Oxygen Therapy

1. BY
ANAESTHESIOLOGY UNIT

2. ¨What is oxygen?
¨Hypoxia /Hypoxemia
¨Indications for oxygen therapy
¨Oxygen delivery systems
¨Complications of oxygen therapy
¨Conclusions

3. ¨Oxygen is a gas with chemical formula of O2
¨Colourless, odorless, tasteless
¨Boiling point -183 C
¨Melting point –216.6C
¨Critical temp. –118.4C , Critical pressure
736.9psi
¨Constitutes about 20.95% of atmosphere
¨Used at cellular level as the final electron acceptor
in the electron transport chain in the mitochondria
of cell

4. Inadequate delivery of O2 to the tissue
Type of hypoxia
1. Hypoxic hypoxia ( decrease diffusion of O2 across the
alveolar-capillary membrane
-low inspired FiO2
-V/Q inequalities
-increased shunt(eg cardiac anomalies)
2. Stagnant hypoxia (decreased cardiac output resulting in
increased systemic transit time
-Shock
-Vasoconstrictio
3. Anaemic hypoxia ( decreased O2 carrying capacity in the
blood)
-Anaemia

5. -Carbon monoxide poisoning
4. Histotoxic hypoxia ( inability the tissue utilize available O2)
- Cyanide poisoning
Reduced O2 concentration/tension in the blood
PaO2<80mmhg.

6. Should be determined through evaluation of the patient
(clinical assessment and blood gas result)
In general the indication are:-
4.Hypoxemia/hypoxia
5.Excessive work of breathing
6.Excessive myocardial work
7.Improvement of oxygenation in patient with decreased
O2 carrying capacity ( anaemia)
8.Promotion of absorption of air in the body cavity

7. THIS PERSON NEED O2 ????????

8. Many devices for administering supplemental
O2 are available
Classification
Low-Flow Systems/Variable performance
Definition: Do not provide all gases
necessary to meet the patient minute
ventilation
- Nasal canula
- Face mask
- Partial rebreathing mask
- Nonrebreathing mask

9. High-Flow Systems/Fixed performance
Definition : Flow sufficient to meet all of patient Mv
and ensure patient receive constant inspired O2
concentration
- Venturi masks
- Head box
- Semi closed/closed anaesthetic circuit

10. Nasal canula
¨Capable to deliver an FiO2 ranging from 0.24-0.44
depending on the amount of flow
¨Maximum of 6LPM Why?
causes crusting of the secretion, drying of the nasal
mucosa and epistaxis
¨Advantages –inexpensive,well tolerated, comfortable
patient can eat and drink
¨Disadvantages – pressure sore, irritant to the mucosal
Flow FiO2
1LPM 0.24
2LPM 0.28
3LPM 0.32
4LPM 0.36
5LPM 0.40
6LPM 0.44

11. Simple face mask
¨Increases the O2 reservoir- higher FiO2
¨O2 flow must be more than 5LPM Why?
- To prevent rebreathing
Flow FiO2
5-6LPM 0.40
6-7LPM 0.50
7-8LPM 0.60
>10LPM ?
¨Advantages – simple, light, deliver higher FiO2
¨Disadvantages – need to remove for eat, drink, speak
- uncomfortable for facial trauma

12. Partial rebreathing and Non rebreathing mask
¨Similar to simple mask with addition of the O2 reservoir
to increase FiO2 greater than 0.60
¨Non rebreathing mask – one way valve to prevent
rebreathing
Partial rebreathing
Flow FiO2
7LPM 0.65
8-15LPM 0.70-0.80
Non rebreathing
Flow FiO2
Set to prevent collapse of bag 0.85-1.0

13. Venturi mask
¨Operate on Bernoulli principle
- As gas flow under pressure at rapid flow rate an area of
pressure develops lateral to the small opening and lead to
entrainment of room air through the side port.
¨Advantages – delivery of very predictable FiO2
- may use in COAD patient
¨Disadvantages – same like face mask
Flow FiO2
4 0.24
6 0.28
8 0.35-0.40
12 0.60

14. Hypoventilation and Carbon Dioxide NarcosisHypoventilation and Carbon Dioxide Narcosis
-the increased PO2 decreased and eliminates the hypoxic
drive ( esp. in pt. with chronic CO2 retention )
-Under this circumstances O2 must be given at low
concentration <30%
Absorption AtelectasisAbsorption Atelectasis
- Nitrogen a relatively insoluble and exists 80% by volume
of the alveolar gas.N2 assists in maintaining alveolar
stability.O2 therapy replaced N2. Once O2 absorb into the
blood the alveolar will collapse esp. in alveolar distal to
the obstruction.

15. Pulmonary Oxygen ToxicityPulmonary Oxygen Toxicity
-The exposure of the high O2 and for prolonged period
can lead to parenchymal changes
-In general FiO2 > 50% for prolonged period shows
increased O2 toxicity
-Pulmonary changes mimic ARDS (Exudative changes and
proliferative changes.)
-Sx –cough, burning discomfort, nausea and vomiting,
headache, malaise and etc
Retrolental FibroplasiaRetrolental Fibroplasia
-Excessive O2 to pre-mature infants may result in
constriction of immature retinal vessels, endothelial
damage, retinal detachment and possible blindness
-Recommended that PO2 be maintained between 60-90
mmHg range in neonate

16. Fire
O2 support combustion
Do not smoke while receiving O2 therapy

17. Patient on Chemotherapy
Patient on chemotherapy especially bleomycin
will develop pulmonary fibrosis if get
excessive O2 therapy

18. O2 can be store either
1)Cylinder
Oxygen can be stored under pressure in
cylinders made of molybdenum steel.
Cylinders are black with white shoulders.
The pressure inside at 15°C is 137 bar.
2)Oxygen concentrators
An oxygen concentrator is a device which
extracts oxygen from atmospheric air using
canisters

20. Nitrogen is filtered out and oxygen produced.

3)Vacuum Insulated Evaporator (VIE).
Designed to store liquid oxygen.
It consists of two layers, where the outer carbon
steel shell is separated by a vacuum from an inner
stainless steel shell, which contains the oxygen
The oxygen temperature is -170 C at 10.5 atm.
The VIE system is used in large hospitals which
have a pipeline system, and where liquid oxygen
can be supplied by road tanker

22. ¨O2 therapy is the delivery of any O2 conc. Greater
then 21%
¨The need for O2 should be determined through the
thorough evaluation
¨One must consider advantages and disadvantages
when choosing the appropriate technique
¨No procedure without complication