Renal Exam 3 Flashcards
Which vertebrae are the kidney’s typically situated between?
T12 - L3
Which kidney is slightly more posterior? Why?
Right kidney is more posterior to accommodate the liver.
What stimulates erythropoietin release from the kidneys?
Inadequate O₂ to the kidneys
How much of CO do the kidneys receive?
20 - 25% (1-1.25L/min)
What is Azotemia? What causes it?
Abnormally high levels of nitrogen containing compounds such as Urea and Creatinine. Azotemia is caused by dysfunctional kidneys.
Where are your osmolality sensors located? What occurs when you have hyperosmolality?
Anterior Hypothalamus. Hypothalamus signals pituitary gland to stimulate thirst and secrete ADH.
What degree of hyponatremia would give you pause for surgery?
Less than 125 mg/dL
What are some conditions that can cause hyponatremia?
Prolonged sweating, Vomiting/diarrhea, Insufficient aldosterone, Excessive H₂O intake
How would hyponatremia be treated?
This is highly dependent on underlying pathology. Treatment of underlying disease, NS, Hypertonic Saline, Lasix, Mannitol.
What pathology could occur with rapid over-correction of hyponatremia?
Osmotic Demyelination Syndrome (“Locked-in Syndrome”)
At what degree of hypernatremia would you typically cancel surgery?
155 mg/dL or greater
What is the most common cause of hypernatremia?
Insufficient replacement of water loss. Back home we called this dehydration.
What is the complication from rapid correction of hypernatremia?
There is little evidence of morbidity from rapid hypernatremia correction. 0.5 mmol/L/hr to an absolute change of 10 mmol/L/day would be best to avoid cerebral edema, seizures, and other neurological sequelae.
Severe hyponatremia/hypernatremia both result in what?
Seizures, coma, and death
What are normal levels of serum potassium?
3.5 - 5 mg/dL
Excessive intake of what food is known to cause hypokalemia?
Licorice
When does hypokalemia need to be treated with K⁺ repletion?
Serum K⁺ < 3 mg/dL
What types of symptoms are generally seen with hypokalemia?
Cardiac & neuromuscular
What EKG sign is seen with hypokalemia?
“U”-waves
What other lab(s) needs to be checked when replenishing K⁺?
Serum Phosphorus and Mg⁺⁺
A patient presents with a gun shot wound to the thorax necessitating exploratory thoracostomy. The patient’s serum K⁺ level is 5.7 mg/dL, what do you do?
Emergent surgery so proceed and treat the hyperkalemia. If the surgery was not emergent you would treat the K⁺ til it was below 5 mg/dL.
What are hyperkalemia’s effects on EKG? What about on the cardiac cellular membrane?
Peaked “T” Waves. ↑ Vᵣₘ and ↓ APD (action potential duration)
What is the treatment for hyperkalemia?
“C BIG K” Calcium gluconate (1° treatment), Bicarbonate, Insulin, Glucose, Kayexelate.
What is a normal GFR?
125 - 140 mL/min
What is normal serum creatinine?
0.6 - 1.2 mg/dL
What is better for acute monitoring of renal function, GFR or creatinine?
Creatinine for acute monitoring. GFR for chronic/trending.
A 100% increase in creatinine is indicative of a _____ decrease in GFR.
50%
What populations would have lower creatinine levels? Who would have higher?
↓ in women and elderly. ↑ in body builders.
What is the normal BUN:Creatinine ratio?
10:1
What is normal urine specific gravity?
1.001 - 1.035
What is normal BUN?
8 - 20 mg/dL
Large amounts of what macromolecule would be suggestive of glomerular injury?
protein
What is the primary metabolite of protein metabolism in the liver?
Urea. Amino acids → ammonia → urea.
Which of these two compounds is subject to filtration at the glomerulus? - Creatinine - Urea
Trick question. Both are subject to filtration.
Which of these two compounds is subject to reabsorption in the nephron? - Creatinine - Urea
Urea is reabsorbed unlike creatinine (and therefore can’t be used to measure GFR).
What would a BUN:Creatinine ratio of greater than 20:1 indicate?
Pre-renal Azotemia
What is normal urine output in adults?
1 mL/kg/hr
Your pre-operative patient has had less than 500 mLs of urine output in the past 24 hours. How would you classify this patient?
Oliguric
What’s the greatest risk factor for AKI?
Pre-existing renal disease
What lab values would be indicative of acute renal failure?
Serum creatinine increase by > 0.5 mg/dL, 50% decrease in creatinine clearance.
What is a typical BUN:Creatinine ratio in pre-renal AKI?
> 20:1
What is the most common cause of pre-renal AKI?
Renal Hypoperfusion. shock, burns, trauma, blood loss, aortic clamping, etc.
Differentiate pre-renal oliguria from Acute Tubular Necrosis.
What is a typical BUN:Creatinine ratio in intra-renal AKI?
< 15:1
Why are urea levels (in the urine) higher in intra-renal AKI?
Whole nephron is failing so urea is not being reabsorbed in the PCT.
What is the cause of intra-renal AKI?
Renal parenchymal (inner kidney) damage. ATN, glomerulonephritis, CKD, etc.
What is the cause of post-renal azotemia?
Urinary tract blockage
What BUN:Creatinine ratio is typically seen in post-renal AKI?
Initial: > 15:1. Chronic = ↓ BUN:Cr
What is the most common neurological complication of AKI?
