1. Oxygen Therapy surgical department
Aishamudin bin Abdul Rahman
Norsafina binti Zainun
Supervisor : Dr. Muhaimin

2. Outline
1. Introduction 2. Indication 3. Principles of Oxygen Therapy 4. Oxygen Supplementation Devices 5. Hazards of Oxygen Therapy 6. Take Home Messages

3. Introduction
Oxygen is a colorless, odorless, tasteless gas that is essential for the body to function properly and to survive.
The air that we breathe in contains approximately 21% oxygen
Oxygen therapy is administration of O2 at concentrations greater than that in room air to treat or prevent hypoxemia.

5. Hypoxemia : Hypoxia : reduction of oxygen levels in arterial blood
a PaO2 of less than 8.0 kPa (60 mmHg) or
oxygen saturations less than 93%.
Hypoxia :
insufficient oxygen supply in the tissues
leads to organ damage

6. Recognition of Hypoxia
Clinical signs and symptoms include:
Altered mental status (agitation, confusion, drowsiness, coma)
Cyanosis
Dyspnoea, tachypnea
Restlessness
Hypoventilation

7. RESPIRATORY FAILURE
It is defined as a PaO2 < 8 kPa (60 mmHg) and subdivided into 2 types according to PaCO2 level.
Type 1
Type 2
PaO2 < 60mmHg with a normal or low PaCO2
PaO2 < 60mmHg with hypercapnia (PaCO2 > 50mmHg)
Caused primarily by ventilation/perfusion (V/Q) mismatch
Caused by alveolar hypoventilation with or without V/Q mismatch
e.g.:
Pneumonia
Asthma
Pulmonary embolism
ARDS
Pulmonary diseases: COPD
Reduced respiratory drive: sedation, CNS tumour, trauma
Neuromuscular ds: cervical cord lesion, diaphragmatic paralysis, myasthenia gravis
Thoracic wall disease: flail chest, kyphoscoliosis

8. Indication of oxygen therapy
Documented hypoxemia as evidenced by
PaO2 or SaO2 below desirable range for a specific clinical situation
Respiratory distress (RR > 24/min)
Acute care situations in which hypoxemia is suspected
Increased metabolic demands (Burns, multiple injuries, severe sepsis)
Cardiac failure or myocardial infarction
Short term therapy (Post anaesthesia recovery)

9. Goals of oxygen therapy
1. Correcting Hypoxemia
By raising Alveolar & blood level of oxygen
2 Decreasing symptoms of Hypoxemia
Supplemental O2 can relieve symptoms
Lessen dyspnea/ work of breathing
Improve mental function
3 Minimizing Cardiopulmonary workload
Cardiopulmonary system will compensate for hypoxemia by:
Increase ventilation to get more O2
Increasing cardiac output to get oxygenated blood to tissues

10. Principle of Oxygen Therapy
Starting patient on oxygen therapy
Critically ill patient:
Give high dose oxygen first (HFM or manual bagging)
Manual bagging if during resuscitation. Consider invasive ventilation
Serous illness requiring moderate level of supplemental oxygen:
NPO2 2-6L/min or simple face mask 5-10L/min
HFM if SPO2 <85%
Monitoring patient on oxygen therapy
Clinically: patient less breathlessness, less tachypneic, pink
SpO2 using pulse oximetry. Aim SPO %
ABG STAT
pO2
pCO2

11. Monitoring first hour of oxygen therapy
Observe SPO2 at least 5 mins after starting oxygen.
If SPO %:
treat appropriately.
ABG after 1 hour.
If SPO2 <94%:
Change to HFM
assessment by senior medical staff
Consider invasive ventilation if respiratory deterioration
Titrate the oxygen up or down
To maintain the target oxygen saturation
choose the most suitable delivery system and flow rate

12. Discontinue oxygen therapy in stable patient:
Step down to next lower oxygen therapy dose
Stop if patient clinically stable on low dose oxygen
SpO2 should be monitored for 5 mins after stopping oxygen therapy

13. Oxygen device

14. Oxygen supplementation devices
The oxygen concentration that can be deliver to patients depends on the;
Delivery device
Oxygen flow rate
Patient’s breathing pattern, rate and volume.

15. Oxygen delivery devices
Fixed performance system
Variable performance system
FiO2 is independent of patient factor.
FiO2 depends on O2 flow, device factors and patients factor.
Provide relatively constant o2 concentration to the lungs.
Provide variable o2 concentrations depending the patient’s ventilation pattern.
Air entrapment mask (venturi mask)
Nasal canula
Simple face mask
Tracheostomy masks
High flow mask
Oxygen headbox
Incubator
Fraction of inspired oxygen (FiO2) is the fraction or percentage of oxygen in the space being measured

16. Fixed performance FiO2

17. Venturi mask
Goal- to create an open system with high flow about the nose and mouth, with a fixed FiO2.
Operate the Bernoulli principle.

18. As gas flows through a tube at high linear velocity -> lateral wall pressure of the tube can become subatmospheric - >causing the entrainment of room air through the ports located along the side of tube.

