OXYGEN THERAPY

Dr. Tejasree

What is oxygen?

Why do we need oxygen?

What is oxygen therapy?

When do we need oxygen therapy?

How to give oxygen therapy?

WHAT IS OXYGEN?

In 1775 by joseph priestley an english

scientist.

Oxygen is a chemical element with

symbol O and atomic number 8.

Highly reactive nonmetallic element

and oxidizing agent that readily

forms compounds.

3rd most abundant element in the universe.

Colorless, odorless, and tasteless

WHY DO WE NEED OXYGEN?

Cellular respiration.

Biochemical energy from nutrients to ATP.

Aerobic respiration.

Anaerobic respiration.

AEROBIC RESPIRATION

Pyruvate from glycolysis.

Kreb’s cycle

Electron transport chain

WHAT IS OXYGEN THERAPY?

Oxygen therapy is administration of oxygen

in concentration more than in ambient air as

a medical intervention.

Thus providing adequate oxygen in the

blood, while decreasing the work of breathing

and reducing the stress on the myocardium.

7

INDICATIONS FOR OXYGEN THERAPY

Hypoxemia

Inadequate amount of oxygen in the blood

SPO2 < 90%

PaO2 < 60 mmHg

Excessive work of breathing

Excessive myocardial workload

FACTORS INFLUENCING OXYGEN

TRANSPORT

Cardiac output

Arterial oxygen content

Concentration of Hb

Metabolic requirements

Hypoxemia

decrease in the arterial oxygen content in

the blood

Hypoxia

decreased oxygen supply to the tissues.

10

CAUSES OF HYPOXEMIA

Shunt

Hypoventilation As carbon dioxide increases oxygen falls

V/Q mismatching (ventilation/perfusion) Pneumonia

Pulmonary edema

ARDS

Increased diffusion gradient asbestosis

Early pulmonary edema

CLINICAL MANIFESTATIONS OF

HYPOXIA Impaired judgment, agitation (restlessness),

disorientation, confusion, lethargy, coma

Dyspnea

Tachypnea

Tachycardia, dysrhythmias

Elevated BP

Diaphoresis

Central cyanosis

CAUSES OF HYPOXIA

Hypoxic hypoxia

Anemic hypoxia

Ischemic or stagnant hypoxia

Histotoxic hypoxia

NEED FOR OXYGEN IS ASSESSED BY

Clinical evaluation

Pulse oximetry

ABG

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OXYGEN THERAPY

Goal of therapy is an SPO2 of >90% or for documented COPD patients(Spo2 88–92%)-(Pao2=55-60)

As SPO2 normalizes the patients vital signs should improve” Heart rate should return to normal for patient

Respiratory rate should decrease to normal for patient

Blood pressure should normalize for patient

CAUTIONS FOR OXYGEN THERAPY

Oxygen toxicity – can occur with Fio2 > 60% longer than 36 hrs

Fio2>80%longer than 24 hrs Fio2>100%longer than 12hrs

Suppression of ventilation – will lead to increased CO2 and carbon dioxide narcosis

Danger of fire

Absorbtion Atelectasia

Premature retrolental fibroplasia

OXYGEN DELIVERY DEVICES

1. High flow (fixed performance) delivery

systems.

2. Low flow (variable performance) delivery

systems.

Low flow systems

contribute partially to inspired gas client breathes

do not provide constant FIO2

Ex: nasal cannula, simple mask

High flow systems

deliver specific and constant percent of oxygen

independent of client’s breathing

Ex: Venturi mask, non-rebreather mask, trach collar, T-

piece

Low Flow Oxygen Delivery Devices :

These include:

i. Nasal cannula.

ii. Simple mask / Mary Carterall mask.

iii. Oxygen tents.

iv. Non rebreathing mask.

v. Rebreathing mask.

vi. Polymask.

High flow oxygen delivery devices:

i. Venturi mask

ii. Air entertainment nebulizers.

iii. High flow air-oxygen blenders.

iv. Bag & mask ventilation

NASAL CANNULA

BNCV

NASAL CANNULA

MERITS DEMERITS Easy to fix

Keeps hands free

Not much interference

with further airway care

Low cost

Compliant

Unstable

Easily dislodged

High flow uncomfortable

Nasal trauma – drying and

crusting

Mucosal irritation

FiO2 can be inaccurate and

inconsistent

NASAL CANNULA

Oxygen flow rate(l/min) Fio2 range

1 0.21-0.24

2 0.23-0.28

3 0.27-0.34

4 0.31-0.38

5 0.32-0.44

The Inspired percent oxygen increases by

approx. 1-2%(above 21%) per litre of oxygen

flow.

