Renal Failure and Dialysis Patients: What the EMS Provider Should Know

Your crew is dispatched to a local dialysis center for a patient experiencing chest pain. The dispatcher advises that your patient is a 56-year-old male, who was undergoing hemodialysis when he experienced chest pain. Upon your arrival, the dialysis technician reports that the patient was asymptomatic when he started hemodialysis. Dialysis was uneventful until two liters of fluid were removed. The patient then developed substernal chest pain, mild shortness of breath and dizziness. His vital signs then showed pulse 118, respiratory rate 26 and blood pressure 80/52. The dialysis technician gave a 500cc fluid bolus and put the patient into the Trendelenburg position. The patient remained symptomatic, so dialysis was stopped and EMS was called. The technician also tells you that the patient is dialyzed three days a week; his dry weight is 88 kg, and he weighed 92 kg before dialysis today. His past medical history includes diabetes complicated by chronic renal failure and coronary artery disease. Knowing that this patient has renal failure, you are able to focus your history and physical exam accordingly.

Anatomy and Physiology

EMS providers are called on to take care of patients with renal failure for a variety of reasons. It is important to understand renal anatomy, physiology, pathophysiology and, in some cases, the dialysis procedure to assess and treat these patients.

The kidneys are located in the retroperitoneal space (behind the abdominal cavity), just inside the lower ribs. Blood enters the kidneys through the renal arteries that branch directly from the abdominal aorta. After entering the kidney, the blood is filtered as it passes through a series of structures called nephrons, which are the essential functional units of the kidney. There are over a million nephrons in the kidney, each divided into two parts: the glomerulus and the tubule. The glomerulus can be thought of as a “ball of capillaries” surrounded by a “funnel” known as Bowman’s capsule. These capillaries have special fenestrated walls that allow filtration to occur. Pressure in the capillaries forces fluid, electrolytes and other molecules through the holes of the capillary walls, creating “filtrate.” Larger constituents, such as red blood cells, white blood cells, platelets and large proteins, are not able to pass through the fenestrations. Once the filtrate is formed, it flows through the tubule, where it is modified to become urine. In the tubule, important fluid and electrolytes are returned to the bloodstream, while further “waste” products are secreted into the filtrate. The newly formed urine then flows from the tubules to the collecting ducts, on to the renal pelvis, then to the ureter. Each ureter carries urine from a kidney to the bladder, where it is stored until it is expelled from the body via the urethra during urination.

Functions of the Kidney

The kidneys maintain the volume and composition of blood and other bodily fluids. They are a major regulator of blood pressure, fluid balance, electrolyte balance and acid-base homeostasis. These vital organs also function to rid the body of waste, stimulate red blood cell production and produce urine. The kidneys filter the volume of fluid in your body four times a day. A total of 50 gallons of blood flow through the kidneys each day.

Modification of urine is carried out through the exchange of components between the filtrate and the blood that surrounds the tubule. One part of the tubule particularly relevant to EMS is the loop of Henle. It is in this part of the tubule that sodium, potassium and chloride are removed from the filtrate and reintroduced back into the blood. This is important because furosemide (Lasix) and all other “loop” diuretics work by blocking this process. We know that water follows sodium. The reduction in the return of sodium to the blood results in an increased volume of water being retained in the urine for excretion from the body. Unfortunately, more potassium also remains in the urine when this mechanism is blocked, making these patients susceptible to hypokalemia.

Renal Failure

Renal failure occurs when there is a significant decrease or actual cessation of kidney function. Renal failure patients lose the ability to remove toxins from the blood, maintain fluid and electrolyte balance, control blood pressure and produce red blood cells. As a result, these patients can develop congestive heart failure (due to fluid overload), electrolyte disorders, bleeding disorders, anemia and symptoms related to toxin accumulation.

