Oxygen therapy

Question 1

ABG reference range : PH/PaCO2/PaO2/HCO3/BE

Answer 1

• pH : 7.35-7.45
• PaCO2 : 4.7 - 6 kPa
• PaO2 : 11-13
• HCO3- : 22-26
• BE : -2 to +2

Question 2

Oxygen therapy : FiO2 defintion

Answer 2

FiO2 - Fraction of inspired oxygen

Definition : measure of the concentration of oxygen in the gas that a person inhales

Question 3

Oxygen therapy : What is the normal PO2

Answer 3

• PaO2 - normally >10kPa
• If receiving oxygen therapy PaO2 should be 10kPa less than % inspired conc FiO2

Question 4

Oxygen therapy: Nasal cannula : FiO2?

Answer 4

1. 1L - 24%
2. 2L - 28%
3. 3L -32%

Question 5

Oxygen therapy: Simple face mask : Indication

Answer 5

Indication :
* High flow rate and concentration of oxygen is required than using a NC.
* Can deliver max FiO2 of 40-60% at flow rate of 15L -

Not accurate as O2 delivery is variable depending on O2 flow/mask fit

Question 6

Oxygen therapy: Simple face mask : Contraindication

Answer 6

1. Not be used in flow rate of <5L - in

• Low flow rates oxygen can become diluted with room air and increase the risk of rebreathing exhaled CO2
• Which can worsen hypoxia and lead to hypercapnia.

Question 7

Oxygen therapy: Non rebreathe masks : indication for use

Answer 7

*Indication : *
* used if very unwell and no risk of CO2 retention

• Delivers high concentration of FiO2 in critical condition where rapid and substantial oxygen supplementation is needed such as severe hypoxia

60-90% oxygen conc at flow rate 10-15L/min

Question 8

Oxygen therapy: Non rebreathe masks : MOA

Answer 8

• Contains one-way valve which prevents rebreathing exhaled CO2 air
• Ensuring high O2 and low CO2 supply at all times.

Question 9

Oxygen therapy: Non rebreathe masks : Contraindication

Answer 9

1. High risk of developing hypercapnia in CO2 retainer patients - use with caution
   * Venturi masks are preferred for treating hypoxia in COPD

Question 10

Oxygen therapy: Venturi mask : Indication

Answer 10

*Indication : *
used to deliver controlled and precise oxygen concentration to patients on controlled oxygen therapy

Question 11

Oxygen therapy: Venturi mask : MOA

Answer 11

• Venturi valve traps specific about of room air into the oxygen flow resulting in a precise FiO2 mixture
• gives accurate concentration of oxygen regardless of flow rate
• Different masks have different suggested flow rates.

Meets target oxygen saturations and reduces risk of hypercapnia
Suitable for patients who need a known concentration of oxygen

• 24-28% Venturi used in patients with risk of CO2 retention