AQUIFER Family Medicine 07: 53-year-old man with leg swelling

 

case study: Mr smith 53-year-old man with leg swelling

You are working at a family medicine clinic with Dr. Hill. She tells you, “The next patient, Mr. Smith, is a 53-year-old male with a chief concern of swelling and pain in his left lower extremity.”

 

Before you go to see Mr. Smith, a quick review of the chart reveals that he has type 2 diabetes, hypertension, and hyperlipidemia. You note that he has not been to the office in the past six months, and it appears that he should be out of all of his medications.

 

When you enter the examination room, Mr. Smith, an obese, middle-aged male, greets you from where he is sitting. You introduce yourself and ask him what brings him to the office today.

 

He replies, “It’s my left leg. The past four days it has been red, swollen, and painful—and it seems to be getting worse.”

 

You ask him to tell you more about this problem.

 

He says, “It began several days ago, and the swelling seems to be getting worse. It hurts all the time; it doesn’t even get better when I rest it. It seems to get a little worse when I move around. It hurts to walk as soon as I try to stand on it.”

 

Now that you have a general sense of Mr. Smith’s issue, you ask more focused questions.

 

“Did you do anything to injure your foot?”

He replies, “I do not remember any injury, but there has been this sore on the bottom of my foot for several months. There’s nothing draining out of the sore and it doesn’t hurt, although my foot doesn’t have much feeling in it.”

 

“Before this happened, were you sitting down for a long time without getting up and using your legs, such as taking a long airplane trip; or have you been on bed rest?”

“I wish I could go somewhere on an airplane and get a good vacation, but I can’t afford anything like that. I haven’t been on bed rest. I’ve been pretty busy lately.”

 

“When was the last time you were in the office?”

“It has been a long time now because my daughter and new baby recently moved in with me and I have been trying to take care of the baby as well as keep my job as a bus driver,” he explains.

 

“Have you been taking your medication?”

He replies, “I have been out of my medication for several weeks now.”

 

After talking with Mr. Smith more, you discover:

 

Social History: Does not drink alcohol, but does smoke 1.5 packs of cigarettes daily, he is unmarried, and lives in public housing with his three children and one grandchild.

 

Review of Systems: No fever or chills, no chest pain, no shortness of breath, and no swelling of the right leg.

 

Question

Of the following risk factors which causes the most deaths in the U.S.? Choose the single best answer.

 

The best option is indicated below. Your selections are indicated by the shaded boxes.

 

A. Diabetes

B. Hypertension

C. Obesity

D. Smoking

Answer Comment

The correct answer is D. Smoking, including second hand smoke, causes more than 480,000 deaths annually in the U.S. In 2005 it was reported to alone have caused 467,000 deaths (1,2).

 

Incorrect options: In 2005, hypertension (B) caused 395,000 deaths, diabetes (A) caused 190,000 deaths and overweight-obesity (C) caused 216,000 deaths.(2)

 

TEACHING POINT

U.S. Mortality Due to Smoking, Hypertension, Diabetes, and Obesity

Deaths caused by smoking

 

 

Smoking is the single greatest preventable cause of death in the U.S.

 

From 2005–2009 approximately 480,000 people in the United States annually died prematurely from cigarette smoking or exposure to secondhand smoke.

 

This figure has grown from an average annual estimate of approximately 443,000 deaths from 2000–2004, but this increase is predominantly due to population growth. Although deaths from cigarette smoking have not increased significantly, they remain high. Among adults, 160,848 (41%) of deaths were attributed to cancer, 128,497 (32.7%) to cardiovascular diseases, and 103,338 (26.3%) to respiratory diseases.

 

The three leading specific causes of smoking-attributable death were lung cancer at 127,200, ischemic heart disease at 124,800, and chronic obstructive pulmonary disease (COPD) at 100,600. An estimated 41,284 lung cancer and heart disease deaths annually were attributable to exposure to secondhand smoke. Smoking resulted in an estimated annual average of 278,500 deaths among males and 202,000 among females in the United States.