Renal failure is divided into two main types: acute and chronic. Acute renal failure usually has an abrupt onset, an identifiable cause, and, in most cases, is reversible. Chronic renal failure (CRF) is a longstanding, smoldering illness that is not reversible. The progressive failure of the kidneys in these patients will result in death if left untreated. The definitive treatment for chronic renal failure is kidney transplantation. Dialysis is used while patients are awaiting transplantation, or if they are not a candidate for this surgery.

Dialysis

Dialysis provides artificial kidney function to patients without functioning kidneys. The basic concept of dialysis is straightforward: to place a semipermeable membrane between blood and a special fluid called dialysate and allow pressure and diffusion to balance electrolytes between the two fluids, while drawing waste products and excess water out of the blood and into the dialysate. The semipermeable membrane only allows small particles and water to cross, just like the capillaries in the glomerulus.

EMS providers may encounter two types of dialysis. The most common is hemodialysis, which is generally conducted in a specialized medical setting. During hemodialysis, blood is removed from the body through a shunt and directed into a machine where the dialysis process takes place. The dialyzed blood is then pumped back into the body through the same shunt.

The other type—peritoneal dialysis— involves placing dialysate directly into the patient’s peritoneal cavity. The natural lining of the abdominal cavity (the peritoneum) is used as the semipermeable membrane through which diffusion occurs. Diffusion occurs between dialysate in the peritoneal cavity and blood vessels adjacent to the peritoneum. Patients are required to instill and remove dialysate into their abdomen through a surgically created port up to four times a day. Peritoneal dialysis can be accomplished at home without any direct supervision by medical personnel, but it requires active participation of the patient or his/her caregiver. Since a peritoneal dialysis port does not enter blood vessels, it cannot be used for vascular access.

Shunts, Fistulas and Grafts

For hemodialysis, the required blood flow is greater than a peripheral vein can handle. This increased demand requires that a line be used to access large vessels. When a patient first undergoes hemodialysis, access is usually obtained using a central catheter placed in either the subclavian or the internal jugular vein. Patients requiring long-term dialysis need a more permanent solution, usually from an arteriovenous (A-V) shunt, or a connection between an artery and vein. This allows for large flow rates and can be done surgically using one of two methods: a fistula or a graft (Figure 1).

A fistula is formed by surgically connecting the walls of an artery to the walls of a vein. Fistulas are usually created in a patient’s upper extremities.

A graft is created by connecting the artery and vein with a synthetic tube. Grafts are also usually placed in a patient’s upper extremities.

Due to the increased vascular pressure in an extremity where an A-V shunt has been created, EMS providers should avoid any extremity with a shunt when starting an IV or measuring blood pressure. If an ALS provider cannot obtain IV access in a life-or-death situation, an IV catheter may be inserted into the A-V shunt as a last resort, if local protocol allows. It is important to note that, if this is used, care should be taken to properly clean these sites prior to IV insertion. These ports can be easily infected or damaged, with significant long-term implications for the patient. If the patient is still at the dialysis center when EMS determines that emergency access is necessary, ask the dialysis center staff to obtain access. They are experienced in this area and can minimize the potential for complications. If the patient has multiple shunts, ask which shunt is active. It is not uncommon for an old, nonfunctional shunt to be left in place. If your patient has shunts in both arms, it is acceptable to use the nonfunctional side for procedures and blood pressures.

Selected Complications of Renal Failure

Uremia

Uremia is the term used to describe the signs and symptoms that are often present in a patient with inadequately treated renal failure. Uremia can present with nausea, vomiting, diarrhea, weakness, dyspnea, irritated and itchy skin (pruritis), headache and bruising or irregular darkening of the skin (hyperpigmentation). The treatment for uremia is dialysis.

Fluid Overload

Fluid overload is caused by a reduction in the body’s ability to excrete fluid through the urine. It may manifest as hypertension, peripheral edema, ascites or pulmonary edema. The definitive treatment for fluid overload in a CRF patient is dialysis, but medications causing vascular dilation, such as nitroglycerin, can be used as a temporizing measure. Also, if the CRF patient has some residual renal function, diuretics can sometimes be helpful.

