principles of oxygen therapy and sleep apnoea Flashcards
what are some sources of oxygen treatment? 4
how is it delivered?
- oxygen cylinders
- wall supply
- oxygen concentrators
- liquid oxygen
- litres/ minute
describe oxygen cylinders? 6
- widely available, home and institutional
- various sizes
- limited length of supply
- suitable for limited/ short duration treatment
- relatively expensive
- 100% oxygen supply
describe wall supply? 4
- in hospital only
- central supply piped into clinical areas
- may not be available in clinical areas (clinic rooms)
- supply 100% oxygen
describe oxygen concentrators? 5
- mains operated machine
- molecular sieve removed nitrogen
- oxygen predominant gas >90% concentration
- regional suppliers with franchise for isolation and support
- use in the home or when out
describe liquid oxygen? 4
- more highly compressed
- larger gaseous volume per cylinder volume
- allow higher flow rates
- well developed in the US and parts of Europe
name 3 patient interfaces for spontaneously breathing patients?
how can these be measured? 2
- nasal cannula
- uncontrolled masks ( Hudson, non-rebreathe)
- controlled makes ( fixed percentage Venturi)
- litres/ min
- percentage inspired oxygen
describe a nasal cannula? 7
- well tolerated
- accepts flow rates of 1-4l/ min
- delivers 24-40% oxygen
- % delivered depends on multiple factors
- used for not critically ill patients. with mild hypoxaemia
- can’t provide humidified oxygen
- can dry out nose
describe a Hudson mask? 4
- delivers 30-60% O2
- flow rate of 5-10l/min
- mixing of O2, room air and exhaled air mask
- used less often
describe a non-rebreathe mask? 3
- delivers 85-90% oxygen with 15L flow rate
- one way valve in the bag stops mixing with room sit and patient rebreathe for expired air
- used for acutely unwell patients- step down as soon as possible
describe a Venturi mask? 2
- controlled oxygen
- Venturi valve allows delivery of a fixed concentration of oxygen
describe the clinical indications for using oxygen as a drug? 5
- oxygen is a treatment for hypoxaemia, not breathlessness
- acutely hypoxaemic patients
- chronically hypoxaemic COPD patients with acute exacerbation
- chronically hypoxaemic COPD patient who are stable
- palliative use in advanced malignancy
what are the target oxygen saturation’s for
normal young adult
over 70 years
96-98%
94-96%
there needs to be a balance between what is safe and what is normal
what else do we have to do for these patients besides increase their oxygen saturation 5
- secure and maintain airway patency
- enhance circulation
- avoid or reverse respiratory depressants
- establish reason for hypoxaemia and treat
- if not improving ventilate
who is at risk of hypercapnia if given a high does of Oxygen? 4
- chronic hypoxic lung disease- COPD, cystic fibrosis
- chest wall disease
- neuromuscular disease
- obesity related hypoventilation
how do we assess response to treatment for patients with CO2 retention? 4
- arterial blood gases check frequently
- adjust dose of oxygen accordingly
- if not improving may need non invasive ventilation
- not nasal cannula, dangerous as inspired oxygen percentage varies according to the patients respiratory characteristics
how do we prescribe oxygen? 5
- on a drug chart
- state target oxygen saturation range
- state delivery device
- state the dose- flow rate or percentage of inspired oxygen
- patients may carry an oxygen treatment card
what is LTOT? 4
- long term oxygen treatment for at least 15 hours a day
- for some patients with COPD
- patient needs to be in stable state
- no sooner than 4 weeks after an exacerbation
what are the indications for the needs of LTOT? 6
- COPD patients with pO2 <7.3 kPa
- COPD patients with pO2 7.3<8 kPa and
- secondary polycythaemia
- nocturnal hypoxemia
- peripheral oedema/evidence of right ventricular failure
- evidence of pulmonary hypertension
what are the benefits for LTOT? 7
- improved long term survival
- prevention of deterioration in pulmonary hypertension
- reduction of polycythaemia (raised Hb)
- improved sleep quality
- increased renal blood flow
- reduction in cardiac arrhythmias
- improved quality of life
what is portable oxygen? 4
- may improve breathlessness in some patients
- may extend the duration of LTOT
- but most patients, breathlessness is not due to low pO2
- we also need to consider the weight of the cylinders and the duration of the supply
what is sleep apnea? 5
- apnoea cessation of airflow for 10 seconds or longer
- central= respiratory control centre= no respiratory effect
- obstructive= the collapse of the pharyngeal airway during sleep
- OSA=5 or more obstructive apnoea’s per hour
- hypopnea= reduction in the airflow by 50% accompanied by desaturation of 4% and or arousal from sleep
what is the prevalence of sleep apnoea? 3
2% women
4% adult men
increasing
what are the risk factors of sleep apnoea? 6
- male
- obesity
- neck circumference greater than 43cm
- smoking
- alcohol/ sedative use
- pharyngeal abnormalities
what is the cycle of sleep apnoea? 7
- sleep
- relaxation of muscles and tissues surrounding pharyngeal airway
- collapse and obstruction of airway- snoring
- apnoea
- arousal
- muscle tone returns- airway clears
- resumption of breathing
what are the clinical features of sleep apnoea? 7
- snoring
- nocturnal chocking/ waking with a start
- unrefreshing
- morning dry mouth
- morning headaches
- excessive daytime sleepiness- difficulty concentrating, irritability/mood changes, sleeping at an inappropriate time
- nocturia
what can be the complications of sleep apnoea? 2
- right heart failure, secondary respiratory disease
- excess of red blood cells
how do we investigate sleep apnoea? 3
- repetitive apnoea’s and symptoms of sleep fragmentation with excessive daytime sleepiness
- Epworth sleepiness scale
- sleep studies
what is polysomnography?
- way to measure oxygen saturation during sleep
what are the consequences of OSA? 7
- increased risk of accidents
- hypertension
- type 2 diabetes
- ischaemic heart disease
- heart failure
- stroke
- death
how can we manage OSA? 8
- resolve signs and symptoms
- improve sleep quality
- patient education- don’t drive if sleepy
- weight loss
- avoid alcohol
- treat contributing problems
- mandibular advancement device
- continuous positive airway pressure (CPAP)
what is CPAP? 7
- device generates airflow
- positive pressure delivered to the airway via a mask
- intraluminal pharyngeal pressure is a surrounding pressure
- pharynx stays open
- patients with mild OSAHS and additional co-morbidities
- for patients with mild OSAHS and a high-risk profession
- not for patients with mild OSAHS and no additional symptoms
what are the benefits of CPAP? 2
- symptoms resolve
- normalises BP
what are the problems with CPAP? 4
- adherence is an issue
- airway drying/ irritation
- mask problems
- normally lifelong treatment
