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 In this section, we will go over the following:

• Peripheral Vascular Disease

• Rhabdomyolysis

• DVT

Peripheral vascular disease

Peripheral vascular disease (PVD) refers to a group of disorders that affect the blood vessels outside of the heart and brain. It primarily involves the arteries and veins that supply blood to the extremities, such as the legs and arms. In the intensive care unit (ICU), PVD can present significant challenges and complications for patients.

Common Causes of PVD:

• Atherosclerosis: One of the primary causes of PVD is atherosclerosis, a condition characterized by the buildup of plaque in the arteries. Plaque is made up of cholesterol, fat, calcium, and other substances that accumulate on the inner walls of the arteries, narrowing the blood vessels and reducing blood flow. Atherosclerosis can occur throughout the body, including the peripheral arteries, leading to PVD.

• Diabetes: Diabetes is a significant risk factor for the development and progression of PVD. High blood sugar levels associated with diabetes can damage the blood vessels, leading to inflammation and narrowing of the arteries. Additionally, diabetes can also cause peripheral neuropathy, a condition that affects the nerves in the extremities, further increasing the risk of PVD.

• Smoking: Smoking is a well-known risk factor for PVD. The chemicals in tobacco smoke can damage the lining of the blood vessels, leading to inflammation and the formation of plaque. Smoking also constricts blood vessels, reducing blood flow to the extremities. Individuals who smoke are at a significantly higher risk of developing PVD and experiencing more severe symptoms.

• Hypertension: High blood pressure is a common risk factor for various cardiovascular diseases, including PVD. Chronic hypertension can damage the blood vessels, making them more susceptible to atherosclerosis and narrowing. The increased pressure within the arteries can also lead to the formation of blood clots, further obstructing blood flow and increasing the risk of PVD.

• Hyperlipidemia: Hyperlipidemia, or high levels of cholesterol and triglycerides in the blood, is strongly associated with the development of atherosclerosis and PVD. Elevated levels of LDL (low-density lipoprotein) cholesterol, often referred to as "bad" cholesterol, can contribute to the formation of plaque in the arteries. Similarly, high triglyceride levels can also increase the risk of PVD.

• Obesity: Obesity is a significant risk factor for PVD due to its association with other cardiovascular risk factors such as hypertension, diabetes, and hyperlipidemia. Excess body weight puts additional strain on the circulatory system, leading to increased blood pressure and a higher risk of atherosclerosis. Adipose tissue also produces inflammatory substances that can further contribute to the development of PVD.

• Age and Gender: Advancing age is a non-modifiable risk factor for PVD. As individuals age, the blood vessels naturally become less elastic and more prone to damage. Additionally, hormonal changes in women during menopause can increase the risk of PVD. However, it is important to note that PVD can affect individuals of all ages and genders.

• Family History: A family history of PVD or other cardiovascular diseases can significantly increase an individual's risk of developing PVD. Genetic factors can influence the structure and function of blood vessels, making some individuals more susceptible to atherosclerosis and other vascular disorders. It is important for individuals with a family history of PVD to be vigilant about their cardiovascular health and take preventive measures.

• Other Risk Factors: Other risk factors for PVD include a sedentary lifestyle, poor diet, chronic kidney disease, certain autoimmune disorders, and previous history of blood clots. Additionally, certain occupations that involve prolonged sitting or standing, such as truck driving or nursing, can increase the risk of PVD.

The clinical presentation of PVD in the ICU can vary depending on the severity and location of the disease. Patients may complain of pain, numbness, or tingling in the affected limb. They may also experience muscle weakness, cramping, or fatigue during physical activity. In severe cases, patients may develop non-healing wounds or ulcers on the legs or feet, which can be a sign of critical limb ischemia.

Physical examination findings can also provide valuable clues for diagnosing PVD. The affected limb may exhibit decreased or absent pulses, cool skin temperature, and hair loss. The skin may appear pale or cyanotic, and the patient may have decreased sensation or muscle atrophy in the affected limb. In some cases, the presence of bruits (abnormal sounds) over the arteries can be detected during auscultation.

To confirm the diagnosis of PVD, various diagnostic tests and imaging modalities can be utilized. For stable patients, this includes checking an Ankle-Brachial Index (ABI) and MRA. For unstable patients with acute pathologies, we often use the following:

1. Doppler Ultrasound: This imaging technique uses sound waves to evaluate blood flow in the arteries and veins. It can help identify blockages, stenosis, or blood clots in the affected vessels.

2. Computed Tomography Angiography (CTA): Similar to MRA, CTA uses X-rays and a contrast dye to visualize the blood vessels. It can help identify blockages, aneurysms, or other abnormalities in the arteries and veins.