PENDANT RESERVOIR

NASAL RESERVOIR

NASAL CATHETER

NASAL CATHETER

MERITS DEMERITS

Good stability

Disposable

Low cost

Difficult to insert

High flow increases back

pressure

Needs regular changing

May provoke gagging, air

swallowing, aspiration

Nasal polyps, deviated

septum may block insertion

TRANSTRACHEAL CATHETER

A thin

polytetrafluoroethylene

(Teflon) catheter

Inserted surgically with a

guidewire between 2nd and

3rd tracheal rings

FiO2 – 22-35%

Flow – ¼ - 4L/min

Increased anatomic

reservoir

TRANSTRACHEAL CATHETER

MERITS DEMERITS

Lower O2 use and cost

Eliminates nasal and skin

irritation

Better compliance

Increased exercise

tolerance

Increased mobility

High cost

Surgical complications

Infection

Mucus plugging

Lost tract

NASAL MASK

Hybrid of nasal cannula and face mask.

Supplemental oxygen equivalent to nasal

cannula under low flow conditions for adult

patients.

Advantage – patient comfort.

does not produce sores around nares

Dry oxygen is not jetted into nasal cavity.

NASAL MASK

NASAL MASK

NASAL MASK

SIMPLE OXYGEN MASK

SIMPLE OXYGEN MASK

MERITS DEMERITS

Disposable

Light weight

Covers both nose and

mouth

Elastic headband

No reservoir bag

Maleable metal nose bridge

Incomplete seal

Inboard leaking

Mixture of oxygen and

entrained room air

Uncomfortable

Speech is muffles

Drinking and eating are

difficult

Oxygen flow rate (L/min) Fio2 range

5-6 0.30-0.45

7-8 0.40-0.60

Masks lacking oxygen reservoirs best for

Patients who require concentrations of

oxygen greater than cannulas provide

Need oxygen therapy for fairly short

periods of time

Example: medical transport or therapy,

PACU, ER

not for patients with severe respiratory

disease who are hypoxemic, tachypneic or

unable to protect their airway from

aspiration.

MASK WITH RESERVOIRS

Partial rebreathing mask

Non rebreathing mask

PARTIAL REBREATHING MASK

Consists of mask with exhalation ports and reservoir bag

Reservoir bag must remain inflated

O2 flow rate - 6 to 10L

FIO2=60%-80%

Client can inhale gas from mask, bag, exhalation ports

Poorly fitting; must remove to eat

PARTIAL REBREATHING MASK

No valves

Mechanics –

Exp: O2 + first 1/3 of exhaled gas (anatomic dead space) enters the bag and last 2/3 of exhalation escapes out through ports

Insp: the first exhaled gas and O2 are inhaled

FiO2 - 60-80%

FGF > 8L/min

The bag should remain inflated to ensure the highest FiO2 and to prevent CO2 rebreathing

Exhalation

ports

O2

Reservoir

+

NON-REBREATHING MASK

Consists of mask, reservoir bag, 2 one-way valves at exhalation ports and bag

Client can only inhale from reservoir bag

Bag must remain inflated at all times

O2 flow rate- 10 to 15L

Fio2= 95-100%

Poorly fitting; must remove to eat

NON-REBREATHING MASK

Has 3 unidirectional valves

Expiratory valves prevents air entrainment

Inspiratory valve prevents exhaled gas flow into reservoir bag

FiO2 - 0.80 – 0.90

FGF – 10 – 15L/min

To deliver ~100% O2, bag should remain inflated

Factors affecting FiO2

air leakage and

pt’s breathing pattern

O2

Reservoir

One-way valves

Fixed performance

(High – Flow) equipment

VENTURI MASK

• Most reliable and accurate method for delivering a precise O2 concentration

• Consists of a mask with a jet

• Excess gas leaves by exhalation ports

• O2 flow rate 4 to 15L & Narrowed orifice

• Fio2, 24%-60%

• Can cause skin breakdown; must remove to eat

AIR ENTRAINMENT NEBULIZER

Have a fixed orifice, thus, air-to-O2 ratio

can be altered by varying entrainment port

size.

Fixed performance device

Deliver FiO2 from 28-100%

Max. gas flows – 14-16L/min

Device of choice for delivering O2 to

patients with artificial tracheal airways.

Provides humidity and temperature control

AIR ENTRAINMENT NEBULIZER

Aerosol

mask

Face tentTracheostomy

collar

T tube

HOW TO INCREASE THE FIO2 CAPABILITIES OF

AIR-ENTRAINMENT NEBULIZERS?

1. Adding open reservoir (50-150ml aerosol tube)

2. Provide inspiratory reservoir (a 3-5 L anaesthesia bag) with a one way expiratory valve

3. Connect two or more nebulizers in parallel

4. Set nebulizer to low conc (to generate high flow) and providing supplemental O2 into delivery tube

BAG AND MASK VENTILATION

TRACHEOSTOMY COLLAR/MASK

O2 flow rate 8 to 10L

Provides accurate

FIO2

Provides good

humidity; comfortable

T-PIECE

Used on end of ET tube

when weaning from

ventilator

Provides accurate FIO2

Provides good humidity

FACE TENT

Low flow

O2 wet

O2 flow, 4-8 lit

Fio2=40%

Oxygen tent

Hood

Incubator

ENCLOSURES

OXYGEN TENT

Consists of a canopy placed over the head and shoulders or over the entire body of a patient

