M103 T4 L6 Flashcards
What are the four sources of oxygen? (CONCENTRATion OWL)
o2 Concentrators
Oxygen Cylinders
Wall Supply
Liquid Oxygen
What are six features of oxygen cylinders?
Widely available (home & institutional) Relatively expensive Various sizes Limited length of supply Suitable for limited/short duration treatment Supply 100% oxygen
What are four features of wall supplied oxygen?
In hospital only
Central supply piped in to clinical areas
May not be available in all clinical areas (clinic rooms)
Supply 100% oxygen
What are oxygen concentrators used for?
at home for patients that need long term oxygen
portable options for when the patient is out
How do oxygen concentrators operate?
Molecular sieve- removes nitrogen
Oxygen predominant gas >90% concentration
doesn’t run out
Mains operated machine
What are advantageous features of liquid oxygen?
More highly compressed
Larger gaseous volume per cylinder volume - may be easier for people to take outside with them
Allow higher flow rates
Well developed in US & parts of Europe
What are disadvantageous features of liquid oxygen?
a bit difficult to to organise
expensive
Why might liquid oxygen be a bit difficult to to organise?
patients need to be able to fill them up in their own home so they need to be have some degree of dexterity
How is oxygen delivered to spontaneously breathing patients?
Nasal cannulae
Uncontrolled masks
Controlled masks
What units is oxygen delivery measured in?
litres per minute
% inspired oxygen
What are beneficial features of nasal cannulae for oxygen delivery?
usually well tolerated
patients can talk, eat and take oral medication
What type of patients are nasal cannulae used on?
patients with mild hypoxaemia who are not critically ill
What factors does the percentage of oxygen delivered via nasal cannulae depend on?
flow rate
respiratory rate
alveolar volume
What are disadvantageous features of nasal cannulae?
can’t provide humidified oxygen, so it tends to dry out the nose
can cause a sort of bleeding / crusting
can’t deliver higher flow rates
What are disadvantageous features of uncontrolled simple face masks for oxygen delivery?
can’t regulate specific oxygen levels
used less often
What are the flow rates and o2%s via nasal cannulae?
1-4L/min (lower frs)
24-40% (= FiO2 of 0.24-0.4)
What is breathed in by the patient when using a nasal cannulae?
oxygen
room air
exhaled air in mask
What are the flow rates and o2 %s via Simple uncontrolled masks?
fr: 5-10L/min
30-60% O2 (high levels)
What type of patients are uncontrolled masks used on?
acutely unwell patients with low oxygen levels
How is the bag in uncontrolled Non-rebreathe masks designed and what does the patient breathe in?
the bag has one-way valve stops
oxygen mixing with room air and rebreathing of expired air
What are beneficial features of venturi masks for oxygen delivery?
the venturi valve allows for the delivery of a fixed / specific concentration of o2
How are oxygen dosages prescribed?
according to a drug chart with target oxygen saturations
In what conditions / patients is oxygen used?
acutely or chronically hypoxaemic patients (either who are stable or with acute exacerbation)
palliative use in advanced malignancy
sats <90% and breathless, though often multifactorial
What are the normal oxygen saturation levels for different age groups?
Normal young adult average = 96-98%
Over 70yrs age 94-98%
Target in most patients = 94-98%
What could acute breathlessness with hypoxaemia develop into?
acute cardiac dysrhythmia & organ failure
How is acute breathlessness with hypoxaemia treated generally?
Maximal oxygen treatment
Target SpO2 = 94-98%
Other than using oxygen supplies, how else could airway patency be maintained?
Secure and maintain airway patency
Enhance circulation (volume, anaemia, cardiac output)
Avoid/reverse respiratory depressants
Establish reason for hypoxaemia and treat
If not improving, may need ventilation
What diseases will put patients at risk of hypercapnia (CO2 retention) if given high dose oxygen? (CHiLD, CWD, NMD, ORH)
Chronic hypoxic lung disease
Chest wall disease
Neuromuscular disease
Obesity related hypoventilation
What are two examples of Chronic hypoxic lung diseases?
COPD
Bronchiectasis / Cystic fibrosis
What is an example of a chest wall disease?
Kyphoscoliosis
What is the compensation mechanism for chronically hypoxaemic patients with COPD who have an acute exacerbation?
hypoxaemic drive
if you over-correct their pO2 you may switch off their respiratory drive
Hypoxaemia may still be a risk to them
What could not providing o2 to a Chronically hypoxaemic patient with COPD who have an acute exacerbation respiratory drive result in?
further CO2 retention
worsening acidosis
Narcosis - reduced level of consciousness
(& death - you can kill the patient with oxygen)
What are the aims of oxygen treatment?
to maintain modest oxygenation whilst preventing CO2 retention & acidosis
to deliver oxygen by fixed % Venturi o2 masks starting at 24% (controlled o2 therapy)
to reach target saturations of 88-92%
How is the response to oxygen treatment measured?
frequently checked ABGs
pO2, pCO2, pH measured
Adjust dose of oxygen accordingly
What happens if the patient isn’t improving after oxygen therapy?
non-invasive ventilation
Why not use nasal cannulae?
