11- Acid Base Disturbance

Question 1

What are normal blood values

Answer 1

Hb 130 to 170 g/L
pH 7.35 to 7.45
PCO2 4.7 to 6.4 kPa (35 - 48 mm 
PO2 >10 kPa (>80 mmHg)
HCO3-  22-26 mEq/L
BE -2 to +2 mmol/L or mEq/L

Question 2

What are Blood gas values in mixed venous and arterial blood

Answer 2

PaO2 5.3 kPa
SaO2 75%
PaCO2 6.1 kPa

PaO2 >10 kPa
SaO2 >95%
PaCO2 A4.7-6.4 kPa

Question 3

What is an alkalaemia and alkalosis

Answer 3

Osis: A higher than normal pH
Aemia: a lowered pH

Question 4

What are the basic guidelines for Pa02

Answer 4

Basic guidelines for PaO2
>10 kPa is normal
8-10 kPa is mild hypoxaemia
6-8 is moderate hypoxaemia
<6 kPa is severe hypoxaemia

Question 5

What are the pH in arterial and venous blood

Answer 5

Arterial pH = 7.4

Venous pH = 7.36

Question 6

What are the 2 compensatory mechanisms

Answer 6

Changes in ventilation can stimulate a RAPID compensatory response to change CO2 elimination and therefore alter pH

Changes in HCO3- and H+ retention/secretion in the kidneys can stimulate a SLOW compensatory response to increase/decrease pH

Question 7

What 4 things can you interpret from blood gases

Answer 7

Type of imbalance?
Acidosis (or acidaemia) / Alkalosis (or alkalaemia) / Normal
Aetiology of imbalance?
Respiratory (acidosis or alkalaemia) / Metabolic (acidosis or alkalosis) / Mixed (respiratory and metabolic) / Normal
Any homeostatic compensation?
Uncompensated / Partially compensated / Fully compensated
Oxygenation?
Hypoxaemia / Normoxaemia / Hyperoxaemia