Acid-base balance

Question 1

3 attempts of buffering

Answer 1

bicarbonate in serum, phosphate in urine

skeleton

intracellular accumulation/loss of H+ ions

Question 2

Does Respiratory compensation for a primary metabolic disturbance occur rapidly?

Answer 2

Yes

Question 3

How long does metabolic compensation take?

Answer 3

36-72h

Question 4

why does metabolic compensation take longer?

Answer 4

requires enzyme induction from increased genetic transcription and translation etc

Question 5

how do lungs compensate for metabolic acidosis?

Answer 5

hyperventilation

Question 6

how do lungs compensate for respiratory acidosis

Answer 6

hypoventilation

Question 7

describe renal compensation mechanism

Answer 7

ATP receptors on tubular cells that exchange Na/K- to excrete K

Also have Na/H exchanger in kidneys. This receptor is vital in alkalosis or acidosis

Na/H always has priority in acidosis/alkalosis- increased action results in increased H excretion in the blood. Will result in hyperK as K isn’t being excreted.

Question 8

does acidosis result in hyperK or hypoK?

Answer 8

hyperK

Question 9

does alkalosis result in hyperK or hypoK?

Answer 9

hypoK

Question 10

4 things you must ensure with ABG sample

Answer 10

Expel air
Mix sample
Ensure no clot in syringe tip
Need to collect blood anaerobically into a heparinsed blood gas syringe or capillary – NO air bubles (to prevent loss of CO2 from blood into air
K+ result may not be valid if haemolysed sample – but YOU WILL NOT KNOW!

Question 11

ABG results for respiratory acidosis

Answer 11

low pH, high CO2, normal bicarb

Question 12

ABG results for respiratory alkalosis

Answer 12

high Ph, low CO2, normal bicard

Question 13

ABG results for respiratory acidosis with metabolic compensation

Answer 13

low pH, high CO2, high bicarb

Question 14

ABG results for respiratory alkalosis with metabolic compensation

Answer 14

high Ph, low CO2, low bicarb

Question 15

3 causes of respiratory acidosis

Answer 15

airway obstruction- COPD, bronchospasm, aspiration, strangulation

resp centre depression- anaesthetics, sedatives

Neuromuscular disease- MND

Pulm disease- RDS, pneumonia

Extrapulmonary thoracic disease- flail chest

Question 16

3 cause of respiratory alkalosis

Answer 16

hypoxia
pulm oedema
PE
hepatic failure
resp stimulants e.g salicylates
voluntary hyperventilation

Question 17

3 causes of metabolic acidosis

Answer 17

ketoacidosis
lactic acidosis
poisoning- methanol, ethanol, salicylate 
renal failure
diarrhoea

Question 18

3 causes of metabolic alkalosis

Answer 18

chronic alkali ingestion
gastric aspiration
vomiting
diuretic use 
potassium depletion 
mineralocorticoid excess e.g. Cushing's

Question 19

How do you calculate the anion gap?

Answer 19

[cations- Na+ and K+]- [anions- bicarb and cl-]