19. The smaller the orifice of the adapter ->the lesser air being entrained - > the higher the 02 concentration delivered to patient.
These mask are used when it is necessary to control the FiO2 or to know the FiO2.

20. These masks give an accurate FiO2 which depends on their construction and the O2 flow rate administered.
Colour coded.
24% 2L
28% 4L
31% 6L
35% 8L
40%
10L
60%
15L
24%
28%
31%
35%
40%
50%
60%

21. Variable performance FiO2

22. Nasal cannula FiO2 varies with O2 flow rate and patient’s ventilation.
changes in minute ventilation and inspiratory flow affect air entrainment-> fluctuation in FiO2.
normal flow rate administer is 2-3 L/min
> 3 L/min may cause discomfort to patient, may get dislodged and cause nasal trauma.

23. For each 1 L/min increase in flow, the FiO2 is assumed to increase 4%.
Flow rate ( L/min)
Approximate FiO2 1
0.24 2
0.28 3
0.32 4
0.36 5
0.40 6
0.44
For each 1 L/min increase in flow, the FiO2 is assumed to increase 4%.
FiO2 = 20% + (4 × oxygen litre flow)

24. Advantages
Disadvantages
Easy and comfortable
Cheap
Less claustrophobic compared to mask
CO2 re-breathing does not occur.
Provides unreliable FiO2
May cause dryness of nasal mucosa
Mucosa edema
Deviated septum

25. Simple face masks Simple semi-rigid plastic mask
The 02 flow rate should be at least 5L/min
to prevent re-breathing CO2.
Usual flow rate 5-6 L/min.
Patients may feel claustrophobic and its usage interferes with feeding.

26. Tracheostomy mask
These are small plastic masks placed over the tracheostomy tube or stoma.
Perform similarly to simple face masks
The usual flow rate is 5-6 L/min.

27. High flow mask FiO2 greater than simple face masks Reservoir bag
provide a large effective dead space.
should be at least 1/3 full at all time.
Minimum flow rate L/min must be applied to prevent collapse bag.
CO2 rebreathing occurs if the oxygen supply fails or is reduced.

28. Symptoms of CO2 rebreathing: Discomfort Fatigue Dizziness headache
muscular weakness.
Rebreathing can be eliminated if unidirectional valves are added.
Between mask and reservoir bag
to prevent exhaled air from returning to bag
At the exhalation ports
to prevent dilution of 02 with air entrainment.
One way valve

29. Positive pressure ventilation

30. Positive Pressure Ventilation
Forces air into the lungs
Prevent alveoli collapse at the end of respiration
less work required from respiratory muscle
creates greater functional residual capacity
Using a bag valve mask or mechanical ventilation

31. Continuous Positive Airway Pressure (CPAP)
Delivers a set positive airway pressure throughout each cycle of inhalation and exhalation.
Effect is to open collapsed alveoli.
Patients who may benefit include those with:
atelectasis after surgery or
cardiac-induced pulmonary edema
sleep apnea.

32. Bilavel positive airway Pressure (BiPAP)
Delivers a set inspiratory positive airway pressure each time the patient begins to inspire.
At exhalation, it delivers a lower set end-expiratory pressure.
Together the two pressures improve tidal volume.
positive pressure keep the alveoli open and improve gas exchange

33. Hazards of Oxygen therapy
Oxygen toxicity
Only a problem when high concentration which is >50% are given for long periods of time
Neurological effects
Hyperbaric oxygen can precipitate convulsion.
Carbon dioxide narcosis
Severe respiratory depression with LOC can occur when high oxygen concentrations are administered to patients with ventilator y failure who are dependent on hypoxic drive.
Bronchopulmonary dysplasia
Seen when immature lungs are ventilated with high FiO2.
Retinopathy of prematurity
Occurs in premature babies who exposed to Pa02 more than 80mm Hg.

34. Take home messages
Primary goal of oxygen therapy is to correct alveolar and tissue hypoxia, aim for PaO2 > 60mmHg or oxygen saturation more than 93%.
02 dissociation curves shift to the right or reducd affinity when increase in body temperature, acidosis and increase in 2,3-DPG.
At tissue level, mitochodrial activity requires oxygen for aerobic ATP syntesis for cellular activity.
Observe spO2 for 5 minutes after changing of oxygen therapy and repeat ABG after 1 hour after the oxygen therapy.
Consider invasive ventilation if respiratory failure or deterioration on HFM/ manual bagging
Nasal mucosa dryness, mucosa edema or a deviated septum can be caused by O2 rate > 3L/ min delivered through the nasal cannula.
In simple face masks, the O2 flow rate should more than 5L/min to prevent CO2 re-breathing.
Minimum flow rate L/min should be used in high flow mask to prevent collapse of reservoir bag.
Oxygen toxicity is only a problem when administered over prolonged period of time.

35. Refferences Kumar and Clark 8th edition. American Thoracic Society.
The Principles of Oxygen Therapy
American Thoracic Society.
Oxygen Therapy
British Thoracic Society
in-adult-patients-guideline/
Anesthesiology for Medical Field
International Islamic University Malaysia, 2011