Oxygen Therapy

1. Oxygen Therapy
Dr.Indubala Maurya MD,DNB,MNAMS
Assistant Professor
Dept of Aanesthesia & Critical
Care,MGMCRI

2. • Definition
• Physiology
– O2 content
– Hypoxia
• Orthobaric Oxygen Therapy
– Indication
– Device for oxygen therapy
• Hyperbaric oxygen therapy
• Side effects of Oxygen Therapy

3. Why oxygenWhy oxygen
is required foris required for
survival?survival?

4. Aerobic metabolismAerobic metabolism
oxidative phosphorylationoxidative phosphorylation
Glucose → CO2 + H2O + 38 ATPGlucose → CO2 + H2O + 38 ATP
Anaerobic metabolismAnaerobic metabolism
Glucose → Lactic acid + 2 ATPGlucose → Lactic acid + 2 ATP
↓↓
H+ + lactate –H+ + lactate –

5. Anoxia
No oxygen availability in
tissues
Hypoxia
Lack of oxygen availability in
tissues
Hypoxemia
Lack of oxygen in the blood
Basic
s

6. What is O2 Therapy ?
Oxygen therapy is the administration
of oxygen at concentrations greater
than that in room air to treat or prevent
hypoxia.

7. Types of Oxygen TherapyTypes of Oxygen Therapy
• Giving Oxygen more
than 21% at ambient
atm pressure
• Giving Oxygen more
than 21% at high atm
pressure ( >1 atm)
Orthobaric Hyperbaric

8. Three clinical goals of O2
therapy
1. Treat hypoxia
2. Decrease work of breathing
3. Decrease myocardial Work

9. • FIO2 ( Fraction of O2 in inspired gas)
– 0.21 (21%)
• PaO2(Partial pressure of Oxygen in arterial blood
– 98-100 mmHg ( 5 -6 times of FIO2)
• SaO2(saturation of Hb in arterial Blood)
– 100%
• PvO2 (Partial pressure of Oxygen in Venous blood )
– 40 mmHg
• SvO2 (saturation of Hb in Venous Blood)
– 75%

10. Oxygen Transport
O2 Content in Blood

11. Hemoglobin-Bound O2
• Oxygen-binding capacity of hemoglobin : 1.34 mL O2 /gm of Hb)
• SO2 : O2 saturation of Hb
Dissolved O2
• Solubility of oxygen in plasma
– solubility coefficient 0.003 mL/100 mL/mm Hg
• Partial pressure of oxygen (PO2) in blood.
Hb X 1.34 X SaO2
0.003 X PaO2 mmHg

12. Arterial O2 Content (CaO2)
eg
Normal person
Hb: 14g
SaO2: 98-100%
PaO2: 100 mmHg
Art. bloodArt. blood = 14g x 1.39 x 100% + 0.3= 14g x 1.39 x 100% + 0.3 = 20 ml / 100ml of blood= 20 ml / 100ml of blood
0.003 X PaO2 mmHgHb X 1.34 X SaO2

13. Venous O2 Content (CvO2)
Normal Person
Hb: 14g
SvO2: 75 %
PvO2: 40 mmhg
Ven. bloodVen. blood 14g x 1.39 x 75% + 0.1 =14g x 1.39 x 75% + 0.1 = 15ml /100ml of blood15ml /100ml of blood
Tissue extraction = 5ml/ 100 ml of bloodTissue extraction = 5ml/ 100 ml of blood
Hb X 1.34 X SvO2 0.003 X PvO2 mmHg

14. Dissolved ODissolved O22 inin
plasmaplasma
0.003ml / mm PO2 / 100ml of blood
Breathing Air (PaO2 100mm Hg)
0.3ml / 100ml of blood
O2 therapy
Orthobaric
Breathing 100% O2 (PaO2 600mm Hg)
1.8ml / 100ml of blood
Hyperbaric
Breathing 100% O2 at 3 Atm. Pressure

