Respiratory - ABGs Flashcards
What is type 1 respiratory failure?
Normal PaCO2 with low PaO2 (one affected)
What is type 2 respiratory failure?
Raised PaCO2 with low PaO2 (two affected)
What indicates respiratory acidosis?
Low pH
Raised PaCO2
Patient acutely retaining CO2 and become acidotic
What happens to bicarbonate levels in acute respiratory acidosis?
Bicarbonate acts to buffer acidosis but cannot act fast enough in acute respiratory acidosis as it takes the kidneys time to produce it
What does raised bicarbonate indicate?
Patient chronically retains CO2
Kidneys produce additional bicarbonate to balance acidic CO2 and maintain pH
Seen in COPD patients
What can happen in acute exacerbation of COPD?
Kidneys unable to keep up with rising CO2 levels so patient becomes acidotic
What happens in respiratory alkalosis?
Patient has raised respiratory rate and blows off too much CO2
Low PaCO2
High pH
How do you differentiate between respiratory alkalosis due to anxiety vs pulmonary embolism?
PE- low PaO2
Anxiety- High PaO2
What happens in metabolic acidosis?
Low pH
Low bicarbonate
What causes metabolic acidosis?
Raised lactate
Raised Ketones (especially DKA)
Increased H+ ions due to renal failure, type 1 renal tubular acidosis or rhabdomyolysis
Reduced bicarbonate- diarrhoea, renal failure or type 2 renal tubular acidosis
What happens in metabolic alkalosis?
Raised pH
Raised bicarbonate
What causes metabolic alkalosis?
Loss of H+ ions
GI tract- vomiting
Kidneys- increased activity of aldosterone, increased excretion
What causes increased activity of aldosterone?
Conn’s syndrome
Liver cirrhosis
Heart failure
Loop diuretics
Thiazide diuretics
