Respiratory Failure

Question 1

What is hypoxaemia?

Answer 1

Lack of O2 in arterial blood

PaO2 < 8 kPa

Question 2

What is hypercarbia?

Answer 2

Too much CO2 in arterial blood

PaCO2 > 7 kPa

Question 3

What is type 1 respiratory failure?

Answer 3

• Oxygenation failure
• Hypoxaemia with normal/low PaCO2
• Affects part of lung - remaining able to excrete CO2

Question 4

What is type 2 respiratory failure?

Answer 4

• Ventilatory failure
• Hypoxaemia + Hypercarbia
• Affects whole lung - inadequate ventilation = CO2 accumulation

Question 5

What are the causes of type 2 RF?

Answer 5

• Depression of respiratory centre
• Respiratory muscle weakness
• Chest wall deformity
• Severe lung disease

Question 6

What are the signs of low O2?

Answer 6

Confusion, restlessness, cyanosis, tachypnoea (rapid breathing)

Question 7

What are the signs of high CO2?

Answer 7

Drowsiness, confusion, headache, agitation, bounding pulse, asterixis

Question 8

How is type 2 RF treated?

Answer 8

• Oxygen - LT 16 hours/day

- Poor prognosis

Question 9

How is type 1 RF treated?

Answer 9

• Ventilation + non-invasive ventilation
• Even poorer prognosis
• Overnight ventilation

Question 10

What is normal blood pH?

Answer 10

7.35-7.45

Question 11

What pH is alkalaemia?

Answer 11

pH > 7.45

Question 12

What pH is acidaemia?

Answer 12

pH < 7.35

Question 13

How are changes in CO2 controlled?

Answer 13

Changes in ventilation

Question 14

How are changes in HCO3 controlled?

Answer 14

Renal absorption/excretion

Question 15

What is normal oxygen saturation?

Answer 15

> 94 %

Question 16

What causes respiratory acidosis/alkalosis?

Answer 16

Abnormal CO2 clearance

Question 17

What causes metabolic acidosis/alkalosis?

Answer 17

Abnormal regulation bicarbonate

Question 18

What is base excess?

Answer 18

Amount of acid required to return pH to normal at normal PaCO2

Question 19

What does a BE < -2 indicate?

Answer 19

Metabolic acidosis

Question 20

What does BE > + 2 indicate?

Answer 20

Metabolic alkalosis

Question 21

What does low pH, BE & HCO3 indicate?

Answer 21

Metabolic acidosis

Increased ventilation to blow off CO2

Question 22

What does high pH, BE & HCO3 indicate?

Answer 22

Metabolic alkalosis

Decreased ventilation to retain CO2

Question 23

What does low pH and high PaCO2 indicate?

Answer 23

Respiratory acidosis
Acute type 2 RF
Compensated metabolic alkalosis - excrete H+, retain HCO3

Question 24

What does high pH and low PaCO2 indicate?

Answer 24

Respiratory alkalosis
Hyperventilation
Acute + unstable to sustain for long
Compensated metabolic acidosis - kidneys excrete HCO3