2. WHAT IS OXYGEN DELIVERY SYSTEM
•An oxygen delivery system is a device used to
administer, regulate, and supplement oxygen to
a subject to increase the arterial oxygenation.
•In general, the system entrains oxygen and air
to prepare a fixed concentration required for
administration.
•Oxygen delivery systems are generally
classified as low-flow or variable-performance
devices and high-flow or fixed-performance
devices.
3. INDICATIONS FOR OXYGEN THERAPY
• Peri and post cardiac or respiratory arrest.
• Hypoxia - oxygen saturation levels of <92%.
• Acute and chronic hypoxemia PaO2 < 65mmHg, SaO2 < 92%.
• Signs and symptoms of shock.
• Low cardiac output and metabolic acidosis HCO3 <
18mmol/l.
• Chronic type two respiratory failure (hypoxia and
hypercapnia).
• Dyspnoea without hypoxemia.
• Post-operatively, dependent on instruction from surgical
team.
• Treatment of pneumothorax.
4. DEFINITIONS
• FiO2 is defined as the percentage or concentration of
oxygen that a person inhales. The air that we inhale on
a day to day basis is made up of 21% of oxygen, 78% of
nitrogen and 1% of trace elements such as argon,
carbon dioxide, neon, helium and methane.
• Sometimes, 21% of oxygen may not be enough to
maintain adequate oxygen saturations. In these
situations, supplemental oxygen can be administered
via various oxygen delivery devices ranging from nasal
prongs to invasive ventilation.
• This allows the concentration of oxygen to be
increased, potentially increasing the FiO2 to 100%.
5. SpO2
• SpO2 is an estimate of arterial oxygen
saturation, or SaO2, which refers to the
amount of oxygenated haemoglobin in the
blood.
• Normal SpO2 95 – 100%
6. PaO2
• PaO2 is the partial pressure of oxygen
dissolved in the blood, expressed in mmHg.
• If PaO2 is < 80 mmHg, the patient has arterial
hypoxemia.
• 79 - 70 mmHg mild hypoxemia.
• 69 - 60 mmHg= moderate hypoxemia
• 59 - 50 mmHg = severe hypoxemia
• < 50 mmHg = extreme hypoxemia
7. LOW FLOW OXYGEN DEVICES
• These provide a fraction of the patient’s minute ventilatory requirement
as pure oxygen.
• The remainder of the ventilatory requirement is filled by addition of
entrained room air. Flows supplied through these devices are low, usually
less than 6L/min.
• These are oxygen devices where some room air will be entrained, and
therefore the exact FiO2 cannot be calculated, however it can be
estimated. How much FiO2 is delivered to the patient is dependent on:
Liter flow set at the flowmeter, respiratory rate and pattern of the ad
equipment reservoir.
• Nasal cannula, simple mask and oxygen conserving reservoir cannula are
the most widely used devices for delivery of low flow oxygen.
• Simple, inexpensive, easy to use and well tolerated.
8. NASAL CANNULA
• Low-flow nasal cannulae set to deliver oxygen
at flows between 1-6L/min lead to an
FiO2 between 0.24 and 0.44.
• Flows above 6L/min do not significantly
increase FiO2 above 0.44. These higher flows
may result in drying of mucous membranes
and nose bleed.
9. OXYGEN MASKS
• A simple mask is usually used for patients who require a moderate flow
rate for a short period of time.
• It is composed of a plastic mask that fits snugly over the patient’s mouth
and nose. The mask has holes on each side that are used for exhalation
and for air entrainment if the flow rate is too low.
• Simple mask has the ability to deliver oxygen concentrations of 40% to
60% with flow rates from 6 to 10 L/min.
• Because carbon dioxide can build up in the mask at low flow rates, do not
use a flow rate lower than 6 L/min with this type of mask. When using this
mask, consider humidification to keep the patients’ mucous membranes
from becoming dry.
10.
11. RESERVOIR CANNULAS
• Reservoir cannulas — Reservoir cannulas function by storing oxygen during
exhalation, making that oxygen available as a bolus upon the onset of the next
inhalation. Reservoir cannulas are particularly useful in patients who require a flow
rate of oxygen 4 L/min or higher.
• These cannulas are available in two configurations:
• A moustache configuration in which the reservoir is located directly beneath the
nose and a pendant configuration in which oxygen is stored in a reservoir located
on the anterior chest. The reservoir membrane is pushed forward during
exhalation, creating a chamber. This enables oxygen to be stored during exhalation
in the reservoir. When the patient is ready to inhale, he/she receives the stored
oxygen along with the continuously flowing supply oxygen, increasing the percent
oxygen in the air that the patient inhales.