15. What are the Types ofWhat are the Types of
HypoxiaHypoxia??

16. Types of hypoxiaTypes of hypoxia
• Hypoxic hypoxia – PaO2↓
• Anaemic hypoxia – O2 content ↓, PaO2 normal
• Stagnant hypoxia
• Histotoxic hypoxia

17. Hypoxic hypoxiaHypoxic hypoxia
• Causes
– O2 poor air, hypoxic gas mixture
– High altitude
– Hypoventilation
– Shunts – Septal defects
– Diffusion defects - pneumonia, lobar
collapse

18. Anaemic hypoxia
• Oxygen carrying capacity of blood is
decreased.
– Anemia :↓ haemoglobin
– Altered haemoglobin
• CO poisoning
• meth / sulph-haemoglobin
Normal Person (breathing 100% O2)
(14gm x 1.34ml ) + 1.8ml = 20.5ml (1.8 is 9% 20.5)
Anaemic patient (breathing 100% O2)
(4gm x 1.34ml )+ 1.8ml = 7.2 ml (1.8 is 25% of 7.2)

19. Stagnant hypoxia
• Inadequate tissue perfusion
• Generalized:
- Hypovolemia
- Mitral stenosis
- Constrictive pericerditis
- Myocardial ischaemia
• Localized hypo perfusion:
- Arterial obstruction, thrombus,
oedema

20. Histotoxic hypoxia
• Cells can not utilize the oxygen .
• Electron transfer system of cytochrome
oxidase is paralysed.
• e.g.
– cyanide poisoning

21. Benefit of OBenefit of O22 therapy intherapy in
HypoxiaHypoxia
Hypoxic hypoxia + + +
Anaemic hypoxia +
Stagnant hypoxia +
Histotoxic hypoxia -

22. Clinical presentation
of Hypoxia

23. Effects of hypoxia
• Acute hypoxia :
- Restlessness
- Disorientation, confusion
- In-coordination, Impaired judgment
- Hyperventilation air hunger
-Circulatory changes (tachycardiabrady )
• Chronic hypoxia :
- fatigue, drowsiness, ↓ work capacity
- inattentiveness ,apathy, delayed reaction time

24. Assessment of need
• Presence of clinical indicators
• Measurement of inadequate oxygen saturations
– by invasive or noninvasive methods,
• Arterial blood gas
• Pulse oximetry
Errors in pulse oximetry
• Artificial fingernails
• Dark pigmentation
• Electrical interference
• Intravenous dyes
• Movement
• Nail Polish
• Pulsatile venous system
• Radiated light

25. How to assess oxygenation ?
• Arterial blood gases
• PaO2 = 100 mmhg
• Pulse oximetry
• SpO2=98-100%
Oxygen therapy is must wheneverOxygen therapy is must whenever
PaO2 < 60 mmHg or SpO2 < 90 %PaO2 < 60 mmHg or SpO2 < 90 %

26. FACTORS THAT DETERMINE WHICH SYSTEM
TO USE
1. Patient comfort / acceptance
2. The level of FiO2 that is needed
3. The requirement that the FiO2 be controlled
within a certain range
4. The level of humidification and /or
nebulization
5. Minimal resistance to breathing
6. Efficient & economical use of oxygen

27. Orthobaric Oxygen therapy

28. Oxygen therapy devices
Variable performance devices
• No capacity – nasal catheters, cannulae
• Small capacity – masks
• Large capacity – mask with bag
Fixed performance devices
• HAFOE systems (High air flow oxygen enrichment
device
» Venti Mask
• Anaesthesia circuits
• Ventilators

29. Variable performance device
e.g.
• Nasal cannula
• Simple face mask
• Partial rebreathing mask
• Non - rebreathing mask
FiO2 depends on
•O2 flow
•Patient factors
•Device factors

