Chapter 41 Urinary Elimination PDF

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Urine elimination depends on factors such as food consumption, fluid intake, medications, and fluid loss through breathing and perspiration. • Healthy adults eliminate approximately 1400 mL of urine each dayNormal Structure and Function of the Urinary System Kidneys The kidneys excrete and reabsorb ...

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! • Urine elimination depends on factors such as food consumption, fluid intake, medications, and fluid loss through breathing and perspiration. ! • Healthy adults eliminate approximately 1400 mL of urine each day!

Normal Structure and Function of the Urinary System • Kidneys products such as urea and conserving useful substances. Urea is produced when protein-rich foods are digested. The urinary system helps control blood pressure and plays a crucial role in electrolyte and acidbase balance.!

blood, regulate blood volume and pressure, produce erythropoietin for red blood cell formation, synthesize vitamin D to help control calcium levels, and maintain the acid- base balance of the extracellular fluid.!

‣ The renal corpuscle is made up of a network of blood capillaries called the glomerulus, which is surrounded by the Bowman capsule. ! ‣ The renal tubule is composed of the proximal tubule, the loop of Henle, and the distal convoluted tubule! ‣ Reabsorption occurs in the renal tubule as most of the filtrate moves back into the blood. At this point waste products, excess solutes, and small amounts of water are not reabsorbed but are secreted. ! ‣ As tubular secretion takes place, urine is produced. Urea, water, and other waste substances form urine as they pass through the nephrons down the renal tubules • Ureters

the kidneys, the patient becomes susceptible to kidney infections. • Bladder and urethra

through the urethra. Sphincter muscles at the base of the bladder help keep urine from leaking by closing tightly like a rubber band around the opening of the bladder. The urethra transports urine from the bladder to outside the body for elimination and bladder emptying.!

the bladder through the urethra. When all of the signals occur in the correct order, normal micturition, or urination, occurs. • Normal urine characteristics

day is dependent on the amount of fluids consumed, medications, medical conditions, and dietary intake, such as salt.!

Altered Structure and Function of the Urinary System • Abnormal urination patterns • Urinary incontinence, the inability to control urination, is prevalent, particularly in women, and can greatly affect quality of life.

occurs as a result of any process that limits effective blood flow through the kidneys. ! ‣ Dialysis is a technique by which fluids and molecules pass through an artificial semipermeable membrane and are filtered by means of osmosis.! ‣ During hemodialysis, the patient's blood flows continually from the body through vascular catheters to the dialysis machine. The blood then goes through the machine's filters, and ultrafiltrate (a liquid from which the blood cells and the blood proteins have been filtered out) is created.! ‣ Peritoneal dialysis is performed by instilling dialysis solution into the patient's abdominal cavity through an external catheter.

adults, or less than 500 mL/day in adults.! ‣ Prerenal failure occurs as a result of reduction in blood flow to the kidneys. ! C f l f il i l d d h d ti l ll dl

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‣Structural issues with the kidneys, from primary glomerular diseases or vascular lesions, result in renal failure.! ‣ Postrenal failure is related to a mechanical or functional obstruction of the flow of urine. ! ‣ The patient may be breathless, with pale, clammy, and cool skin, and have a low blood pressure; there may be signs of edema or anemia; and changes in the heart rhythm, hepatomegaly, and hypertension may be present.! ‣ If the intravascular volume is low, fluids should be administered for restoration.! ‣ Potassium levels need to be monitored, and dialysis may be initiated to reduce serum potassium levels to less than 5.5 mmol/l! ‣ The overall goal of dialysis is to remove toxins and to maintain fluid, electrolyte, and acid-base balance.! ‣ Measuring and recording intake and output (I&O) constitute an essential part of care for a majority of hospitalized patients, especially those experiencing fluid retention or excretion problems. Patients with acute or chronic renal failure may be placed on stringent fluid intake restriction, with orders for the nurse to maintain meticulous I&O records.

• For an adult, this would be 2500 mL or more of urine per day. ‣ Nocturia commonly is seen in men with benign prostatic hyperplasia (BPH) and in postmenopausal women because of decreased bladder tone. ! ‣ It also may be associated with the use of medications such as diuretics, as well as with UTIs, congestive heart failure, cystitis (inflammation of the bladder), and diabetes.

yeast infection, kidney or bladder stones, prostatic enlargement, malignancy, and allergic or irritant reaction to soaps, vaginal lubricants, spermicides, contraceptive foams and sponges, tampons, and toilet paper.

