This document discusses oxygen therapy and its various delivery methods. It defines oxygen therapy as the administration of oxygen at a higher concentration than found in the air. The goal is to ensure adequate oxygen delivery to tissues. Low-flow devices like nasal cannulas and masks deliver variable concentrations of oxygen under 15 L/min, while high-flow devices like venturi masks and generators deliver fixed concentrations by exceeding minute ventilation. Indications, benefits, hazards and prescribing oxygen are covered in detail.

1. Dr Arvind Kr Verma

2. What is oxygen therapy
 Oxygen therapy is the administration of oxygen at a concentration
or pressure greater than that found in the environment.
 Goal of supplemental oxygen therapy is to ensure appropriate
oxygen delivery to vital end-organ tissues.
 Oxygen therapy is a key treatment in respiratory care.

3. Tissue hypoxia
 Tissue hypoxia is governed by the balance between oxygen
delivery and oxygen utilization.
 Generally, failures in oxygen delivery lead to most instances of
tissue hypoxia.
 Do2(oxygen delivery) = cardiac output × Cao2 ( oxygen content of
arterial blood)
 Cao2 Is calculated by the formula
Cao2 = 1.34 × Heamoglobin concentration × Sao2+ (.0031 × Pao2 )

4.  From this formula, the causes of poor oxygen delivery can be
narrowed to three categories:
1 Low cardiac output states (i.e., various forms of shock)
2 low hemoglobin concentration states (i.e., anemia)
3 low SaO2 states (i.e., arterial hypoxemia or hemoglobinopathies
Supplemental oxygen therapy addresses only arterial
hypoxemia.
For other causes of tissue hypoxia, more specific therapies are
generally required, such as vasoactive agents or intravenous
fluid administration to reverse shock, and blood transfusions for
anemia.

5. OXYGEN – A PRESCRIBED DRUG
 Must be written legibly by the doctor.
 Prescriptions should be dated by the doctor.
 Doctor must indicate duration of O2 therapy.
 The O2 concentration must be prescribed.
 The flow rate must be prescribed .

6. INDICATIONS FOR OXYGEN THERAPY
1 – INDICATIONS IN ACUTE CIRCUMSTANCES
Accepted Indications
 Documented hypoxemia, defined as PaO2 below the normal range.
Usually PaO2 <60 mm Hg or SaO2 <90%.
 Acute care situation in which hypoxemia is suspected, such as
respiratory distress. Requires substantiation of hypoxemia (by SaO2
or PaO2) in a reasonable time.
 Acute myocardial infarction with hypoxemia
 Low cardiac output with metabolic acidosis
 Hypotension (systolic blood pressure < 100 mm Hg)

7. Questionable Indications
 Acute myocardial infarction without hypoxemia
 Dyspnea without hypoxemia (palliative)
 Sickle cell pain crisis.
 Pneumothorax

8. 2 - LONG-TERM OXYGEN THERAPY
 All patients with chronic hypoxemic lung disease are candidates
for LTOT.
 Following guidelines are used to select patients for instituting
the treatment.
1. A definitive documented diagnosis responsible for chronic
hypoxaemia.
2. An optimal medical treatment should be in effect.
3. Patient in a stable condition.
4. Oxygen administration should have been shown to improve
hypoxaemia and provide clinical benefit in such patients.
Following specific indices are used for prescribing LTOT :

9. PaO2 SaO2 LTOT Indication Qualifier
<55 mm Hg <88% Absolute None needed
55-59 mm Hg 88-90% Relative with
qualifier
Presence of any of the
following signs of cor
pulmonale
-History of dependent
edema
-Polycythemia
(HCT>55%)
-P pulmonale on EKG
≥ 60 mm Hg ≥90% None unless qualifier Atleast one of the
following:
-Exercise desaturation
-Sleep desaturation not
corrected by CPAP
-Lung disease with
dyspnea responding to
Oxygen therapy.

10.  According to NOTT trial 1980 and BMRCD trial 1981 in patient with
COPD and hypoxemia, we can infer that supplemental oxygen for >15
h/d is better than no oxygen at all, and that continuous supplemental
oxygen is better than nocturnal-only therapy.
 Based on the BMRCD trial, most prescriptions for oxygen are written
for at least 15 hour/day
 SOURCE :
 NOTT Trial : Nocturnal Oxygen Therapy Trial Group. Ann Intern Med.
1980;93(3):391–398.
 BMRCD (British Medical Research Council Domiciliary )Trial : Report of
the Medical Research Council Working Party. Lancet. 1981;1(8222):681–686.

11. BENEFITS OF LTOT
 Improvement in duration of survival.
 Improved intellectual function.
 Improves the severity of right heart failure.
 Decrease in red cell mass and hematocrit level
POTENTIAL BENEFITS
1- Increased exercise ability.
2-Improved quality of life.
3-Decrease in dyspnea.
4-Delayed development of cor pulmonale.
5-Decrease in hospitalization and exacerbations of respiratory failure .