33. Nasal CatheterNasal Catheter
O2 Flowrate (L/min)
1
2
3
4
5
6
Fi O2
0.24
0.28
0.32
0.36
0.40
0.44

34. Nasal CatheterNasal Catheter
Merits
• Easy to fix
• Keeps hands free
• Not much interference with further airway
care
• Useful in both spont. breathing and
apnoeic
Demerits
• Mucosal irritation (uncomfortable)
• Gastric dilatation (especially with high flows)

37. Nasal cannula
• Simple plastic tubing + prongs

38. Simple face maskSimple face mask
Simple Face Mask – ?

39. Simple face maskSimple face mask
NO YES
Simple Face Mask

40. Simple face mask
Placing of mask over the
patient’s face increases
the size of the oxygen
reservoir beyond the
limits of the anatomic
reservoir ;therefore a
higher FiO2 can be
delivered.
.

41. Simple face maskSimple face mask
O2 Flowrate (L/min)
5-6
6-7
7-8
Fi O2
0.40
0.50
0.60

42. • Advantages:
– Simple
– lightweight, FiO2 upto 0.60
• Disadvantages:
– need to remove when speak, eat, drink, vomiting,
expectoration of secretions
– drying / irritation of eyes
– uncomfortable when facial burns / trauma
– Application problem when RT in situ

43. Partial Rebreathing maskPartial Rebreathing mask
(polymask)(polymask)

45. Partial Rebreathing maskPartial Rebreathing mask
(polymask)(polymask)
O2 Flowrate (L/min)
6
7
8
Fi O2
0.60
0.70
0.80

46. Advantages:
• FiO2 delivered >0.60 is delivered in mod. to
severe hypoxia,
• Exhaled oxygen from anatomic dead space is
conserved.
Disadvantages:
• insufficient flow rate may lead to rebreathing of
CO2,
• Claustrophobia
• drying and irritation of eyes

47. Non Rebreathing maskNon Rebreathing mask

49. 10 – 15 Ltr/min flow rate – 50-100 O2 conc.

50. Merits
• Higher Oxygen Conc.
Demerits
• Air dilution (if not fitting properly)
• Rebreathing (if O2 flow is inadequate)
• Interfere with further airway care
• Uncomfortable (sweating, spitting)

51. Fixed performance device: Ventimask

52. Simple face maskSimple face mask
NO YES
Simple Face Mask

53. VENTURI VALVE

54. Color FiO2 O2 Flow
Blue 24% 2 L/min
White 28% 4 L/min
Orange 31% 6 L/min
Yellow 35% 8 L/min
Red 40% 10 L/min
Green 60% 15 L/min
Venturi valve

55. Venturi principle

56. Hyperbaric Oxygen therapy
Hyperbaric oxygen (HBO) exposure (breathing
oxygen at increased ambient pressure, typically 2-
3 atmospheres absolute [ATA]) causes an
increase in PaO2.

57. Indication For HBOT
• Poisoning :
• Carbon monoxide
• Infections :
– Clostridial myonecrosis
• Acute ischemia
– Crush injury
• Chronic ischemia
– Radiation necrosis
• Ischemic ulcers
– diabetic ulcers

59. If conc. of OIf conc. of O22 which a patient is gettingwhich a patient is getting
is not knownis not known
then the situation is similar tothen the situation is similar to
a drug being administereda drug being administered
without knowing the dosewithout knowing the dose
which can do harm if given morewhich can do harm if given more
or provide insufficient effect if given lessor provide insufficient effect if given less
O2 ToxicityO2 Toxicity

60. Side Effects
• Rentrolental fibroplasia in neonates
• Resp system:
– Loss of surfactant
– Atelactasis
– Hypoventilation in COPD pt
• CNS:
– Convulsion (HBOT)

61. 100% - not more than 12hrs100% - not more than 12hrs
80% - not more than 24hrs80% - not more than 24hrs
60% - not more than 36hrs60% - not more than 36hrs