Spring 2024 (Exam III) Renal Assessment Flashcards
The kidneys sit retroperitoneal between _______ and _______.
Which kidney is slightly more caudal (lower) to accommodate the liver?
T12 and L4
Right
What is the functional unit of the kidney and what are its components?
- Nephron
-Glomerulus
-Tubular system - Bowman capsule
- Proximal Tubule (PCT)
- Loop of Henle
- Distal Tubule (DCT)
- Collecting duct
The kidneys receive ________% (range) of CO
The _____ _____ receives the majority of RBF (85-90%)
- 20% (1 L)
- Outer Layer
*LOH particularly vulnerable for developing necrosis in response to HoTN ((↓kidney perfusion)
Besides the kidneys, what organ is retroperitoneal?
Spleen
Primary functions of the kidneys (6 functions).
- Maintain extracellular volume and composition (RAAS and ANP)
- Blood Pressure Regulation (Intermed/Long)
- Excretion of Toxins and Metabolites
- Maintain Acid-Base Balance (excretion of HCO- and H+
- Hormone Production (Renin, Erythropoietin, Calcitrol, PGs)
- Blood glucose homeostasis (Gluconeogenesis and glucose reabsorption)
Calcium requires ________ for adequate absorption and utilization.
Calcitriol (Active Vitamin D)
How does Vitamin D get activated?
Through the kidneys
What hormone will stimulate the release of Ca++ from the bones and which hormone promotes storage of Ca++?
PTH; Calcitonin
____-% of body weight in non-obese patients is composed of water.
about 60%
What are the two main fluid compartments?
ECF and ICF
Per this lecture ECF is _______ the volume of ICF.
< 1/2 volume of TBW
____ ____ is mainly mediated by osmolality-sensors in anterior hypothalamus
Osmolar homeostasis
_____ _____ is mediated by juxtaglomerular apparatus
Volume homeostasis
What are the ways osmolality sensors in the anterior hypothalamus regulate fluid?
- Stimulate thirst
- Release Vasopressin (ADH)
- Cardiac atria releases ANP→ act on kidney to ↓Na+/H20 reabsorption
What are ways JGA regulates fluid?
- ↓Vol @ JGA triggers Renin-Angiotensinogen-Aldosterone system (RAAS)→Na+/H20 reabsorption
What is a normal sodium level?
135-145 mEq/L
There are no absolute cut offs for sodium level for surgery, but these numbers will be a good reference.
Na level below _________ mEq/L and above _______ mEq/L are a no go for surgery.
Below 125 mEq/L
Above 155 mEq/L
What are some causes of hyponatremia?
- Prolonged sweating
- Vomiting/diarrhea
- Insufficient aldosterone secretion
- Excessive intake of water
- Burns
- Trauma
What percent of people in the hospital have hyponatremia and why?
- 15%
- over fluid-resuscitation
- ↑endog vasopressin
There are two patient populations where we are most concerned about sodium levels.
Neuro patients
Kids
The most severe consequence of hyponatremia are these three things:
- Seizures
- Coma
- Death
What are treatments for hyponatremia?
Treat underlying causes
* Normal Saline
* Hypertonic 3% Saline
* Lasix
* Mannitol
What is the correction rate when supplementing Na with 3% saline?
- Na+ correction should not exceed 1.5 meq/L/hr
- Dose: 80 mL/hr over 15h
Rapid correction of Na faster than 6 mEq/L in 24 hours can cause __________ syndrome.
What could this result in?
osmotic demyelination
Seizures, coma, death
What is the dose and rate of 3% hypertonic saline for patients that are hyponatremic and seizing?
- Medical Emergency
- 3-5 mL/kg of 3% saline
- Give dose of over 20 minutes until seizures resolve
Hyponatremic seizures are a medical emergency and can cause __________ brain damage.
Irreversible
What are the causes of hypernatremia?