 

Deaths caused by hypertension

 

Hypertension is the single largest risk factor for cardiovascular mortality in the US. Overall uncontrolled hypertension decreases life expectancy by 20 years. Most of these deaths are due to the increased risk that hypertension incurs for coronary artery disease, hypertensive cardiomyopathy, cerebrovascular disease and chronic renal disease.

 

Deaths caused by diabetes

 

Deaths caused by diabetes in the U.S.: 213,062. The majority of deaths from diabetes also results primarily from the increase in cardiovascular disease and chronic renal failure. Diabetics have twice the mortality of non-diabetics. The risk of cardiovascular disease in diabetics is so high that it is assumed that they have cardiovascular disease if they have diabetes.

 

Deaths caused by obesity

 

Deaths caused by obesity in the US: 300,000. Obesity is rapidly gaining on smoking as the single greatest cause of mortality in our country. A body mass index (BMI) of over 32 kg/m2 has been associated with a doubled mortality rate among women over a 16-year period and obesity is estimated to cause an excess 111,909 to 365,000 death per year in the United States. Obesity on average reduces life expectancy by six to seven years. A BMI of 30–35 reduces life expectancy by two to four years while severe obesity BMI > 40 reduces life expectancy by 20 years for men and 5 years for women.

 

References

Centers of Disease Control and Prevention. Strategies for reducing morbidity and mortality from diabetes through health-care system interventions and diabetes self-management education in community settings. A report on recommendations of the Task Force on Community Preventive Services. MMWR Recomm Rep. 2001;50(RR-16):1‐15.

 

Danaei G, Ding EL, Mozaffarian D, et al. The preventable causes of death in the United States: comparative risk assessment of dietary, lifestyle, and metabolic risk factors [published correction appears in PLoS Med. 2011 Jan;8(1). PLoS Med. 2009;6(4):e1000058.

 

U.S. Department of Health and Human Services. The Health Consequences of Smoking—50 Years of Progress. A Report of the Surgeon General. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2014. https://www.cdc.gov/tobacco/data_statistics/sgr/50th-anniversary/index.htm. Accessed June 24, 2020.

 

Whitlock G, Lewington S, et al. Body-mass index and cause-specific mortality in 900 000 adults: collaborative analyses of 57 prospective studies. Lancet. 2009;373(9669):1083‐96.

 

You examine Mr. Smith and find:

 

Lower extremity exam:

 

Mr. Smith’s entire left leg is swollen and erythematous. The measurement of the circumference of the largest left calf section is 3.5 cm larger than his right calf at the same location.

 

While his affected limb is swollen, it is still soft and pits easily. Mr. Smith’s left leg is warm and tender to the touch, especially along the distribution of the deep venous system.

 

Dorsalis pedis and posterior tibialis pulses are palpable on both feet. Digital capillary refill time is two seconds. Deep tendon reflexes are present (2+).

 

He has decreased sensation and is unable to determine the location of a monofilament test on either foot up to the ankle in a stocking distribution.

 

You note an ulceration on the plantar surface of Mr. Smith’s left foot.

 

Cardiovascular and lung exam:

 

Unremarkable.

 

At this point, you excuse yourself to discuss your findings with Dr. Hill, assuring Mr. Smith you will return in a few moments.

 

Answer Comment

Mr. Smith is a 53-year-old man with obesity, type 2 diabetes, hypertension, hyperlipidemia, and tobacco use who presents with a four-day history of left lower extremity edema. He reports no fever, chest pain, dyspnea, known malignancy, trauma, or period of inactivity. There is an ulcer on the plantar surface of his left foot and edema and erythema involving the entire left leg.

