2. Indications for use of O2 therapy
Potential complications of O2 therapy.
Identify the signs and symptoms of O2 toxicity
Identify the various methods of O2 delivery
Humidification
Patient positioning
Expectoration/Deep breathing/effective cough
Aims and objectives
4. Oxygen therapy is a treatment for hypoxaemia not
breathlessness.
Aim is to achieve normal or near normal oxygen
saturations for all acutely ill patients.
Oxygen should be prescribed to achieve a target
saturation of 94–98% for most acutely ill patients or
88–92% for those at risk of hyper-capnic respiratory
failure
Indications for use
5. Indications for use
• Oxygen is used as a
medical treatment for
both chronic and
acute respiratory
difficulties.
6. It can be used in chronic conditions for those who
require additional oxygen therapy.
It can be used therapeutically for those in
cardiac/respiratory or neuro-degenerative diseases
Chronic Patient
7. Oxygen forms an important part of medical
treatment in resuscitation, trauma, massive
haemorrhage, active convulsion and
hypothermia.
It can also be used as cautious care in post
anaesthesia .
In the critically ill where oxygen requirements
increase or gas exchange becomes compromised
due to the nature of their illness.
Acute patient Indications
8. Acute hypoxaemia is considered
dangerous to healthy subjects, with a
Pao2 of <6kpa or with oxygen
saturations of around 80%.
In acute illness, chronic organ disease
and/or ischaemia, they are likely to be at
risk with Pao>6kpa.
Acute Hypoxaemia
9. A track and trigger such as a NEWS score may be high
with little or no change in oxygen saturation levels.
Equally critical illness may present with only a small
fall in saturation levels
Be aware that compensation mechanisms may mask
the patients true oxygen requirements.
NEWS Scores
10. BTS Guidelines
2008
The lower end of the
target saturation limit
is 94%, this is to ensure
that saturations stay
above 90%, most of all
the time
The upper end of the
target saturation limit
is 98%.
11. O2 therapy for Non-Hypoxic
conditions
Indicated in carbon
monoxide poisoning
where the carbon
monoxide has combined
with the haemoglobin to
form
carboxyhaemoglobin.
12. To resolve pnuemothorax in
those who do not require a
chest drain.
By over oxygenating the
patient (hyperoxaemia) it
changes the pressure
gradient in the pulmonary
capillaries which draws air
out of the pleural cavity.
O2 therapy for Non-Hypoxic conditions
13. • Drying of mucous
membrane
• Pulmonary
atelectasis
• Remember
monitoring of
saturations indicates
oxygenation not
ventilation.
Potential Complications of
oxygen therapy
14. Signs and symptoms of oxygen
toxicity
• Oxygen toxicity affects the
human body in different ways
depending on the type of
exposure.
• Short exposures to high partial
pressures at greater than
atmospheric pressure can lead
to central nervous system
toxicity.
• Occular and pulmonary toxicity
results from longer exposure
at normal atmospheric
pressure.
Thomson & Paton 2014
18. Simple face mask
Venturi system
Nasal cannulae
Reservoir mask
High flow oxygen
OXYGEN THERAPY
19. Face Mask
Oxygen flow rate
(L/min) % Oxygen delivered
2 24
4 35
6 50
8 55
10 60
12 65
15 70
Oxygen concentrations vary
depending on the flow rate
and the patient's breathing
pattern
These masks are useful for
patients who need a higher
percentage of oxygen
temporarily whilst the cause of
their hypoxia is treated.
21. Nasal Cannulae
Oxygen flow
rate (L/min)
% Oxygen
delivered
1 24
2 28
3 32
4 36
5 40
6 44
Nasal cannulas provide an
alternative to a mask, but can be
used only where the patient
requires a low percentage of
oxygen and are usually used with
flow rates of 1–4 litres of oxygen
per minute and provide
approximately 24–35% oxygen
They cannot be attached
satisfactorily to an external
humidification device but in many
cases the oxygen will be
humidified as it passes through the
nasal passages into the trachea
22. Reservoir mask
Non‐rebreathing masks are similar to
the simple semi‐rigid plastic masks
with the addition of a reservoir bag,
which allows the oxygen to be
delivered at concentrations between
60% and 90% when used at flow rates
of 10–15 L/min
Note that if the oxygen flow is too
low, the carbon dioxide can
accumulate in the reservoir bag and
fail to meet the patient's
requirements, resulting in an increase
in carbon dioxide
23. High Flow oxygen
High‐flow oxygen therapy allows the
accurate delivery of oxygen therapy
of up to 100% FiO2 at a flow rate of up
to 60 L/min
High‐flow oxygen therapy emulates
the temperature and humidity of a
healthy adult lung (37°C and 44 mg/L
H2O), optimizing mucociliary
clearance by preserving the function
of the ciliated mucosa, reducing the
risk of respiratory tract infections and
ensuring good oxygenation and
ventilation. HFOT also reduces
dryness of the upper airway mucosa
24. Pulse Oximetry
Oxygen Saturation of Arterial
Blood
SaO2
Detector Probe
Fingertips
Earlobe
Bridge of the nose
Unreliable
Poor Tissue Perfusion
Cold Digits
Nail Varnish
26. Humidification
BTS emergency oxygen
guidelines (2008) state
that humidification is not
required for the delivery
of low flow oxygen
(4L/minute and under) or
short term use of high
flow oxygen for short
periods.