Uncontrolled therapy; potentially dangerous as actual inspired o2% varies according to the patient’s respiratory characteristics
What do untreated patients of chronic hypoxaemia develop if not treated with long term o2?
pulmonary hypertension
r. ventricular hypertrophy
r. ventricular failure (cor pulmonale)
2o polycythaemia (raised Hb)
What are the indications that the patient needs LTOT?
baseline gas levels COPD patients with pO2 < 7.3 kPa or COPD patients with pO2 7.3 < 8 kPa AND: 2o polycythaemia nocturnal hypoxaemia peripheral oedema/evidence of r. ventricular failure evidence of pulmonary hypertension
How is LTOT administered?
Provided from an oxygen concentrator
Regional concentrator supply service
O2 treatment for ≥15 hours per day
What are the benefits of LTOT?
Prevention of deterioration in pulmonary hypertension
Reduction of polycythaemia (raised Hb), in cardiac arryhthmias
Improved sleep quality, renal blood flow, long term survival & QoL
What happens in sleep apnoea?
the relaxation and narrowing of muscles/tissues surrounding pharyngeal airway
What are the physical nocturnal symptoms of sleep apnoea?
Snoring (Hx often from partner)
Nocturnal choking/waking with a “start”
Nocturia
What are the baseline gas levels that indicate that the patient needs LTOT?
COPD patients with pO2 < 7.3 kPa
COPD patients with pO2 7.3 < x < 8 kPa
What are the complications of sleep apnoea?
Cor pulmonale
Secondary Polycythaemia
What is the equation used to calculate the Apnea–Hypopnea Index?
AHI = apnoeas + hypopnoeas / total sleep time in hours
What do the different AHI scores indicate?
Mild: AHI 5–14per hour
Moderate: AHI 15–30per hour.
Severe: AHI more than 30per hour.
What other diseases is obstructive sleep apnea associated with?
Hypertension Type 2 diabetes Ischaemic heart disease Heart failure Cerebrovascular disease/stroke Cardiac arrhythmias Death
What are the goals in management of obstructive sleep apnea?
to resolve signs and symptoms of OSA
to improve sleep quality
to normalise apnoea-hypopnoea index (AHI) and oHb sat levels
What is the management plan for patients with obstructive sleep apnea?
can’t drive if excessively sleepy
to treat contributing problems
to review medications - e.g. sedating drugs might be causing weight gain
How can sleep apnea be managed?
Mandibular advancement devices
Surgery
What are the behavioural changes required in the management plan for patients with obstructive sleep apnea?
Weight loss
Avoid sleeping supine
Avoid alcohol
Describe the CPAP machine
a mask that fits over the sleeper’s nose and mouth
the mask is connected to a pump that pumps air into the person’s airways
forces the airways to remain open via intraluminal pharyngeal pressure
What is the function of mandibular advancement devices?
Hold soft tissues of oropharynx forward
When are mandibular advancement devices used to treat obstructive sleep apnea?
in patients with mild to moderate obstructive sleep apnea
if it’s the patients preference
if CPAP failed
When is surgery used to treat obstructive sleep apnea?
Surgery - to remove obstructing lesion and make it easier to breathe
In what type of patients is CPAP used to treat obstructive sleep apnea?
mild OSAHS AND additional co-morbidities
mild OSAHS and high risk profession (e.g. bus driver)
patients with moderate/severe OSAHS regardless of symptoms
In what type of patients is CPAP not used to treat obstructive sleep apnea?
patients with mild OSAHS, no additional risk factors who aren’t excessive sleepy
What are the advs of CPAP?
the symptoms are resolved ↓ apnoea/hypopnoea ↓ daytime sleepiness ↓ risk road accidents ↑ quality of life Normalises BP
What are the disadvs of CPAP?
Adherence an issue
Airway drying/irritation - can humidify
Mask problems - air leak, comfort
Normally life long treatment
What is the flow rate and percentage oxygen delivered by Non-Rebreathe uncontrolled masks?
15L flow rate
delivers 85-90% (high levels)
What is an example of a simple uncontrolled face mask?
Hudson mask
What is the first line of treatment for acute breathlessness with hypoxaemia?
High flow uncontrolled mask
Alter flow and delivery device when stable to lower the oxygen levels
If a nasal cannulae delivers 24-40% o2%, what is the FiO2?
0.24-0.4
What are the morning physical symptoms clinical features of sleep apnoea?
Unrefreshing/restless sleep
Morning dry mouth
Morning headaches
What are the day time physical symptoms clinical features of sleep apnoea?
Excessive daytime sleepiness
Difficulty concentrating
Irritability/Mood changes
Sleeping at inappropriate times
What are the levels that should be aimed for in oxygen treatment?
pO2 <10
pCO2 falling from peak or maintained <6.0
pH increasing/maintained >7.35