FiO2 – 40-50% @12-15L/minO2

Variable performance device

Provides concurrent aerosol therapy

Disadvantage Expensive

Cumbersome

Difficult to clean

Constant leakage

Limits patient mobility

OXYGEN HOOD

An oxygen hood covers only

the head of the infant

O2 is delivered to hood

through either a heated

entrainment nebulizer or a

blending system

Fixed performance device

Fio2 – 21-100%

Minimum Flow > 7/min to

prevent CO2 accumulation

INCUBATOR

Incubators are polymethyl

methacrylate enclosures that

combine servo-controlled

convection heating with

supplemental O2

Provides temperature control

FiO2 – 40-50% @ flow of 8-

15 L/min

Variable performance

device

HYPERBARIC O2 THERAPY (HBOT)

DEFINITION

A mode of medical treatment wherein

the patient breathes 100% oxygen at a

pressure greater than one Atmosphere

Absolute (1 ATA)

1 ATA is equal to 760 mm Hg at sea level

PHYSIOLOGICAL EFFECTS OF HBO

Bubble reduction ( boyle’s law)

Hyperoxia of blood

Enhanced host immune function

Neovascularization

Vasoconstriction

INDICATIONS OF HBOT

ACUTE CONDITIONS CHRONIC CONDITIONS

Decompression sickness

Air embolism

Carbon monoxide

poisoning

Severe crush injuries

Thermal burns

Acute arterial

insufficiency

Clostridial gangrene

Necrotizing soft-tissue

infection

Ischemic skin graft or flap

Radiation necrosis

Diabetic wounds of lower

limbs

Refratory osteomyelitis

Actinomycosis (chronic

systemic abscesses)

METHODS OF ADMINISTRATION OF HBOT

PROBLEMS WITH HBOT

Barotrauma

Ear/ sinus trauma

Tympanic membrane rupture

Pneumothorax

Oxygen toxicity

Fire hazards

Clautrophobia

Sudden decompression

COMPLICATIONS OF OXYGEN

THERAPY

COMPLICATIONS OF OXYGEN THERAPY

1. Oxygen toxicity

2. Depression of ventilation

3. Retinopathy of Prematurity

4. Absorption atelectasis

5. Fire hazard

1. O2 TOXICITY

Primarily affects lung and CNS.

2 factors: PaO2 & exposure time

CNS O2 toxicity (Paul Bert effect)

occurs on breathing O2 at pressure > 1 atm

tremors, twitching, convulsions

PULMONARY OXYGEN TOXICITY

C/F

acute tracheobronchitis

Cough and substernal pain

ARDS like state

PULMONARY O2 TOXICITY (LORRAIN-SMITH

EFFECT)

Mechanism: High pO2 for a prolonged period of time

↓

intracellular generation of free radicals e.g.: superoxide,H2O2 , singlet oxygen

↓

react with cellular DNA, sulphydryl proteins &lipids↓

cytotoxicity↓

damages capillary endothelium,

↓

Interstitial edema

Thickened alveolar capillary membrane.

↓

Pulmonary fibrosis and hypertension

A VICIOUS CYCLE

HOW MUCH O2 IS SAFE?

100% - not more than 12hrs

80% - not more than 24hrs

60% - not more than 36hrs

Goal should be to use lowest possible

FiO2 compatible with adequate tissue

oxygenation

INDICATIONS FOR 70% - 100% OXYGEN

THERAPY

1. Resuscitation

2. Periods of acute cardiopulmonary

instability

3. Patient transport

2. DEPRESSION OF VENTILATION

Seen in COPD patients with chronic hypercapnia Mechanism

↑PaO2

suppresses peripheral V/Q mismatch

chemoreceptors

depresses ventilatory drive ↑ dead space/tidal volume ratio

↑PaCO2

3. RETINOPATHY OF PREMATURITY (ROP)

Premature or low-birth-weight infants who receive supplemental O2

Mechanism↑PaO2

↓retinal vasoconstriction

↓necrosis of blood vessels

↓new vessels formation

↓Hemorrhage → retinal detachment and

blindness

To minimize the risk of ROP - PaO2 below 80 mmHg

4. ABSORPTION ATELECTASIS100% O2

oxygennitrogen

PO2 =673

PCO2 = 40

PH2O = 47

A B

A – UNDERVENTILATED

B – NORMAL VENTILATED

DENITROGENATION ABSORPTION

ATELECTASIS

The “denitrogenation” absorption atelectasis

is because of collapse of underventilated

alveoli (which depends on nitrogen volume to

remain above critical volume )

↓

Increased physiological shunt

5. FIRE HAZARD

High FiO2 increases the risk of fire

Preventive measures

Lowest effective FiO2 should be used

Use of scavenging systems

Avoid use of outdated equipment such as

aluminium gas regulators

Fire prevention protocols should be followed

for hyperbaric O2 therapy