2. Content
• Respiratory Failure
• Types of Hypoxia
• Tissue Oxygenation and Hypoxia
• Assessment of tissue hypoxia
• Indications of Oxygen therapy
• Techniques of oxygen administration
• Oxygen Toxicity
• Hyperbaric Oxygen
• Clinical Senarios
3. What is oxygen therapy and why it’s needed?
• Giving oxygen at 21% atmospheric pressure or more than
atmospheric pressure is used to treat or prevent hypoxia and
Hypoxemia.
• Hypoxia refers to reduced oxygen levels at tissues
• Hypoxemia refers to reduced oxygen tension in blood. When PaO2
<60mmHg ( Spo2 <90%)
4. Respiratory Failure
• TYPE 1 Respiratory Failure
• PaO2 <60 mm Hg
• PaCO2 normal or low
• REQUIRES OXYGEN THERAPY
• Type 2 respiratory Failure
• PaCO2 >45 mmHg
• Associated with hypoxia (PaO2
<60 mm of Hg)
• REQUIRES VENTILATORY
SUPPORT
24. Choice of delivery system is based upon:
1) Degree of Hypoxemia
2) Requirement for precision of delivery
3) Patient comfort
4) Cost
25. LOW FLOW OXYGEN DEVICES HIGH FLOW OXYGEN DEVICES
Cannot deliver constant FiO2 Maintain constant FiO2
Flow 6-8 L/min Delivering O2 at very high flow
Mixture of oxygen+ room air Flow usually 4 times the actual
minute volume
FiO2 varies with tidal volume
-Shallow breathing= less
entrainment of room air
(High FiO2)
Used in- treatment of hypoxic
pts who depend on hypoxic
drive to breathe and require
controlled increments in FiO2
-deep, hyperpneic breathing=
more entrainment of room air
(FiO2)
Young and vigorous pts with
Hypoxemia with ventilatory
requirement exceeding the
capability of low flow system.
26. Low flow or variable performance
equipments
• Adequate for patients with
• Minute Ventilation less than or equal to 8 to 10L/min
• Breathing frequencies greater than or equal to 20 breaths/min
• Tidal volumes less than or equal to 0.8 L
• Normal inspiratory flow (10-30 L/min)
27. High flow or Fixed Performance Equipment
• Indicated in Patients who require
• Consistent FiO2
• Larger inspiratory flows of gases (>40L/min)
28. Common low flow devices
• Nasal cannula
• Nasal catheters
• Transtracheal catheter
• Face mask
• Partial rebreathing mask
• Non rebreathing mask
• Tracheostomy mask
30. Nasal Cannula
• Consist of 2 soft prongs attached to the O2 supply tubing.
• A flow rate of 2-4 L/ min delivers an FiO2 of 0.28-0.36 respectively.
• No increase in FiO2 if flow is more than 6 L / min.
• Nasopharyngeal acts like a reservoir if patients breath through the
mouth.
31. Nasal Prongs
Advantages
• Ideal for patients on long term
oxygen therapy
• Light weight and comfortable
• Patient able to speak, eat and
drink
• Humidification not required
• Low Cost
Disadvantages
• Cannot provide high flow O2
• Cannot be used in nasal
obstruction
• FiO2 varies with respiratory
effort
• High flow rates are
uncomfortable
32. Simple Face Mask
• Transparent mask provided with side holes.
• Reservoir capacity 100-150 ml
• Patients receive a mixture of oxygen and secondary entrained room
air, depending on the size of the leak, oxygen flow and breathing
patterns.
33. SIMPLE FACE MASK
Advantages
• Can be used in both nose and
mouth breathers
• Patients receive a mixture of
oxygen and entrained gas
depending on the oxygen flow and
breathing pattern.
Disadvantages
• Require a tight seal
• FiO 2 varies with breathing efforts
• Interferes with eating, drinking and
communication
• Chances of rebreathing are high.
• Not a device of choice in pts who
are Tachypneic, Hypoxemia and
unable to protect their airway from
aspiration.
34. Masks with gas reservoirs
• Two type of reservoir mask are commonly used: partial rebreathing
mask and non rebreathing mask.
• Either style of mask is indicated for patients with significant
Hypoxemia but relatively normal spontaneous minute ventilation.
35. Partial rebreathing mask
• Commonly holds less than 600ml of gas volume.
