Oxygen therapy

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 :
• 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. • 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
e.g.:
•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 ofoxygen 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. Goalsof 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. • 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 SPO2 94-98%
• ABG STAT
• pO2
• pCO2
Principle of OxygenTherapy

11. • Monitoring first hour of oxygen therapy
• Observe SPO2 at least 5 mins after starting oxygen.
• If SPO2 94-98%:
• 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%.
• FiO2 = 20% + (4 × oxygen litre flow)
Flow rate ( L/min) Approximate FiO2
1 0.24
2 0.28
3 0.32
4 0.36
5 0.40
6 0.44

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 10- 15 L/min must be applied to prevent
collapse bag.
• CO2 rebreathing occurs if the oxygen supply fails or is reduced.

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

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 10-15 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.
• The Principles of Oxygen Therapy
• American Thoracic Society.
• Oxygen Therapy 2013. www.thoracic.org/statement
• British Thoracic Society
• https://www.brit-thoracic.org.uk/guidelines-and-quality-standards/emergency-oxygen-use-
in-adult-patients-guideline/
• Anesthesiology for Medical Field
• International Islamic University Malaysia, 2011