- Homeostasis: The body’s natural tendency to maintain a relatively constant internal environment through negative and positive feedback loops.
- Hyperkalemia: An excessive amount of potassium in the bloodstream.
- Myoglobinuria: The presence of myoglobin in the urine that is commonly evidenced as a brown discoloration.
- Rhabdomyolysis: Breakdown of skeletal muscle tissue, leading to release of myoglobin and other cellular components into the bloodstream.
- Uremia: An abnormal accumulation of urea and other waste products in the blood resulting from the kidneys’ inability to eliminate urea from the body.
It’s another hot and humid summer day when the crew of Rescue 102 is summoned to a private residence for a report of significant muscular pain and discolored urine. On arrival, a woman greets the crew and takes them to the restroom where her husband is hunched over the sink in obvious distress. The patient reports feeling significant pain and swelling in his legs and has been nauseous and vomited twice. His wife states that he ran an ultramarathon yesterday and has been feeling ill since. She also reports that he has tea-colored urine.
The patient’s vital signs reveal an elevated temperature and mild hypotension. Oxygen is provided by an EMT while the examination continues. A paramedic questions the patient about his past medical history, which reveals nothing noteworthy. The patient reports having taken ibuprofen for an arm injury prior to the marathon but takes no prescribed medications. The crew completes their assessment and loads the patient into the ambulance. IV access is established, and a 500 mL fluid bolus is administered.
No changes occur during transport. The patient is transferred to the hospital staff with a full report. Later in the day, the crew learns that the patient underwent hemodialysis for acute renal failure due to rhabdomyolysis likely caused by extreme muscle strain.
The kidneys play an incredibly important role in maintaining homeostasis in the body. Most of us will live our entire lives without compromise to these vital organs, but they can be injured through a number of mechanisms. If the injury to the kidneys is significant and abrupt, the patient may experience acute renal failure, which can be life-threatening. In other cases, the kidneys are injured over time and shut down due to chronic renal failure. It’s fairly common; one in 10 American adults will suffer from some form of chronic kidney disease during their lifetime.1
Prehospital caregivers play a vital role in ensuring that renal failure patients are quickly identified, properly treated and transported to an appropriate ED for continued care.
Anatomy & Physiology
The kidneys are bean-shaped organs located in the retroperitoneal space at approximately the level of the 12th ribs. The left kidney is positioned slightly higher than the right. In adults, the kidneys are approximately four inches long, 2.5 inches wide and 1.5 inches thick. A fatty pouch comprised of the renal capsule, adipose capsule and renal fascia surrounds each kidney. Large renal arteries bring approximately 1.2 liters of blood to the kidneys every minute for filtration and production of urine. The blood passes through a complex system of vessels, eventually leaving the kidneys through the renal veins.
The kidneys have two layers: the outer cortex and inner medulla. Although the two layers are visible during dissection, they function as one complete unit in the healthy individual. The outer cortex contains most of the glomeruli (described in more detail later) and the vast amount of nephrons that function to create urine. The medulla is the inner layer that is largely comprised of the renal pyramids. These cone-shaped structures serve to channel urine into the renal calyces.
On a microscopic level, a kidney’s main functional unit is the nephron, which consists of the renal corpuscle (glomerulus and Bowman’s capsule) and tubules. Filtration occurs in the renal corpuscle where the glomerulus filters blood across Bowman’s capsule. Filtration is the first step in forming urine.
Reabsorption occurs through specialized capillaries known as peritubular capillaries. Water, glucose, sodium and other nutrients and ions are brought back into the blood. The next step in the formation of urine is known as secretion whereby the remaining fluid and constituents pass through the loop of Henle and into the collecting tubule. The urine then passes into larger ducts that eventually empty into a renal calyx. From the renal calyx (plural is calyces), the urine then passes into the renal pelvis, down the ureter and into the urinary bladder until it is passed through the process of urination. Through filtration, reabsorption and secretion, the kidneys help to regulate the body’s fluid, electrolyte and acid-base balance.
The kidneys also produce important hormones known as erythropoietin (EPO) and calcitriol. EPO serves to stimulate production of red blood cells in the red marrow of bone while calcitriol is the active form of vitamin D, which helps the body absorb calcium from food and obtain calcium from the bone for distribution in the blood stream. Lastly, the kidney secretes an enzyme known as renin. This important enzyme helps to maintain blood pressure through the renin-angiotensin-aldosterone pathway.
