Chapter 45 Nursing Assessment Renal system S. Buckley, RN, MS ( adapted from Mosby pp) Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved.
Nephron Basic function is to clean or clear blood plasma of unnecessary substances ~ 1million nephrons in each kidney Contains: glomerulus, Bowman’s capsule, tubules ( proximal, convoluted, loop of Henle, distal convoluted)
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Physiology of urine formation * Primary function of kidneys: filter blood, maintain body’s internal homeostasis. * Primary function of kidneys: filter blood, maintain body’s internal homeostasis. * Multistep process of: filtration, reabsorption, secretions, excretion of water, electrolytes and metabolic waste. * Urine formation begins at glomerulus (blood filtered) * Urine formation begins at glomerulus (blood filtered) * Glomerular filtration rate (GFR)- amount of blood filtered by the glomeruli in a given time, * Glomerular filtration rate (GFR)- amount of blood filtered by the glomeruli in a given time, normal is ~ 125ml/min. normal is ~ 125ml/min.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. The normal kidney can alter its excretion of salt to match loss with gain.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Structures and Functions of the Urinary System Primary function of kidneys: 1. Regulation of water and ion balance (electrolyte and acid base balance) 2. Removal of metabolic waste products from the blood and excretion in urine 3. Removal of foreign chemicals from the blood and excretion in urine 4. Secretion of hormones: a. Erythropoietin, which controls erythrocyte production b. Renin, which controls formation of angiotensin and influences blood pressure and sodium balance c. 1, 25-dihydroxyvitamin D3, which influences calcium balance
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Renal processes for sodium and water Sodium and water freely filter form the glomerular capillaries into Bowman’s space and undergo reabsorption, Normally ~99% Most reabsorption (2/3) occurs in proximal tubule, water reabsorption is by diffusion and dependent upon sodium reabsorption. Major influence on the reabsorption of sodium and water in tubules is ADH ( increases reabsorption of sodium and water and therefore decreases urine output Sodium excreted=sodium filtered-sodium reabsorbed Serum sodium mEq/L
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Renal water regulation Major change caused by water loss or gain out of proportion to sodium loss or gain is a change in osmolarity of the body fluids. Change in osmolarity is responded to via osmoreceptors in hypothalamus, controlling ADH secretion.
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Thirst and salt appetite Must replace sodium and water losses by intake THIRST, drives ingestion of water, stimulated by low extracellular volume and high plasma osmolarity.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Potassium regulation Most abundant intracellular ion. Only 2% of total body K is in extracellular fluid. K concentration in extracellular fluid is important for the function of excitable tissues (nerve and muscle). Any increase (or decrease) in extracellular K, changes resting membrane potential of cells (in heart can result in abnormalities of heart rhythm, or arrythmias or weakness). K in urine=amount ingested minus amount eliminated in feces and sweat. Deficit or excess controls aldosterone secretion, which determine excretion of K in urine. Serum potassium mEq/L
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Water balance, acid-base balance Function of: 1. ADH 2. Aldosterone 3. HCO3 and H+ (acid/base balance) 4. ANP
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Antidiuretic hormone (ADH)-required for water reabsorption in the kidney, important in fluid balance. makes tubules and collecting ducts permeable to water, allowing water to be reabsorbed into the peritubular capillaries and returned to the circulation. Functions in concert with hypothalamus and neural input as loop mechanism decreases urine output
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. aldosterone Released from adrenal cortex, acts on distal tubule to cause reabsorption of Na+ and water. Influenced by blood concentrations of Na+ and K+ In exchange for Na+ reabsorption, potassium ions (K+) are excreted.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Atrial Natriuretic peptide (ANP) Hormone secreted from cells in R atrium in response to atrial distention due to an increase in plasma volume. Acts on kidneys to increase Na+ excretion. Inhibits renin, ADH and action of angiotensinII on the adrenal glands, thus suppresses aldosterone secretion. ANP causes relaxation of afferent arteriole, thus increasing the GFR Combined effects of ANP=production of large volume of dilute urine
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Renin angiotensin aldosterone system You tube; Dr. Najeeb, 1-7 short video’s, RAAS/kidney function. OBdU OBdU
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Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Other Kidney functions (continued) Erythropoietin -stimulates the production of red blood cells (RBCs) in bone marrow produced and released in response to hypoxia and decreased renal blood flow. In renal failure, a deficiency of erythropoietin occurs leading to anemia Vitamin D- hormone obtained in diet and sun. requires metabolism in liver and kidney to be “activated”, essential for absorption of Ca+ from GI tract. In renal failure manifestation of problems of altered Ca+ and PO 2 balance.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Other Kidney functions Calcium balance -parathyroid hormone (PTH) is released from parathyroid gland in response to low serum ca+ levels. PTH works by causing increased tubular reabsorption of CA 2 + and decreased tubular reabsorption of phosphate ions (PO 4 2 -) In renal disease, the effects of PTH may have major effect on bone metabolism.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Other Kidney functions (continued) Renin -regulates BP, involved in splitting of angiotensin cascade (p. 1138). Angiotensin II stimulates release of aldosterone (causes Na+ and water retention leading to increased ECF volume) Also causes peripheral vasoconstriction. (both increase BP) Produced and secreted by cells in kidneys, released into blood in response to decreased; renal perfusion, arterial BP, ECF, Na+ Released into blood in response to increased urinary Na+ concentration
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Other kidney functions (continued) Prostaglandins (PGs)- involved in the regulation of cell function and host defenses PG synthesis occurs in the medullla of the kidney. PGs increase renal blood flow and promote Na+ excretion. Counteract the vasoconstrictor effect of angiotensin and norepinephrine =decreased systemic vascular resistance= decreased BP.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Acid base regulation Reabsorbing and conserving bicarbonate (HCO 3 ) and secreting Hydrogen (H+) in response ph of ECF Distal tubule functions to maintain the ph of ECF within range of Metabolic response to ph along with respiratory acid/base balance.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Urinary Bladder Serves as reservoir for urine Bladder muscle-detrusor muscle Normal urine output, ~1500ml/day, varies with intake of food and water, diurnal pattern. ~250ml of urine in bladder cause moderate distention and urge to urinate.