27. The normal lung warms and humidifies
INSPIRED air
Recovers heat and moisture from EXPIRED air
Defending the lung from contaminants.
Normal Breathing
28. The upper airway warms the inspired gas to core
body temp and achieves 100% relative humidity just
below the Carina.
Cleans inspired air by filtering and clearing foreign
matter, e.g. sneezing, gagging, coughing and the
mucociliary transport system.
This optimises gas exchange and protects the delicate
lung tissue.
Inspired Air
29. Expired Air
As the air is exhaled, only
a quarter of the heat and
moisture is recaptured.
Replenishment from the
systemic reserves is
necessary to prepare for
conditioning of the next
inspired breath.
Insensible Loss
30. Defence Of The Lung
The lung is defended by a Mucociliary
Transport System (respiratory escalator).
Extends from the nasopharynx towards the
respiratory bronchioles.
Traps and neutralises inhaled contaminants
and transports them up the airway to be
swallowed.
31. The warmer the gas, the more vapour it can hold but
if the temperature of the gas falls, water held as
vapour will condense out of the gas into the
surrounding atmosphere
(Khan and O'Driscoll, O'Driscoll et al. )
Mucocillary Transport
32. Patients with Tracheostomy- As inspired gases enter
directly into the lower airway and bypasses the
moistening and filtering effects of the upper airway.
Oxygen delivery over 35% via a Venturi or > 4L/min
nasal cannulae as this will dry the Mucosa halting the
Mucociliary Transport System
When to Humidify?
33. The Lung At Risk
If the temperature and humidity of inspired gases are less than core
temperature, the patient is at risk of excess moisture loss from the upper
airways and compromised mucociliary transport, resulting in reduced airway
patency and lung compliance.
34. Mucociliary Transport System
• Function depends on thickness of Mucus
• Depth of the Sol Layer (lubrication layer)
• Cilia beat frequency
36. External Sources - introduced by opening the
breathing circuit for procedures such as suctioning.
Internal Sources – aspiration from the gut and upper
airway from endogenous pathogens.
Intubated - The secretions leak continuously around
the ET cuff and a bolus may be delivered when PEEP
is lost.
Endogenous pathogens - are the predominant cause
of nosocomial pneumonia
Pathogens
37. • Increasing clearance = decrease
pathogens
• Limiting replication - preventing pools of
mucus
How is this done in practice?
.
Getting Humification Right!
38. Types of Humidifiers Used in ICU
Heat Moisture Exchange (HME) Filter
Hot water Humidifier
Heated Wire Humidifier
Nebulization
How much 02 is in room air??
oxygen 21%
carbon dioxide 0.03%
nitrogen 79%
So if spo2 are 90% on room air(ie 21%) and we give 28% fio2 what might our Spo2 increase to?
7% more o2 given (might see and increase upto 97%)
Hypoxaemia = an abnormally low concentration of oxygen in the blood (below 90% of oxygen saturated)
No indication of benefit to the non hypoxaemic,breathless pt.
What are normal oxygen saturations? Normal for the patient? Baseline on admission (if lucky may have baseline ABG)
Normal daytime haemoglobin Sao2 is 96–98% in young adults in the seated position at sea level but the lower limit falls slightly with age and is about 95% in adults aged >70 years. [Evidence III]
Chronic copd infective
Acute,chest infection or permenant o2 requirement
BTS recc only in hypoxaemia if below baseline saturation
Chronic conditions? What might they be?
Many patients with chronic lung disease, congenital cyanotic heart disease or chronic neuromuscular conditions have oxygen saturations substantially below the normal range, even when clinically stable.
O2 therapy may reduce the levels of co2 in the breathless patient (no controlled trails to prove this)
Some patients with chronic lung disease may be accustomed to living with Sao2 as low as 80% (Pao2 about 6 kPa or 45 mm Hg) while other patients with acute organ failure may be harmed by short-term exposure to Sao2 <90% (Pao2 <8 kPa or 60 mm Hg).
