Oxygen Therapy And Humidification

Question 1

Discuss the difference between controlled and uncontrolled oxygen therapy

Answer 1

Controlled oxygen therapy provides the patient with a known concentration of FiO2 while uncontrolled oxygen therapy does not allow an accurate estimate of FiO2 to be calculated.

Controlled - Venturi mask, mechanical ventilator, head box
Uncontrolled - nasal prongs, simple face mask

Question 2

Discuss the use of high flow oxygen therapy

Answer 2

High flow of between 15-45L/min
Nasal prongs - up to 45L/min, requires humidification.
FiO2 0.24-0.6
Used for patients who are not responding to controlled ventilation with FiO2 of >0.4

Question 3

List the dangers and contraindications to oxygen therapy

Answer 3

Fire
Oxygen toxicity - adult - destruction of alveolar-capillary membrane, deceased cilial activity, acute trachebronchitis. Child - retrolentil dysplasia and bronchopulmonary dysplasia
Decreased drive to breathe (COPD)
Absorption atelectasis
V/Q mismatch due to oxygen induced vasodilation

Question 4

State the target SpO2 of adults receiving oxygen therapy

Answer 4

SpO2 = 98-100%

In COPD patients = 90%

Question 5

Discuss the effect of humidity on mucocillary apparatus

Answer 5

Humidity prevents the drying of the mucosa and the sol layer above the cilia.
Increased depth of sol layer = improved secretion clearance
Thins tenacious secretions for easier clearance
Decreased airway resistance and bronchospasm = improved secretion clearance and increased PEFR

Question 6

Describe the ways humidification may be increased in a clinical setting

Answer 6

Water bath ($$, risk of infection, cost, risk of overheating)
Bubble
Nebuliser (saline 0.9% or 3-9% used as an osmotic agent)
Aqua Pak and High-Flow oxygen have built in humidification

Question 7

List the medical interventions that can be used to increase PaO2

Answer 7

Improve diffusion - Increase FiO2, Increase barometric pressure
Improve surface area - CPAP, PEEP