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Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Gerontologic Considerations Effects of Aging on the Urinary System 20-30% decrease in size with aging, by 70 yrs old, 30-50% of glomeruli have lost function. Decreased renal blood flow, decreased GFR, alterations in hormone levels (ADH, aldosterone, ANP=decreased urinary concentration, limitations in excretion of water, Na+, K+ and acid).
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Benign prostatic hyperplasia (BPH) Enlargement of prostate Prevalence-50% of men over 50 yrs, 90% of men over 80 yrs. Symptoms result from urinary obstruction; Obstructive symptoms-decrease in caliber and force of urinary stream, difficulty initiating voiding, intermittency, dribbling Irritative symptoms- (associated with inflammation or infection)- frequency, urgency, dysuria, nocturia, incontinence
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. BPH (continued) Complications -urinary retention, UTI; potential sepsis, urinary calculi, hydronephrosis leading to renal failure, pyelonephritis, bladder damage. Diagnostic -DRE ( digital rectal exam ), PSA ( prostate- specific antigen-blood level associated with ca and BPH ) Collaborative care -drug therapy, diet, catheterization, surgery (TURP), laser prostatectomy, stent placement, monitor for infection, hemorrhage, education, emotional support.
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Women’s gerontological urinary issues Urethrovesical unit undergoes loss of elasticity, vascularity and structure, may result in incontinence (stress), irritation, bladder infections, prolapse Hormonal changes result in decrease in estrogen, mucosal dryness and irritation (cystitis)
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Incidence of uti Most common bacterial infection, not reportable (US) 7 million office visits, 1million ER visits, 100,000 hospitalizations. 1in 3 women will have 1 episode requiring antibiotics by age 24, ½ of all women in lifetime Increased in pts with; infants, pregnancy, aids, ms, dm, BPH Catheter associated uti: most common nosocomial, >1million cases a year. Costs: 1.6 billion.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Conditions impacting voiding Any disease or trauma that affects function of the brain, spinal cord, nerves that innervate bladder, sphincter or pelvic floor can affect bladder function. These include: DM, MS, paraplegia, quadriplegia, spinal problems, drugs affecting nerve transmission.
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Assessment of the Urinary System Subjective data Important health information Past health history-related diseases, surgeries, include family hx, occupation/environment, diet, water intake, exercise, elimination pattern Past health history-related diseases, surgeries, include family hx, occupation/environment, diet, water intake, exercise, elimination pattern Smoking hx; major factor in risk for bladder ca. tumors occur 4x more frequently. Smoking hx; major factor in risk for bladder ca. tumors occur 4x more frequently. Medications Medications Surgery or other treatments Surgery or other treatments
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Assessment terms (p.1145)
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Assessment of the Urinary System (cont’d) Functional health patterns Health Perception–Health Management Pattern Health Perception–Health Management Pattern Nutritional-Metabolic Pattern Nutritional-Metabolic Pattern Elimination Pattern Elimination Pattern Activity-Exercise Pattern Activity-Exercise Pattern Sleep-Rest Pattern Sleep-Rest Pattern Cognitive-Perceptual Pattern Cognitive-Perceptual Pattern Self-Perception–Self-Concept Pattern Self-Perception–Self-Concept Pattern Role-Relationship Pattern Role-Relationship Pattern Sexuality-Reproductive Pattern Sexuality-Reproductive Pattern
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Assessment of the Urinary System (cont’d) Objective data Physical examination Inspection Inspection Palpation Palpation Percussion Percussion Auscultation Auscultation
Copyright © 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved. Diagnostic Studies of the Urinary System Urine studies- accuracy of results influenced by: proper procedure, pt. cooperation, often require bowel prep (KUB, IVP). Urinalysis; 1 st test done, best obtained in am, Creatinine clearance- Creatinine: waste product produced by muscle breakdown, Creatinine clearance- Creatinine: waste product produced by muscle breakdown, most accurate indicator of renal function Normal value: ml/min Serum creatinine: mg/dl BUN-10-30gm/dl Urodynamics; measures urinary tract function Specific gravity;
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Fig. 45-7
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