 

The ideal summary statement concisely highlights the most pertinent features without omitting any significant points. The summary statement above includes:

 

Epidemiology and risk factors: 53-year-old man with obesity, type 2 diabetes, hypertension, hyperlipidemia, and tobacco use

Key clinical findings about the present illness using qualifying adjectives and transformative language:

Four-day history

Unilateral

No fever, chest pain, dyspnea, known malignancy, trauma, or period of inactivity

Associated plantar ulcer

Edema and erythema involving entire leg

 

Most Likely Diagnoses

 

Mr. Smith’s concern of swelling that is unilateral is an important finding to support the diagnosis of cellulitis, lymphedema, or deep vein thrombosis (DVT). In contrast, for venous insufficiency or peripheral artery disease (PAD), one would expect bilateral leg swelling.

 

Cellulitis and DVT are acute processes. Lymphedema, PAD, and venous insufficiency are less likely, given the acute nature of Mr. Smith’s symptoms.

 

Which of the following diagnostic tests is the best initial test with high predictive value for determining whether your patient has cellulitis or DVT? Choose the single best answer.

The best option is indicated below. Your selections are indicated by the shaded boxes.

· A. Complete blood count

· B. Culture and sensitivity of the ulcer

· C. D-dimer

· D. MRI of the affected extremity

· E. Venous Doppler of the lower extremity

SUBMIT

Answer Comment

The correct answer is E.

TEACHING POINT

Predictive Value of Diagnostic Tests to Evaluate DVT vs Cellulitis

Complete blood count Elevated white blood cell count might make you consider cellulitis. However, a normal white count would not rule it out, nor is a leukocytosis specific enough to give you the diagnosis.
Culture and sensitivity Would not tell you whether cellulitis is present, and is usually not useful in evaluating chronic ulcers.
D-dimer Is a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis. It is a relatively sensitive, but poorly specific test for the presence of DVT. While a negative result (low D-dimer concentration in the blood) practically rules out thrombosis, a positive result can indicate thrombosis, but does not rule out other potential causes, such as infection. Its main use, therefore, is to exclude thromboembolic disease where the probability is low.
MRI Could identify the presence of thrombus. Expensive compared to venous doppler.

Venous Doppler of the lower extremity should tell you with good sensitivity and specificity if DVT is present.

 

 

Dr. Hill asks:

“What test do you think we should order?”

You tell Dr. Hill, “I guess we should have a Doppler ultrasound done because it has the best predictive value for a DVT.”

“Suppose I told you that this test was relatively expensive and often overused,” Dr. Hill proposes, “Would that change your thinking?”

You respond, “Well you mentioned that the D-dimer test is highly sensitive. Perhaps we could rule out DVT by doing that one.”

“Very good thinking. That is precisely the appropriate role of that study. But, remember that the D-dimer test is best used to rule out a DVT if the pretest probability of having a DVT is relatively low.”

“Is there some way to estimate Mr. Smith’s pretest probability of having DVT?”

“I have read that no singular clinical finding is helpful in that,” you tell her.

“That is true,” Dr. Hill concurs. “But if we use several clinical findings, we may be able to do a better job of predicting pretest probability. I am speaking here of the Wells criteria.”

TEACHING POINT

Wells criteria for the diagnosis of DVT

Active cancer (treatment ongoing or within previous six months or palliative) 1
Paralysis, paresis, or recent plaster immobilization of the legs 1
Recently bedridden for more than three days or major surgery within four weeks 1
Localized tenderness along the distribution of the deep venous system 1
Entire leg swollen 1
Calf swelling by more than 3 cm compared with the asymptomatic leg (measured 10 cm below the tibial tuberosity) 1
Pitting edema (greater in the symptomatic leg) 1
Collateral superficial veins (non-varicose) 1
Alternative diagnosis as likely or more likely than that of deep vein thrombosis -2

Low probability 0 or less, moderate probability 1–2, high probability 3 or more.

Question

Given what you know of Mr. Smith so far, which of the following is likely to represent his pretest probability of DVT? Choose the single best answer.