‣ The color of the urine does not reflect the degree of blood loss. ! ‣ Causes of hematuria include irritation or inflammation of the mucosa and invasion by bacteria. Malignancy, renal stones, trauma, infection, medications, tumors of the kidney, renal cysts, infarction, and arteriovenous malformations (AVM, abnormal connections between arteries and veins) may contribute to hematuria.

‣ Stress incontinence is loss of urine control during activities that increase intraabdominal pressure, such as coughing, sneezing, laughing, or exercise. ! ‣ Urge incontinence involves a sudden strong urge to void, followed by rapid bladder contraction. The affected person does not have enough time for toileting between recognition of the urge to urinate and the onset of voiding. ! ‣ Mixed incontinence is a combination of both stress and urge incontinence. ! ‣ Functional incontinence refers to lack of urine control in the absence of any abnormalities of the urinary tract; it occurs when some physical limitation in functioning, such as difficulty with clothing fasteners or impaired mobility, hinders reaching the toilet before voiding occurs. ! ‣ Overflow incontinence is seen in patients who are unable to empty the bladder completely, resulting in a constant dribbling of urine or increased frequency of urination. Overflow incontinence results from weakened muscles of the bladder, which may be a consequence of certain pathologic conditions. ! ‣ Temporary incontinence can occur in association with factors such as severe constipation, infections in the urinary tract or vagina, or medication usage.! ‣ Causes of acute urinary incontinence include extended bed rest, medications, increased amount of urine, mental confusion, pregnancy, prostate infection or inflammation, stool impaction, and UTIs. Chronic urinary incontinence issues may be related to bladder cancer, bladder spasms, depression, enlarged prostate, neurologic conditions, pelvic prolapse in woman, pelvic floor muscle damage that may occur with a hysterectomy, spinal injuries, or weakness of the bladder sphincter.

neurologic disorder. ! ‣ Conditions that contribute to urinary retention include vaginal childbirth, infections of the brain or spinal cord, diabetes, stroke, neurologic disorders, heavy metal poisoning, pelvic injury or trauma, prostate enlargement, infection, surgery, bladder stones, bladder tumors, rectocele, cystocele, constipation, urethral stricture, and medications such as antihistamines, anticholinergics, antispasmodics, and tricyclic antidepressants. • Factors affecting urinary elimination • The cause of enuresis, the involuntary passing of urine, may be structural or pathologic, although it may be related to nonurinary problems such as constipation, stress, and illness. ! • During the initial patient interview ask questions about the patient's urinary system function in a non-judgmental manner to establish trust and increase patient comfort.

‣ Preschoolers may have acquired the ability of independent toileting; however, accidents may occur and enuresis may be an issue until the age of approximately 5 years. ! ‣ By school age, the child's elimination patterns should be well established. ! R id l i di th ld l ti t t bl dd i f ti

necessary to initiate voiding.

quantity of urine produced. Dietary changes, such as the intake of different food, can cause changes in the color or odor of the urine.

autonomic nervous system may interfere with the urination process, causing urinary retention. Blood pressure medications, specifically diuretics, change the ratio of water and electrolyte reabsorption within the kidneys, which will alter the concentration of urine.

to contract and expand completely. Changes in the muscle tone of the pelvic floor can alter sphincter control, causing urine leakage.

urine can be affected by swelling of surrounding tissues. Postoperative bleeding can change the color and quantity of the urine. Anesthesia contributes to urine retention by decreasing awareness of the need to void.

blood flow to the kidneys, affecting urine production. Calculi may obstruct the ureter, blocking the flow of urine. Dehydration causes water retention, resulting in decreased urinary output. Some pathologic conditions can result in bladder removal. In such instances, urine will need to be diverted from the urinary tract to exit the body.

