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• Review the incidence of kidney disease
• Describe normal renal physiology
• Discuss the differences between acute and chronic renal failure
• Review how dialysis works
• Discuss prehospital management of dialysis patients
Chronic kidney disease (CKD) is a complex medical condition that can be difficult to understand. The ultimate end of CKD is end-stage renal disease, which typically results in patients requiring the life-sustaining treatment of dialysis. Dialysis is a complicated, life-altering and expensive process. This article explores the pathophysiology of CKD, the process of dialysis and the complications commonly encountered by EMS providers treating and transporting these patients.
Kidney disease is a serious and expanding problem; end-stage renal disease has a three-year mortality of greater than 50%.1 More than 10% of the U.S. population has some sort of chronic kidney disease.2 Chronic kidney disease is the progressive and irreversible loss of the kidneys’ ability to filter wastes and toxins from the blood. Kidney function is measured by the glomerular filtration rate (GFR): the amount of blood filtered by the nephron’s glomeruli in a minute. Normal GFR is greater than 90 mL/min/1.73m2. In the U.S., CKD is classified into five stages, beginning with mild damage for which the body can compensate and ending with end-stage renal disease (ESRD), defined by a GFR of less than 15 mL/min and the need for chronic renal replacement therapy (RRT). In 2010, 114,000 people began dialysis, and nearly 3,000 more received kidney transplants as their initial ESRD intervention.1
The only definitive treatment for ESRD, a kidney transplant, is not available for many patients. More than 95,000 individuals currently await kidney transplants.3 The increasing number of patients receiving hemodialysis helps demonstrate that the overall number of kidney transplants is quite low compared to the actual need. At the end of 2010, there were more than 400,000 patients on dialysis and only 180,000 living with kidney transplants.
While the many causes for renal failure will be discussed later in this article, diabetes is by far the leading cause of ERSD, and its incidence has been increasing since 1996.4 Together, diabetes and hypertension are the primary causes of kidney disease in more than 70% of cases.5
Normal Renal Physiology
The kidney is a bean-shaped organ found in the retroperitoneal region. It is located just lateral to the vertebral column between the 12th thoracic and third lumbar vertebra. Typically the right kidney is situated slightly inferior compared to the left because of the liver (Figure 1). Like all solid organs, the kidney is enclosed in a fibrous capsule that provides protection.
Blood enters the kidney through the renal artery at the hilum, which is the deep slit in the kidney’s medial aspect. The continuous pale outer tissues of the kidney are known as the renal cortex, which surrounds the inner renal medulla. The shape and interaction of the renal medulla and cortex cause the medulla to take on triangular shapes known as renal pyramids.