Anemia

Anemia is defined as a deficiency of hemoglobin (the oxygen-carrying material in red blood cells). Red blood cell production is stimulated by a protein produced in the kidneys called erythropoietin. As renal function decreases, erythropoietin secretion diminishes. Without erythropoietin, red blood cell production decreases, causing anemia. As a result, most patients with end-stage renal disease have anemia as a natural course of the disease. To compensate, CRF patients often receive weekly doses of erythropoietin.

Hypertension

The kidneys play a large part in blood pressure management. Almost all patients with kidney failure have hypertension. Many require multiple medications to control their blood pressure, but the definitive treatment for acute hypertension in these patients is dialysis. High blood pressure alone, although unhealthy, does not require urgent treatment unless it is associated with symptoms of end-organ damage, such as chest pain or altered mental status (this is referred to as a hypertensive emergency). EMS providers who are managing patients with a suspected hypertensive emergency should make liberal use of online medical control.

Potassium Homeostasis

Hyperkalemia, or high potassium, is a common complication of renal failure. Malfunctioning kidneys are not able to effectively remove potassium from the body. With continued dietary intake of potassium, blood levels may increase. Patients may also present with hypokalemia (low potassium levels) if they are on an aggressive potassium-restricted diet, are improperly dialyzed or overuse loop diuretics without potassium supplementation. The recognition and treatment of hyperkalemia are critical points for EMS providers to understand. Although renal failure patients can tolerate higher levels of potassium in their blood, hyperkalemia can lead to cardiac toxicity and cause fatal dysrhythmias if left untreated. Characteristic ECG changes are shown in the accompanying box, as is the emergency treatment of hyperkalemia. Calcium stabilizes the cardiac cell membranes, but does not reduce potassium level in the blood, while insulin, sodium bicarbonate and beta agonists cause a reduction in serum potassium levels. Note that when insulin is used to reduce hyperkalemia, it must be given along with glucose to avoid causing hypoglycemia.

Coronary Artery Disease

Chronic diabetes rarely causes renal failure without also causing coronary artery disease and peripheral neuropathy (nerve degeneration). As a result, sensory nerves from the heart may not be fully functional and classic symptoms of myocardial ischemia, such as chest pain, may not be present. A high level of suspicion for acute coronary syndrome must be maintained in CRF patients.

Complications of Dialysis

EMS providers are frequently called on to care for chronic renal failure patients, both between and during dialysis treatments. The prehospital provider should understand the following complications that may occur with dialysis.

Hypotension

Hypotension is the most common complication of dialysis. Fifteen to 30 percent of patients experience hypotension during dialysis, usually for either (or both) of two reasons. First, 300–400cc of blood is drawn into the dialysis machine during hemodialysis, temporarily reducing total blood volume. Second, in both hemodialysis and peritoneal dialysis, the process may remove fluid faster than the body can compensate. As with any other cause, hypotension during dialysis leads to decreased tissue perfusion, which can manifest as dizziness, weakness, syncope, altered mental status, angina, arrhythmia, seizures or myocardial ischemia. Hypotension is often managed by dialysis center staff by reducing the hemodialysis flow rate, administering a fluid bolus and placing the patient in the Trendelenburg position. Occasionally, the patient’s symptoms continue and EMS is called. Prehospital care for these patients includes standard treatment of hypotension (i.e., fluid resuscitation) and any other presenting problems.

Disequilibrium Syndrome

Disequilibrium syndrome, which can occur during or immediately following hemodialysis, results from a reduction of the blood urea level relative to the levels found in brain tissues. Urea, which is removed from the blood during dialysis, is an osmotic agent and causes a fluid shift from the vascular space into the cerebral space. This can result in cerebral edema and increased intracranial pressure. It may present with headache, nausea, vomiting, altered mental status or seizures. Supportive care is the appropriate prehospital treatment (which may include intubation and hyperventilation). If seizures occur, they should be controlled with benzodiazepines.

