ACID-BASE PRINCIPLES Flashcards
Why is a severe acidosis life-threatening?
Causes myocardial depression → decreased contractility → decreased BP → shock
Why do patients with a high carbon dioxide level get headaches?
Hypercapnic cerebral vasodilation
What happens to potassium levels in acidosis? Explain why
Hyperkalaemia
Hydrogen shifts into cells in exchange for potassium
How does acidosis shift the oxygen dissociation curve? Explain why
Body thinks that due to high levels of hydrogen ions this means there is a lot of metabolic activity and therefore the curve is shifted to the right
What does alkalosis due to the following:
- Cerebral blood flow
- Potassium
- Oxygen dissociation curve
- Cerebral vasoconstriction
- Hypokalaemia
- Left shift of oxygen dissociation curve: haemoglobin less likely to give up oxygen
When somebody has a metabolic acidosis or alkalosis, disturbance in which electrolyte is involved?
When there is a respiratory acidosis or alkalosis, disturbance in which gas is involved?
- Metabolic: bicarbonate
- Respiratory: carbon dioxide
How is a metabolic acidosis and alkalosis compensated?
How is respiratory acidosis and alkalosis compensated?
Discuss the primary abnormality in each and the compensation of each
Key point: in simple disorders the culprit and the compensatory change are in the same direction
Somebody with acidosis and deep, laboured breathing is exhibiting which physiological response to metabolic acidosis?
Kussmaul breathing: attempting to blow off carbon dioxide
Underlying cause needs to be treated
What is Winters formula and when would you use it?
Calculates expected PCO2 with respiratory compensation in cases of metabolic acidosis.
(HCO3 (mmol/L) x 1.5) + 8 ± 2 = expected PCO2 (mmHg)
NOTE: PCO2 given as mmHg. CO2 out of expected range indicates improper compensation or mixed acidosis/alkalosis
