acid base principles Flashcards
what is the normal arterial pH ?
7.37 to 7.42
what is the clinical test done to determine ph ?
arterial blood gas
when does acidosis without acidemia happen ?
in mixed disorders
what are the effects of acidosis ?
1-myocardial depression ( low contractility)
2-cerebral vasodilation due to high levels of CO2 , may lead to high ICP
3- hyperkalemia
4- shifts the oxyhemoglobin dissociation curve to the right
what are the effects of alkalosis ?
1- cerebral vasoconstriction
2- hypokalemia
3- shift of the oxyhemoglobin curve to the left
what are the 2 acid base disorders ?
either metabolic or respiratoy disorders
if metabolic - excess or insufficient HCO3
if respiratory - too much or too little carbon dioxide
what are the steps for acid base problems ?
1- check the pH
2- then check HCO3 and pCO2
3- determine if its metabolic or respiratory
4- calculate the anion gap if metabolic acidosis
what are the compensatory mechanisms for both respiratory and metabolic disorders ?
respiratory , compensated by renal
metabolic - compensated by respiratory
what are the methods of respiratory compensation ?
hyperventilation or hypoventilation to alter the CO2 levels
hyperventilation for metabolic acidosis (kussmaul breathing)
what are the methods of renal compensation ?
in acidosis - there is more hydrogen ion excretion , more bicarb reabsorption and more bicarb generated
in alkalosis - excrete more bicarb ba2a
what are the clinical scenarios associated with mixed acid base problems ?
both vomiting and diarrhea at the same time
what is the biggest clue that an acid base disorder is mixed ?
if the pH is normal
what is winters formula ?
pCo2= 1.5(HCO3) + 8 +/-2
what does the mnemonic ROME refer to ?
Respiratory opposite
metabolic equal
comparing the pH and the pCO2
when is winters formula used ?
exclusivley for metabolic acidosis
once you calculate winters formula what are the different answers u can get ?
if the answer is below what you are expecting - then there is Concurrent respiratory alkalosis
if the answer is above what you are expecting - Concurrent respiratory acidosis
if the answer is within the range - then there is appropriate compensation
what is the winters formula equivalent if you are calculating for metabolic alkalosis ?
pco2 = 0.7 x difference in HCo3 ( the patients and the normal level )
what are the 2 forms of respiratory acidosis ?
1- acute compensation - happens in minutes, intracellular buffers raise the bicarb levels
2- chronic compensation - takes days , renal generation of bicarb
what is the difference in values when comparing acute compensation vs chronic compensation of respiratory acidosis ?
acute compensation - 1 bicarb for every 10 co2 s o the equation would be (difference in Co2/10)
chronic compensation - 3.5 hco3 for every 10 pco2 so the equation would be ( 3.5* by the difference in pCO2)/10