12. Physiologic Indications for Nocturnal Oxygen Therapy
Patients with significant desaturation while sleeping may warrant
nocturnal supplemental oxygen.
 PaO2 <55 mm Hg with sleep or SaO2 <88% with sleep
Or
 PaO2 decreases more than 10 mm Hg with sleep
Or
 SaO2 decreases more than 5% with sleep and signs of nocturnal
hypoxemia including
• Pulmonary hypertension
• Daytime somnolence
• Cardiac arrythmias
 Patient should be evaluated for a sleep disorder and need for
positive pressure device

13. Oxygen Therapy In Air Travel
 Modern aircrafts are pressurised to cabin altitudes upto 8000
feet.
 At this altitude oxygen will be equivalent to that of breathing
15% at sea level.
 Patients whose PaO2 ≥70 mm Hg (SpO2 > 95%) at ground level,
their in-flight PaO2 will likely exceed 50 mm Hg, which is
generally considered adequate .

14.  Methods for preflight hypoxia testing are:
 6 Minute Walk Test - if a patient has an abnormally low 6-minute
walk distance, has significant dyspnea during the test, or experiences a
decline in SpO2 to <85%, the patient will likely need supplemental
oxygen during air travel.
 Hypoxia altitude simulation test - In this test, an arterial blood gas is
drawn just prior to administration of a gas mixture with an FIO2 of 15.1%.
Another arterial blood gas is drawn 20 minutes later, while the patient
breathes the hypoxic gas mixture. If the PaO2 is <50 mm Hg,
administration of supplemental oxygen during flight is recommended.
If the PaO2 is between 50 and 55 mm Hg, further testing should be
considered, including a 6-minute walk test.

15. OXYGEN DELIVERY DEVICES
LOW FLOW (VARIABLE
PERFORMANCE)
HIGH FLOW (FIXED
PERFORMANCE)
1 Nasal cannulae
2 Oxygen Mask
3 Mask with reservoir bag
1 Venturi mask
2 High flow nasal cannulae
3 High flow oxygen generators

16. WHAT IS: LOW FLOW
 Low-flow systems deliver only a fraction of the patient’s minute
ventilation as pure oxygen
 The maximum flow in these systems is 15 L/min.
 Since a patient’s tidal volume usually varies from breath to
breath, and the delivered flow of oxygen from the device is
constant, the fraction of inspired oxygen for any given breath is
impossible to predict.
 Because of the uncertainty of the FIO2 delivered by low-flow
devices, they are sometimes referred to as “variable performance
devices.”

17. Nasal cannula (prongs):
 It is disposable plastic device with two protruding prongs for
insertion into the nostrils, connected to an oxygen source.
 Used for low-medium concentrations of Oxygen (24-44%) at a
flow rate of 1L to 6L per minute .Flow above 6L/min do not increase
FiO2 above 44%

18. Advantages Disadvantages
 Client able to talk and eat with
oxygen in place.
 Easily used in home setting.
 Safe and simple.
 Easily tolerated.
 Delivers low concentrations of
O2
 Unable to use with nasal
obstruction .
 Can dislodge from nares easily.
 Causes excessive mucosal
dryness and epistaxis at 6
L/min or higher .

19. The simple Oxygen mask

20.  It delivers 40 % to 60% oxygen .
 Flow rate for simple mask range from 5 to 12 liters per minute,
which usually require some room air to be entrained via the side
ports of the mask to meet the patient’s minute ventilatory
needs.
 The flow rate of a simple mask should never be <5 L/min; below
this level, carbon dioxide rebreathing may occur, along with an
increased resistance to inspiration.

21. Advantages Disadvantages
•Can provide increased delivery
of oxygen for short period of
time.
• The face mask is indicated in
patients with nasal irritation or
epistaxis
• Tight seal required to deliver
higher concentration
• Difficult to keep mask in
position over nose and mouth
• Uncomfortable for pt while
eating or talking.
• Claustrophobia

22. Mask with reservoir bag
 Two type
1 partial rebreathing reservoir mask
2 Non rebreathing reservoir mask

23. The partial re-breathing reservoir mask:
 The mask has a reservoir bag that must remain inflated during
both inspiration & expiration.
 It collects the first parts of the patients' exhaled air.
 The oxygen flow rate must be maintained at a minimum of 6
L/min to ensure that the patient does not rebreath large amounts
of exhaled air.
 The remaining exhaled air exits through vents.
 It is used to deliver oxygen concentrations up to 80%
 .

24. NURSING INTERVENTION
 Keep reservoir bag free of twists or kinks.
 Prevents the reservoir bag to collapse or be empty
 Prevents anyone to squeeze the
reservoir bag

25. ADVANTAGES DISADVANTAGES
 Can inhale room air through
opening in mask if oxygen
supply briefly interrupted.
 Require tight seal
 Eating and talking
difficult,uncmfortable
 claustrophobia

26. The non rebreathing reservoir mask
 Provides highest concentration of oxygen(60 -100%) at flow rate
of 4 - 10 L/min.
 Similar to the partial rebreather mask except that two one way
valves are present to conserve the exhaled air. The bag is an
oxygen reservoir.
 When the patient exhales, the one way valve closes and all the
exhaled air is vent out and the patient does not re breath any of
the exhaled air.

