Week 7 - Respiratory Failure, O2 therapy and ABGs

Question 1

Define the two types of respiratory failure

Answer 1

Type I - Pa02 of less than 8 and a normal or low PaCO2, transfer of O2 across alveoli and transport of O2 to tissues is compromised
Type II - Pa02 of less than 8kPa with an increase in CO2 > 7kPa, compromise is also to removal of CO2 from blood to alveolus and atmosphere

Question 2

What are the four types of TI respiratory failure?

Answer 2

Hypoxic hypoxaemia/ diffusion disorder
Ischaemic hypoxaemia
Anaemic hypoxaemia
Toxic hypoxaemia

Question 3

What is Henrys’ law?

Answer 3

Amount of gas in solution depends on partial pressure of gas and it’s solubility

Question 4

What causes TII respiratory failure?

Answer 4

Any disorder or pathology that affects ventilation, e.g. CNS depression, GBS, disorders of SC

Question 5

Describe why you may not give O2 to patients with chronic respiratory failure

Answer 5

Patients with chronic respiratory failure may be breathing on hypoxic drive. Instead of high levels of CO2 causing increase in rate and depth of breathing, low O2 drives respiratory pattern.
If too much O2 is given, patient thinks it has enough and stops breathing.

Question 6

What is a strong indicator for O2 therapy?

Answer 6

Pa02 <9kPa

Sa02 <90% (some say 92% on room air)

Question 7

Describe some complications of O2 therapy

Answer 7

Oxygen toxicity
Depression of ventilation
Retinopathy of prematurity
Absorption atelectasis

Question 8

Name 3 types of variable performance devices and the amount of air you would give with these

Answer 8

Nasal cannula 1/4-4/5 l/min
Simple face mask - 5-8 l/min
Reservoir masks >8 l/min

Question 9

What are fixed performance devices?

Answer 9

Deliver a fixed proportion of air and O2 ensuring accurate conc of O2 delivery regardless of inspiratory volumes/ rate
E.g. venturi mask

Question 10

Describe respiratory acidosis

Answer 10

pH less than 7.35 with a PaCO2 > 6kPa. Increase in CO2 combines with water to produce carbonic acid.

Question 11

Describe respiratory alkalosis

Answer 11

pH greater than 7.45 with a PaCO2 less than 4.7kPa. Hyperventilation removes CO2 at a faster than normal rate resulting in a decrease of H+

Question 12

How do you know whether acidosis or alkalosis has occurred when compensation has also occurred?

Answer 12

Use pH above or below 7.4