The best option is indicated below. Your selections are indicated by the shaded boxes.

· A. Cannot determine

· B. High probability

· C. Low probability

· D. Moderate probability

SUBMIT

Answer Comment

The correct answer is B.

Review of Mr. Smith’s history and physical exam reveals that he has:

· Localized tenderness along the distribution of the deep venous system (1)

· Entire leg swollen (1)

· Calf swelling by more than 3 centimeters compared with the asymptomatic leg (measured 10 centimeters below the tibial tuberosity) (1)

· Pitting edema (greater in the symptomatic leg) (1)

Note, one aspect of the Wells criteria for the diagnosis of DVT is an alternative diagnosis as likely or more likely than that of deep vein thrombosis (-2). While cellulitis is a possible explanation for Mr. Smith’s condition, DVT is much more likely, especially given his obesity and history of smoking.

Mr. Smith’s score is 4; a high pretest probability (B).

Incorrect Answers: You can determine his pretest probability using the Wells Criteria. A low probability score is 0 (C), a moderate probability score is 1–2 (D).

 

You conclude, “Given Mr. Smith’s high pretest probability of DVT, I don’t think I would trust a negative D-dimer result even with its high sensitivity. I think we have to get Mr. Smith a Doppler ultrasound instead.”

Dr. Hill agrees and adds, “Are there other diagnostic studies that you would order now?”

Question

Which of the following would you order at this point? Select all that apply.

The best options are indicated below. Your selections are indicated by the shaded boxes.

· A. Arterial blood gas

· B. Chest x-ray

· C. Complete blood count

· D. C-reactive protein

· E. Electrolytes, glucose, creatinine, and blood urea nitrogen (BUN)

· F. Hemoglobin A1C

· G. Sedimentation rate

· H. Thyroid studies

SUBMIT

Answer Comment

The correct answers are C, E, F.

CBC (C) Leukocytosis might make you consider an infectious process
Electrolytes, glucose, BUN & creatinine (E) Evaluate diabetic control and renal function
Hemoglobin A1C (F) Determine diabetic control

Thyroid studies (H) are unlikely to provide any useful information about the absence of signs and symptoms of thyroid disease.

Sedimentation rate (G) and c-reactive protein (D) might be elevated, but would be in both cellulitis and DVT, so it is not particularly useful in determining a diagnosis at this point.

Arterial blood gas (A) or chest x-ray (B) in a patient without symptoms of respiratory difficulty is unlikely to be useful.

 

You and Dr. Hill return to Mr. Smith’s room together. After greeting him, Dr. Hill explains, “Mr. Smith, we have a good idea of what may be causing the issues with your leg. We would like to gather some more information by taking a blood sample and sending you over to radiology for a Doppler ultrasound so that we can determine the best course of treatment for you.”

After Mr. Smith assents to the plan, Dr. Hill washes her hands and asks to take a look at his leg. She agrees with your assessment.

She walks you through a diabetic foot examination:

On Mr. Smith’s exam, Dr. Hill finds 3 out of 10 sites imperceptible using the 10-gram monofilament test, indicating some loss of protective sensation.

She finds Mr. Smith’s dorsalis pedis and posterior tibialis pulses intact bilaterally.

She notes a 2 cm ulcer on the plantar surface of his foot, with some surrounding erythema, and callous formation. The ulcer is deep, including full skin thickness, down to muscles and ligaments, but no exposed tendons, or bony involvement, and there appears to be no abscess formation.

She finds that the skin on Mr. Smith’s feet is dry and his toenails are dystrophic and incurvated, demonstrating inappropriate self-care.

At the end of the diabetic foot exam, Dr. Hill turns to you and asks, “What do you think we should do about his foot ulcer?”

You admit, “I’m not sure about that. Would antibiotics help?”

“They would if his wound is infected, but first we should evaluate the grade of the ulcer,” Dr. Hill explains.