Hemorrhage

Occult internal bleeding may occur during dialysis. Dialysis patients have decreased platelet function and are administered heparin (an anticoagulant) during dialysis to prevent blood from clotting in the dialysis machine and its tubing. Due to the systemic effects of the heparin, providers must maintain a high level of suspicion for abdominal, GI and intracranial bleeding.

Both external and internal shunts can cause profuse bleeding if they are ruptured. Bleeding can occur secondary to trauma, or after routine puncture for hemodialysis. Heparin is added to blood as it goes through the dialysis machine (to avoid clotting), and this may exacerbate the problem. Shunt hemorrhage should be treated as an arterial bleed and should be managed with direct pressure and elevation of the affected extremity.

Equipment Malfunction

Equipment malfunction can introduce an air embolus or foreign body into a patient’s vasculature during dialysis. An air embolus enters the venous side of the bloodstream and proceeds to the right heart where it is broken up into a frothy solution, similar to blowing bubbles in a glass of milk. This froth can obstruct the pulmonary circulation. Air emboli may present with signs and symptoms similar to a pulmonary embolism, with an acute onset of chest pain, shortness of breath, hypotension and diaphoresis. Treatment includes oxygen and simultaneous left lateral decubitus and the Trendelenburg positioning. This is a life-threatening complication, and EMS providers should move rapidly, communicating with medical control to advise the receiving hospital if the condition is suspected by either the EMS provider or dialysis center staff.

Medication Removal

Another complication of renal failure is the inadvertent removal of therapeutic medications during dialysis. Renal failure patients are likely to have several medical problems and may be on several medications. Certain medications are removed during the dialysis process. For instance, a patient with a seizure disorder controlled by the anticonvulsant gabapentin (Neurontin) may become more susceptible to seizures after dialysis if the dosage has not been adjusted for the amount removed during the procedure.

Assessment of Renal Failure Patients

EMS providers should focus on certain details of a history and physical exam when presented with a renal failure patient.

1. History

A comprehensive assessment should include information about past dialysis and complications. If fluid overload is suspected, obtain a diet history to include recent salt, potassium and fluid intake. If the patient is at the dialysis center, obtain information about the current dialysis session from the facility staff. Appropriate details include the dialysis schedule, how long the patient has been on dialysis, the patient’s dry weight and how much fluid was removed before the session was terminated. A patient’s dry weight is the estimated weight of the patient in normal fluid balance. (This is helpful in determining how much fluid to remove during dialysis, since one liter of fluid weighs one kilogram.)

2. Physical Assessment

The general physical assessment of renal failure patients is similar to that of any other patient, but some areas require more attention. These include fluid status, mental status, cardiac rhythm and shunt location. When examining these patients, you must raise your index of suspicion for associated medical problems such as arrhythmias, internal bleeding, hypoglycemia, altered mental status and seizures.

3. Fluid Status

Consider the clinical situation when evaluating your patient. After dialysis, patients are more likely to be hypovolemic and present with cold, clammy skin; poor skin turgor; tachycardia and hypotension. On the other hand, patients who have delayed dialysis will likely be hypervolemic, and thus will have signs of fluid overload such as abnormal lung sounds (crackles), generalized edema, hypertension or jugular venous distension.

4. Mental Status

Altered mental status can be difficult to evaluate in the field, but it is an important indicator of serious underlying pathology. As with any patient, altered mental status in the CRF patient may be caused by a number of pathologies. Remember that the CRF patient is often also diabetic and may be prone to hypoglycemia.

5. Cardiac Rhythm

Assessment of cardiac rhythm is essential in every symptomatic renal failure patient. A 12-lead electrocardiogram can indicate underlying electrolyte disorders, cardiac ischemia or potentially malignant arrhythmias.

Treatment Misconceptions

Because renal failure and dialysis are often misunderstood, there are misconceptions about appropriate treatment. If EMS providers have questions about appropriate treatment of the renal failure patient, liberal use of online medical control should be considered. In conversations with medical control physicians, it is important that they understand you are dealing with a patient with renal disease. It is also important to note whether or not the presenting problem occurred around the time the patient received dialysis.