Once the diagnosis of PVD is confirmed, further evaluation may be necessary to determine the underlying cause and assess the severity of the disease. This may involve additional laboratory tests, such as lipid profiles, blood glucose levels, and coagulation studies to identify risk factors and associated conditions.

Rhabdomyolysis

Rhabdomyolysis is a condition characterized by the breakdown of muscle tissue, leading to the release of toxic substances into the bloodstream. In the ICU, patients with rhabdomyolysis often present with a triad of symptoms including muscle pain, weakness, and dark-colored urine.

The muscle pain experienced by patients with rhabdomyolysis can range from mild discomfort to severe, debilitating pain. It is often localized to the affected muscles and may be exacerbated by movement or pressure. Muscle weakness is another common symptom and can affect both the proximal and distal muscles. Patients may have difficulty performing daily activities or even experience difficulty breathing if the respiratory muscles are affected. Dark-colored urine, often described as tea-colored or cola-colored, is a result of the breakdown of muscle proteins and the release of myoglobin into the bloodstream. This myoglobin is filtered by the kidneys and excreted in the urine, giving it a dark appearance. Other signs and symptoms of rhabdomyolysis may include fatigue, fever, nausea, and vomiting.

The diagnosis of rhabdomyolysis in the ICU involves a combination of clinical evaluation, laboratory tests, and imaging studies. The initial assessment includes a thorough medical history and physical examination to identify potential causes and assess the severity of the condition.

Laboratory tests play a crucial role in confirming the diagnosis of rhabdomyolysis. Elevated levels of creatine kinase (CK), a muscle enzyme, are a hallmark finding in this condition. CK levels can be significantly elevated, often reaching several thousand units per liter. Other laboratory findings may include elevated levels of myoglobin, lactate dehydrogenase (LDH), and potassium.

Imaging studies, such as ultrasound or magnetic resonance imaging (MRI), may be performed to evaluate the extent of muscle damage and identify any underlying causes, such as compartment syndrome or traumatic injuries.

Deep Venous Thrombosis

Deep Vein Thrombosis (DVT) is a condition characterized by the formation of blood clots in the deep veins, most commonly in the legs. In the ICU, patients with DVT may present with a variety of clinical manifestations, ranging from asymptomatic to life-threatening complications.

Common symptoms of DVT include pain, swelling, and warmth in the affected limb. The pain is often described as a deep ache or cramping sensation and may worsen with movement or prolonged standing. Swelling occurs due to the impaired blood flow caused by the clot, leading to fluid accumulation in the tissues. The affected limb may also appear red or discolored, and the skin may feel warm to the touch. For patients whom are on a ventilator, a fever can also be the first sign of a DVT. In some cases, DVT can lead to more severe complications, such as pulmonary embolism (PE). PE occurs when a blood clot dislodges from the leg veins and travels to the lungs, causing a blockage in the pulmonary arteries. Symptoms of PE may include sudden onset shortness of breath, chest pain, rapid heart rate, and coughing up blood.

Clinical assessment includes a thorough medical history and physical examination. The presence of risk factors, such as recent surgery, immobilization, or a history of DVT, can help guide the diagnostic process. Physical examination findings, such as swelling, tenderness, and warmth in the affected limb, can raise suspicion for DVT.

Laboratory tests, such as D-dimer, can be used as an initial screening tool for DVT in the emergency room. D-dimer is a protein fragment that is elevated in the presence of blood clots. However, it is important to note that a positive D-dimer test is only useful in the pre-hospital setting; critically ill patients that have been in the ICU almost all have elevated D-dimers. Imaging studies are the gold standard for diagnosing DVT. The most commonly used imaging modality is compression ultrasound, which involves applying pressure to the veins to assess their compressibility. If a clot is present, it will impede the flow of blood and prevent vein compression.

The Role of CDT in DVTs

Catheter-directed thrombolytics (CDT) is a treatment option for patients with DVT in the ICU. It involves the administration of thrombolytic medications directly into the clot through a catheter, allowing for targeted dissolution of the clot.

CDT is typically reserved for patients with extensive DVT or those who are at high risk for complications, such as those with massive iliofemoral DVT or phlegmasia cerulea dolens (marked swelling of the extremities with pain and cyanosis, which may lead to arterial ischemia and gangrene). The procedure is performed under imaging guidance, such as ultrasound or fluoroscopy, to ensure accurate catheter placement.

Thrombolytic medications, commonly alteplase, are infused through the catheter over a specified period. These medications work by breaking down the clot and restoring blood flow in the affected vein. Close monitoring of the patient's vital signs and coagulation parameters is essential during the procedure to minimize the risk of bleeding complications.

CDT can be an effective treatment option for selected patients with DVT. However, it is important to weigh the potential benefits against the risks, including bleeding complications, before initiating this therapy. The decision to proceed with CDT should be made in consultation with a multidisciplinary team, including interventional radiologists, vascular surgeons and hematologists.