• Called ‘partial’rebreathing mask because part of the expired tidal
volume fills the bag
• CO2 retention does not occur because rebreathing occurs for the
dead space ventilation.
36.
37. Partial Rebreathing Mask
Advantages
• Inspired gas not mixed with
room air
• Patients can breath room air
through exhalation ports if
oxygen supply gets interrupted
Disadvantages
• More oxygen flow does not
increase FiO2
• Interfere with eating and
drinking.
38. Non Rebreathing Mask
1. Provided with one way valves
between mask and bag,
exhalation ports
2. FiO2 of 95% can be achieved
with an oxygen flow rates of 10
to 15 L/min
39. Non Rebreathing Mask
Advantages
• Highest possible FiO2 without
intubation
• Suitable for spontaneously
breathing patients with severe
hypoxia
Disadvantages
• Require a tight seal,
uncomfortable
• Interfere with eating and
drinking.
• Not suitable for long term use
• Malfunction can cause CO2
buildup, suffocation.
41. Venturi Mask
• 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 presssure
generated, so more ambient air is entrained and the FiO2 is
decreased.
• FiO2 can be 0.24, 0.28, 0.31, 0.35, 0.4, 0.6
42.
43. • Because of 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 dependant on the hypoxic
drive.
44.
45.
46.
47. VENTURI MASK
ADVANTAGES
• Fine control of FiO2 at fixed flow
• Fixed,reliable and precise FiO2
• Can be used for low FiO2 also
• Helps in deciding whether the
oxygen requirement is
increasing or decreasing.
DISADVANTAGES
• Uncomfortable
• Expensive
• Interfere with eating and
drinking.
48. HIGH FLOW NASAL CANNULA
• Delivers heated and humified oxygen via special devices
• The 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 and completely humidified,
mucocillary functions remain good and little discomfort is reported.
51. Indications
• Patients with arterial oxygen (PaO2 <55mm Hg) at rest in non
recumbent position, despite optimal treatment of underlying
condition.
• Patients with PaO2 > 55mm Hg associated with evidence of central
nervous system dysfunction, cor pulmonary, secondary pulmonary
hypertension or polycythemia.
• Patients with demonstrable fall in PaO2 below 55 mmHg and
desaturation during sleep and/or exercise.
52. Long Term O2 delivery Systems
• Gas supplies
• Oxygen concentrators
• Compressed gas
• Liquid oxygen
• Delivery devices for LTOT include most
of the low flow devices
59. How much O2 is safe?
• 100 % not more than 12 hrs
• 80% not more than 24 hrs
• 60% not more than 36 hrs
• Goal should be to use lowest possible FiO2 compatible with adequate
tissue oxygenation.
67. Hyperbaric Oxygen
Toxicity
It is directly related to the
pressures as well as the duration
of exposure.
Prolonged exposure of O2 at
pressures exceeding 0.5
atmosphere can cause pulmonary
O2 toxicity. Present initially with
retrosternal burning, cough, chest
tightness.
At pressure more than 2 atmos
causes central nervous changes
like nausea, vertigo muscle
twitching or convulsions.
68. Clinical scenario 1
• 35 yr female patient presented with HR 150/min, non recordable bp
and saturation. On examination pt is disoriented and gasping for air(
air hunger present), respiratory rate 35/min, and on auscultation b/l
coarse crepts present
• These are emergencies with suspected tissue hypoxia
• Cardiac/ respiratory failure, shock, trauma
• Highest possible FiO2 ideally 100% notmobaric is necessary in a high
flow closed reservoir system
69. Clinical scenario 2
• A middle aged man underwent laparoscopic hernia surgery under
General Anaesthesia. Immediately in the post op period pt is not
maintaining saturation (SpO2 is 85 % on room air)( all vitals during the
surgery were normal)
• Patient has mild to moderate Hypoxemia
• Systems with low performance variable FiO2 can be used like nasal
cannula/ simple face mask.
70. Clinical Scenario 3
• Adult patient with COPD present with acute onsent exacerbation of
the underlying condition
• Goal- adequate arterial oxygenation without dEpressing ventilation
• Adequate- (SpO2 of 85-92%) (PaO2 50-70 mm Hg)
• Ideally a concentration Venturi mask 0.24 -0.28 or a low flow nasal
cannula can be used.
