Acute Renal Failure
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Other names for kidneys
- -eliminates urine
5 Functions of the Kidney
- 1. Urine formation and elmination
- 2. Electrolyte balance
- 3. Acid-Base Balance
- 4. Blood Pressure regulation (through Renin-Angiotensin mechanism)
- 5. RBC production via Erythropoietin
- --( hormone that stimulates RBC production by stem cells in bone marrow. Released in response to decreased levels of oxygen in body tissue.)
Acute Renal Failure Definition
- Kidney fails to:
- - Eliminate waste in adequate or normal amounts
- - Regulate fluid, electrolyte, and acid-base balance
- - Regulate RBC production
- -Older age-diabetes
- -underlying renal insufficiency- heart failure
- - Major trauma: large volumes of Blood transfusions
- -Hypovolemia: regardless of cause-could be major trauma, large vol. blood transfusions.
- - Sepsis
- - Radiologic Dyes
- -Nephrotoxic Agents: antibiotics, anesthestics, pesticides, heavy metals
- - Hypotension
Criteria of ARF
- 1. Acute onset
- 2. Oliguria (UO<20 ml/hr)
- 3. Inability to elminate water, K, and nitrogenous waste
- 4. Acidotic blood pH
- 5. Elevated potassium, and phosphate
- 6. Low calcium
Three Causes of Acute Renal Failure:
- 1. Prerenal Acute Kidney Failure- Anything that leads to decreased blood flow ; afferent arterial pressure falls below 60-70 mmHg and GFR ceases- little to no UO (which is early recognition sign)
- 2. Intrarenal acute kidney failure is anything that causes damage to renal tissue. Associated with several systemic diseases but is commonly related to acute tubular necrosis (abbreviated ATN).
- 4. Postrenal kidney failure is associated with diseases that obstruct the outflow of urine from the kidneys
What is Prerenal Acute Renal Failure?
- Anything that leads to reduction in renal blood flow
- - Afferent arterial pressure falls below 60-70 mmHg
- - GFR ceases and little to no UO
- - Early manifestations is decreased UO
What type of ARF are the following known to cause?
Hypotension, Shock, CHF, Hypovolemia, Renal Artery Obstruction- AAA, Stenosis, Anesthesia, Complications of Pregnancy: Placenta previa, hemorrhage, septic abortion, eclampsia (seizures)
All known to cause Prerenal ARF
What is of Intrarenal acute kidney failure?
Associated with several systemic diseases but is commonly related to acute tubular necrosis (abbreviated ATN).
-Systemic Diseases: Ischemia, injury to Glomerular membrane, ATN, INTRATUBULAR obstruction, acute pyelonephritis
What are the causes of Intrarenal acute kidney failure?
- Nephrotoxic Agents
- Transfusion reaction
- Trauma to the kidney
- Hypersensitivity Reactions
- Acute Glomerulonephritis
- Collagen-Vascular diseases
What is Post-Renal acute kidney failure?
associated with diseases that obstruct the flow of urine from the kidneys
What are the causes of Postrenal Acute Kidney Failure?
- BPH= Enlarged prostate (benign prostate hyperplasia)
- Urinary Stones
- Trauma during surgery
- Trauma to outflow tract
What are the three Stages of Acute Renal Failure?
