This second part of the presentation mainly aims at imparting knowledge regarding various oxygen delivery devices with its indication and contra-indications

1. Oxygen Therapy 2
Dr. Kaustubh M. Mohite

2. Today’s topics….
5. Indications of oxygen therapy
6. Techniques of oxygen administration
(Oxygen delivery devices)
7. Newer modalities
8. Oxygen toxicity
8.
7.
6.
5.

3. Indications for oxygen therapy:
• Acute Oxygen therapy
• Long term Oxygen therapy
5.

4. 5.
Clinical Manifestation:

5. 5.
Acute Oxygen Therapy:
• Acute Hypoxemia (PaO2 < 60mm Hg; SpO2 < 90%)
• Respiratory distress (RR > 2 SD for age)
• Cardiac & Respiratory arrest
• Hypotension (SBP < 5th centile)
• Low cardiac output states with metabolic acidosis
(HCO3 < 18 mmol/L)
• Severe trauma
• Carbon mono-oxide poisoning

6. Long term Oxygen Therapy
CONTINUOUS OXYGEN
• 1. Resting PaO2 <55 mm Hg / SpO2 < 88 %
• 2. Resting PaO2 of 56- 59 mm Hg / SpO2 of 89% in the
presence of cor-pulmonale
• Dependent oedema (CHF)
• P pulmonale on ECG
• Polycythaemia (PCV > 56%)
5.

7. • NON-CONTINUOUS OXYGEN (not recommended now a days)
• 1. During exercise: PaO2 < 55 mm Hg or SpO2 < 88 % with
low level of exertion
• 2. During sleep: PaO2 < 55 mm Hg or SpO2 < 88% with
associated complications
• pulmonary hypertension
• daytime somnolence
• cardiac arrhythmias
5.

8. Oxygen Delivery System
“Oxygen delivery system is a device which is used to
administer, regulate and supplement oxygen to a subject
to increase the arterial oxygenation”
6.

9. 6.
Oxygen Source
Pressure reducing valve
Patient outlet
Flow meter
Oxygen delivery device at the patient
interface

10. Oxygen Source:
There are 3 main types of oxygen sources:
1. Compressed gas cylinders
2. Liquid Oxygen in cryogenic containers
3. Oxygen concentrators
6.

11. Compressed Gas Cylinders:
• Oxygen is packaged and shipped as a high-pressure gas in
seamless steel or aluminium cylinders.
• Pressure in the container is related both to temperature and
the amount of oxygen in the container.
• Full high-pressure cylinders normally contain gas at
15.169 kPa (2200 psig) at 21 °C (70°F).
6.

12. 6.

13. 6.
Cylinder duration equation:
Time for which a cylinder will
efficiently provide oxygen supply
=
Pressure of cylinder (PSIG) x Tank factor
Flow rate
Tank factor: E cylinder – 0.28
H cylinder – 3.14
Consider that your patient is requiring nasal canula with oxygen flow
of 2 lit/min and is using E cylinder and is full (2200 psig)
Duration = 0.28 x 2200 / 2
= 308 minutes = 5 hrs and 8 min

14. 6.

15. Liquid oxygen in Cryogenic containers:
• Cryogenic containers store liquefied oxygen and vapour.
• Various sizes of cryogenic containers exist.
6.
A. Bulk liquid Oxygen System:
• Fractional distillation of air at site of
manufacturing and delivered at
healthcare facility.
• Stored in large cryogenic vessels called as
DEWARS.
• As the liquid oxygen passes through
warming coils and is allowed to evaporate,
the gas is delivered to a medical gas
pipeline and then directly to the bedside.

16. Portable liquid oxygen:
• Smaller, base-unit, cryogenic
containers (reservoirs).
• Used at homes, hospitals to fit in
smaller spaces.
• Patient can ambulate with it.
• Can offer continuous or intermittent
flow of oxygen as and when needed.
6.

17. Oxygen Concentrators:
• Provides a safe source of oxygen-enriched air.
• Employs selective removal of nitrogen from room
air to increase the concentration of oxygen in the
delivered gas product.
• Electrically powered and controlled device
6.

18. Portable oxygen concentrator:
• Provides portable source of oxygen at
home.
• Separates oxygen from air using
molecular sieve or semi-permeable
membrane.
• 3 types:
• Stationary Concentrator
• Having ability to fill portable aluminum
cylinder
• Battery operated portable oxygen
concentrated
6.