- Excessive evaporation
- Poor oral intake(very young, old)
- Overcorrection of hyponatremia
- Diabetes Insipidus
- GI losses
- Excessive sodium bicarb to tx acidosis
Symptoms of hypernatremia
- Orthostasis
- Restlessness
- Lethargy
- Tremor/ Muscle Twitching/ spasticity
- Seizures
- Death
How do we treat hypernatremia?
- Hypovolemic: 0.9% NaCl
- Euvolemic: water replacement (PO or D5W)
- Hypervolemic: diuretics
What is the recommended Na+ reduction rate and what are the side effects if reduced too quickly?
- ≤0.5 mmol/L/hr and ≤ 10 mmol/L per day
- Cerebral edema, seizures, and neurologic damage
Be cautious when using sodium bicarb to treat acidosis, what is a good alternative to use if you want to avoid raising sodium?
Tromethamine injection (THAM) is indicated for the prevention and correction of metabolic acidosis.
Treatments for hypernatremia?
First, assess volume status (tachycardic, hypotensive, u/o, skin turgor, CVP, SV variation)
Then treat the cause.
Treatments for the following.
Hypernatremic Hypovolemia:
Hypernatremic Hypervolemia:
Hypernatremic Euvolemic:
Hypernatremic Hypovolemia: normal saline
Hypernatremic Hypervolemia: diuretic
Hypernatremic Euvolemic: water replacement (PO or D5W)
What is normal potassium level?
3.5 to 5 mEq/L
Patients will not go to surgery if potassium is less than ______ or greater than _______ mEq/L.
K+ less than 3 mEq/L
K+ greater than 5 mEq/L
What are the causes of hypokalemia?
Excessive release of aldosterone
Diuretics drugs (Lasix, hydrochlorothiazide)
Kidney disease
Excessive intake of licorice (kids eating too much licorice.)
DKA (frequent urination)
Effects of hypokalemia
Generally, cardiac and neuromuscular (K+ of 2mEq/L)
Dysrhythmias (K+ of 2mEq/L)
Muscle weakness
Cramps (Eat a banana)
Paralysis
Illeus (lose parastalsis)
What changes in EKG will you see with hypokalemia?
U-waves
You will see this on the exams and boards.
Treatments for hypokalemia
- Treat the underlying cause
- PO > IV Potassium
May require days to correct
Avoid excessive insulin, β-agonists, bicarb, hyperventilation, diuretics
10 mEq of potassium will increase serum K+ by ________ mEq/L.
0.1 mEq/L
Why may PO potassium be faster in increasing serum potassium levels?
A larger dose can be given PO compared to 10-20 mEq/hr with IV.
When replacing potassium levels, what other electrolytes do you need to keep an eye on?
Phosphorus (normal levels 2.5 - 4.5 mg/dL)
Who are at the most risk of dysrhythmias when getting potassium replacement?
CHF patients
Digoxin patients
What are the causes of hyperkalemia?
Renal failure
Hypoaldosteroinism
Drugs that inhibit RAAS
Drugs that inhibit K-secretion
Use of depolarizing NMBD (Succs)
Acidosis (Resp./ Metabolic)
Cell Death (trauma, tourniquet)
Massive Blood Transfusion
With hyperventilation, a pH increase of 0.1 will cause a ____ in potassium.
0.4 to 1.5 mEq/L decrease in potassium
Succynlcholine will increase serum K by ______
about 0.5-1.0 mEq/ L
What are the effects of hyperkalemia?
- Potentially asymptomatic
- GI upset
- Malaise
- Skeletal muscle paralysis, ↓fine motor
- Severe cardiac dysrhythmias (cardiac arrest)
- Lowers resting membrane potential
- Decreases action potential duration
What are EKG presentations of hyperkalemia?