- 1. Oliguric Stage
- 2. Diuretic Stage
- 3. Recovery Stage
Oliguric Stage of Acute Renal Failure
- -Rapid progressing Azotemia
- -Nitrogenous waste build up
- - Increase in BUN and Cr levels
- - Oliguria= UO < 400 ml/24 hrs
- - From days to weeks
**Early detection and intervention depend on bring the patient through oliguric stage with the least amt of damage
Diuretic Stage of ARF
- - Part of recovery
- - Regeneration of renal tubules
- - UO> 400ml/24 hr but unable to concentrate urine
- - BUN and Cr still rise
- -Lasts several days
Recovery stage of ARF
- -Reestablishment of renal tubule function
- - Fall in BUN and Cr
- - Renal function improves of 3-6 months
Diagnostic Findings used with ARF
–H & H
–Proteinuria, WBC and RBC
- Increased: Potassium (K+), Blood Urea Nitrogen (BUN), Creatine (Cr), Phosphate (PO4), Magnesium (Mg)
- Low: pH (acidosis), Bicarbonate (HCO3), Hematocrit (Hct), Hemoglobin (Hgb), Calcium (Ca), Sodium (Na)
- BUN> 23
- Cr> 1.2
- PO4> 4.5
- Mg> 2.1
- pH<7.35 (acidosis cause hyperventilation)
- HCO3< 2
- Hct<37 or 40
- Hgb<12 or 13
- Ca<8.4 (cause muscle twitch)
Clinical Manifestations of ARF
-Body Systems involved
- 1. Urinary= UO<400 ml/24 hr
- 2. GI= Anorexia, constipation, N&V, Hiccups, Stomatitis, Abdominal distention, diarrhea, GI bleed
- 3. CV= Hypotension w. late hypertension, CHF, volume overload- BIG problem, Arrhythmias-due to elevated K, Pericarditis
- 4. Respiratory= Pulmonary edema, hyperventilation to compensate for Acidosis
- 5. Hematopoietic= anemia *seen in first 48, Elevated WBC, decrease in platelet adhesiveness
- 6. Neurologic= Change in mental status- drowsy, delirium, coma, convulsions, psychosis
- 7. Musclo-skeletal= Muscle twitching due to low Ca levels
Treatment of Acute Renal Failure
- 1. Maintain Vital Function- Restrict K and Na, protect from infection, position-turn-skin, observe neuro, HOURLY I&O and Vitals and cardiac monitoring, Resp care, Good oral care (stomatitis), monitor for bleeding,
- 2. Keep chemical status within limits- Diet and fluid intake, Correct pH and electrolyte imbalance<-get K+ down with polarize solution (hypotonic?) Kaexilate,
Determination of the cause...
Indications for Dialysis=
- Uncontrollable hyperkalemia
- Severe acidosis
- azotemia - BUN approachin 200
- fluid overload
- removal of nephrotic agents
- uremic symptoms - anorexia, n&v
Either of two medical procedures to remove wastes or toxins from the blood and adjust fluid and electrolyte imbalances by utilizing rates at which substances diffuse through a semipermeable membrane--
The process of removing blood from an artery (as of a kidney patient), purifying it by dialysis, adding vital substances, and returning it to a vein—called also hemodialysis
A procedure performed in the peritoneal cavity in which the peritoneum acts as the semipermeable membrane abdomen—called also peritoneal dialysis *Won't in critical care*
CRRT= Continuous Renal Replacement Therapy
The concept behind continuous renal replacement techniques is to dialyse patients in a more physiologic way, slowly, over 24 hours, just like the kidney. Intensive care patients are particularly suited to these techniques as they are, by definition, bed bound, and, when acutely sick, intolerant of the fluid swings associated with IHD.
What is essential in preventing ARF?
Prompt, early management!!
+be aware of at risk patients, avoid compromising the renal status of pt, be aware of nephrotoxic meds, be alert to UO, fluid overload, rising BUN and rising Creatinine, Avoid hypovolemia (blood), Avoid hypotension (low bp), early correction of electrolyte imbalance, early treatment of decreased urine output with fluid challenges and diuretics.
What meds are indicated for Acute Renal Failure?
Osmitrol (mannitol)-- reduce risk of ARF in "low flow" conditions like dehydration, hypotension, hypovolemic shock. MUST BE IV
Lasix (furosemide)-- Drug of choice when rapid effects required such as in pulmonary edema and ARF!!-- MOST FREQUENTLY used diuretic
What complications during Pregnancy are known to cause Prerenal ARF?
Placenta previa, hemorrhage, septic abortion, eclampsia (seizures)
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