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CE ARTICLE Table 3: Causes of Chronic Renal Failure Table 2: Causes of Acute Renal Failure to Ask Type ............... Mechanism Prerenal ..........renal hypoperfusion (hypovolemia, hypotension) Intrarenal .........Rhabdomyolosis, infection Post renal ........kidney stones, tumors a serious emergency with a high mortality. There are three types of ARF, which are named to describe the location of the pathology. Prerenal failure results from renal hypoperfusion, which can occur for a variety of reasons such as hypotension or sepsis. Intrarenal failure indicates injury or pathology affecting the nephron or renal parenchyma, and post renal failure generally suggests an obstructive pathology in the drainage system. Patients with severe acute renal failure may briefly require dialysis, but otherwise the treatment of ARF focuses on correcting the underlying cause. ARF cannot be corrected until the actual cause is identified. Without intervention ARF can cause chronic renal failure. It is not uncommon for patients with CRF to have acute-on-chronic renal failure from isolated events such as an obstructive renal stone or infection. It is beyond the scope of this article to identify all of the causes of ARF, as most cannot be managed in the prehospital environment. Chronic Renal Failure While ARF is a true medical emergency with a rapid onset, its causes are reversible and often transient in nature. CRF is life-altering and permanent once it develops. There are many causes of chronic renal Pathologic Glomerulonephritis Interstitial nephritis Tumors Transplant rejection Congenital disease failure, which are outlined in Table 3. Of note, children can develop CRF as a result of congenital abnormalities or diseases such as sickle cell anemia or following traumatic injury. The diagnosis of CKD is determined based on a patient's estimated glomerular filtration rate (eGFR). A normal GFR, or the amount of blood passing through glomeruli in a minute, is greater than 90 mL/min/1.73m2. Diagnosis of CKD is defined as: kidney damage for three months or more as indicated by structural or functional abnormalities of the kidney, with or without decreased GFR, or a GFR less than 60 mL/min for three months or more, with or without kidney damage.6 CKD progresses through stages 1–5 based on the eGFR. Stages 1–3 have a GFR greater than 30, and patients are often asymptomatic. Typically patients become symptomatic with a GFR less than 30 mL/min (stage 4). CKD has an impact on nearly every system in the body; many laboratory values become abnormal as kidney function worsens. Table 4 lists the normal ranges for some of the lab values often altered in patients with CKD. When patients reach stage 5, their GFR is less than 15 mL/ min/1.73m2, and dialysis is indicated. Patients do not commonly go directly from healthy to a diagnosis of Physiologic Hypertension Diabetes mellitus Chronic urinary tract infections Congenital abnormalities Vascular disease HIV CKD. With the exception of situations such as major trauma, a patient will typically experience a progression of renal dysfunction as they move toward renal failure. As a patient's GFR decreases, azotemia, the accumulation of nitrogen and other wastes usually removed through urine within the blood, begins to occur. As the patient's failure to excrete wastes via kidney progresses, the concentration of urea (byproduct of protein breakdown) rises, and a more severe condition develops: uremia. Simultaneously, the hormones released by the kidneys decrease in blood concentration as kidney function declines. These hormones include erythropoietin, which controls red blood cell production, a lack of which causes anemia. Decreased production of another hormone, renin, disrupts the renin-angiotensin-aldosterone system (RAAS), contributing to the often-severe hypertension observed in these patients. Dedicated to improving your Inventory, Asset, Purchasing and Fleet Management. Life With CRF and Dialysis The definitive treatment for end-stage renal disease is a kidney transplant. Unfortunately, transplant is only available for a small percentage of the population; annually fewer than 20,000 transplants are performed in the United States.6 877-217-3707 emsworld@operativeiq.com www.operativeiq.com © 2013 EMS Technology Solutions For More Information Circle 38 on Reader Service Card EMSWORLD.com | MARCH 2013 53