Peaked T-waves (can progress into sine waves if hyperkalemia is severe)
* P wave disappearance
* Prolonged QRS
* Asystole
Treatment of hyperkalemia
- Dialyze within 24h prior to surgery (can also cause hypovolemia)
- Calcium- 1st initial treatment (quickly stabilize cell membrane)
- Hyperventilation (↑pH by 0.1 →↓K+ by 0.4-1.5 mmol/L)
- Insulin +/- glucose (10u IV: 25g D50) * works in 10-20 min
- Bicarb
- Loop Diuretics
- Kayexalate (hrs to days)
- *Avoid Succs, hypoventilation, LR & K+ containing IV fluids
What do CRNAs do that can cause hyperkalemia in a patient?
Massive Transfusion Protocol and Blood Products
How much Ca++ is in the ECF?
Only 1% body’s Ca++ is in ECF; 99% stored in bone
What is the normal range of iCa?
Normal iCa++: 1.2-1.38 mmol/L
How does alkalosis affect Ca++?
- ↑pH/Alkalosis→↑Ca++ binding to albumin;** therefore ↓iCa++**
What are the causes of hypocalcemia?
- ↓Parathyroid hormone (PTH) secretion
- Complication of thyroid/PT surgery
- Magnesium deficiency
- Low Vit D or disorder of Vit D metabolism
- Renal failure (kidneys not responding to PTH)
- Massive blood transfusion (citrate preservative binds Ca++)
What is required for PTH production?
________ can lead to laryngospasms
- Magnesium
- Parathyroidectomy
The majority of patients with hypercalcemia have ____ or cancer
Hyper-parathyroid
Less common causes of hypercalcemia
- Vitamin D intoxication
- Milk-alkali syndrome (excessive GI Ca++ absorption)
- Granulomatous diseases (sarcoidosis)
Signs and symptoms of hypercalcemia
- Confusion, Lethargy
- Hypotonia/ ↓DTR
- Abd pain
- N/V
- Short QT-I
- Chronic ↑Ca++→ Hypercalciuria & nephrolithiasis
What are the causes of hypomagnesemia?
- Low dietary intake or absorption
- Renal Wasting
What are the signs and symptoms of hypomagnesemia?
- Muscle weakness
- Seizures
- Ventricular Dysrhythmias (Polymorphic Vtach/ Torsades)
What is the treament for hypomagnesemia?
- depends on severity of sx
- Slower infusions for less severe
- Torsade’s/seizures→ 2g Mag Sulfate
What are the causes and S/S of Hypermagnesemia?
- Very uncommon
Generally due to over treatment - Pre-eclampsia/Eclampsia
- Pheochromocytoma
Symptoms - 4-5 mEq/L: Lethargy, N/V, Flushing
- > 6 mEq/L: HoTN, ↓DTR
- > 10 mEq/L: Paralysis, apnea, heart blocks, cardiac arrest
What is the treatment for Hypermagnesemia?
- Diuresis
- IV Calcium (stabalize cell membrane)
- Dialysis
What are lab tests for renal function?
GFR (best measurement) 125-140 ml/min
best measure for renal function overtime
Heavily influenced by hydration status
**Creatinine Clearance ** 110-140 mL/ min
Freely filtered, not reabsorbed
Most reliable measure of GFR
Serum Creatinine 0.6-1.2mg/dL- correlates with muscle mass
Good for acute monitoring; inversely related to GFR
Double SC= 50% decrease in GFR
What is creatinine?
A substance produced by skeletal muscle and is a byproduct of creatine breakdown.
Creatinine production is constant and directly __________ to muscle mass.
proportional
A emaciated individual will probably have a lower creatinine level compared to a bodybuilder. But if you see that a cachectic person has a high creatinine level, it might be a sign that the kidneys are not working well.
Creatinine undergoes renal _________ but not _________, making it a useful indicator of GFR.
Creatinine undergoes renal filtration but not reabsorption, making it a useful indicator of GFR.
What are normal BUN ranges?
10-20 mg/dL
BUN can be misleading. Diet and changes in intravascular volume can increase or decrease BUN.
