1. Oxygen therapy- Rationale & PrescriptionBy
Subin Solomen MPT-CRD(Manipal)
Professor
EMS Memorial Co-operative Hospital & Research Centre
Kerala
Experience : 10 years, Publications: 17, Book Vascular rehabilitation under jaypee publishers :

2. Definition
Increasing the concentration of oxygen in the inspired air to correct or prevent hypoxemia is oxygen therapy
O2 administration aims at increasing PAO2 and there by increasing PaO2 and SPO2 of arterial blood
Supplemental O2 delivery of oxygen more than 21%
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Subin Solomen MPT(Manipal)- CRD

3. Rationale To treat or prevent hypoxemia
There by preventing tissue hypoxia which may result in tissue injury and even cell death
At the tissue level, mitochondrial activity requires oxygen for aerobic ATP synthesis for cellular activity
In case of CO poisoning and cluster head ache
In this case affinity of Hb to CO can be reduced
The Half life of CoHb reduced from 4 hours to 40 minutes
To resolve pneumothorax who do not require a drainage
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Subin Solomen MPT(Manipal)- CRD

4. Indications Treatment of documented hypoxemia
Adults, children, infants > 28 days,PaO2 < 60mm,SaO2 < 90%
Neonates – PaO2 < 50mm hg, SaO2 < 88%
Situations in which hypoxemia is suspected
To decrease the work of breathing
To decrease myocardial work
Temporary hypoxaemia
Before and after suction
First time administration of bronchodilator with side effect
Prior to heart surgery
During exercise
Patients with decreased oxygen carrying capacity
Anaemia , sickle cell disease.
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Subin Solomen MPT(Manipal)- CRD

5. Assessment of need
Use of lab measures to document hypoxemia – Hb, PaO2, SPO2
Based on clinical problems
CO poisoning, Cyanide poisoning, Shock, Trauma, Acute MI
Clinical manifestations
Respiratory- Tachypnea, Dyspnea, Cyanosis
Cardio-Vascular - Tachycardia, Mild hypertension
Neurological - Restlessness, Disorientation
Skin – cool, clammy
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Subin Solomen MPT(Manipal)- CRD

6. Oxygen delivery systems
Low flow systems – variable performance
Reservoir systems
High flow systems – fixed performance
Enclosures – Tent , Hood, Head Box
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Subin Solomen MPT(Manipal)- CRD

7. Low flow systems Provides a portion of inspired gas
Does not meet patients total ventilation
Reservoir will be nasopharynx or oropharynyx
Less than 8l/m
Nasal cannula
Nasal catheter
Trans tracheal catheter
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Subin Solomen MPT(Manipal)- CRD

8. 1. Nasal cannula Max Flow rate 6 L/m
Prongs
Max Flow rate 6 L/m
Prong are inserted directly to nose
FIO2 from.24 to .44
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Subin Solomen MPT(Manipal)- CRD

9. Nasal Cannula Advantages Disadvantages Patient can eat and drink
Well tolerated
Low cost
Disposable
Easy to apply
Unstable
Easily dislodged
Pressure sore around ear and nose
May dry and irritate nasal mucosa
Deviated septum may block flow
Best use : Stable patient needing low FiO2, Home care patient requiring long term oxygen therapy
25/2/2016
Subin Solomen MPT(Manipal)- CRD

10. 2. Nasal catheter Soft plastic tube with several holes at tip
Inserted until the tip reaches the oropharynx
Flow 6t08 l/m
Best use : Procedures when cannula difficult to use in case of bronchoscopy
25/2/2016
Subin Solomen MPT(Manipal)- CRD

11. 3. Trans tracheal catheter
Directly to trachea
2nd or 3rd rings
Flow 4 l/m
Best use : Ambulatory patients who need increased mobility or do not accept nasal oxygen
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Subin Solomen MPT(Manipal)- CRD

12. Reservoir systems – A) Cannula Reservoir cannula store O2 between breaths Types
1. Nasal reservoir
2. Pendent reservoir
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Subin Solomen MPT(Manipal)- CRD

13. Reservoir System- B) Mask
Simple mask
Partial rebreathing mask
Non rebreathing mask
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Subin Solomen MPT(Manipal)- CRD

14. 1. Simple mask Cover both nose and mouth This increases the size
of reservoir So
higher FIO2
can be delivered
Flow 5-12l/m
Entrainment of room air & release of exhaled gases
Vent Holes
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Subin Solomen MPT(Manipal)- CRD

15. Simple Mask Disadvantages Advantages
Patient may need to remove the mask for speaking, expectoration of secretions
Difficulty in placing when Ryles tube in place
Drying or irritation of eyes
Uncomfortable with facial trauma
Block vomitus in unconscious patients
Light weight
Inexpensive
Easy to apply
Disposable
Can use with humidifier
Delivery of FIO2 up to 0.60
Best use : Emergency patients requiring short term oxygen therapy with moderate fiO2
25/2/2016
Subin Solomen MPT(Manipal)- CRD

16. 2. Partial rebreathing mask
Reservoir bag
No valves
First one third expired gas enters reservoir bag
This is form anatomic reservoir so it is high in oxygen and contains little CO2
Flow 6-10 l/m
FIO2 from .60 to .80
Mask +
Oxygen reservoir bag
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Subin Solomen MPT(Manipal)- CRD

17. Partial Rebreathing Mask
Advantages
Disadvantages
Higher delivery of FIO2
>0.60
Exhaled oxygen from the anatomic dead space is conserved
Insufficient flow rate may lead to rebreathing of CO2 leads to suffocation hazard
Limited access to mouth for eating, drinking, expectorating
Eye irritation
Best use : Emergency patients with short term oxygen therapy with moderate to high fiO2
25/2/2016
Subin Solomen MPT(Manipal)- CRD