TEACHING POINT

Ulcer Classification: The Wagner Grading System

The Wagner Grading System

1. Grade 1: Diabetic ulcer (superficial)

2. Grade 2: Ulcer extension (involving ligament, tendon, joint capsule or fascia)

3. Grade 3: Deep ulcer with abscess or osteomyelitis

4. Grade 4: Gangrene forefoot (partial)

5. Grade 5: Extensive gangrene of foot

Images for the corresponding ulcer classifications.

Question

Which of the following describes the grade of Mr. Smith’s ulcer? Choose the single best answer.

The best option is indicated below. Your selections are indicated by the shaded boxes.

· A. Grade 1

· B. Grade 2

· C. Grade 3

· D. Grade 4

· E. Grade 5

SUBMIT

Answer Comment

The correct answer is B.

· Mr. Smith’s ulcer is grade 2 (B).

It is a deep ulcer, penetrating down to ligaments and muscle, but no bone involvement or abscess formation. However, Mr. Smith’s wound does not demonstrate any signs of infection.

· Mr. Smith’s ulcer is more serious than grade 1 because it is not superficial (A)

· Mr. Smith’s ulcer is not as serious as grade 3 (C) because it does not involve abscess formation or osteomyelitis. It is not grade 4 (D) or 5 (E) because it does not involve gangrene.

Dr. Hill emphasizes at this point that based on clinical examination, it does not appear that Mr. Smith has cellulitis and more likely his diagnosis will be a DVT.

TEACHING POINT

Ulcer Management

· Grade 1 and 2 ulcer management generally can be done as outpatient and should include extensive debridement, local wound care, and relief of pressure. If there is significant erythema and/or purulent exudate, then treatment for infection is warranted.

· Grade 3 lesions require evaluation for possible osteomyelitis as well as peripheral artery disease. Both of these conditions may need to be addressed prior to resolution of the ulcer. Typically at least a brief hospitalization is required to address these issues.

· Grade 4 and Grade 5 lesions require emergent hospitalization and surgical consultation, often resulting in amputation.

You and Dr. Hill determine that Mr. Smith’s foot ulcer does not require antibiotics at this time, but does require debridement, which you will address after he’s had his tests done. Mr. Smith has his blood drawn and a Doppler ultrasound performed.

 

A few hours later, you see that the results of the labs have returned:

 

Complete Blood Count:

 

Lab Value

 

Conventional

 

SI

 

WBC

 

7.5 x103/μL

 

7.5 x109/L

 

Hgb

 

13.2 g/dL

 

132 g/L

 

Hemoglobin A1C

 

10.2 %

 

.102

 

Chemistry:

 

Lab Value

 

Conventional

 

SI

 

Na

 

137 mEq/L

 

137 mmol/L

 

K

 

4.0 mEq/L

 

4.0 mmol/L

 

Cl

 

98 mEq/L

 

98 mmol/L

 

C02

 

25 mEq/L

 

25 mmol/L

 

BUN

 

18 mg/dL

 

6.3 mmol/L

 

Creatinine

 

1.0 mg/dL

 

88 mmol/L

 

Glucose

 

232 mg/dL

 

12.7 mmol/L

 

See the associated reference ranges in conventional and SI units.

 

Question

Which of the following best describes the findings above? Choose the single best answer.

 

The best option is indicated below. Your selections are indicated by the shaded boxes.

 

A. An infectious process

B. Uncontrolled diabetes

C. Uncontrolled diabetes and anemia

D. Uncontrolled diabetes and an infectious process

E. Uncontrolled diabetes and renal dysfunction

Answer Comment

The correct answer is B.

 

Elevated glucose and HGBA1c are evidence of uncontrolled diabetes (B).

 

WBC is normal (A, D), so there is no evidence for an infectious process. Between the lack of leukocytosis, the lack of fever, and the clinical findings of a grade 2 ulcer, cellulitis is now a very unlikely diagnosis for Mr. Smith.