What is BUN: Creatinine ratio?What does it indicate?
10:1
good measure of hydration status
What is the normal value for proteinuria and what would a high value indicate?
- <150 mg/ dL
- > 750 mg/ dL could = glomerular injury or UTI
What is urine specific gravity?
- 1.001-1.035
- Comparing 1ml urine to 1ml distilled water
- measures nephron’s ability to concentrate urine
What causes BUN of <8 mg/dL?
Overhydration, too much hydration, dilution.
Decrease Urea production (malnutrition, liver dz)
EtOH patients will forget to eat and get calories just from the booze.
What causes a BUN of 20-40 mg/dL?
Dehydration
Increase Protein Input (high protein, GIB, Hematoma breakdown)
Catabolism (Trauma, Sepsis)
Decrease GFR
A medical condition characterized by abnormally high levels of nitrogen-containing compounds (such as urea, creatinine, and various body waste compounds) in the blood. It is largely related to insufficient or dysfunctional filtering of blood by the kidneys.
Azotemia
Oliguria definition.
Oliguria is decreased u/o 500 mL in 24 hours
What number indicates good urine output from an anesthesia standpoint?
30 mL/hr (no standardization for weight and no clinical picture)
0.5-1 mL/kg/hr is more accurate
What should we assess/ consider when determining volume status?
Look at the big picture
* H/P
* Orthostatic BPs
* ↓BE
* ↑Lactate
* Drop in UOP ** late sign**
What is an early indicator of volume change (arm just got cut off)?
-Base Excess or Base Deficits will indicate volume loss (Indicator of acid/base balance in the blood).
-Increase in Lactate
What are ways we can monitor volume?
- US to assess IVC
- CVP, RAP
- LAP, PCWP
- PAP
- Stroke Volume Variation (SVV)
_______ is a powerful stimulus for renal vasoconstriction.
Left atrial pressure (wedge pressure)
Increase LAP, increase vasoconstriction. Afferent arteriole will increase to decrease hydrostatic pressure.
What does stroke volume variation in assess?
- Compares inspiratory v expiratory pressure
Assumes pt is vented and in NSR
An IVC greater than _______% collapse indicates a fluid deficit.
50%
To assess, place an ultrasound on IVC and perform a passive leg raise, if the quick change in volume dilates IVC, the patient may be in a fluid volume deficit.
What is acute renal failure?
- Deterioration of renal function over hours to days.
- Failure to excrete nitrogenous waste products or maintain fluid/ electrolyte homeostasis
*generally caused by hypotension, hypovolemia, and nephrotoxins (ie. IV contrast)
If someone with AKI progress to dialysis and MSOF, mortality is now greater than ________.
50% (due to sepsis, CV dysfunction, pulmonary compilations)
*Reversible with timely interventions. CVVHD to get through the temporary insult
What are the risk factors for AKI?
- Pre-existing renal disease
- Advanced age
- Congestive HF
- PVD
- DM
- Sepsis (hypotension)
- Jaundice
- Major Operative Procedures (Cross-Clamped)
- IV Contrast
Diagnosing AKI lab and physical symptoms
Labs
↑SCr by 0.3 mg/dL within 48 h
↑SCr by 50% within 7 days
↓Creatinine clearance by 50%
Abrupt oliguria although not always seen in AKI
Physical
Asymptomatic
Malaise
HoTN
Hypovolemic or hypervolemic=
What are the types of AKI?
Pre-renal Azotemia
Renal Azotemia
Post-renal Azotemia
What are the causes of prerenal azotemia (ARF)?
Hemorrhage
GI fluid loss
Trauma
Surgery
Burns
Cardiogenic shock
Sepsis
Aortic clamping
Thromboembolism
Anesthesia meds+ volume/ blood loss → ↓RBF
All these will decrease renal perfusion
What are the causes of Renal Azotemia (ARF)?