18. 3.Non re breathing mask
One way valves over side ports and above reservoir bag
Limits entrainment of air
Prevent entrainment of room air
Prevent exhaled gas entering into bag
25/2/2016
Subin Solomen MPT(Manipal)- CRD

19. Non Rebreathing Mask Advantages Disadvantages Higher delivery of FIO2
Uncomfortable
Limited access to mouth for eating, drinking, expectorating
Eye irritation
Best use : Emergency patients with short term oxygen therapy with moderate to high fiO2
25/2/2016
Subin Solomen MPT(Manipal)- CRD

20. High flow devices
Are those in which the flow of gases is sufficient to meet all of the patients minute ventilation requirements
Fixed air-oxygen entrainment ratio
Venturi mask
Large volume aerosol system
High humidity tracheostomy mask
High humidity T piece
High humidity face mask
High humidity face tent
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Subin Solomen MPT(Manipal)- CRD

21. High humidity face tent
High humidity T piece
High humidity face mask
High humidity tracheostomy mask
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Subin Solomen MPT(Manipal)- CRD

22. Venturi mask Jet nozzle and entrainment ports
Delivered Fio2 dependent on the size of the nozzle, size of the entrainment ports and O2 flow
Smallest jet provides highest O2 velocity , thus most air entrainment and the lowest fiO2
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Subin Solomen MPT(Manipal)- CRD

23. 1) As forward velocity of gas increases
Venturi mask
Operates on Bernoulli principle
2) its lateral pressure decreases
1) As forward velocity of gas increases
This leads to entrainment of room air
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Subin Solomen MPT(Manipal)- CRD

24. Venturi mask Advantages Disadvantages Delivery of predictable FIO2
Useful in patients to whom delivery of excessive oxygen could depress the respiratory drive
Limited access to mouth for eating, drinking, expectorating
Claustrophobia
Irritation to eyes
Uncomfortable
Noisy
Best use : Unstable patients requiring precise low FiO2
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Subin Solomen MPT(Manipal)- CRD

25. Venturi mask- port
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Subin Solomen MPT(Manipal)- CRD

26. High humidity T-piece One end Attaches to ET to TT tube
Other end attaches to oxygen
Third end attaches to reservoir
Provide oxygen + humidification
FiO2 range from 0.28 to 1.0
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Subin Solomen MPT(Manipal)- CRD

27. High Humidity T- piece Advantages Disadvantages
Prevents drying of mucous
Helps to thin secretions
Accurate Fio2 can be delivered
Tubing can become heavy with accumulated water
Accidently accumulated water may drain into patients airway during position change
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Subin Solomen MPT(Manipal)- CRD

28. Enclosures Oxygen Tent Oxygen hood 25/2/2016
Subin Solomen MPT(Manipal)- CRD

29. Hazards of supplemental O2
Oxygen toxicity
Oxygen induced hypoventilation
Absorption atelectasis
Retinopathy of prematurity
Fire hazards
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Subin Solomen MPT(Manipal)- CRD

30. 1. Oxygen toxicity Primarily involves lungs and CNS
CNS: tremors , twitching and convulsion
100% fio2 complains chest tightness , decreased VC, Residual volume, lung compliance
Results in broncho pneumonia , interstitial oedema, destruction of type I and 2 cells
Due to over production of free radicals
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Subin Solomen MPT(Manipal)- CRD

31. 2. Oxygen induced hypo ventilation
Normally carbon dioxide (hypercapnea) is primary stimulant drive for respiration
In patients with chronic hypercapnea CNS response to elevated CO2 level become blunted , then hypoxemia becomes major drive
But Administration of high FiO2 blunts this drive which results in hypoventilation
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Subin Solomen MPT(Manipal)- CRD

32. 3. Absorption atelectasis
Due to depletion of alveolar and blood nitrogen
All the alveolar oxygen is replaced to capillaries
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Subin Solomen MPT(Manipal)- CRD

33. Absorption atelectasis Pathophysiology
Normally
Reduced ventilation leads to vasoconstriction to the affected segments
With 100% FiO2
Vasoconstriction becomes dilated
Whole nitrogen in alveoli and blood is replaced by oxygen
Distal to obstruction whole air in the alveoli is absorbed to capillary
Results in atelectasis
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Subin Solomen MPT(Manipal)- CRD

34. 4. Retinopathy of pre maturity
In neonates and infants
Excessive O2 leads to retinal vasoconstriction which leads to necrosis=
New vessels form and results in hemorrhage, results in scarring
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Subin Solomen MPT(Manipal)- CRD

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Subin Solomen MPT(Manipal)- CRD

36. Limitations
Directing oxygen into throat does not guarantee its arrival at the mitochondria
Oxygen does not improve ventilation directly
If hypoxemia is due to a large shunt then oxygen therapy is refractory to hypoxemia
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Subin Solomen MPT(Manipal)- CRD

37. Oxygen Prescription
Oxygen should be prescribed to achieve a target saturation of 94–98% for most acutely ill patients
or 88–92% for those at risk of hypercapnic respiratory failure
The target saturation should be written (or ringed) on the drug chart
Oxygen should be reduced in stable patients with satisfactory oxygen saturation.
Oxygen should be crossed off the drug chart once oxygen is discontinued
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Subin Solomen MPT(Manipal)- CRD

38. Summary Target the saturation range Choose the goal
Short term oxygen therapy
Long term oxygen therapy
To choose a delivery system consider
Device advantages & disadvantages
FIO2 limits
Appropriateness for a particular patient
To call a high flow device atleast60l/min
20l/m is the upper limit for sick people
25/2/2016
Subin Solomen MPT(Manipal)- CRD