Figure 1: Kidney
Acute & Chronic Renal Failure
Acute renal failure can occur over hours to days based on the underlying mechanism of injury and relative health of the individual. Complications that arise when acute renal failure is present include disturbances in fluid and electrolyte balances and accumulation of metabolic wastes in the blood. Acute renal failure is often reversible if it’s recognized early and treated promptly. Despite the chances that it may be reversible, it has a mortality rate ranging from 50–80%.2
The causes of acute renal failure are commonly grouped into three major categories: pre-renal, intrarenal and post-renal failure.3 Pre-renal is the most common for renal failure and arises from such conditions as rhabdomyolysis, hemorrhage, sepsis, burns, trauma and a host of other factors. Intrarenal causes are classified by area affected: tubular, glomerular, interstitial and vascular.3 Diseases that can injure the kidneys include diabetes mellitus, systemic lupus erythematosis, persistent hypertension, renal blood vessel occlusion and other disease processes. Post-renal failure can occur when there’s an obstruction in the urinary tract. Kidney stones, trauma, bladder cancer and enlargement of the prostate can lead to post-renal failure.
In contrast to acute renal failure, chronic renal failure is a gradual process occurring over time with a resulting decline in renal function. Depending on the level of severity, chronic renal failure may be treated with dialysis and possibly by kidney transplantation. Over time, chronic renal failure can lead to a permanent and irreversible loss of renal functioning, known as end stage renal disease (ESRD).
Complications that can be expected to arise in the acute or chronic renal failure patient include fluid and electrolyte abnormalities, particularly hyperkalemia. EMS providers should be alert to the possibility of fluid retention, which may be evidenced by pulmonary and systemic edema. The patient may develop hypo- or hypertension depending on the cause and type of renal failure.
Figure 2: The Retroperitoneal Space
Assessment of the renal failure patient begins with performing an initial assessment to detect and treat threats to life. Once life-threatening conditions are addressed, the EMS provider should turn to gathering a complete patient history and performing a detailed examination. Use the SAMPLE (signs/symptoms, allergies, medications, past medical history, last oral intake and events preceding the call for help) mnemonic as a guide to asking basic questions. Question the patient about vomiting, diarrhea or inadequate fluid intake, and be alert for signs of dehydration. While patient questioning is occurring, ensure that other providers are assessing vital signs. Pulse oximetry, blood pressure, pulse, respirations and temperature should all be assessed and recorded.
Ask if the patient has been diagnosed with renal failure. Question the patient about difficulties or changes in urination, including a reduction or cessation in urinary flow, any discoloration to the urine, and passage of any kidney stones. Determine if the patient has pain. When pain is present, assess it using the OPQRST mnemonic (onset, provocation, quality, region/radiation, severity and time).
Since acute and chronic renal failure can manifest in many different ways, the EMS provider should assess the entire body following the head-to-toe format. Determine if there’s any trauma. If present, assess the mechanism of injury and determine the likelihood of kidney injury by considering the forces involved and location of injury.
Unlike many organs in the abdomen, the kidneys are located outside of the protective peritoneum, a membrane that contains adipose and connective tissue that often serves as a cushion to absorb kinetic forces. While there is a good level of protection from the posterior muscular wall of the abdominal cavity, the kidneys can be injured from blunt or penetrating trauma, particularly when forces are transmitted posteriorly. In fact, the kidneys are the most commonly injured genitourinary organ with blunt trauma being the most common offending insult.4 Adding to the risk is the fact that bleeding into the retroperitoneal space can accumulate as much as 3,000 milliliters of blood. Given the amount of blood that can be lost in this space, acute renal failure can develop with or without direct insult to the kidneys.
Check for jugular venous distention, and assess the breath sounds for any abnormalities. Inspect and palpate the abdomen to determine if there’s tenderness, guarding or injury. A patient with an obstruction that prevents emptying the bladder may be in significant distress with the bladder palpable above the pubic symphysis.
Assess the extremities for signs of edema. If the patient is bedridden, the edema may accumulate posteriorly in the pre-sacral area. Assess the skin color, condition and temperature. A patient with chronic renal failure may have uremic frost on the skin, which is a powdery deposit of urea and uric acid salts resulting from severe uremia. Examine both upper extremities to determine if the patient has a vascular access point for hemodialysis through an arteriovenous fistula or graft.5 If neither is present, it’s also possible that the patient may have a catheter inserted at the neck, chest or groin area.