27. NON REBREATHER MASK

28. Nursing Intervention
 Maintain flow rate so reservoir bag collapse only slightly during
inspiration.
 Check that valves and rubber flap are functioning properly (open
during expiration)
 Never allow anybody to squeeze the bag empty.

29. ADVANTAGES DISADVANTAGE
 Delivers the highest possible
O2 concentration.
 Suitable for patient breathing
spontaneously with severe
hypoxemia.
 Impractical for LTOT.
 Malfunction can cause CO2
build up.
 Suffocation
 Expensive
 claustrophobia

30. Differnce between simple, partial rebreathing,
non rebreathing O2 mask
Simple O2 Mask
1. Provide FiO2 40 to 60% at
a flow 6 to 10L/min.
2. Flow rate must be 5
L/min to prevent CO2
rebreathing.
3. No one way valve
present for inspired and
expired gases.
Partial rebreathing
reservoir O2 mask
1. Provide FiO2 60 to
80% at a flow 6 to 10
L/min.
2. Flow rate must be
6L/min to ensure that
patient does not
rebreath exhaled air.
3. No one way valve
present for inspired and
expired gases.
Non rebreathing
reservoir O2 mask
1. Provide FiO2 60 to
100% at a flow 4 to
10L/min
2. Flow rate should be set
high to prevent
deflation of reservoir
bag usally about
15L/min.
3. One way valve present
for inspired and expired
gases.

31. ESTIMATING FiO2
O2 Flow rate FiO2 O2 Flow rate FiO2 O2 Flow rate FiO2
Nasal cannula Oxygen mask Mask with reservoir
1 0.24 5-6 0.4 6 0.6
2 0.28 6-7 0.5 7 0.7
3 0.32 7-8 0.6 8 0.8
4 0.36 9 0.9
5 0.4 10 > .99
6 0.44

32. HIGH-FLOW OR FIXED-PERFORMANCE
OXYGEN DEVICES
 High-flow oxygen devices deliver a constant FIO2
 Therefore referred as “fixed performance devices.”
 The devices allow for a fixed FIO2 by providing very high flows of
pure oxygen which exceed the patient’s minute ventilation,
sometimes by a factor of four.

33. Venturi mask
 Venturi mask consists of a mask, a jet nozzle, and entrainment ports .
 Oxygen is delivered under pressure via the jet nozzle, which acts to
dramatically increase the velocity of the gas
 Provide high concentration of oxygen from 24-60% at 3 to 15 litre per
minute
 Venturi mask has interchangeable or adjustable valves that enable the
clinician or respiratory therapist to better titrate the FIO2 to the
patient’s needs.
 For treatment of patients with COPD in emergency departments, the
British Thoracic Society recommends oxygen administration using a
Venturi mask to ensure an appropriate FIO2.

34. Venturi Mask

35. Venturi Mask
 Advantages
Delivers most precise oxygen Concentration
Doesn’t dry mucous membranes
 Disadvantages
uncomfortable
Risk for skin irritation
Produce respiratory depression in COPD patient with high
oxygen concentration >50%

36. High-Flow Generators for O2 therapy
 High-flow generators are used to ensure non invasive delivery of
a constant, high concentration of inspired oxygen.
 High-flow generators are capable of delivering gas in excess of 40
to 60 L/min.
 Given the high flows delivered, a constant FIO2 is achieved,
regardless of the patient’s minute ventilation and fit of the
mask.
 The devices are noisy and require specialized personnel to set up
and monitor, limiting their usage to intensive care settings.

37. High-Flow Nasal Cannulae
 Recently, nasal cannulae that can deliver much higher rates of
flow than simple nasal cannulae have been developed (e.g.,
Vapotherm®) that allow delivery of much higher flows (and
therefore, higher FIO2) of humidified oxygen.
 The devices can deliver between 1 and 60 L/min and may be
more comfortable than a facemask.

38. High flow nasal canulae

39. HAZARDS OF O2 THERAPY
1.Drying of mucous membrane.
2.Depression of ventilation in COPD.
3. Atlectasis due to absorption collapse.
4.O2 toxicity.

40. OXYGEN TOXICITY
 Clinical toxicity is generally absent when the FIO2 is <50%.
 The exposure level at which oxygen toxicity occurs has not been
clearly identified, although a higher FIO2 experienced for a
longer period of time is associated with an increased risk.
 Pulmonary oxygen toxicity (Lorrain-Smith effect)
- Symptoms:
- substernal pain, irresistable cough, dyspnoea,
- Vital Capicity decreases , compliance decreases .
- pulmonary interstitial edema leading to fibrosis.

41.  2.Retrolental fibroplasia :
- Occurs when PaO2 more than 80mmhg for more than 3 hrs in
new born.
- Very premature babies are more susceptible.
- O2 saturation must be around 90-92 %, to prevent it.

42. Thank you