Common misconceptions include the following:

Fluid Administration: “These patients can’t excrete fluid, so I’ll put them into pulmonary edema if I give any fluids.” While this may be true in the fluid-overloaded patient, it does not mean that IV fluids should be withheld from a renal failure patient who is in need of fluid resuscitation. Hypovolemic or hypotensive patients should receive a fluid bolus when indicated. In contrast, EMS providers should be careful to limit fluids in patients who do not need fluid resuscitation. IV fluids that are inadvertently left wide open can certainly cause damage to renal failure patients. Renal failure patients typically are difficult to obtain IV access for, and although multiple attempts should be avoided, when IV access is indicated, it should not be deferred simply because a patient has renal failure.

Diuretic Administration: “The kidneys don’t work, so what good is a diuretic?” Some end- stage renal failure patients continue to have some degree of residual kidney function. In fact, these patients may retain up to 20% of normal renal function. Thus, a patient who presents in pulmonary edema may respond to a large dose of a loop diuretic like furosemide (Lasix). The patients themselves will be able to tell the EMS provider whether they still make urine, which will indicate whether diuretics will be effective in increasing urine output. Renal failure patients often require large doses of diuretics, so the EMS provider should seek medical control if necessary. It is important to note that in addition to decreasing fluid volume through increased renal excretion, furosemide causes venodilation and so has a secondary therapeutic effect in fluid overload.

Morphine Administration: “I know the end products of morphine are excreted by the kidney, so I’m afraid they will build to toxic levels in the renal failure patient.” It is true that the metabolites of morphine are excreted through the renal system, and that morphine doses should be reduced in long-term therapy for a renal failure patient. But in the emergency setting, it is safe to administer morphine when it is indicated under local protocol (such as for pulmonary edema or myocardial infarction).

Conclusion

EMS providers often encounter renal failure patients, and it is important for all providers to understand the anatomy, physiology and pathology involved with renal failure and dialysis. A history and physical exam tailored to the special concerns of renal failure is desirable and may enable the provider to identify problems that would otherwise be overlooked.

Bibliography

• American Academy of Family Physicians. Patient Information: How to Treat Your High Blood Pressure with Lifestyle Changes. American Family Physician 50:1, July 1994.
• Bledsoe BE, Porter RS, Shade BR. Paramedic Emergency Care, 3rd Ed. Upper Saddle River, NJ: Brady Prentice Hall, 1997.
• Campbell NA. Biology. 3rd Ed. New York: Benjamin Cummings Publishing, Inc., 1993.
• Costanzo LS. Physiology. Philadelphia: Williams and Wilkins, 1995.
• Fauci AS, Braunwald E, Isselbacher KJ, et al. Harrison’s Principles of Internal Medicine, 14th Ed. New York: McGraw-Hill, 1998.
• Netter FH. The Ciba Collection of Medical Illustrations, Volume 6: Kidneys, Ureters, and Urinary Bladder. West Caldwell, NJ: CIBA Pharmaceutical Company, 1979.
• Pons PT, Cason DC. Paramedic Field Care. St. Louis, MO: Mosby-Year Book, Inc., 1997.
• Rose BD, Rennke HG. Renal Pathophysiology. Philadelphia: Williams and Wilkins, 1995.
• Stedman’s Concise Medical Dictionary. Philadelphia: Williams and Wilkins, 1997.
• Virginia Commonwealth University Medical College of Virginia, Department of Nephrology, M2 Renal Syllabus. Unpublished educational document, November, 1997.

The authors wish to thank the following individuals for their assistance in reviewing this article: Joseph Ornato, MD, professor and chair, Department of Emergency Medicine, and Todd Gehr, MD, Department of Internal Medicine Division of Nephrology, both of the Virginia Commonwealth University Medical College of Virginia, Richmond, VA; Christopher Cowen, AEMT-CC, and Heather Wilson, AEMT-CC, both of Potsdam Rescue Squad, Potsdam, NY.