19. 6.
Oxygen
delivery
systems
Normobaric
Low
dependency
Variable
performance
Fixed
performance
Medium
dependency
High
dependency
Hyperbaric

20. 6.
Types of Normobaric O2 delivery devices:
Type Definition Respiratory pattern
Low Dependency Supplemental oxygen
alone is sufficient to
correct hypoxia
Spontaneous breathing
present
Medium Dependency Supplemental oxygen
and a degree of
respiratory assistance is
required
Spontaneous breathing
present but requires
additional support.
Eg. CPAP
High Dependency Supplemental oxygen
and full respiratory
support is required
Absent spontaneous
respiration.
Eg. NIPPV or IPPV

21. Low dependency system
6.
Variable performance devices /
low flow devices
Fixed performance devices /
high flow devices

22. 6.

23. Variation in FiO2 in low flow devices
6.

24. 6.

25. 6.
Low
dependency
devices
Low flow
devices
Nasal Canula
Nasal
Catheter
Simple Mask
Reservoir
Mask
Partial
rebreather
Non
Rebreather
High Flow
devices
Venturi
mask
HFNC

26. 6.
Nasal Canula

27. Nasal Canula:
• 2 soft prongs attached to O2 supply.
• A flow rate of 2–4 L/min delivers an FiO2 of 0.28–0.36
respectively.
• FiO2 = 21% + (3 to 4 × oxygen litre flow)
• No increase in FiO2 if flow is more than 6L/min
• Nasopharynx acts as a reservoir
• If patient breaths through mouth, air flow produces a Venturi
effect in the posterior pharynx entraining oxygen from the
nose
6.

28. Advantages:
• Ideal for patients on long-term oxygen therapy
• Light weight and comfortable
• The patient is able to speak, eat and drink
• Humidification not required
• Low cost (Rs.70)
Disadvantages:
• Can not provide high flow O2.
• Irritation and can not be used in nasal obstruction
• FiO2 varies with respiratory efforts
• High flow rates are uncomfortable
6.

29. Nasal Catheter
6.

30. • Single lumen catheter, which is lodged into the anterior
naris by a foam collar, inserted to just above the uvula
• Oxygen flows of 2–3 L/min can be used.
• FiO2 35-40%.
• It should not be used when a nasal mucosal tear is
suspected because of the risk of surgical emphysema.
• Deep insertion can cause air swallowing and gastric
distension
• Must be repositioned every 8 hours to prevent
breakdown.
• No advantages over nasal cannula
6.

31. 6.

32. Simple Face Mask
6.

33. • Transparent mask provided with side holes.
• Reservoir capacity 100–250 ml.
• Different oxygen flow rates result in a highly variable
and unpredictable FiO2.
• Rebreathing of CO2 can occur with O2 flow rates of
less than 2 Lit O2 /min or if minute ventilation is very
high
• 4 L/min of oxygen flow delivers an FiO2 of about
0.35–0.4 provided there is a normal respiratory
pattern.
• Flow rates greater than 8L/min do not increase FiO2.
6.

34. Advantage:
• Less expensive (Rs. 80/-)
• Can be used in mouth breathers
Disadvantage:
• Uncomfortable
• Require tight seal
• Do not deliver high FiO2
• FiO2 varies with breathing efforts
• Interfere with eating, drinking, communication
• Difficult to keep in position for long
• Chances of rebreathing are high
6.

35. Partial Rebreathing mask
6.

36. • Mask with reservoir bag of capacity 1lit.
• Oxygen flows directly into the reservoir bag, which fills during
exhalation.
• Designed in such a way that it captures exhaled gases from
initial part of expiration from the dead spaces.
• Deliver an FiO2 between 0.6 and 0.8.
• A minimum of 8L/min should enter the mask to remove
exhaled CO2 and to refill oxygen reservoir.
• Flow rate must be sufficient to keep bag 1/3 to 1/2 inflated at
all times.
6.

37. Advantage:
• Inspired gas not mixed with room air.
• Patient can breath room air through exhalation ports if oxygen
supply get interrupted.
Disadvantage
• More oxygen flow does not increase FiO2.
• Interfere with eating and drinking.
6.

38. Non Rebreathing mask
6.

39. • Provided with one way valves between mask and bag,
exhalation ports.
• FiO2 of 95% can be achieved with an oxygen flow rates of 10
to 15 L/min.
• Ideally NRM should not allow entrainment of air, but because
of safety concerns one of the two exhalation ports is not
provided with valve.
• Higher oxygen supply rates are required.
• Desirable in cases where rebreathing of CO2 would be
detrimental, for example after head injury.
• Best results will be achieved by adequate flow rates such that
the reservoir bag empties by no more than a third during
inspiration and by best seal possible between the mask and
the face.
6.

40. Advantage:
• Highest possible FiO2 without intubation
• Suitable for spontaneously breathing patients with severe
hypoxia
Disadvantage
• Expensive
• Require tight seal, Uncomfortable
• Interfere with eating and drinking
• Not suitable for long term use
• Malfunction can cause CO2 build up, suffocation
6.

41. 6.