tract, usually Escherichia coli, invade the urethra and multiply. UTI is one of the most common health care–associated infections

function is impaired owing to trauma or disease involving the bladder, the distal ureters, or, rarely, the urethra.! ‣ With cutaneous urinary diversion, urine exits the body through a stoma created on the abdomen. ! ‣ With incontinent diversions (ileal conduits, ureterostomies, and other urostomies), an appliance, or bag, must be worn to collect urine as it is excreted from the body. ! ‣ For cutaneous continent diversions (Kock pouch, Mainz pouch, Indiana pouch), a collection reservoir is surgically created using a segment of the intestine; the patient then needs to catheterize the reservoir through a cutaneous stoma every 4 to 6 hours to drain stored urine. ! ‣ The orthotopic bladder substitute (i.e., ileal neobladder) is the most common continent diversion performed today because it most closely resembles the original bladder in both location and function. With this type of urinary diversion, a segment of the intestine is used as a urinary reservoir and is anastomosed (connected) to the patient's native urethra. ‣ An orthotopic neobladder eliminates the need for a cutaneous urinary collection device and, in some cases, the need for intermient catheterization. The type of urinary diversion performed depends on a combination of clinical factors and patient preference.

Assessment • Abdominal assessment Normally, the abdomen is not distended and is symmetric and free of bruises, masses, and swelling. A distended bladder may be visible in the suprapubic area. A bladder scan can be conducted by the nurse with hand-held ultrasound equipment to quickly determine the extent of urinary retention. Abdominal distention may be seen in conditions such as polycystic kidney disease, pyelonephritis, ascites, and pregnancy. In addition, auscultation of the left and right renal arteries is performed to assess circulation sounds. Normally, no sounds are heard.

performed over the lower abdomen. The abdomen should be soft and nondistended. Deep palpation, which can be done to outline the shape of the bladder, usually is performed by the patient's PCP. Using a bimanual technique, the PCP will aempt to palpate the kidneys, which rarely are palpable unless they are enlarged from tumors, cysts, or hydronephrosis. Palpation of an enlarged kidney may be painful for the patient.! ‣ Assessment by a PCP may include blunt or indirect percussion to further assess the kidneys. The patient should feel no pain or tenderness with pressure or percussion. Pain or discomfort during or after percussion is suggestive of kidney disease. Percussion of the bladder determines location and degree of fullness.

(such as vitamin B), foods (such as asparagus or elderberries), and food dyes. Urine color may be altered by certain health problems. Concentrated urine is darker (deep amber) and may be the result of dehydration, low fluid intake, or reduced urine production. Dilute urine ranges in color from clear to pale straw and may be a consequence of excessive fluid intake or the inability of the kidneys to concentrate urine. Red or pink urine may be associated with bleeding, strenuous exercise, UTI, enlarged prostate, kidney or bladder stones, kidney disease, or cancer. • Food

Asparagus consumption may result in green urine. • Medication orange. Blue or green urine can be seen in patients receiving medications such as cimetidine, indomethacin, or promethazine. • Pathological conditions yellow-orange and tea color.

bladder or kidney surgery, patients may excrete bloody urine containing clots. These patients typically require irrigation (flushing) of the bladder using a three-way catheter to prevent potential blockage.

in smaller volume. Foods (most notably asparagus), genetics, and some diseases are associated with a change in the odor of urine. In uncontrolled diabetes, the urine can have a sweet, fruity odor, whereas in infections, a strong, unpleasant odor may be evident.

retention. The normal urinary output is approximately equal to fluid intake. Adult urinary output of approximately 0.5 mL/kg/h is considered normal.!

• Laboratory tests

and is measured as BUN. Creatinine is a waste product that is produced in the blood as a by-product of muscle metabolism.! ‣ BUN concentration is a measure of the urea level in the blood. Urea is cleared by the kidney, and levels may be increased in the patient who is dehydrated or who has a disease that compromises the function of the kidney. Normal values for BUN in the blood are 7 to 20 mg/dL. Elevated levels may indicate kidney injury or disease as well as conditions such as diabetes, high blood pressure, blockage of the urinary tract, a high-protein diet, severe burns, gastrointestinal bleeding, or problems such as dehydration or heart failure, which affect blood flow. Medications also may elevate BUN levels. Low BUN values may be caused by a low- protein diet, malnutrition, liver damage, or drinking excessive amounts of liquids. No pretest preparation is required; however, medications, such as certain antibiotics, corticosteroids, and diuretics, may affect test results.! ‣ Creatinine is filtered along with other waste products from the blood by the kidney and eliminated in the urine. It is made at a steady rate, and levels are not affected by diet or by normal physical activities. The patient with kidney damage has decreased urinary creatinine but increased serum levels. The amount of creatinine in the blood is directly related to muscle mass; generally, creatinine levels are higher in men than in women. Normal values of serum creatinine are 0.6 to 1.2 mg/dL for women and 0.8 to 1.4 mg/dL for men.! ‣ BUN and serum creatinine are viewed in relationship to each other. Sudden rises in BUN-to-creatinine ratios occur in acute kidney failure associated with shock, dehydration, or severe gastrointestinal bleeding. Low BUN-to-creatinine ratios are seen in patients on low-protein diets or those with severe muscle injury, cirrhosis of the liver, or syndrome of inappropriate antidiuretic hormone (SIADH).

