B4.051 Prework 1 Acid Base Balance Flashcards
normal blood gas values
PaO2 95 mmHg
PaCO2 40 mmHg
pH 7.4
HCO3- 24 mM
stimuli of alveolar ventilation
decreased PaO2
increased PaCO2
decreased arterial pH (increased H+ conc)
respiratory acid base changes
due to a change in alveolar ventilation causing a chance in PaCO2
metabolic acid base changes
change in production of loss of acid or base
what is a metabolic compensation
kidneys alter excretion/absorption of H+ ions
take several days to develop
what is a respiratory compensation
alter alveolar ventilation to change PaCO2 levels and production of acid from carbonic acid
occur rapidly
what is the plasma buffer curve
change in pH and HCO3 when CO2 levels in plasma are altered
buffer equation
CO2 + H2O <> H2CO3 <> H+ + HCO3-
result of increased PaCO2 on buffer curve
increased H+ and HCO3-
shifts right
result of decreased PaCO2 on buffer curve
decreased H+ and HCO3-
shifts left
slope of plasma buffer curve
-10 mmol HCO3- per pH unit
how does a change in 10 mmHg PaCO2 alter pH
change of 0.08
why is the 10 mmHg/ 0.08 pH rule useful
helps distinguish between acute and chronic disturbances
what is the key point of Henderson hasselbach
pH is proportional to ratio of bicarb/ PCO2
what is the davenport diagram
HCO3- on y axis
pH on x axis
plasma buffer curve (horizontal) plotted along with PCO2 isobars (vertical)
in reality do you see noncompensated metabolic disturbances?
no
respiratory compensation is almost immediate
uncompensated resp acidosis
PaCO2 is increased and HCO3 is increased slightly
compensated resp acidosis
PaCO2 is still increased and HCO3- is increased even more (urine will be acidic)
uncompensated metabolic acidosis
PaCO2 normal and HCO3- is decreased
compensated metabolic acidosis
PaCO2 decreased due to hyperventilation and HCO3- is decreased even more (due to decreased PaCO2)
uncompensated respiratory alkalosis
PaCO2 decreases and HCO3- is decreased slightly
compensated respiratory alkalosis
PasCO2 decreased and HCO3 is decreased even more (urine will be alkalotic)
uncompensated metabolic alkalosis
PaCO2 is normal and HCO3- is increased
compensated metabolic alkalosis
PaCO2 is increased due to alveolar hypoventilation and HCO3- is increased even more (due to increased PaCO2)