42. 6.
High flow devices:
Venturi Mask:

43. Works on the basis of Venturi modification of Bernoulli
principle.
Bernoulli effect describes the change in pressure that occurs
when a fluid flows through a constriction.
The venture principle uses this phenomenon to allow a second
fluid to be entrained into the stream of the first, either through
a side arm that opens into the area of low pressure or via
co-axial arrangement.
6.

44. 6.

45. 6.
• Delivers fixed concentration of oxygen.
• The size of the constriction determines the final concentration of
oxygen for a given gas flow.
• As forward flow of inspired gas increases, the lateral pressure
adjacent and perpendicular to the vector of flow decreases,
resulting in entrainment of gas.
• The smaller the orifice is, the greater the negative pressure
generated, so the more ambient air entrained, the lower the FiO2.
• FiO2 can be 24% to 60%.
• Because of the high fresh gas flow rate, the exhaled gases are
rapidly flushed from the mask, via its holes. Therefore there is no
rebreathing and no increase in dead space
• These masks are recommended when a fixed oxygen concentration
is desired in patients whose ventilation is dependent on the
hypoxic drive

46. Advantage
• Fine control of FiO2 at fixed flow.
• Fixed, reliable, and precise FiO2.
• High flow comes from the air, saving the oxygen cost.
• Can be used for low FiO2.
• Helps in deciding whether the oxygen requirement is increasing or
decreasing.
Disadvantage
• Uncomfortable.
• Expensive (Rs. 400-600).
• Cannot deliver high FiO2.
• Interfere with eating and drinking.
6.

47. 6.

48. 6.

49. 6.
HHHFNC: (heated, humidified, high flow)

50. Mechanism of action:
H – heated and humidified
I – Inspiratory demands (fulfills)
F – Functional Residual Capacity (increases)
L – Light weight (more compliant)
O – Oxygen dilution (decreases)
W – Washout of dead space
6.

51. Concept of O2 dilution:
6.
On Nasal Canula On HFNC

52. • High flow washes out carbon dioxide in anatomical dead
space.
• Creates positive nasopharyngeal pressure.
• FiO2 remains relatively constant.
• Because gas is generally warmed to 37°C and completely
humidified, muco-ciliary functions remain good and little
discomfort is reported.
6.

53. Oxygen therapy & Humidity
• Humidity refers to the water vapour content of a gas.
• Normally, much of the humidification of the air we inspire
takes place via the nasal passages and upper airway.
• When a patient receives a supplemental medical gas it is
generally cool and dry and can cause drying of the secretions
and mucosa potentially leading to airway obstruction and
tissue injury.
• Ideally inspired gas should be humidified to 37℃ &
44 mm H2O/L
6.

54. Types of humidifiers:
Active humidifiers:
Actively adding heat or water or
both to the device-patient
interface:
• Bubble humidifier
• Passover humidifier
• Nebulizers of bland aerosol
• Vapourizers
Passive Humidifiers:
• Recycling exhaled heat and
humidity from the patient.
• Heat and moisture exchanger
(HMEs).
6.

55. Bubble humidifier:
6.
• Gas passes through tube to the
bottom of water reservoir
• Gas bubbles through the
humidifier.
• Unheated bubbles through
humidifier provides humidity
for oxygen therapy.

56. Passover humidifier:
6.
Directs gas over liquid or over surface
saturated by liquid
Types:
• Simple reservoir model
• Wick units
• Membrane devices

57. Heat moisture exchanger:
6.
• Passive humidifier
• Traps heat and humidity in expired gas
• Used to provide humidity for
spontaneously and mechanically
ventilated patients.
Types:
• Simple condenser
• Hygroscopic condenser
• Hydrophobic condenser

58. Clinical signs & symptoms of inadequate
airway humidification:
• Atelectasis
• Dry, non-productive cough
• Increased airway resistance
• Increased incidence of infection
• Substernal pain
• Thick dehydrated secretions
6.

59. Other high flow devices:
• CPAP machines
• Resuscitation bags
• Invasive Mechanical ventilation
• Hyperbaric oxygen chambers
6.

60. Positive Pressure Ventilation by
Non-invasive modalities:
7.
Newer Modalities

61. Indications of NIV:
• Hypoxia despite maximum FiO2.
• Hypoventilation
• CO2 retention
Requirements:
• Conscious
• Co-operative
• Vitally stable
• Protected airways
7.

62. CPAP:
• Preset ePAP (PEEP)
• Patient initiates
breathing.
• ePAP: 4 – 20 cmH2O
• Opens more alveoli
(recruitment)
Obstructive airway disease
which decreases venous
return
BiPAP:
• Preset iPAP & ePAP
• Patient initiates breathing
• Can set backup RR.
• iPAP: 8 – 20 cmH2O
• ePAP: 4 – 10 cmH2O
Acute hypercapnia
OSA
7.