• Urinalysis for specific gravity monitors the balance of water and solutes (solid maer) in urine. Normal specific gravity in an adult is 1.005 to 1.030. The higher the level of specific gravity, the more solid material is contained in the urine. Fluid intake has a direct relationship to specific gravity. If large volumes of water are consumed, dilute urine is produced, which has a low specific gravity. Specific gravity is high in conditions of dehydration. ‣ pH • The acid-base balance in the body is determined by pH, which reflects the acidity or alkalinity of the urine. Urine normally is slightly acidic, with an average pH of 6. Urine with a pH of 4 is very acidic. A pH of 7 is neutral, and a pH of 9 is very alkaline.! • The pH is useful in determining the kidneys’ response to acid base imbalances In metabolic acidosis the urine

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pH decreases as the kidneys excrete hydrogen ions; in metabolic alkalosis, pH of the urine increases. Maintaining a healthy pH helps prevent formation of kidney stones. Urine for protein • Normally, urine does not contain protein. Protein modules generally are too large to escape from the glomerulus capillaries into filtrate. Protein in the urine may be associated with fever, vigorous exercise, pregnancy, and some diseases, such as kidney disease. In conditions such as glomerulonephritis (inflammation of the glomeruli of the kidney), the cell membrane can become permeable and allow proteins to cross. Glucose • Normal urine contains very little to no glucose. The urine glucose concentration is used to screen for diabetes and to assess glucose tolerance. Glucose in the urine may be a sign of kidney damage or disease. Urine glucose levels are not an adequate measure of blood glucose levels. In the uncontrolled diabetic patient, glucose may appear in the urine. Ketones • The presence of ketones in the urine (ketonuria) indicates that fat has broken down for energy. Ketones are normally not passed in the urine. Large amounts of ketones in the urine may indicate diabetic ketoacidosis. A diet low in sugars and carbohydrates, prolonged fasting or starvation, and vomiting also may be associated with ketonuria. Microscopic analysis • For microscopic analysis, urine is spun in a centrifuge and sediment settles at the bottom. The sediment is then spread on a slide and checked for red or white blood cells, casts, plugs, or crystals. The presence of crystals in the urine may indicate that stones are present. Bacteria, yeasts, and parasites are not normally present in urine and, when present, usually indicate infection. Suspected urinary tract infection • If a UTI is suspected, urine may be checked for nitrates. Nitrate levels increase when bacteria are present. A leukocyte esterase test determines the level of white blood cells in the urine; elevated levels indicate presence of a UTI.

not contain bacteria or organisms. If organisms grow in the culture, sensitivity testing is performed to determine the appropriate antibiotic for treatment.

timed specimen also is used to measure levels of protein, hormones, minerals, and other chemical compounds in the urine. Creatinine clearance, which measures how well creatinine is removed from the blood by the kidneys, provides information about kidney function. Factors or conditions that may interfere with the accuracy of a 24-hour urine collection include failure to include some portion of the output, continuing the collection beyond 24 hours, spilling the specimen, inability to keep the specimen cool, and previous ingestion of certain foods or medications.! ‣ Preparation is not required before initiation of a 24-hour urine collection. The time of the patient's first morning void is the best start time for the 24-hour specimen collection. The first voided specimen is not saved; all urine produced after the first (discarded) specimen is collected in a special opaque container and kept cool. At the completion of the 24 hours, the first voided specimen of the second day (if the collection was started in the morning) is included in the specimen, and the container is transported to the laboratory for analysis. The 24-hour urine collection may be performed on an outpatient or inpatient basis. • Diagnostic examinations

ultrasound technology, blood flow can be monitored during the procedure. Ultrasound studies may be safely conducted in pregnant women and in patients who have allergies to contrast media, because no radiation or contrast dyes are used. Factors or conditions that interfere with ultrasound results include severe obesity, recent barium studies, and excessive flatus or intestinal gas. Gener...