 

While there is evidence for uncontrolled diabetes, renal function (BUN & creatinine) appears normal (E) and he is not anemic because he has a normal hemoglobin (C).

 

Dr. Hill informs you, “I just received a call from the radiologist. It looks as if our suspicions were correct. Doppler ultrasound shows that Mr. Smith has a DVT in the femoral vein. So now the question is: What do we do about it?”

You respond, “Well he needs anticoagulation to prevent a pulmonary embolus (PE), right?”

“Right. His short-term risk of a PE is high, so we need to anticoagulate him right away.”

TEACHING POINT

Prevention of Embolism

More than 95% of pulmonary emboli arise from thrombi in the deep venous system of the lower extremities. Ninety percent of deaths due to pulmonary embolism result within an hour or two—before diagnostic and therapeutic plans can be implemented. Therefore, prevention and prompt treatment of DVT is the most effective approach to prevent embolism and death due to PE.

Question

Which of the following can be appropriate treatment options for an acute DVT? Select all that apply.

The best options are indicated below. Your selections are indicated by the shaded boxes.

· A. Inpatient admission with administration of unfractionated heparin overlapping with the initiation of warfarin

· B. Outpatient initiation of dabigatran alone

· C. Outpatient initiation of low molecular weight heparin (LMWH) overlapping with the initiation of warfarin

· D. Outpatient initiation of rivaroxaban alone

· E. Outpatient initiation of warfarin alone

SUBMIT

Answer Comment

The correct answers are A, C, D.

Rivaroxaban (D) can be initiated on its own for the treatment of acute DVT. Unfractionated heparin or LMWH overlapping with the initiation of warfarin is also appropriate (A, C). Both Warfarin (E) and Dabigatran (B) cannot be initiated as monotherapy and require overlap with unfractionated heparin or LMWH.

TEACHING POINT

Requirement for Treating DVT on Outpatient Basis

In order to treat DVT on an outpatient basis:

The patient must be:

· Hemodynamically stable

· With good kidney function

· At low risk for bleeding

The home environment must be:

· Stable and supportive

· Capable of providing the patient with daily access to INR monitoring (if using warfarin as the anticoagulant)

The day-to-day risk of the development of a pulmonary embolism (PE) is high in patients with acute DVT, so immediate anticoagulation is necessary. This is to be distinguished from the day-to-day risk of a stroke in patients with newly diagnosed atrial fibrillation (which is much lower!).

Most patients with DVT may be managed in the out patient setting, though there are a few important exceptions (see below).

NOACs are direct-acting agents that are selective for one specific coagulation factor, either thrombin (e.g., dabigatran) or factor Xa (e.g., rivaroxaban, apixaban, and edoxaban, all with an “X” in their names). Two of the oral factor Xa inhibitors (rivaroxaban and apixaban) have been demonstrated to be safe as monotherapy for DVT. These agents have been shown to have similar efficacy to warfarin in preventing PE, but have been demonstrated to cause fewer bleeding episodes than warfarin. Advantages include that they do not require any laboratory monitoring, so they are much easier for patients to take. Disadvantages include their cost (compared to warfarin, which is very inexpensive) and the unavailability of immediate reversal agents in the case of dangerous bleeding. The American College of Chest Physicians recently recommended the choice of factor Xa inhibitors or the direct thrombin inhibitor dabigatran (collectively referred to as non-vitamin K antagonist oral anticoagulants or NOACs) over warfarin for the management of DVT or PE.

The direct thrombin inhibitor dabigatran is another option for oral anticoagulation that has similar advantages to rivaroxaban and apixaban. It has not been studied as monotherapy however, so it is recommended that patients be initiated on LMWH in addition to dabigatran, with the LMWH being stopped after 5-10 days.