Question the patient about the ability to void normally. Patients with chronic renal failure may have the ability to pass some urine. Ask the patient about recent changes in urinary habits. The patient may report a change in color or report the presence of blood in the urine. Tea-colored urine is indicative of protein in the urine, more formally known as myoglobinuria.
Advanced-level providers should perform an ECG to determine if there are any dysrhythmias or abnormalities and when there’s known or suspected hyperkalemia.6 Patients with hyperkalemia may present initially with peaked T waves.7 If the patient has significant hyperkalemia, there may be widening of the QRS complexes to the point where they may become indistinguishable from the T waves. It’s important to detect hyperkalemia rapidly because the mortality can reach as high as 67%.8
Basic treatment of the patient in renal failure should include providing oxygen and establishing IV access. A patient with renal failure combined with signs of dehydration and hypotension should be treated cautiously with IV fluids. Provide the fluid in small, incremental boluses (200–250 mL) while frequently assessing for changes in blood pressure and auscultating breath sounds for the development of pulmonary edema.
If pulmonary edema is present, the patient may be a candidate for bi-level positive airway pressure (BiPAP) or continuous positive airway pressure (CPAP). The patient in severe respiratory distress may require endotracheal intubation and positive-pressure ventilation. Pharmacological interventions vary by local protocol but may include administration of furosemide for its diuretic and vasodilatory properties. Sublingual nitroglycerin is also a common treatment in many EMS protocols; however, the provider should ensure that the blood pressure is 90 mm/Hg or greater prior to administering nitroglycerin. Fluid overload in a patient in chronic renal failure is typically best managed by transporting the patient to a facility that can provide dialysis.
Treatment of hyperkalemia may include the administration of calcium, bicarbonate, insulin and dextrose 50%. Protocols vary widely in which any of these medications can be administered in the out-of-hospital setting. Common adult dosing for calcium chloride
is 8–16 mg/kg via IV, dextrose 50% at 25 grams via IV, and sodium bicarbonate administered at 1 mEq/kg of an 8.4% solution via IV. If regular insulin is administered in the out-of-hospital environment, the dosage is typically 10 units administered subcutaneously. Some protocols also call for the administration of nebulized albuterol at 2.5 mg.
Definitive therapy for patients in renal failure is provided in the hospital environment or dialysis centers. Dialysis is one of the best therapies for patients in chronic renal failure, particularly when the patient hasn’t undergone the standard scheduled therapy. Long-term treatment for a patient with ESRD may include kidney transplantation; however, prospects of obtaining a donor from a non-family member are often dim. In 2010, nearly 76,000 patients were awaiting a kidney transplant, but only 16,843 transplants were performed on patients over the age of 20.9
Prehospital providers can be faced with a patient experiencing either acute or chronic renal failure. While the opening case presented an interesting acute renal failure patient presentation, the purpose was to focus the reader on the assessment findings and not to be distracted by atypical presentations. The general assessment approaches work well in caring for these patients, and they can be combined with some specific fact-gathering and physical assessment considerations. Standard therapy includes early administration of oxygen and establishing IV access. If fluids need to be administered, they should be provided cautiously with frequent assessments before, during and after administration. All renal failure patients should be transported to the emergency department for additional assessment and treatment. jems
1. National Kidney and Urologic Diseases Information Clearing House. (Nov. 15, 2012.) Kidney disease statistics for the United States. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH). Retrieved on June 30, 2013, from www.kidney.niddk.nih.gov/kudiseases/pubs/kustats.
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4. Voelzke BB, McAninch JW. The current management of renal injuries. Am Surg. 2008;74(8):667–678.
5. National Kidney and Urologic Diseases Information Clearing House. (Sept. 2, 2010.) Vascular access for hemodialysis. NIDDK, NIH. Retrieved on June 28, 2013, from www.kidney.niddk.nih.gov/kudiseases/pubs/vascularaccess.
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7. Mitchell SH, Brady WJ. The electrocardiogram in hyperkalemia. In Brady WJ, Hudson K, Braithwaite S, et al. (Eds.), The ECG in Prehospital Emergency Care. Blackwell Publishing Ltd., Oxford, U.K., pp. 112–116, 2012.
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9. U.S. Renal Data System (USRDS). USRDS 2012 Annual Data Report: Atlas of Chronic Kidney Disease and End-Stage Renal Disease in the United States [report]. National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases: Bethesda, Md., 2012.