AKI ppt (chap 26) Flashcards
Define AKI.
Abrupt reduction in kidney function that leads to elevated creatinine, elevated blood urea nitrogen (BUN), and usually decreased urine output (oliguria). AKI is potentially reversible
What is the most common cause of AKI?
Sepsis and MODS
Why is the goal of AKI early diagnosis and prevention?
Since the prognosis is often reversible it is best to recognize and treat (the nurse should keep in mind that AKI often occurs in hospitalized pts). AKI has a high morbidity and mortality and the risk for it increases in sepsis, bleeding, and cardiac events. AKI is expensive to treat due to prolonged hospital stays and the need for dialysis or other RRTs
What are the phases of oliguric AKI?
Initiation, oliguric, diuretic, recovery
Describe phase one of oliguric AKI.
Intiation: begins at time of renal insult and continues until signs and symptoms are apparent. It lasts from hours to days with minimal effect on the endocrine function of the kidneys
Describe phase two of oliguric AKI.
Oliguric: usually last 5 to 10 days but can last weeks. Functional changes such as decreases in glomerular filtration, urine formation, and renal clearance. ↑ in serum concentration of urea, creatinine, uric acid, K, Mg, and urine output is
Describe phase three of oliguric AKI.
Diuresis: usually last 1 to 3 weeks but can last for months. Starts with gradual increase in urine output but watch for signs of dehydration (initial UO being 1 - 3 L/d then, possibly 3 - 5 L/d). Pt is unable to concentrate urine. Labs, acid-base, BUN/Cr start normalizing
Describe phase four of oliguric AKI.
Recovery: usually last for months to 1 year. Starts with increasing GFR and maximal kidney functions start to return such as regulatory and excretory mechanism.
BUN/Cr plateau, then decrease
What are the normals for specific gravity, urine osmolality, cr clearance, serium cr, urea nitrogen (BUN), BUN to cr ratio.
specific gravity - 1.010-1.025 urine osmolality - random; 50-1200 mOsm/kg H2O cr clearance - 85-135 mL/min serium cr - 0.6-1.2 mg/dL urea nitrogen (BUN) - 5-25 mg/dL BUN to cr ratio - about 10:1 or 15:1
Out of these serum lab values which ones will increase or decrease with AKI: BUN, cr, uric acid, K, Cl, P, Ca, albumin.
BUN, cr, uric acid, K, Cl, P - increase
Ca, albumin - decrease
Out of these urine lab values which ones will increase,decrease, or be postive with AKI: protein, glucose, cr clearance, uric acid
protein - increase
glucose - positve
cr clearance, uric acid - decrease
What will be some abnormal findings with ABG, CBC, urine analysis of electrolytes, urinalysis.
ABG: metabolic acidosis
CBC: low hcg & hct, WBC possibly increased
Urine analysis of electrolytes: not valued if on diuretics, valuable indicators of functioning renal tubules, fractional excretion of Na+ (FENa)
Urinalysis: renal epithelial or granular casts maybe present
What are the different types of AKI?
Pre-renal, intra-renal, post-renal
Describe pre-renal injury. What is the patho behind it?
Occurs above/before the kidneys which leads to reduced blood flow to the kidneys by evoking renal salt and water retention. Pathophysiology: hypoperfusion to the kidney leads to the release of renin
which activates RAAS. RAAS leads to peripheral vasoconstriction, increased sodium reabsorption, release of antidiuretic hormone, enhance vasoconstriction, water reabsorption, decrease urine output, and increased urea
What are causes of pre-renal injury?
HYPOVOLEMIA - which can be caused by hemorrhage, burns, shock, excessive sweating, peritonitis, nephrotic syndrome, gastrointestinal losses, renal losses (e.g. diuretics, diabetes insipidus, malignancies), or systemic vasodilation (e.g., sepsis,* neurogenic shock)
ALTERED PERIPHERAL VASCULAR RESISTANCE/ VASODILATION - which can be caused by sepsis, antihypertensive medications, drug overdose, anaphylactic reactions, neurogenic shock, or NSAIDs)
CARDIAC DISORDERS/ DECREASED OUTPUT - which can be caused by CHF, MI, cardiac tamponade, or arrhythmias)
RENAL ARTERY DISORDERS - which can be caused by emboli, thrombi, stenosis, aneurysm, occlusion, or trauma
HEPATORENAL SYNDROME
What will be the volume, specific gravity, urine Na, osmolality, urine cr, and sediment when doing a urine test for pre-renal injury?
volume - decreased to normal specific gravity - high urine Na - low osmolality - high urine cr - normal sediment - normal
Describe intra-renal injury. What is the patho behind it?
Injury to renal tissue. Damage to one or more parenchymal structure(s) which can lead to acute tubular necrosis (causes 45-58% of all renal failure). Usually associated with intrarenal ischemia, toxins, or both. Pathophysiology: vasoconstriction from ischemia and SNS stimulate RASS which causes further vasoconstriction, ischemia diminishes cellular metabolism and tubular transport causing anaerobic metabolism and acidosis which leads to tubular cell swelling and necrosis
What are causes of intra-renal injury?
Nephrotoxic agents, inflammatory processes (bacterial, viral, toxemia of pregnancy), immune processes (autoimmunity, hypersensitivity, rejection), trauma, radiation nephritis, obstruction (neoplasm, stones, scar tissue), intravascular hemolysis (transfusion reaction), and systemic and vascular disorders (renal vein thrombosis, malaria, myeloma, sickle-cell disease, DM, SLE)
Name some nephrotoxins.
Drugs (anesthetics, antimicrobials, anti-inflammatories like NSAIDs, chemo,) contrasts media, biologic substances (tumor products, heme pigments such as hemoglobin, myoglobin), environmental agents (pesticides, fungicides, organic solvents such as diesel fuel, phenol), heavy metals (lead, mercury, gold, arsenic, bismuth, uranium, cadmium), plant and animal substances (mushrooms, snake venom)
What will be the volume, specific gravity, urine Na, osmolality, urine cr, and sediment when doing a urine test for intra-renal injury?
volume - oliguria/nonliguria specific gravity - low urine Na - high osmolality - low urine cr - low sediment - casts present
Describe post-renal injury. What is the patho behind it?
Obstruction of urine flow which leads to increases in intranephronal pressure and
impairment in tubular function. Pathophysiology: bilateral obstruction results in anuria, urine congestion backflows which leads to slow tubular flow and GFR.
Prolonged, collecting system dilates and compress tissues which damages nephrons, leading to dysfunction in concentrating and diluting mechanism
What are causes of post-renal injury?
Ureteral, bladder neck, or urethral obstruction (calculi, neoplasms, sloughed papillary tissue, strictures, trauma, blood clots, congenital abnormalities, foreign object, surgical ligation), prostatic hypertrophy, retroperitoneal fibrosis, abdominal and pelvic neoplasms, pregnancy, neurogenic bladder, bladder rupture, drugs (antihistamines, ganglionic blocking agents)
What will be the volume, specific gravity, urine Na, osmolality, urine cr, and sediment when doing a urine test for post-renal injury?
volume - oliguria to anuria specific gravity - normal to varies urine Na - normal to varies osmolality - normal to varies urine cr - normal to varies sediment - normal to varies