oxygen therapy

Question 1

aim

Answer 1

• Correct hypoxaemia and therefore aim to tissue hypoxia
• WOB
• Myocardial work
• Cerebral vasodilation

Question 2

Delivery

Answer 2

A) Continuous
B) Intermittent
C) Nocturnal

Question 3

Dangers

Patients with COPD

Answer 3

• PaO2 becomes main stimulus to breathe (compared to inc. PaCO2 levels)

• Supplemental O2 may lead to inc. PaO2 > dec. drive to breathe
• PaCO2 > CO2 narcosis

Question 4

Dangers

Oxygen Toxicity

Answer 4

• FiO2 0.5 – 0.6 (50-60%) for long periods
o Pulmonary changes:
♣ Pulmonary oedema
♣ dec. Pulmonary compliance

Question 5

Dangers

Depression of Ciliary Function

Answer 5

• Thickening of secretions

- Further secretion retention

Question 6

Dangers

Absorption Atelectasis

Answer 6

• Nitrogen = structural role to hold alveoli open
• With inc. O2 in alveoli, nitrogen is moved out
o Leads to structural collapse (atelectasis)
o Alveoli perfused but not ventilated
o V/Q mismatch
Parts of the lung can start to collapse

Question 7

Mx Dangers

Answer 7

COPD
Oxygen Toxicity
Depression of Ciliary FUnction
Absorption Atelectasis

¬ Ensure correct flow and FiO2
¬ Ensure correct fit of device
¬ Monitor improvements/ deterioration
o Titrate FiO2 accordingly

¬ Minimise side effects

Question 8

preventing adverse rxs of o2 therapy

Answer 8

Hydration - IV lines
Nebulisation
Humidification
Tracheotomy

Question 9

Nebulisation

Answer 9

Mechanism
Converts solution into fine droplets, suspended in a stream of gas.
• Carried into airways via mouthpiece or mask - driven by wall oxygen or nebulizer pump
• Used to deliver respiratory medications:
o Bronchodilators, corticosteroids, antibiotics, antifungals, mucolytics, saline (hypertonic)
• Useful for moistening upper airway of surgical patient (normal saline)

Application
¬	Need flow rate 6-8L/min to nebulize
o	Care with patient with hypoxic drive (use medical air instead of O2)
o	21% O2
•	Upright sitting
•	Slow, deep breaths (slow laminar flow)
•	Interspersed with TV (prevent hyperventilation)
•	Mouth breathing

Question 10

Humidification

Answer 10

Indications
•	FiO2 > 0.35
•	Thick secretions
•	Consolidation
•	Major infection
•	Following surgery
•	Artificial airway
•	Diuretic therapy
•	Dehydrated
Types
•	Water vapour
•	Nebulised particles

Question 11

Aerosol Therapy

Answer 11

Mechanism
• Suspension of fine liquid or solid particles in air
• Used to deliver bronchodilators, inhaled corticosteroids, anticholinergics
• Spacer device ( inc. deposition of drug in lungs instead of oropharynx by approximately 15%)
• Topical deposition of drug (in lungs) > smaller dose, faster acting, less side-effects (minimal systemic absorption)
• Pattern of deposition according to size of particles
o Gravitational sedimentation = time dependent & enhanced by breath hold

Inhaler Devices
• Metered dose inhaler
• Turbohaler

Considerations
• Choice of device: must consider patient age, coordination, dexterity, severity, preference
• Oral candidiasis: dec. by rinsing mouth following inhalation of steroids; use space device
• Turbohaler is breath-actuated (releases drug on inspiration); suitable for people who are unable to coordinate MDI