Acute glomerulonephritis
Vasculitis
Interstitial nephritis
ATN
Contrast dye
Nephrotoxic drugs
Myoglobinuria
Real kidney injury. Think infections and inflammation.
What are the causes of postrenal azotemia (ARF)?
Nephrolithiasis (kidney stones, most common cause)
BPH
Clot retention
Bladder carcinoma
UTI- cellular debris
Trauma to the urinary tract
Think mechanical obstruction post-kidney
Easiest to treat
Pre-renal azotemia makes up _________ of hospitalized acquired cases.
If pre-renal azotemia is not treated in time, it will progress to _____.
- Half
- ATN (Pre-renal → Renal)
Treatment of pre-renal azotemia.
Restore RBF
* Fluids, Mannitol, Diuretics, maintain MAP, Pressors
What will be the BUN: Cr ratio of renal azotemia?
What happens to GFR?
What happens to Urea?
What happens to Creatinine?
Less than 15
GFR will decrease, and nothing will get filtered
Urea does not get reabsorbed; low urea in the blood, high urea in the urine.
Creatinine filtration decreases, leading to higher Cr in the blood.
Neurological complications from AKI
- Uremic Encephalopathy (improves with HD)
- Mobility Disorders
- Neuropathies
- Myopathies
- Seizures
- Stroke
*Related to protein/ amino acid builid up in blood
List the order of incidence of cardiovascular compilations from AKI:
Order of incidence:
1. Systemic HTN
2. LVH
3. CHF
4. Ischemic heart disease
5. Anemic Heart Failure
6. Rhythm Disturbances
7. Pericarditis W/ WO effusion
8. Cardiac Tamponade/ Uremic Cardiomyopathy
Hematological complications of AKI
Anemia
* ↓ EPO production
* ↓ red cell production
* ↓ red cell survival
Platelet dysfunction
vWF disrupted by uremia
* Prophylactic DDAVP
* ↑VWF & Factor VIII to improve coagulation
Metabolic complications of AKI.
Hyperkalemia
Water and Sodium retention
Hypoalbuminemia - responds slower to medication
Metabolic Acidosis
Anesthesia concerns of AKI.
- Correct fluid, electrolytes, acid/base status
- Volume- NS preffer for renal (no K+)
- Careful with colloids
- MAP W/I 20% of baseline
- Vasopresseors (Alpha-agonists, Vasopressin)
- Prophylactic sodium bicarb
- decreases the formation of free radicals and prevents ATN from causing renal failure
____ preferentially constricts the efferent arteriole better than ____ ____ for maintaining RBF.
Vasopressin; alpha agonists
What are anesthesia implications for a patient with an AKI
- Low threshold for invasive hemodynamic monitoring
- Prefer preopertaive HD
- Recent labs (esp. K+)
- Have POC equipment available
- Tailored drug dosing
- Avoid drugs w/ active metabolites and renal toxins or drugs that ↓RBF
Unlike AKI, CKD is ______ and __________.
What is the leading cause of CKD?
Progressive and Irreversible
DM and HTN
Describe stages of ESRD and GFR for each stage.
On average, GFR decreases by ______ per decade starting from age 20.
10
CV effects of CKD
-
Systemic HTN (cause and consequence)
- Retention of sodium and water
- Activation of RAAS
-
Dyslipidemia
- Triglycerides > 500
- LDL > 100 -
Prediposed to “Silent MI”
- Peripheral and autonomic neuropathy, sensation may be blunted
Which populations are a high risk for silent MI?
Women and Diabetics
What is the first line treatment for CKD induced systemic HTN?
- Thiazide Diuretics
*ACE-I/ ARBS may be needed as well
What are the hematological complications of CKD?
Anemia
- responsive to exogenous erythropoietin
- Target HBG 10
Platelet Dysfunction
Transfusion Risk v Benefits
- excess HGB leads to sluggish circulation
Acidosis and hyperkalemia are also associated with blood transfusions
What are the five indications of dialysis?
