Blood gases

Question 1

Describe some things where people should get a blood gas

Answer 1

Critically ill
Hypoxic 
Deteriorating patient who needs oxygen
Risks of hypercapnic respiratory failure
Breathless and at risk of metabolic conditions

Question 2

What are the risks of ABG?

Answer 2

nerve injury, digital ischaemia, bleeding and haematoma

Question 3

What can not be assessed via VBG?

Answer 3

p02

Question 4

What are normal ranges for pH?

Answer 4

7.35 - 7.45

Question 5

Whats a normal pa02?

Answer 5

> 10kPa

Question 6

Whats normal PaC02?

Answer 6

4-6kPa

Question 7

Whats normal base excess?

Answer 7

-2 to +2

Question 8

Whats normal lactate?

Answer 8

<2

Question 9

Whats the 5 step approach to interpreting blood gases?

Answer 9

1. How is the patient clinically?
2. is the patient hypoxiaemic?
3. are they acidaemic or alkalotic?
4. whats happening to the PC02?
5. What has happened to the base excess or bicarbonate?

Question 10

Describe some causes of normal anion gap metabolic acidosis

Answer 10

ureteric diversion
small bowel fistulae 
DKA
carbonic anyhdrase inhibitors
Addisons
renal tubular acidosis
pancreatic fistula

Question 11

Describe some low anion gaps of metabolic acidosis

Answer 11

hyperkalaemia

multiple myeloma

Question 12

Describe increased anion gap metabolic acidosis

Answer 12

MURKLESEPTIC
Methanol
uraemia
renal failure
ketoacidosis
lactic acidosis
Ethanol
salicyltes
cyanide and carbon monoxide

Question 13

How can causes of respiratory alkalosis be divided?

Answer 13

Two ways

• stimulated respiratory drive
• hypoxaemia induced

Question 14

causes of respiratory acidosis

Answer 14

Decreased respiratory drive -CNS tumour, drugs, haemorrhage, narcotics and sedative
Decreased chest wall movement - neurological (mysthenia gravis, tetanus), toxicity (muscle relaxants), resp (trauma, chest wall deformitiy) COPD