle and foot. Leg exercises may be added to further enhance venous return to the heart and prevent venous stasis. Demonstrate all exercises to the patient and have the patient perform a return demonstration to acknowledge understanding.
Figure. How a thromb...Image Tools
Elastic stockings or sequential compression devices (SCDs) may be applied in the immediate preoperative period for DVT prevention unless contraindicated. Tell the patient to expect early ambulation after surgery, and to be prepared to take an oral or injectable medication to prevent DVT. Rivaroxaban, approved in July 2011, is an oral factor Xa inhibitor indicated for prophylaxis of DVT and PE in patients following hip or knee replacement surgery.17 Low-molecular-weight heparin, in addition to SCDs, is recommended as VTE prophylaxis in patients having THA, TKA, or hip repair surgery. Treatment should continue for up to 35 days, extending thromboprophylaxis from the minimum time of 10 to 14 days.8
Before surgery, insert a venous access device and infuse fluids at the prescribed rate. This restores fluid volume that was reduced during the normal required fasting period and corrects dehydration, a contributing factor to hemoconcentration and hypercoagulability.15 Apply SCDs before anesthesia induction because of the hemodynamic changes anesthesia produces.
The intraoperative nurse who receives the patient into the OR should review the preoperative patient history and physical findings to determine if the patient is at risk for complications, including VTE. Intraoperative prevention of DVT is challenging because general anesthesia, the type of surgical procedure, and length of surgery increase DVT risk. Also, some positions required for specific surgeries increase the risk of venous stasis. OR nurses can minimize venous stasis by positioning the patient to encourage adequate circulation. To prevent circulation impairment, be sure that SCDs or elastic stockings aren't twisted or turned during the procedure, and keep the patient's extremities at, but never below, the level of the OR table.
Damage to the endothelial system can be caused by instruments used during the surgery. Remind OR team members not to place pressure on the anesthetized patient to avoid circulatory compromise. Use extra padding on pressure points to prevent tissue damage and circulatory impairment.
Confirm that straps to secure the patient on the table aren't too tight.9 When a pneumatic tourniquet is needed, place padding between the patient's skin and the cuff and follow facility guidelines for pneumatic tourniquet use. The circulating nurse needs to be aware of and address these concerns.
Immediate postoperative nursing care begins when the OR nurse gives a complete verbal report or generates an electronic documentation of the intraoperative events to the postanesthesia nurse, in accordance with National Patient Safety Goal 2.18 Information relevant to the patient's risk for developing DVT postoperatively includes the type and length of surgery, specific anesthetic agent used, and patient position during the procedure.
After assessing the patient's airway, breathing, and circulation, inspect the patient's extremities for clinical manifestations of DVT. Compare circumference, color, and temperature of one leg to the other. If the patient is conscious, assess for location and presence of pain and tenderness in lower extremities and report positive findings to the surgeon. Apply elastic thigh or knee-high thromboembolic deterrent stockings or SCDs to one or both extremities as prescribed to prevent venous pooling and promote venous return. Elevating the foot of the bed (unless contraindicated) also promotes venous return. Avoid placing pillows under the patient's knees—this can compress the popliteal veins.
VTE is a major perioperative risk. By being aware of the factors contributing to the development of venous stasis, blood hypercoagulability, and vessel wall injury, and knowing their role in DVT formation, you can help prevent DVT or recognize it early, preventing life-threatening PEs and improving patient outcomes.
Factors that promote DVT 4,6,7,11,15,19–23
The following are risk factors for DVT. According to AORN's Perioperative Standards and Recommended Practices, each facility should develop a system-wide protocol for DVT prevention. A computer-generated alert that identifies the patient at risk for developing DVT should be developed based on the information obtained from the preoperative nursing assessment. The plan of care for each patient should be developed based on the patient's risk factors for DVT and the appropriate DVT prophylaxis initiated.
Factors in venous stasis
* Immobility, prolonged bed rest, or sitting for extended periods
* Atrial fibrillation
* Heart failure—common in older adults
* Spinal cord injury
* General anesthesia—prolonged immobilization and venous stasis (particularly during procedures lasting longer than 30 minutes) significantly increases the patient's risk of developing DVT
* Age over 40
* Orthopedic surgery
* Myocardial infarction
Factors in hypercoagulability
* Patients who've had a preoperative infection also are at higher risk for DVT, especially within the first two weeks, because of thrombocytosis, a response to the infection
* Dehydration—common in older adults, causes hemoconcentration and may lead to increased concentration of coagulation factors
* Malignancies—cancers, especially pancreatic, lung, and genitourinary, affect coagulation factors. The cancerous cells themselves can produce prothrombin and create procoagulation biological substances. The tissue surrounding the cancer cells can also secrete substances that encourage coagulation. Chemotherapy causes endothelial damage and increases coagulation factors that contribute to a thrombus formation, especially in calf veins.
* Factor V Leiden—slowed breakdown of Factor V, a normal clotting factor, creates a prothrombotic state
* Smoking or nicotine use—triggers the intrinsic coagulation pathway, causing vasoconstriction, increased homocysteine levels, and increased fibrinogen that leads to hypercoagulation
* Oral contraceptive use, especially after age 35
* Hormone replacement therapy
* Pregnancy—the expanding uterus places pressure on the pelvic veins and the inferior vena cava, predisposing women to DVT formation, particularly in the left extremity
* Antiphospholipid antibody syndrome
* Factor II, VIII, IX, or XI elevation
* Protein S or C deficiency
Factors in endothelial injury
* Abdominal and pelvic surgery
* Hip, pelvis, or leg fractures
* Personal history of DVT
* Central venous access devices
* I.V. drug abuse
* Hypertonic I.V. solutions
* Buerger disease
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© 2012 Lippincott Williams & Wilkins, Inc.