HAExamIII Flashcards
Which fluid space is more immediately altered by the kidneys?
ECF
What composes the ECF? What’s its volume?
ISF and Plasma = <1/2 volume of TBW
________ is mainly mediated by osmolality-sensors in the anterior hypothalamus
Osmolar Homeostasis
What does osmolar homeostasis consist of?
- Stimulate thirst
- Cause pituitary to release ADH
- Cardiac atria releases ANP
What mediates volume homeostasis? How?
Juxtaglomerular apparatus; Decreased volume at JGA triggers RAAS to stimulate Na+ H2 reabsorption
What’s the underlying cause of hyponatremia?
Hypervolemia
What levels of Na+ needs to be corrected before to an elective cases?
≤125 mEq or ≥ 155 mEq
What are 4 causes different causes of hypovolemia?
- Diuretics
- GI Loss (vomitting/diarrhea)
- Burns
- Truama
What are some causes of euvolemia?
- Glucocorticoid deficiency
- Hypothyroidism
- High sympathetic drive
- Drugs
- SIADH
What are some causes of hypervolemia?
- ARF
- HF
- Hyperaldosteronism
- Cushings
Serum Na+: <120 mEq/L
- Restlessness
- Lethargy
- Seizures
- Brain-stem hernation
- Respiratory arrest
- Death
Serum Na+: 120-130 mEq/L
- Malaise
- Unsteadiness
Serum Na+: 130-135 mEq/L
Depressed reflexes
How fast can we run hypertonic saline (3% NaCl)?
80 mL/hr
What can cause osmotic demyelination syndrome?
> 6 mEq/L of Na+ in 24 hours
What can cause hypernatremia?
- Excessive evaporation
- DI
- Excessive NaHCO3
- GI Losses
What should be the Na+ reduction rate?
≤ 0.5 mmol/L/hr or ≤ 10 mmol/L per day to avoid cerebral edema, seizures, and neurological damage
What is a major ICF cation?
K+
Serum K+ reflects?
Transmembrane K+ regulation
What does aldosterone do?
Causes the distal nephron to secrete K+ and reabsorb Na+
Aldosterone inversely effects K+
What are some common causes of hypokalemia?
- Renal Loss - diuretics, hyperaldosteronism
- GI loss - V/D, malabsortion
- Transcellular shift
- Low PO intake
- DKA
- Excessive black licorice
What causes an intracellular shift of K+?
- Alkalosis
- Beta Agonists
- Insulin
For every 10 mEq IV K+, serum K+ increases by how much?
0.1 mmol/L
What can cause hyperkalemia?
- Renal failure
- Hypoaldosteronism
- Depolarizing NMB (Succs)
- Acidosis
- Cell death (trauma)
- Drugs that inhibit RAAS
What is the EKG progression of hyperkalemia?
- Peaked T wave
- P wave disappearance
- Prolonged QRS complex
- Sine wives
- Asystole
What are some of the primary treatments for hyperkalemia?
- Dialysis
- Ca2+
- Hyperventilation
- Insulin + Glucose (10-20minutes)
- Bicarb
- Kayexalate (hrs to days)
How much does hyperventilating improve pH? K+?
Increases pH by 0.1 for every 0.4-1.5 mmol/L decrease in K+
How much Ca2+ is in the ECF? bone?
1%; 99%
What is ionized Ca2+? Why is this important?
Ca2+ is not protein bound. Only non-protein bound Ca2+ is physiologically active
What is a normal iCa2+?
1.2-1.38 mmol/L
What two things affect iCa2+?
- Albumin level
- pH
What is the effect of increased pH/alkalosis on Ca2+?
Increases Ca2+ binding to albumin
What do we need to avoid with hyperkalemia?
- Succs
- Hypoventilation
- LR & K+ containing IV fluids
What does PTH do?
Increases GI absorption, renal reabsorption of Ca2+ and Ca2+ resorption from the bone.
What does calcitonin do?
promotes Ca2+ reabsorption (decreases plasma Ca2+) into the bone
Calcitonin inhibits bone resorption to decreases serum Ca2+
What can cause hypocalcemia?
- Complication of thyroid/PT surgery
- Mg2+deficiency
- Low vitamin D
- Decreased PTH
- Renal failure
- Massive blood transfusion
What can cause hypercalcemia?
Hyper-parathyroid or cancer
Less common causes include:
1. Vitamin D intoxication
2. Milk-alkali syndrome
3. Granulomatous diseases (sarcoidosis)
When should we check our iCa2+?
After 4+ units of PRBCs
What is milk-alkali syndrome?
Excessive GI Ca2+ absorption
What can be caused by chronic hypercalcemia?
- Hypercalciuria
- Nephrolithiasis
What is the major complication of post-parathyroidectomy?
Hypocalcemia induced laryngospasm
Life threatening
What is the serum Ca2+ for hyperparathyroid? Cancer?
Hyperparathyroid: < 11
Cancer: >13
What electrolyte is necessary for PTH production?
Mg2+
What are the causes of hypomagnesia?
- Low dietary intake or absorption
- Renal wasting
What causes hypermagnesemia?