Hypothermia? We could warm the o2 to help with the rewarming process.
Post op patients can benefit for o2 therapy it may reduce nausea and vomiting& reduce risk of surgical wound infections
Critical care patients will benefit from early use of 02 therapy may reduce impact of oragn failure and reduce length of stay.
]Blood oxygen levels below 80 percent may compromise organ function, such as the brain and heart, what would we do in this circumstance?
IE check resp rate/pulse compensatory mechanisms, young falling off cliff!!!!
In assessing an ill patient, the Sao2 level is only one of several physiological variables that should be monitored. Many patients with sudden acute illness such as postoperative pulmonary emboli will have a sudden alteration in physiological variables as assessed by “track and trigger” systems such as the modified Early Warning Scoring system. Such patients may have only a small fall in Sao2 owing to physiological compensation mechanisms such as increased ventilation. Healthcare professionals therefore need to be alert for falls in Sao2 even within the recommended target ranges.
Most guidelines for cardiopulmonary resuscitation and the care of patients with critical illness recommend the use of 100% oxygen in the initial stages of resuscitation.
Half life of carbo oxyhaemoglobin is 4-5hours when breathing air, however is reduced to 40mins when breathing 100% oxygen, why sent to hyperbaric unit and or given highflow 100%
Where you would want oxygen to attach to the haemoglobin the carbon monoxide has a greater affinity. So to speed up half life hyperbaric/highflow
Carbon monoxide competes with oxygen for binding sites on hemoglobin molecules. As carbon monoxide binds with hemoglobin hundreds of times tighter than oxygen, it can prevent the carriage of oxygen
Do not forget that it Is down to the doctor to decide treatment plan.
If the PSP is smaller than 15% and if the patient is asymptomatic, many consider observation to be the treatment of choice. (If the patient is admitted, administer oxygen, as this has been shown to speed resolution of the pneumothorax.)
Pneumothorax has to do with the gathering of gases within the pleural space after a collapsed lung has occurred(two types tension and spont)
The objective is to increase alveolar tension in order to lessen the effort of breathing and the exertion of myocardium. Oxygen must be utilized similar to that of a drug and its dosage should be tailored to the individuals needs.
Central nervous toxicity:- is more often seen in hyperbaric can lead to seizures
Pulmonary and Occular:- can occur 3 hours after oxygen exposure tunnel vision, ringing inears, nausea,dizziness,twitching, seizures
Ask staff
High‐flow oxygen therapy allows the accurate delivery of oxygen therapy of up to 100% FiO2 at a flow rate of up to 60 L/min (system dependent), previously unfeasible via conventional methods of oxygenation
Although research on the effects of HFOT is limited, several studies have shown that high‐flow nasal therapy helps to flush out the anatomical dead space, increasing the alveolar ventilation over minute ventilation.
Most particles of dust and dirt are filtered out by the cillia.
Nb dehydration/fluid management/balance
Fine hairs called cilia
Humidity & temp in the inspired air doesn’t match the patients internal temp/humidity then they will loose more water leading to increased insensible losses and drying of the mucosal transport system.
Cillia topped with lubricated sol topped with mucous layer to encourage smooth transit (sol layer will reduce if dehydrated/not humidified adequatley or in illness)
Ie if ill mucous layer will thicken and movement will slow cillia will get boggged down (ie cystic fibrosis) mucolytics ie cabocystine reduces mucous layer/viscosity.
If less than optimal humidification continues, cell damage occurs and gas conditioning moves deeper into the lung.
If there is a continuing lack of humidity further damage occurs. The cilia can break off, causing damage to the mucosal lining of the respiratory tract.
Passy muir subglottic aspiration, cuff pressure checks. Disconection
Humidification should not be used for patients requiring open system (mask) ventilation when ‘droplet contact’ isolation precautions are required.
Ie VAP
Ie good bronchial toileting,bagging, physio, cough assist(bird) mobilisation encouraging cough, xray, nebs, bronch.
Drainage of secretions will be optimized if the patient and therefore the mucus layer and cilia are well hydrated. This can be ensured by adequate humidification
For effective gas exchange to occur in the lungs, the air would need to be at a temperature of 37°C with 100% humidity
Sit Patient as upright as they can tolerate Orthopnic patient
NG content risk aspiration
Use analgesia scoring tool and treat appropriately
Use regular nebulisers as prescribed
Support wounds when coughing (towel)
Use of incentive spirometers
