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Unequal Pulses

To develop a list of causes of unequal pulses, let us trace the arterial system from its origin in the heart to its termination in the extremities.



  • Heart: Here is the source of arterial emboli from a mural thrombus in auricular fibrillation or myocardial infarction and subacute bacterial endocarditis (SBE).


  • Aorta: This will bring to mind a coarctation of the aorta and/or dissecting aneurysm (thrombosis of the terminal aorta).


  • Proximal arteries: These suggest thoracic outlet syndrome, subclavian steal syndrome, and femoral artery thrombosis or embolism.


  • Distal arteries: These bring to mind peripheral arteriosclerosis, Buerger disease, arterial embolism, and arteriovenous fistula. A fracture may involve the distal arteries causing pulse inequality.


Approach to the Diagnosis

If there is a history of sudden onset of unequal pulses in either the upper or lower extremity, a diagnosis of arterial embolism or dissecting aneurysm must be ruled out with immediate CT scan of the chest or angiography. If there is a history of trauma, fracture must be ruled out with plain films of the extremity. When the patient complains of ischemic symptoms (e.g., intermittent claudication) or the pulse inequality is discovered on a routine physical examination, Doppler studies can be used to determine the cause before proceeding with angiography. If you suspect an arterial embolism, order serial electrocardiograms (EKGs) and cardiac enzymes. An EKG may also diagnose auricular fibrillation. If SBE is a possibility, order blood culture. A cardiologist or cardiovascular surgeon may need to be consulted early in the course.


Other Useful Tests



  • Coagulation studies (disseminated intravascular coagulation [DIC])


  • Echocardiography (valvular stenosis)


Uremia

In developing a list of possible causes of uremia, the first thing to do is to divide them into three categories: prerenal causes, renal causes, and postrenal causes.



  • Prerenal causes: These include congestive heart failure (CHF), hypovolemic shock, starvation, trauma, gastrointestinal (GI) hemorrhage, severe dehydration, septic shock, and transfusion reaction.


  • Renal causes: It is best to further subdivide these using the mnemonic VINDICATE to vindicate yourself.



    • V—Vascular includes renal vein thrombosis, dissecting aneurysm, renal artery embolism, and thrombosis. Malignant hypertension would also fit into this category.


    • I—Inflammatory disorders include glomerulonephritis, pyelonephritis, and SBE.


    • N—Neoplasms include multiple myeloma and leukemia.


    • D—Degenerative disorders are not usually a cause of uremia.


    • I—Intoxication should bring to mind a host of toxins and drugs including aminoglycosides, sulfanilamides, cephalosporins, arsenic, mercury, and lead.


    • C—Congenital disorders should prompt the recall of polycystic kidneys and Henoch–Schönlein purpura.


    • A—Allergic and autoimmune will help one to recall the collagen diseases, serum sickness, Goodpasture syndrome, Wegener granulomatosis, and thrombotic thrombocytopenic purpura.


    • T—Trauma should help to recall crush syndrome, hemolytic transfusion reactions, burns, and massive hemorrhage as possible causes.


    • E—Endocrine disorders, other than diabetes mellitus, are not associated with a high blood urea nitrogen (BUN) level.


  • Postrenal causes: This category includes the causes of uremia that are most likely to be treatable. They are bladder neck obstruction from prostatic hypertrophy, a median bar or interureteric bar, urethral stricture, stones, and neoplasms.

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Sep 23, 2018 | Posted by in CRITICAL CARE | Comments Off on U
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