Acid and base 2 Flashcards
What is normal range of:
pH, HCO3-, PCO2 (units)
·pH- 7.35-4.45
·HCO3- 24-25 mM
·PCO2- 40 mmHg
What is the equation for formation H+ ions?
If high/low pH what is patient suffering from?
Alkalosis- higher pH
Acidosis- lower pH
What changes in equation indicate respiratory issues
Changes in PCO2
H2O shifting equlibrium
What changes in equation indicate metabolic issues?
Changes in H+
HCO3- shifting equilibrium
What does direction of shift represent?
Represents acidosis/alkalosis
If respiratory which axis should follow?
Respiratory- Hb buffer to new pCO2 lvl
Metabolic- PCO2 to HCO3-
How is respiratory compensated?
Airway dysfunction- can’t change PCO2
- kidneys comp
How is metabolic compensated?
Respiratory system compensates
look
Draw davenport diagram?
Resp acidosis
Normal
Resp alkalosis
Draw davenport diagram?
Met acidosis
Normal
Metabolic alkolosis
How are changes in pH compensated?
Base excess- increase/decrease in base counteract rise in acid
What is partial and full compensation?
Partial- pH not returned normal
Fully- pH normal
If no base excess- complex acid/base disturb.
What are causes metabolic acidosis? Define?
Causes- creation, ingestion, retention of acids
·Renal failure
·GI- HCO3- loss e.g. cholera
·Dilution of blood; more H20 in blood, more acidic it gets (H20 dissociates into H+ and OH-)
·Failure of H+ excretion- hypoaldosteronism, - Less Na+ reabsorbed on the Na/H counter-
transporter- less H+ secreted
- Diabetic ketoacidosis- high production ketone
bodies
What is metabolic acidosis?
Increase in acid production or loss of buffering - Result in decreased pH
What is the compensation for metabolic acidosis?
Respiratory compensation
·Stimulate chemoreceptors, enhance
respiration, results in falling PCO2
·Increases the pH to return to normal
What are causes respiratory alkalosis?
Causes; CO2 depletion due to hyperventilation
·Hypoxia
·Type 1 respiratory failure (e.g. pulmonary embolism, decreased O2 and decrease/no change in CO2)
What are signs of type 1 resp failure?
Pulmonary embolism
Decreased O2
Decrease/no change in CO2
Explain respiratory alkalosis? pH?
Too much CO2 loss
40 to 27 mmHg
Increase in pH
What is compensation for respiratory alkalosis?
Renal compensation;
·Kidneys decrease H+ secretion by retaining H+
·This results in decreased HCO3– reabsorption
in the proximal tubules and collecting ducts
(more excreted)
·Less buffering capacity, low base excess
·pH rises
Explain metabolic alkalosis? pH?
Results in increased [HCO3-] and buffering capacity
- Rise in pH
What is the compensation for metabolic alkalosis?
Respiratory compensation
·Inhibition chemoreceptors- reduces
respiration rate
·Increases PCO2
·This decreases the pH
Causes of respiratory acidosis?
Causes; CO2 retention
·Hyperventilation
·COPD
·Respiratory failure; type 1 = pulmonary embolism, type 2 = hypoventilation
What causes type 1 resp failure?
Pulmonary embolism
What causes type 2 resp failure?
Hypoventilation
Explain respiratory acidosis? pH?
Increase pCO2- 40-60 mmHg
pH falls
What is compensation for respiratory acidosis?
Renal compensation;
·Increase HCO3– (high base excess) release into plasma- buffer H+ created by the increased PCO2
Acute phase = CO2 moving into erythrocytes combines with H2O (and carbonic anhydrase) to produce HCO3-.
Chronic response- increase HCO3– reabsorption by the kidneys, better for the stabilisation of pH
·Excrete more H+ in the form of ammonia (NH3+ to NH4)