- Volume overload
- Severe Hyperkalemia
- Metabolic Acidosis
- Symptomatic Uremia
- Medication Overdose d/t a failure to clear
Considerations of dialysis:
HD is more ______ than PD.
PD is more gradual and favored for patients that can’t tolerate __________ associated with HD (CHF/unstable angina).
__________ is the most common adverse event.
_________ is the leading cause of death in dialysis patients.
HD is more efficient than PD.
PD is more gradual and favored for patients that can’t tolerate fluid shifts associated with HD (poor cardiac function).
Hypotension is the most common adverse event.
Infection is the leading cause of death in dialysis patients (impaired immune system/ healing).
The risk of pre-renal azotemia is reduced by maintaining a MAP greater than _______ mmHg and providing appropriate hydration.
> 65 mmHg
Vasopressin preferentially constricts the __________ arteriole. Maintains GFR and UOP better than NE or Neo.
efferent
Anesthesia concerns of CKD.
Assess the stability of ESRD.
Get the accurate weight of the patient within 24 hrs of surgery
Well-controlled BP
Glucose management (A1c).
Aspiration Precaution (increase risk)
Pressors
Uremic bleeding (dysfunctional platelets)
What are treatments of uremic bleeding?
Max effect time:
Duration:
DDAVP - max effect 2-4 hours, last 6-8 hours, give this in pre-op
Cryo (Factor VIII, vWF)
What are some lipid insoluble drugs?
- Thiazide/ Loop diuretics
- Digoxin
- Many abx
What neuromuscular blockers are not dependent on the kidneys?
Atracurium
Cisatracurium
Hoffman elimination- plasma esterases affected by pH and temperature.
When taking care of renal patients, what medications do we worry about having active metabolite?
Opioids (morphine, meperidine)
Morphine is cleared through the urine, active morphine metabolite will lead to respiratory depression.
Lipid insoluble drugs will have a _________ duration of action in renal patients.
prolonged duration
*Eliminated unchanged in urine and dosing should be dependant on GFR
What induction medications are excreted by the kidneys?
Phenobarbital
Thiopental
What muscle relaxants (paralytics) are excreted by the kidneys?
Pancuronium
Vecuronium
If kidneys do not excrete them, the liver will.
What cholinesterase inhibitors are excreted by the kidneys?
Edrophonium
Neostigmine
What CV drugs are excreted by the kidneys?
Atropine
Digoxin
Glycopyrrolate
Hydralazine
Milrinone
What antimicrobials are excreted by the kidneys?
Vancomycin
Aminoglycosides
Cephalosporins
PCN
Patients maintained on dialysis should undergo dialysis _______ hours preceding elective surgery.
24 hours
What is the concern when giving Sugammadex?
- It covalently binds to NMB but if it is not excreted, it could dissociate and both drugs could be bioavailable in the patient
____ of morphine in cleared through the urine
Main concern for Morphine with CKD patients?
- 40%
- circulating active metabolites –> life-threatening respiratory depression
What is the main adverse effect for Meperidine (Demerol)?
Active metabolite Normeperidine –> Neurotoxicity
-nervousness, tremors, muscle twitches, seizures
Normal serum creatinine concentration for males.
Normal serum creatinine concentration for females
Males: 0.8-1.3 mg/dL
Females: 0.6 - 1.0 mg/dL
Normal creatinine clearance (range): _________
110-140 mL/min
These drugs undergo hepatic metabolism and conjugation prior to elimination in the urine (Select all that apply).
A. Pavulon
B. Benzos
C. Opioids
D. Anectine
A, B, and C
Anectine (Sch) is metabolized by plasma cholinesterase
What is the ideal anesthetic agent for renal patients?
Forane (Isoflurane)
Which kidney is lower?
The right kidney is slightly lower than the left kidney.
What is the normal range for BUN and serum creatinine?
10-20 mg/ dL and 0.6-1.3 mg/ dL
