Oxygen Therapy & Adjuncts
RET 2274
Respiratory Care Theory 1
Module 4.0
Oxygen Therapy & Adjuncts
In consultation with the physician, a skilled
clinician should be able to assess the patient’s
need for oxygen therapy, determine the desired
goals of therapy, select the mode of
administration, monitor the patient’s response,
and recommend and implement timely and
appropriate changes
Oxygen Therapy & Adjuncts

General Goals and Clinical Objectives

Correct documented or suspected acute
hypoxemia

Decrease symptoms of associated with chronic
hypoxemia

Decrease the workload hypoxemia imposes on
the cardiopulmonary system
Oxygen Therapy & Adjuncts
AARC Clinical Practice Guidelines (Excerpts)

Indications

Demonstrated hypoxemia as evidenced by:






PaO2  60 mm Hg or an SaO2  90% on room air
Neonates: PaO2 <50 mm Hg, SaO2 <88%, or capillary
PO2 <40 mm Hg
Acute care situation in which hypoxemia is suspected
Severe trauma
Acute myocardial infarction
Short-term therapy, e.g., post anesthesia recovery
Oxygen Therapy & Adjuncts

Assessing Need – Monitoring Aids

ABG



Pulse oximetry


PaO2
SaO2
SpO2
Bedside Calculations


CaO2
O2
Oxygen Therapy & Adjuncts

Assessing Need – Clinical Signs & Symptoms

Respiratory




Cardiovascular



Tachypnea
Dyspnea
Cyanosis
Tachycardia
Hypertension
Neurologic



Restlessness
Confusion
Headache
Oxygen Therapy & Adjuncts

Assessment of Outcome

Improvement of Need Indicators



ABGs
SpO2
Physical Symptoms
 Respiratory
 Cardiovascular
 Neurologic
Oxygen Therapy & Adjuncts

Hazards of Oxygen Therapy

Oxygen Toxicity (lung tissue destruction)


Oxygen-Induced Hypoventilation


In patients with chronic hypercapnia
Absorption (Absorptive) Atelectasis


At FiO2s ≥ 50%
Nitrogen washout
Retinopathy of Prematurity (ROP)


AKA retrolental fibroplasia
Possible at FiO2s as low as 30%
Oxygen Therapy & Adjuncts

Oxygen Delivery Systems

Low-Flow O2 Delivery Devices


Provide part of the patient’s inspiratory gas flow
needs – remainder comes from the room air
FiO2 is variable because it is dependent upon the
patient’s tidal volume (Vt) and respiratory rate (f)
Note: Increases or decreases in Vt or respiratory
rate f alter the delivered FiO2
Oxygen Therapy & Adjuncts

Oxygen Delivery Systems

High-Flow O2 Delivery Devices

Provide a given oxygen concentration at a flow that
equals or exceeds the patient’s inspiratory gas flow
needs – all the inspired gas the patient breathes is
delivered by the oxygen device and none is provided
by the room air
Note: Increases or decreases in Vt or f do not
alter the delivered FiO2
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Nasal Cannula

A disposable plastic device
consisting of two nasal prongs
(approximately 1 cm in length)
that insert directly into the
vestibule of the nose and are
connected to several feet of
small-bore oxygen tubing. The
oxygen supply tubing connects
directly to a flowmeter or bubble
humidifier.
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Nasal Cannula



Oxygen flow from 1 – 6 L/min enters
the patient’s nose, filling the
anatomic reservoir (nasopharynx
and oropharynx)
First 50 ml of each breath (adult) is
pure oxygen, the remainder consists
of oxygen mixed with room air
FiO2 varies with patient’s Vt and
respiratory rate
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Nasal Cannula

Cautions
 Too high of a flow can cause
discomfort, nasal dryness,
bleeding
 Newborns and infants –
maximum 2 L/min
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Nasal Cannula

Oxygen supplied via nasal cannula
at flowrates ≤ 4 L/min need not be
humidified
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Nasal Cannula Oxygen Concentrations
100% O2 flow in liters
1L
2L
3L
4L
5L
6L
Approximate FiO2
0.24
0.28
0.32
0.36
0.40
0.44
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Nasal Catheter



A soft plastic tube with several
small holes at the tip. It is
advanced along the nasal passage
until the tip rests at the level of the
uvula
If blindly inserted, insert it to depth
equal to the distance from the nose
to the ear lobe (too deep can cause
gagging and possible aspiration)
FiO2 delivery is similar to nasal
cannula
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Transtracheal Catheter





A Teflon (polytetrafluoroethylene) catheter
that is surgically inserted into the trachea
between the 2nd and 3rd cartilage ring
Held in place by a custom-sized chain
necklace
Connects directly to flowmeter – no
humidifier
Oxygen builds up in the expanded anatomic
reservoir during exhalation
Achieves a given PaO2 using 40% - 60”%
less O2
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery
Devices