Before the development of the novel oral anticoagulants (NOACs), warfarin was the mainstay of the management of DVT. It remains an acceptable option and remains commonly used in many settings. Warfarin is a better option for patients who can’t afford the cost of the NOACs and who are concerned about the lack of reversal agents. Warfarin takes several days to reach therapeutic efficacy, so simply starting it alone carries an unacceptable risk of PE. Thus, patients must be started on either LMWH or unfractionated heparin while waiting for the patient’s INR to come into the therapeutic range (2-3). LMWH is the preferred anticoagulant to pair with warfarin in most settings, and may be administered in the outpatient setting.

For many years, the standard of care for DVT was admission to the hospital and administration of unfractionated heparin overlapping with the initiation of warfarin. Inpatient management remains the best option for patients who are hemodynamically unstable, who are at serious risk of acute bleeding with the initiation of anticoagulation (e.g. those with prior admission for gastrointestinal bleeding), or who have obstacles to outpatient management. Examples of this include the inability to afford NOACs and LMWH, or inability to get daily INRs checked during the initiation of warfarin therapy.

 

 

Dr. Hill calls Mr. Smith’s pharmacy and finds that his insurance will cover dabigatran, so this is a good option for his outpatient anticoagulation. First, however, he must be overlapped with heparin (as discussed on the prior card). Unfortunately, insurance will not cover enoxaparin (injectable low molecular weight heparin) without prior approval, which may take a day to achieve. (It is late in the day when you are seeing him.) Dr. Hill asks you if you think he would be better managed in the hospital or as an outpatient.

After thinking about it for a minute you respond, “I don’t think it is acceptable to send him home if we can’t ensure that he will be able to get enoxaparin tonight. His day-to-day risk of a pulmonary embolus is too high. Also I am worried about his ability to adhere to new complicated instructions, given that he has a busy home and work life and has not been able to prioritize his own care. He needs to have a plan for managing his medications and he has this foot ulcer. I think it would be best to stabilize him in the hospital and work on having a more supportive home environment.”

Dr. Hill replies, “Excellent. I agree that Mr. Smith will be best treated in the hospital. Let’s look into how we will do that.”

 

Goals of DVT Therapy

1. Immediate inhibition of the growth of thromboemboli

2. Promotion of thromboembolic resolution

3. Prevention of recurrence

Heparin achieves the first goal, it encourages the second by allowing fibrinolytic dissolution to be achieved unopposed. It is available in two forms: unfractionated heparin or low-molecular weight heparin (LMWH).

Question

Which of the following are advantages of using LMWH, instead of unfractionated heparin? Select all that apply.

The best options are indicated below. Your selections are indicated by the shaded boxes.

· A. Dosing is fixed with LMWH.

· B. Laboratory monitoring is not required for LMWH.

· C. LMWH has a longer biologic half-life so it can be administered subcutaneously once or twice daily.

· D. LMWH may be used in the outpatient setting.

· E. LMWH reduces recurrence of clots more than unfractionated heparin.

SUBMIT

Answer Comment

The correct answers are A, B, C, D.

TEACHING POINT

DVT Therapy: Advantages of Low-Molecular Weight Heparin (LMWH) over Unfractionated Heparin

LMWH has several advantages over unfractionated heparin:

· Longer biologic half-life so it can be administered subcutaneously once or twice daily

· Laboratory monitoring is not required

· Dosing is fixed

· Evidence from meta-analyses suggest that LMWH is associated with fewer major bleeding complications than unfractionated heparin

· Bleeding complications are less common

LMWH may be used in the outpatient setting; whereas unfractionated heparin requires hospitalization as it is administered intravenously with the dosage based on body weight and titrated based on the activated partial thromboplastin time. One advantage of unfractionated heparin is that it can be immediately shut off and reversed in the case of bleeding due to its very short half-life. In a patient with a significant bleeding risk (e.g. recent admission for gastrointestinal bleeding), it is advisable to choose unfractionated heparin over low molecular weight heparin, which has a much longer …