• Both reservoir cannulas are simple, reliable, inexpensive, and disposable. They
operate in response to the patient's nasal airflow.
• Both devices are partial rebreathing systems. As they return some of the patient's
warmed expired air with elevated moisture, they effectively increase the relative
humidity of the inhaled oxygen.
12.
13. HIGH-FLOW OXYGEN DEVICES
• These devices meet the inspiratory flow of the
patient, and generate accurate FiO2s so long as
there is a good seal between the mask and the
patient's face.
• The flows are such that the patient will not be
entraining room air that will lower the FiO2.
• Respiratory rate and tidal volume of the patient
have no effect on FiO2 delivered.
• These devices include venturi mask, partial and
non-rebreather mask and high-flow cannulae or
mask.
15. • This device is used to deliver high flow rates and high
concentrations of oxygen. Like the simple mask, the nonrebreather
mask fits snugly over the patient’s mouth and nose.
• A nonrebreather mask has ports on each side that have one-way
valves that keep the patient from breathing in room air to ensure
that a high concentration of oxygen is delivered.
• The mask also has a reservoir bag that is inflated with pure oxygen.
Between the mask and the bag is another one-way valve that allows
the patient to breathe in the oxygen supplied by the source as well
as oxygen from the reservoir. This provides the patient with an
oxygen concentration of nearly 100%.
• A nonrebreather mask can deliver oxygen concentrations of 60% to
95% with flow rates from 10 to 15 L/min. At flow rates slower than
6 L/min, the risk of rebreathing carbon dioxide increases.
16. PARTIAL REBREATHER MASK
• A partial rebreather mask is used for oxygen therapy. It
delivers oxygen gas to the patient at concentrations of
50 to 70 percent.
• This is basically an NRB with both one-way valves
removed from the mask. The estimated FiO2 is 60-65%.
Flow should be set at 6-15 lpm.
• With a partial rebreather mask, when the patient
inhales, they inhale some of the exhaled air, which
contains carbon dioxide. When carbon dioxide enters
the lungs, it stimulates breathing.
• In contrast, non-rebreather masks have vents on the
side of the mask that allow all exhaled air to escape.
18. • A Venturi mask is most often used for critically ill patients
who require administration of a specific concentration of
oxygen. It consists of a mask with holes on each side that
allow exhaled air to escape. At the base of the mask are
color-coded entrainment ports that are adjustable to allow
regulation of the concentration of oxygen administered.
• A Venturi mask can deliver oxygen concentrations from
24% to 60% with flow rates from 4 to 12 L/min. Because
this device delivers a precise oxygen concentration and
carbon dioxide buildup is minimal, it is commonly used for
patients who have COPD. Humidification is usually
unnecessary with this device.
• There is entrainment of room air with these devices, but it
is fixed and not dependent on the patient's PIFR. Therefore
the resulting delivered FiO2 is also constant.
19. HIGH FLOW NASAL OXYGEN
• High flow nasal oxygen therapy is a form of respiratory support where
oxygen, often in conjunction with compressed air and humidification, is
delivered to a patient at rates of flow higher than that delivered
traditionally in oxygen therapy. (Traditional oxygen therapy is up to 16
L/min and high flow oxygen therapy is up to 60 L/min.)
• HFNC can generate FiO2 100% and PEEP of up to 7.4 cmH20 at 60 L/min.
• High flow oxygen therapy is usually delivered using a blender connected to
a wall outlet, a humidifier, heated tubing and nasal cannula.
• It also creates nasopharyngeal dead space washout, thereby decreasing
CO2 rebreathing and provides an oxygen reservoir.
• It offers low levels of PEEP which may contribute to alveolar recruitment
(decreased dead space), improved compliance and decreased work of
breathing.
• Low level of patient compliance needed. Very comfortable and allows
them to communicate, eat.
22. • Oxygen cylinders
• Oxygen cylinders are the primary source for home oxygen portable
systems. The advantages of oxygen cylinders include the fact that
they come in a variety of sizes, do not waste oxygen, they can have
their duration increased with the use of a conserving device and
can provide high liter flows. The disadvantages include often
cumbersome size, limited duration, need for frequent refills and the
high storage pressure of the gas (often up to 2000 psi).
• Home oxygen concentrators:
• Home oxygen concentrators are compressors that use a molecular
sieve material to remove the nitrogen from room air and provide
oxygen concentrations of 85-97% pure oxygen. These concentrators
can provide liter flows from 0.5l/min to 10l/min. Recent advances
have allowed concentrators to become more portable, functioning
on internal batteries, automobile adaptors or standard electricity.
Portable oxygen concentrators are approved for airline travel.