Transtracheal Catheter

Cautions




Infection
Airway obstruction

If patient becomes SOB or
has increased WOB, the
catheter may be obstructed
and needs to be flushed
Subcutaneous emphysema
Hemoptysis
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Reservoir and Pendant Cannula





Reservoir Cannula
Designed to conserve oxygen
Incorporate a mechanism for gathering and
storing oxygen between breaths
Decrease oxygen use by providing FiO2
comparable with that of nonreservoir
systems but at lower flows
Flow: ¼ - 4 L/min, FiO2 0.22 – 0.35
Can reduce O2 use by 50% to 75%
Pendant Cannula
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Simple Oxygen Mask

Lightweight mask applied to the
patient’s face that adds reservoir
space (the mask) in addition to the
anatomical reservoir

During the pause between exhalation
and inspiration, the mask and
anatomic reservoir fill with 100% O2.
During the first part of inspiration,
100% O2 is inhaled. During the latter
part, O2 and room are mixed in the
mask and inhaled
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Simple Oxygen Mask

Input flow range: 5 – 12 L/min

FiO2 range: 35% - 50% - varies with
patient’s Vt and f

Must maintain enough oxygen flow
to flush mask of exhaled carbon
dioxide
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Partial Rebreathing and Non-Rebreathing Masks



Sometimes referred to as reservoir masks
Each has a 1 liter flexible reservoir bag attached to the
oxygen inlet
Because the bag increases the reservoir volume, both
masks can provide a higher FiO2 than a simple mask
Partial Rebreathing Mask
Non-Rebreathing Mask
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Partial Rebreathing Masks

When the patient exhales,
approximately the first third of
expiration is from the anatomic dead
space (does not participate in gas
exchange and is rich in oxygen) fills
the reservoir bag. The remaining
exhaled gas exits through the ports in
the mask. Between exhalation and
inspiration, additional oxygen flows into
the mask and reservoir bag. When the
patient inhales, a mixture of oxygen
and air is inhaled.
Has no valves
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Partial Rebreathing Masks

Input flow range: 6 – 10 L/min


A sufficient enough flow should
be applied so that the reservoir
bag does not completely collapse
during the patient’s inhalation
FiO2 range: 40% - 70% - varies
with patient’s Vt and f
Has no valves
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Exhalation valve
Non-Rebreathing Masks

Oxygen continually feeds into the
reservoir from the O2 supply tubing

During inspiration, the expiratory
valves close (preventing air dilution)
and the inhalation valve opens,
providing oxygen to the patient from
the reservoir bag

During exhalation, the inhalation valve
closes (preventing exhaled gas from
entering the bag) and the expiratory
valve opens allowing exhaled gas to
exit the mask
Inhalation valve
Has 2 one-way valves
Oxygen Therapy & Adjuncts

Low-Flow O2 Delivery Devices

Exhalation valve
Non-Rebreathing Masks

Input flow range: Minimum of 10
L/min
 A sufficient enough flow should
be applied so that the reservoir
bag does not completely
collapse during the patient’s
inhalation

FiO2 range: 60% - 80% - varies
with patient’s Vt and f
Inhalation valve
Has 2 one-way valves
Oxygen Therapy & Adjuncts

Low-Flow Devices

Advantages





Ease of use
Lower Cost
Patient comfort
Minimal equipment
monitoring and
maintenance
Useful when precise
FiO2 is not required

Disadvantages


Does not provide
precise FiO2
FiO2 varies with
respiratory pattern
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

All high-flow O2 devices mix air and oxygen via an
air entrainment system to achieve a given FiO2

All the inspired gas the patient breathes is delivered
by the oxygen device and none is provided by the
room air
Note: Increases or decreases in Vt or f do not alter
the delivered FiO2
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

Basic components of an air-entrainment system.
Pressurized gas passes through a nozzle or jet, beyond
which are air-entrainment ports. Shear forces at the jet
orifice entrain air into the primary gas stream, diluting the
oxygen and increasing the total flow output of the
device.
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

Venti or Air-Entrainment Mask

The device consists of a jet orifice around which is
an air-entrainment port. The body of the mask has
large ports that allow excess flow from the device
and exhaled gas from the patient to escape
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

Venti or Air-Entrainment Mask

FiO2 is regulated by using different adaptors with
specific combinations of entrainment ports and jet
sizes developed by manufacturers
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

If enough flow is provided from the device, the
patient will not entrain any room air, thus,
preventing the dilution of the FiO2 being delivered
by the device – the patient will receive a constant
FiO2 with every breath

This remains true only if the patient’s inspiratory
flow demands do not exceed the flow from the
mask
Oxygen Therapy & Adjuncts

Total device flow must equal 3 – 4 times the
patient’s minute volume

As a rule of thumb, total flow from an air
entrainment device should be at least 60 lpm

