Azotemia Flashcards
What defines azotemia?
Abnormally high concentration of urea and creatinine in the blood
What causes azotemia?
1) diminished capacity of the kidneys to remove these substances
2) related to conditions that affects the volume of blood reaching the kidneys
3) impaired outflow of the urine
* can be classified as prerenal, intrinsic renal and postrenal
Prerenal azotemia
- caused by blood failing to reach the glomerulus
- those that affect circulating intravascular volume
- hypovolemic shock
- third space losses
- resolves quickly if therapy initiated and inciting cause is removed
- TX: aggressive fluid therapy to reverse hypovolemia
- AKI caused by severe hypotensive insult as reduced blood flow causes ischemic injury to kidneys
Intrinsic renal disease AKI
- Common causes:
- ischemia
- nephrotoxins
- infectious agents
- secondary to disease processes
- Px:
- 3 phases:
1) initiation
2) maintenance
3) recovery - Symptoms:
- increased or decreased urine production
- anorexia, restlessness, vomiting, diarrhoea, ataxia and seizures
- Physical examination:
- non-specific: dehydration or overhydration, depression, hypothermia or hyperthermia, injected sclera, small bladder and, firm, larger kidneys (often painful)
- blood work may only show an initiation phase
- Initial diagnostics:
- hypo/hyperkalemia
- dehydration or overhydration
- metabolic acidosis
- hypocalcemia
- Initial interventions:
- IVC
- multilumen to measure CVP
- OLIGURIA
- common presenting sign
- seen in maintenance phase
- low urine volume
- isosthenuria (kidneys lost the ability to concentrate urine)
- Anuria
- grave prognosis
Post-renal azotemia
- outflow obstruction
- urethral obstruction
- ruptured or herniated bladder
- ruptured urethra
- neoplasia
- prostatic dz
- uroliths
*FLUTD
-systemic signs ~24 hrs
-post renal azotemia develop within 48 hrs following obstruction
-must be presented for examination
-cardiovascularly unstable secondary to fluid deficits and metabolic derangements
-O2 should be administered, IVC
-ECG to check for hyperkalemia (bradycardia, tall T waves, absent P waves, prolonged R-R intervals and widening QRS complexes
-metabolic concerns: metabolic acidosis and hypocalcemia
~both can increase cardio toxicity of hyperK
-immediate unblockage required via catheterisation
-IVF blouses should not be withheld
-if catheterisation is unsuccessful: cystocentesis 22 G as last resort due to potential bladder rupture
-watch for post cathetherisation diuresis = becoming very polyuric
-match fluid ins and outs
-watch for hypokelemia and supplement PRN
Fluid in
Includes:
- IV fluids
- IV medications
- Oral fluids or given via feeding tube
Fluid out
Includes:
- normal UOP 1-2ml/kg/hr
- oliguria= <0.27-0.5ml/kg/hr or any patient producing <1-2ml/kg/hr while on IVF
Quantifying UOP
*most important complication of urinary catheterisation is urinary catheter associated urinary tract infection (CAUTI)
Matching ins and outs
*Ins and outs requires you to replace measureable losses plus insensible losses (1/3 of maintenance fluids)
What is kidney autoregulation
It is the process by which the kidney adjusts RBF by constricting and dilating the afferent and efferent arterioles in response to changes in MAP. This allows the kidneys to adjust to variable blood flow, preventing damage to the kidneys. Auto regulation will fail below MAP of 70mmHg. They kidneys do not respond to heart rate but rather blood pressure. The release of ADH and adjustments in heart rate are concurrent actions from the closely related nervous system
Which of the following is not a common complication associated with any of the three types of renal dialysis (peritoneal dialysis, continuous replacement therapy, or intermittent hemodialysis)? A. Septic peritonitis B. Hemorrhage C. Pneumonia D. Hypothermia
C. Septic peritonitis is a risk associated with peritoneal dialysis if contaminants are introduced into the dialysis catheter.
Hemorrhage is a complication seen in 8% of IHD/CRRT cases especially with he use of heparin as the anticoagulant. Hypothermia is a risk of all three forms of dialysis. It will be seen in PD if the large volumes of fluid are not warmed prior to introduction to the abdomen. Hypothermia can occur in IHD/CRRT when the blood cools while passing through the dialysis if not rewarmed before returned to the patient intravenously. These patients will require active warming.
Pneumonia is not considered an expected or frequent complication in any of the version of dialysis.
Which of the following is not usually a finding due to AKI? A. Anaemia b. Elevated BUN C. Electrolyte imbalances D. Metabolic acidosis
A. Anemia is usually seen in chronic renal disease rather than AKI due to ongoing decreased production in erythropoietin. Since RBCs live for several weeks, a decline will not be seen in the acute time frame unless due to a secondary condition.
At which percentage do we first see the signs of kidney insufficiency? A. 20% B.50% C. 66% D. 80%
C. The kidneys are over built when healthy, with far more capacity to perform than is necessary. Therefore, more than half 66% of nephrons must be non functional before we will see signs of kidney insufficiency. Kidney failure will begin around 75% of nephron dysfunction.
You patient is a 34kg dog with acute kidney injury. He has a urinary catheter in place and is currently receiving maintenance fluids. He is producing 2mls of urine/hr as assessed by syringe aspirating a urinary catheter every hour. His urine production would most accurately be termed: A. Anuria B. Dysuria C. Oliguria D. Polyuria
A.
This patient is producing 0.06 mls/kg/hr (2ml/34kgs/hr) which meets the definition of anuria.
Oliguria is 0.2-0.3mls/kg/hr
Polyuria is greater than 2mls/kg/hr
Dysuria does not relate to volume of urine output, but rather has to do with difficulty with the act of urination
Your patient is a 25kg dog with an acute kidney injury. He has become very polyuric and you have been asked to “match ins and outs” every 4 hours. In the last 4 hours, he has produced 1656ml of dilute (USG 1.006) urine. His hourly fluid rate is 250mL. What will be his fluid rate for the next 4 hours? A. 250ml/hr B. 350ml/hr C. 425ml/hr D. 550ml/hr
C. Ins and outs requires you to replace measureable losses plus insensible losses. Insensible losses are 1/3 of maintence fluids. In this case, insensible losses are 11mls/hr ((25kg x 30ml/hr) / 70)/24 hrs)/3. Measureable losses are 414ml/hr (1656/4). So 414 +11 = 425ml/hr should be the new rate.