63. Advantages:
• Decreases work of breathing
• Avoids intubation
• Improves oxygenation
• Improves ventilation
Disadvantages:
• Unprotected airways
• Gastric insufflation
• Tight mask problem
• Slow correction
• Decrease venous return
7.

64. 7.

65. 7.
Monitoring
Mask:
Fit, comfort, air leak, secretions, skin necrosis
Respiratory muscle unloading:
Accessory muscle activity, paradoxical abdomen motion
Abdomen:
Gastric distension

66. To be discontinues if…..
• Inability to tolerate the mask because of discomfort or pain.
• Inability to improve gas exchange or dyspnea.
• Need for endotracheal intubation to manage secretions or
protect airway.
• Hemodynamic instability.
• ECG – arrhythmia
• Failure to improve mental status in those with CO2 narcosis.
7.

67. Hyperbaric Oxygen Therapy:
7.

68. Basic principle of HBO therapy:
• The increased pressure inside the chamber, combined with
the delivery of 100% oxygen, drives the diffusion of oxygen
into the blood plasma at up to 10 times normal concentration
7.

69. Physiologic effects of HBO therapy:
• Greatly increases oxygen concentration in all body tissues, even
with reduced or blocked blood flow.
• Stimulates the growth of new blood vessels to locations with
reduced circulation, improving blood flow to areas with arterial
blockage.
• Causes a rebound arterial dilation after HBOT, resulting in an
increased blood vessel diameter greater than when therapy began,
improving blood flow to compromised organs.
• Stimulates an adaptive increase in superoxide dismutase (SOD),
one of the body's principal, internally produced antioxidants and
free radical scavengers.
• Aids the treatment of infection by enhancing white blood cell
action and potentiating germ-killing antibiotics.
7.

70. Indications:
• Air or Gas embolism
• Carbon mono-oxide poisoning
• Gas Gangrene
• Crush injury, compartment syndrome
• Decompression sickness
• Arterial insufficiencies (CRAO)
• Severe anemia
• Necrotizing soft tissue infection
• Compromised grafts and flaps
7.

71. Potential complications:
Barotrauma:
• Ear or sinus trauma
• Tympanic membrane rupture
• Alveolar over distension and pneumothorax
• Gas embolism
Oxygen toxicity:
• CNS toxic reactions (twitching, sweating, restlessness, seizure)
• Pulmonary toxic reactions
Other:
• Fire
• Sudden decompression
• Visual changes
• Claustrophobia
7.

72. Oxygen Toxicity:
8.

73. Definition:
• Resulting from harmful effects of breathing molecular oxygen
at increased partial pressure.
• Effect of hyperoxia
• Mostly associated with long term oxygen therapy or
hyperbaric oxygen therapy.
8.

74. Factors on which toxicity depends:
• Pressure:
• Normobaric hypoxia
• Hyperbaric hypoxia
• Time of exposure:
• FiO2 > 60% longer than 36 hrs
• FiO2 > 80% longer than 24 hrs
• FiO2 100% longer than 12 hrs
• Oxygen concentration
8.

75. High risk groups
• Long term ventilation with high FiO2.
• Infants & neonates getting 100% oxygen for > 2-3 hrs
• Premature babies
• Exposure to chemicals that increase risk for O2 toxicity
(Chemotherapeutics like bleomycin)
• Undergoing hyperbaric oxygen therapy
• Underwater divers
8.

76. Mechanism:
• Partial reduction of oxygen by one or two electrons to form
reactive oxygen species.
8.

77. Protective factors:
• Under normal circumstances, the
body is able to handle the ROS
produced using anti-oxidants.
• Glutathione is the most effective anti-
oxidant.
• Others: catalase, superoxide
dismutase, vitamin C & E
8.

78. Harmful effects of ROS:
Oxygen radicals react with cell components:
• Lipid peroxidation of membranes.
• Increased permeability – influx of Ca2+- mitochondrial damage
• Protein oxidized and degraded
• DNA oxidized - breakage
8.

79. 8.

80. 8.
Hyperbaric oxygen toxicity:
• Pulmonary: ARDS
• CNS: seizures preceded by facial numbness, twitching,
unpleasant olfactory and gustatory sensation.
• Eye: myopia, nuclear cataract, retrolental fibroplasia
• Abnormal RBC morphology
• Avascular necrosis of bone / dysbaric osteonecrosis
• Ear: serous otitis media
• Barotrauma

81. Take Home messages:
• Oxygen is a very important drug which has a relatively broad
therapeutic window.
• Prompt initiation of oxygen therapy is essential after correctly
diagnosing of the pathology.
• Oxygen therapy is very patient specific and has maximum benefits
when all patient criteria are completely met.
• Gradual weaning of oxygen therapy is equally essential as patient
requirement decreases to prevent detrimental effects of oxygen
toxicity.

82. Thank You