To accomplish that objective . . .
 Using the device’s air/oxygen entrainment ratio,
determine the oxygen flow required to guarantee
the prescribed FiO2.
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

Air to Oxygen Entrainment Ratios
Room Air-to-O2 Ratio
25:1
10:1
8:1
5:1
3:1
1.7:1
1:1
0.6:1
0:1
O2 Concentration
24%
28%
30%
35%
40%
50%
60%
70%
100%
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

Computing Air-to-Oxygen Ratios
Liters of Air
Liters of O2
=
100 – %O2
%O2 – 21
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

Computing Air-to-Oxygen Ratios
%O2 40%
Liters of Air
Liters of O2
Liters of Air
Liters of O2
=
100 – 40
40 – 21
Liters of Air
Liters of O2
=
60
19
Liters of Air
Liters of O2
=
3
1
= 100 – %O2
%O2 – 21
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

Computing Air-to-Oxygen Ratios – Magic Box
Value for Air
Value for Oxygen
Oxygen Therapy & Adjuncts

High-Flow O2 Delivery Devices

Computing Total Flow Output
What is the total flow out put of a 40% Venti mask running at
12 L/min?
1.
2.
Add air-to-oxygen ratio parts
3+1=4
Multiply the sum of the ratio parts by the O2 input flow
4 x 15 = 48
Answer:
A 40% venti mask running at 12 L/min has a
total flow output of 60 L/min
Oxygen Therapy & Adjuncts

When giving a higher FiO2 with an air-entrainment
device (e.g., 0.50 – 1.0), it may be necessary to use
two devices in conjunction in order to provide a
sufficient total flow to meet the patient’s inspiratory
demands
Oxygen Therapy & Adjuncts

High-Flow Adjuncts
Aerosol
mask
Trach mask
(collar)
Face tent
T piece
(Brigg’s adaptor)
Oxygen Therapy & Adjuncts

High-Flow Systems

Advantages


Provide precise and
dependable FiO2
Psychological benefit
for some patients due
to high flow

Disadvantages



More complex to use
More costly
Require closer
monitoring and more
maintenance
Oxygen Therapy & Adjuncts

Enclosures

Enclosing a
patient in a
controlled-oxygen
atmosphere is
among the oldest
approaches to
oxygen therapy.
Liquid Oxygen Tent Designed by Dr. Frank Hartman, 1943
Oxygen Therapy & Adjuncts

Enclosures

With today’s simpler
airway devices,
enclosures are
generally used only
in the care of infants
and children.
Oxygen Therapy & Adjuncts

Enclosures

Three major types of oxygen enclosures



Oxygen Tents
Oxygen Hoods
Incubators
Oxygen Therapy & Adjuncts

Enclosures

Oxygen Tents



AKA – mist tents,
croup tents,
croupettes
Clear plastic tent or
canopy
Large enough to
enclose a small
child
Oxygen Therapy & Adjuncts

Enclosures

Oxygen Tents

Provides environmental control
of …



O2 concentration (.21 - .50)

High-output aerosol device
(air-entrainment)
Humidity

High-output aerosol device
Temperature

Refrigeration coils
containing Freon
Oxygen Therapy & Adjuncts

Enclosures

Oxygen Tents

Primary usage


Pediatric aerosol therapy

Croup or cystic fibrosis
Problems


Wide swings in FiO2 due to opening and closing of
tent

Canopy must remain tucked in
Constant leakage makes a high FiO2 impossible
Oxygen Therapy & Adjuncts

Enclosures

Oxygen Hoods

Clear plastic enclosure


Placed around the
patient’s head
Fixed oxygen
concentration


Air-entrainment device, or
blender, connected to
inlet port
Flow rate must be a
minimum of 7 L/min to
ensure CO2 is flushed out
of hood
Oxygen Therapy & Adjuncts

Enclosures

Oxygen Hoods

Cautions



Oxygen seems to be layered (highest concentration
near the bottom of hood)
O2 concentration needs to be measured
intermittently with an O2 analyzer near the infants
face
When caring for premature infants, ensure that the
gas is warmed to a precise temperature and
humidified

May induce cold-stress   O2 consumption
and even apnea
Oxygen Therapy & Adjuncts

Enclosures

Incubators

Plexiglas enclosures



Provide a neutral
thermal environment

Servo-controlled
heating
Supplemental oxygen
Humidity is provided
with an external
heated humidifier or
nebulizer
Oxygen Therapy & Adjuncts

Enclosures

Incubators


FiO2 is highly variable because of frequent
opening
Best way to control FiO2 in an incubator is with a
Oxyhood

FiO2 and gas temperature must be measured
within the Oxyhood – continuously
Oxygen Therapy & Adjuncts

Enclosures

Incubators


Mechanical
ventilation can
be provided for
infant while in
the incubator
Ventilator circuit
temperature
probe must be
outside of the
incubator