Clinical

Underlying peripheral arterial or venous disease in patients with lower extremity SSTIs

How can hospitalists best recognize and manage these challenging cases?


 

Clinical case

A 56-year-old woman with type 2 diabetes, morbid obesity, and hypertension presents with right lower extremity erythema, weeping, and exquisite tenderness associated with chills. She reports a 2-year history of chronic lower extremity swelling and cramps with a more recent development of scaling and two superficial ulcers on lower third of her leg. For 1 month, she has noted significant pain circumferentially around the ankles with focal tautness and pallor of the skin. She has tried acetaminophen and oxycodone with little relief.

Over the past week, she noted foul smelling discharge from one of the superficial ulcers with redness extending up to the knee prompting presentation to the emergency department. She had a fever to 101.2° F, tachycardia to 105 beats per minute, and leukocytosis to 14.7. She is admitted to the hospitalist service for sepsis secondary to right lower extremity cellulitis.

Introduction

Skin and soft tissue infections (SSTIs) remain among the most common inpatient diagnoses cared for by hospitalists. Most patients admitted to a hospitalist service with an SSTI meet the criteria for either moderate or severe infection as outlined by the Infectious Disease Society of America – systemic signs of infection by SIRS criteria or a high likelihood of an immunocompromised state, methicillin-resistant Staphylococcus aureus infection, trauma, or wounds.1

Often these patients have several comorbid conditions such as diabetes, morbid obesity, or peripheral arterial and venous disease. Though most hospitalists are adept at managing diabetes, blood pressure, and other comorbidities, the ability to recognize and manage peripheral vascular disease can be challenging. This article will discuss ways to help providers better identify and manage underlying peripheral arterial disease (PAD) and/or chronic venous insufficiency (CVI) in patients admitted with lower extremity SSTIs.

1. In addition to an infection, could there also be underlying peripheral arterial or venous disease?

Patients with peripheral edema and vascular disease are predisposed to recurrent lower extremity SSTIs. When assessing for vascular disease, it is important to consider PAD and CVI separately.

CVI refers to the spectrum of syndromes caused by venous valvular incompetency, venous obstruction, or decreased muscle contraction. Veins cannot maximally deliver venous blood back to the heart resulting in venous pooling in the lower extremities. The exact mechanism of the skin changes that accompany venous insufficiency is unknown but may be related to cytokine cascades that result in perivascular inflammation and a weakening of the dermal barrier. Over time, this can develop into spontaneous ulceration of the skin.2,3

PAD refers to atherosclerosis of the noncerebral, noncoronary arteries, which leads to ischemic symptoms and atrophy of the supplied territory. Ulceration usually results from mild trauma due to poor wound healing.4,5 A thorough history, assessment of risk factors, and physical exam are essential to identifying these two potential diagnoses in patients admitted with SSTIs.

First, the provider should assess risk factors for underlying vascular disease. For PAD, these include risk factors similar to those of coronary artery disease (CAD): hypertension, hyperlipidemia, history of smoking, and poorly-controlled diabetes. Chronic kidney disease and family history are also associated with PAD. Since PAD and CAD share similar risk factors, it is often common for patients with CAD (as well as patients with cerebrovascular disease) to have PAD. Risk factors for CVI include obesity, chronic sedentary lifestyle, multiple pregnancies, family history, and prior superficial or deep venous thrombosis.2,4

Next, the provider should ask the patient about symptoms experienced prior to the onset of the current SSTI. Patients with either arterial or venous disease will typically report lower extremity symptoms that have been occurring for months to years, long before the acute SSTI. The classic symptom for PAD is claudication – leg pain or cramping that occurs on exertion and improves with rest. This is due to decreased arterial blood flow to the affected limb, felt most acutely during exercise. Other symptoms include numbness, a cool lower extremity, and lower extremity hair loss. As PAD progresses, a patient may also have rest pain, which may indicate more critical ischemia, as well nonhealing wounds after mild trauma.

In contrast, symptoms of CVI present more variably. CVI can be associated with heaviness, cramping, and pain that are usually worse in the dependent position and relieved with elevation. Patients may also report dry skin, edema, pruritus, scaling, skin tightness, and indolent ulcers at advanced stages.2-6

The physical exam can help the provider distinguish between venous and arterial disease. Patients with PAD often have diminished or nonpalpable distal pulses, bruits in proximal arteries, pallor, hair loss, nail thickening, decreased capillary refill time, and ulceration of the toes. CVI shares some common characteristics but can be distinguished by evidence of varicose veins, telangiectasia, edema (which spares the foot), lipodermatosclerosis, and atrophie blanche (white scarring around the ankle). Patients with venous disease tend to have warm lower extremities and palpable pulses. Often, there is hyperpigmentation, especially around the ankles, and associated eczematous changes with scaling, erythema, and weeping. CVI can also present with ulcers. In addition, if the SSTI is not responding to appropriate antibiotics in the typical time frame, this may be a clue that there is an underlying vascular issue.2-6

Ulcers, whether arterial or venous, comprise a break in the skin’s protective barrier and give bacteria a point of entry. Thus, ulcers often get superinfected, leading to an SSTI rather than SSTIs causing ulcers. The anatomic location can help differentiate between venous and arterial ulcers. Arterial ulcers tend to occur on the toes, heels, and lateral and medial malleoli. Venous ulcers are classically present above the medial malleolus but can occur anywhere on the medial lower third of the leg. Venous ulcers are more superficial and have an irregular shape, while arterial ulcers are deeper, have smoother edges and a “punched-out” shape. Both arterial and venous ulcers can be exudative though venous ulcers are rarely necrotic. Both arterial and venous ulcers can be painful.7-9

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