Overtreatment pre-eclampsia/eclampsia
Serum Magnesium: 4-5 mEq/L
Lethargy, N/V, flushing
Serum Magnesium: > 6 mEq/L
HoTN, decreased DTR
Serum Magnesium: >10 mEq/L
Paralysis
Apnea
Heart blocks
Cardiac arrest
Where are the kidneys located?
Retroperitoneal between T-12 and L-4
How much of the total CO do the kidneys recieve?
20%; 1-1.25 L/min
What part of the kidney is particularly vulnerable for developing necrosis in response to hypotension?
Loop of Henle
What does the RAAS do in simple terms?
Increases serum Na+ and H2O reabsorption
What hormones do the kidneys make?
Renin
Erythropoietin
Calcitriol
Prostaglandins
What are the kidneys functions according to HA class?
- Regulate the volume, composition, and osmolarity of ECF
- Regulate BP
- Maintain acid/base balance
- Excrete toxins/metabolites
- Produce hormones
What is a normal GFR?
125-140 mL/min; best measure of renal function over time
What’s important to know about measuring GFR?
- Best measure of renal function over time
- Heavily influced by hydration status
- GFR better for trending
What’s a normal creatinine clearance?
110-140 mL/min
What’s important to know about creatinine clearance?
Most reliable measure of GFR
What is the normal serum creatinine?
0.6-1.3 mg/dL
Correlates with muscle mass
What is good about serum creatinine?
- Inversely related to GFR
- Better for detecting an acute change in kidney function
- Can be influced by high protein diet, supplements, and muscle breakdown
What is a normal BUN?
10-20 mg/dL
What is a normal BUN:Creatinine ratio? What is this a measurement of?
10:1; hydration status
What is normal proteinuria? Abnormal?
< 150 mg/dL; > 500 mg/dL
> 500 mg/dL suggests glomerular injury or UTI
What is a normal specific gravity?
1.001-1035
What is considered to be a late sign of volume loss?
Drop in UOP
What volume is considered to be oliguria?
< 500 mL in 24 hours
What collapse indicates a fluid deficit?
IVC collapse > 50%
What is considered powerful stimuli for renal vasoconstriction?
LAP, PCWP
A build up nitrogenous products such as urea and creatinine
Azotemia
Hallmark of AKI
What causes prerenal azotemia? (long list)
- Hemorrhage
- GI fluid loss
- Trauma
- Surgery
- Burns
- Shock
- Sepsis
- Aortic Clamping
- Thromboembolism
First 5 most important
What causes (intra)renal azotemia?
- Acute glomerulonephritis
- Interstitial nephritis
- Vasculitis
- Contrast dye
- ATN
What causes post renal azotemia?
- Nephrolithiasis
- BPH
- Clot retention
- Bladder carcinoma
Primary risk factors of AKI
- Pre-existing renal disease
- Age
- CHF
- Diabetes
- PVD
Azotemia: Pre-renal
- Decreased renal perfusion
- Most common form
- Reversible
- Tx: Restore RBF
Azotemia: (Intra)renal
- Nephron injury
- Intrinsic renal disease
- potentially reversible
- decreased GFR is a late sign
Azotemia: Post Renal
- Outflow obstruction
- Easiest to treat
- Tx: Remove obstruction
- Hydronephrosis (increased nephron hydrostatic pressure)
BUN:Cr ratio pre-renal azotemia
> 20:1
BUN:Cr ratio intra-renal azotemia
< 15:1
Vasopressin preferentially constricts what? Why is this important?
Efferent arteriole; better than alpha agonists for maintaining RBF
In anesthesia preparation for the AKI patient, what recent lab is the most important?
K+
What are the two leading causes of CKD?
- Diabetes
- Hypertension
How much does GFR decrease per decade?
10 mL per decade starting from age 20
What is first line treatment for hypertension in the CKD patient?
Thiazide diuretics
What medications are held on the day of surgery to decrease the risk of profound hypotension?
ACE-I/ARBs
What is considered to be dyslipidemia?
Triglycerides > 500
LDL > 100
What is the target Hgb for anemic patients?
10
Which populations are high risk for silent MI?
- Women
- Diabetics
What is the peak and duration of desmopressin (DDAVP)?
Peak: 2-4 hours
Duration: 6-8 hours
Which NMB is best for kidney patients?
What reversal is NOT recommended for kidney patients?
Nimbex (Cisatracurium); Sugammadex
What does the patient’s K+ level have to be prior to surgery?
< 5.5 mEq/L
for elective surgery
Functions of the liver
Long list, just read through them
- Synthesizes glucose via gluconeogensis
- Stores excess glucose as glycogen
- Synthesizes cholesterol and proteins into hormones and vitamins
- Metabolizes fats, proteins, carbs to generate NRG
- Detoxifies blood
- Metabolizes drugs via CYP450 and other pathways
- Involved in the acute-phase of immune support
- Processes Hgb and stores iron
- Synthesizes coagulation factors
- Aids in volume control as a blood reservoir
What are the three hepatic veins? Where do they empty?
Right, middle, left; IVC
Where does bile enter the duodenum?
Ampulla of Vater
s
How much CO does the liver receive?
25%; 1.25-1.5 L/min
Highest proportion out of all the organs