Disadvantages – pressure sore, irritant to the mucosal
Simple face mask
Increases the O2 reservoir- higher FiO2
O2 flow must be more than 5LPM Why ?
- To prevent rebreathing
Advantages – simple, light, deliver higher FiO2
Disadvantages – need to remove for eat, drink, speak
- uncomfortable for facial trauma
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
Set to prevent collapse of bag 0.85-1.0
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
Hypoventilation 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%
- 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.
Complications of O2 therapy
Pulmonary 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
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
O2 support combustion
Do not smoke while receiving O2 therapy
Patient on Chemotherapy
Patient on chemotherapy especially bleomycin will develop pulmonary fibrosis if get excessive O2 therapy
O2 can be store either
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.
An oxygen concentrator is a device which extracts oxygen from atmospheric air using canisters
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
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