MedEd ABG Flashcards
what controls CO2
lungs
what controls HCO3-
kidneys
what are causes of respiratory acidosis
retaining CO2 (hypoventilation)
pulmonary disorders (COPD, asthma) respiratory depression (opiods) impaired neuromuscular transmission or muscular weakness
what causes respiratory alkalosis
losing CO2 (hyperventilation)
CNS (stroke, anxiety)
hypermetabolic (thyrotoxicosis)
drugs (aspirin overdose)
PE
what are the major functions of the kidneys with regards to acid-base balance
1 reabsorption of HCO3-
2 excretion of fixed acids (H+)
what are causes of metabolic acidosis
increased intake (methanol) increased production (DKA) increased retention (renal failure) loss of alkali (T2 Renal Tubule Acidosis)
what is the normal anion gap
8-16
what are causes with a low or normal anion gap
loss of alkali is cause
- proximal renal tubular acidosis
- GI loss (diarrhoea)
what are causes with a high anion gap
increased acid
- renal failure
- DKA
- lactic acidosis
- ingestion of methanol, ethanol
what are causes of metabolic alkalosis
acid loss -vomiting (gastric acid) alkali administration -gaviscon intracellular shift of H+ -hypokalaemia
14 yr old male patient brought to A&E by mother. The patient seems to be passing in and out of consciousness and vomited upon arrival. The patient appears short of breath and is clutching his abdomen in pain. The A&E registrar performed an Arterial Blood Gas, the results of which are:
pH: 7.12 (7.35-7.45) pO2: 11.5 (10–14) pCO2: 3.2 (4.5–6.0) HCO3: 9 (22-26) BE: -17 (-2 to +2)
a) Respiratory Acidosis with partial compensation
b) Metabolic Acidosis with partial compensation
c) Respiratory Alkalosis no compensation
d) Respiratory Alkalosis with partial compensation
e) None of the above
b) Metabolic Acidosis with partial compensation
if the pH is low and the pCO2 is high, what is indicated
resp acidosis
if the pH is low and the pCO2 is low, what is indicated
metabolic acidosis
if the pH is high and the pCO2 is high, what is indicated
metabolic alkalaosis
if the pH is high and the pCO2 is NOT high, what is indicated
resp alkalosis