Uremic Encephalopathy
What are the most common cardiac complications of AKI?
HTN, LV hypertrophy, CHF, Pulm Edema
What are the most common hematologic complications of AKI?
Anemia
Plt dysfunction
What are the most common metabolic complications of AKI?
Hyperkalemia
H₂O & Na⁺ retention
↓ albumin
Metabolic acidosis
What drug is given prophylactically to prevent acidemia and its complications in kidney patients?
Sodium bicarb
What are the leading causes of ESRD?
DM
HTN
What does the acronym RIFLE stand for?
Risk
Injury
Failure
Loss
End-stage
What labs indicate ‘Risk’ according to the RIFLE criteria for kidney disease?
Creatinine 1.5x base
UOP < 0.5 mL/kg/hr for more than 6 hours
What labs indicate ‘Injury’ according to the RIFLE criteria for kidney disease?
Creatinine 2x base
UOP < 0.5 mL/kg/hr for more than 12 hours
What labs indicate ‘Failure’ according to the RIFLE criteria for kidney disease?
Creatinine 3x base
UOP < 0.3 mL/kg/hr for > 12 hours or total anuria for > 12 hrs
What labs indicate ‘Loss’ according to the RIFLE criteria for kidney disease?
Renal replacement therapy needed for > 4 weeks
What labs indicate ‘End-stage’ according to the RIFLE criteria for kidney disease?
Renal replacement therapy needed for > 3 months
On average, GFR decreases by _____ per decade starting from age 20.
10 ml/min
Which population is more likely to have kidney failure compared to other Americans?
Hispanic Americans
It is usually helpful to assume that everyone with CKD also has this condition.
CAD
What drugs are often used to combat chronic kidney disease?
ACEi’s and ARBs
How do ACEi’s and ARBs help treat CKD?
Decrease systemic & glomerular HTN
Decrease proteinuria
Decrease glomerular sclerosis
What antihypertensive drugs need to be held on the day of surgery to decrease the risk of intraoperative hypotension?
ACEi’s & ARBs
Which populations are at a higher risk for silent MI?
Women and diabetics
What lab values reflect dyslipidemia?
Triglycerides > 500
LDL > 100
What are the indications for dialysis?
Volume overload
↑K⁺
Severe metabolic acidosis
Symptomatic uremia
Drug overdose
What is the most common adverse event associated with dialysis?
Hypotension
What is the leading cause of death in dialysis patients?
Infection
When would peritoneal dialysis be preferred to hemodialysis?
PD is preferred for patients who can’t tolerate large fluid shifts (CHF or unstable angina)
What two things reduce the risk of pre-renal azotemia?
Maintain MAP > 65mmHg
Appropriate hydration
Excessive use of 0.9% NaCl leads to what condition?
Hyperchloremic metabolic acidosis
Which of the following fluids are associated with increased risk of renal injury? - Crystalloids - Colloids - Starches
Starches
Treating oliguric AKI patients with diuretics helps improve their condition via diuresing toxic metabolic byproducts of the AKI. T/F?
False. Diuretics in oliguric AKI can further the renal injury.
This drug maintains GFR and urine output better than norepinephrine and neosynephrine via preferential constriction of the efferent arteriole.
Vasopressin
What type of anesthesia is common for TURPs?
Neuraxial (Spinal to T10, usually)
What are the risks and benefits of NaCl used as irrigation fluid for TURPs?
Risk: electric shock with unipolar cautery (only use bipolar electrocautery)
Benefit: Very few side effects, good visibility
What are the risks and benefits of distilled water used as irrigation fluid for TURPs?
Risk: ↑ risk of TURP syndrome
Benefit: Very good visibility
What are the risks and benefits of glycine solution used as irrigation fluid for TURPs?
Risk: ↑ ammonia = ↓LOC and blurry vision
Benefit: ↓ risk of TURP syndrome
What are the risks and benefits of sorbitol solution used as irrigation fluid for TURPs?
Risk: ↑BG, osmotic diuresis, and acidosis
Benefit: ↓ risk of TURP syndrome.
What are the risks and benefits of Mannitol used as irrigation fluid for TURPs?
Risk: Osmotic diuresis and transient plasma expansion.
Benefit: Renally filtered and excreted (doesn’t mess with the liver at all).
What is TURP syndrome? What are its characterizing symptoms?
Absorption of large volume of hypo-osmolar irrigation fluid.
HTN, ↓HR, & LOC changes
How is TURP syndrome treated?
Stop case
If Na⁺ > 120mEq/L → Lasix
If Na⁺ < 120mEq/L → 3% NaCl until at 120mEq/L.
Benzos if seizing
How do urolithiasis patients typically present?
Ca⁺⁺ stones
Colicky pain in the ipsilateral flank & upper abdomen
UTI and/or hematuria
What drugs are given with MET (medical expulsive therapy) for kidney stones?
CCBs
α-blockers
Corticosteroids
What is ESWL?
Extracorporeal ShockWave Lithotripsy
What cardiac considerations exist for ESWL?
Avoid R-on-T phenomena
Pacemakers/ICDs
Calcified Aortic aneurysms
How is idiopathic hypercalciuria treated?
Thiazide diuretics
Why might you want to do regional or GA with paraplegic patients undergoing bladder surgeries?
To avoid autonomic dysreflexia.
