Renal Diseases (Exam III-Mordekai) Flashcards
Which vertebrae are the kidney’s typically situated between?
T12 - L4
Which kidney is slightly more inferior/caudal? Why?
Right kidney is more inferior 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 - 22% ( 1-1.25L/min)
What is Azotemia?
What causes it?
- Abnormally high levels of nitrogen containing compounds in the blood such as urea and creatinine.
- Azotemia is causes 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
6 listed here, theres alot more though
What are some conditions (discussed in lecture) that can cause hyponatremia?
- Prolonged diuretic use
- SIADH
- Acute or chronic renal failure
- Vomiting/diarrhea
- Insufficient aldosterone
- Excessive H₂O intake
5 treatments. Na+ correction should not exceed?
How would hyponatremia be treated?
This is highly dependent on underlying pathology.
- Treatment of underlying disease
- NS
- Hypertonic Saline- 80ml/15 hours
- Lasix
- Mannitol
Na+ correction should not exceed 1.5meq/L/Hr
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
7 listed
What are common causes of hypernatremia?
- Insufficient replacement of water loss
- Excessive sweating
- DI
- Gi losses
- Overcorrection of hyponatremia
- Poor oral intake
- too much bicarb
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 check 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 on EKG?
What about on the cardiac cellular membrane?
- Peaked “T” Waves
- ↑ Vᵣₘ and ↓ APD (action potential duration)
- HYPERkalemia HYPOpolarizes the cell membrane
CH BIG K
What is the treatment for hyperkalemia?
Avoid what?
“CH BIG K”
- Calcium gluconate (1° treatment)
- Hyperventilation
- Bicarbonate
- Insulin
- Glucose
- Kayexelate
Avoid succs, LR & K containing fluids
Best measure of what?
What is a normal GFR?
- 125 - 140 mL/min
- Best measure of renal function overtime
Correlates w/? Influenced by?
What is normal serum creatinine?
Double serum creatinine causes what change to GFR?
- 0.6 - 1.2 mg/dL
- Correlates w/ muscle mass
- Can be influenced by high protein diet, supplements, muscle breakdown –> having a baseline is critical
- Double serum creatinine can decrease GFR by 50% acutely
What is better for acute monitoring of renal function, GFR or creatinine?
- Creatinine for acute monitoring
- GFR for chronic/trending
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
Affected by? High vs low?
What is normal BUN?
- 10- 20 mg/dL
- Affected by diet and intravascular volume
- low= malnourished or fluid overload
- high= dry, high protein diet
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
Four
What lab values would be indicative of acute kidney injury?
- Serum creatinine increase by > 0.3 mg/dL w/in 48hrs
- Serum creatinine increase by 50% w/in 7 days
- 50% decrease in creatinine clearance
- Oliguria (although not always seen)
And treatment? If untreated?
What is the most common cause of pre-renal AKI?
Renal Hypoperfusion
shock, burns, trauma, blood loss, aortic clamping, etc.
Tx by restoring renal blood flow
If untreated –> renal azotemia
Other lab values we would see?
What is a typical BUN:Creatinine ratio in intra-renal AKI?
- < 15:1
- Decreased urea reabsorption in proximal tubule–> decreased BUN
- Low creatinine clearance, high serum creatinine
- Low GFR –> late sx
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
4
What are the most common cardiac complications of AKI?
- Volume Overload → Heart Failure / Pulmonary Edema
- Electrolyte Imbalances → Arrhythmias
- Uremia → Pericarditis
- Hypertension –> Can worsen LV hypertrophy
Two major complications
What are the most common hematologic complications of AKI?
- Anemia
- Due to decreased EPO & hemodilution
- - The relationship between vWF and platelets is disrupted by uremia –> Uremic toxins interfere with platelet glycoprotein receptors that are needed for vWF-mediated adhesion and aggregation.
5
What are the most common metabolic complications of AKI?
- Hyperkalemia
- H₂O & Na⁺ retention
- ↓ albumin
- Metabolic acidosis
- Hyperparathyroidsm (this is actually more commonly seen in CKD)
Benefit of Prophylactic Na+ bicarb in CKD patients?
- Decreases formation of free radicals
- Chronic acidosis can lead to tubulointerstitial injury and fibrosis, accelerating CKD progression.
What are the leading causes of ESRD?
- DM
- HTN
On average, GFR decreases by _____ per decade starting from age 20.
10 ml/min
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
Which patient population is likely to be dyslipidemic?
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 a 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
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.
Stored where? % bound to albumin? How does pH affect? Normal iCal?
Calcium
- 99% stored in bone, 1% in ECF
- 60% is bound to albumin and inactive
- Only iCal is considered physiologically active
-Normal: 1.2-1.38mmol/L - Alkalosis –> ↑ Ca++ binding to albumin –>↓ Decreased iCal
- Acidosis –> ↓ Ca++ binding to albumin–> ↑ Increased iCal
3
Hormones that regulate Ca++
- PTH: Increase GI absorption, renal reabsorption, and regulates bone & plasma levels
- Vitamin D: Increases GI absorption of Ca++
- Calcitonin: Promotes storage of Ca++ in bone
Causes of Hypo/Hyper Ca++
HypoCa++
* Low PTH secretion; thyroid problem or complication of parathyroid surgery –> can lead to laryngospasm
* Low Mg++, Low Vit. D
* Renail failure
* MTP
HyperCa++
* Hyperparathyroid: Ca++ <11
* Cancer: Ca++ >13
Life-threatening symptom of hypoCa++
Post-parathyroidectomy-hypocalcemia induced laryngospasm
HyperMg++
- Very uncommon; due to overtreatment of pre-eclampsia/eclampsia or pheochromocytoma
tx w/ diuresis, IV Ca++, dialysis
Medullary Cortex vs Inner Medulla
Medullary Cortex:
* Outer layer
* Receives 85-90% of RBF
Inner Layer:
* Most vunerable for developing necrosis in response to HoTN
Normal, filtered and not what? most reliable measure of?
Creatinine Clearance
- 110-140ml/min
- Creatinine freely filtered and not reabsorbed
- Most reliable measure of GFR
IVC Collapsibility Indicates…
> 50% collapsibility indicates fluid deficit
Hallmark of AKI?
- Azotemia; buildup of nitrogenous products such as urea and creatinine
2 medical conditions and predisposed to what?
CKD Cardiovascular Effects
- Systeminc HTN
- Dyslipidemia
- Predisposed to MI
Many anesthetics are what? Need to avoid what kind of metabolites?
Anesthesia & CKD
- Many anesthetics are lipid soluble and reabsorbed by renal tubular cells
- Give agents not dependent on renal elimination
- Avoid active metabolites
-Morphine
-Demerol
Two conditions
CKD Hematologic Effects
- Anemia (Target Hgb 10)
- Platelet dysfunction
*
K+? Dialysis needs to happen when?
Preoperative Concerns For Renal Disease
Prophylaxis of what? Blood loss stimulates what?
- K+ <5.5 for elective sx
- Dialysis pts need to be dialyzed w/in 24 hours prior to surgery
- Aspiration prophylaxis
- Blood loss stimulates SNS, resulting in decreased renal blood flow
