Flashcards in Acid-Base Balance and Disturbances Deck (30)
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1
Steps to determining Acid-Base status:
1) from value of pH determine whether the patient is acidotic or alkalotic
2) From values of PaCO2 and HCO3-, determine primary disturbance, whether resp (it is resp if change in PaCO2 is compatible with change in pH) or metabolic (if the change in HCO3- is compatible with the change in pH)
3) From the values of PaCO2 and HCO3-, determine of a compensatory response has occurred
4) normal pH is 7.35-7.45, normal HCO3- is 22-27mEq/L, normal PaCO2 is 35-45 mmHg
2
pH is determined by the ratio of _____ to _____.
HCO3- to PaCO2
3
Name two acid base disturbances that can be COMPLETELY compensated.
1) respiratory acidosis
2) respiratory alkalosis
4
Can complete compensation be achieved if there is metabolic acidosis or metabolic alkalosis?
No
5
If an acid base disturbance is completely compensated, it is a _______ disturbance.
respiratory disturbance
6
________ disturbances are a decrease/increase in blood H+ concentration caused by the addition of bases or acids to/from body fluids.
metabolic
7
________ disturbances are an increase or decrease of blood H+ concentration caused by hypoventilation or hyperventilation leading to either CO2 retention or loss.
respiratory
8
pH= 7.48, HCO3-=38, PaCO2=53
partially compensated metabolic alkalosis
9
pH= 7.37, HCO3-=36, PaCO2=65
compensated respiratory acidosis
10
pH= 7.32, HCO3-=32, PaCO2=65
partially compensated respiratory acidosis
11
What is the underlying mechanism of bicarbonate ion reabsorption?
Na-H+ exchange
12
_______ is a diuretic that works by inhibiting carbonic anhydrase, that ultimately inhibits reabsorption of Na and bicarbonate.
acetazolamide (diamox)
13
______% of the filtered HCO3- is reabsorbed in the proximal tubule.
90%; the 10% that escapes reabsorption in the proximal tubule gets reabsorbed in later segments; HCO3- is not normally excreted
14
____ is actively secreted into the lumen of the proximal tubule in exchange for _____, which enters the cell passively.
H+; Na+
15
The kidneys produce _____ by excreting acids.
HCO3-; the H+-Na+ exchange is the key step in this process
16
______ and _______ are the acids excreted by the kidneys.
titratable acids and ammonia (NH3)
*NH3 enters tubular lumen and reacts with H+ to form ammonium NH4--> very poorly penetrates cell membranes--> remains trapped in tubular lumen and is excreted--> process is called diffusion trapping
17
What is the formula for Anion gap?
Na-Cl+HCO3=anion gap
can also be manipulated;
ex) HCO3= Na-Cl-anion gap
With potassium
The anion gap is calculated by subtracting the serum concentrations of chloride and bicarbonate (anions) from the concentrations of sodium and potassium (cations):
= ([Na+] + [K+]) − ([Cl−] + [HCO3−])
Without potassium (daily practice)
Omission of potassium has become widely accepted, as potassium concentrations, being very low, usually have little effect on the calculated gap. This leaves the following equation:
= [Na+] − ([Cl-] + [HCO3−]) =16 meq/lit
18
What is the normal anion gap range?
~8-16mEq/L; sweat book says 10-12
19
What is the utility of the anion gap?
the measurement of unmeasured anions= the "gap" (HPO4, SO4, etc); useful for the differential diagnosis of metabolic acidosis
20
With an anion gap of 20-29, the diagnosis is ________ 67% of the time.
metabolic acidosis
21
What is urine volume and osmolality when ADH release is inhibited?
osmolality low; Volume Large--> it gets inhibited because the bodys volume is TOO dilute and large.... needs to get rid of it by diuresis
22
How does aldosterone affect sodium and potassium excretion?
Sodium excretion DECREASED and potassium excretion INCREASED
23
What diuretic works by inhibiting the Na-K-Cl symporter?
furosemide (lasix)
24
Spironolactone primarily works on what part of the renal tubule?
collecting duct
25
The chronic renal failure patient has a tendency for increased bleeding, in part because of the production of defective _______.
von Willebrand's factor
26
Blood pressure in the individual at rest is controlled primarily by _______.
renin
27
Which combination of acute electrolyte abnormalities will most stabilize nerve, skeletal muscle, and cardiac ventricular cells?
hypokalemia and hypercalcemia
28
A clinically appropriate K+ concentration for cardioplegia solution is ______mEq/L.
30
29
Which of the following is an important stimulus for aldosterone release from the adrenal cortex?
1) high serum Na
2) high serum K+
3) low levels of ADH
4) low serum K+
2) high serum K+--> aldosterone secretes more K+ to be excreted
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