oxygen therapy & sleep apnoea Flashcards Preview

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Flashcards in oxygen therapy & sleep apnoea Deck (44)
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1
Q

what are the different oxygen sources?

A
  • oxygen cylinders
  • wall supply
  • oxygen concentrators
  • liquid oxygen
2
Q

what units is oxygen delivered in?

A

litres per minute

3
Q

oxygen cylinders?

A
  • widely available
  • various sizes
  • limited length of supply
  • suitable for limited/short duration treatment
  • relatively expensive
  • supply 100% oxygen
4
Q

wall supply oxygen?

A
  • in hospital only
  • central supply piped into clinical areas
  • may not be available in all clinical areas
  • supply 100% oxygen
5
Q

what marks the flow rate for wall supply oxygen?

A

mid-point of the ball

6
Q

oxygen concentrators?

A
  • mains operated machine
  • molecular sieve: removes nitrogen
  • oxygen predominant gas >90% concentration
  • used in home or when out
  • regional suppliers with franchise for installation and support
7
Q

liquid oxygen?

A
  • more highly compressed
  • larger gaseous volume per cylinder volume
  • allow higher flow rates
  • well developed in US and parts of Europe
8
Q

how do you supply oxygen to spontaneously breathing patients?

A
  • nasal canulae
  • uncontrolled masks (hudson, non-rebreathe)
  • controlled masks (venturi)
9
Q

what are the 2 ways oxygen reaches patients?

A
  • litres per minute

- percentage inspired oxygen

10
Q

nasal cannulae?

A
  • well-tolerated
  • accepts flow rates 1-4L/min
  • delivers 24-40% oxygen
  • % delivered depends on multiple factors
11
Q

what are the uses of nasal cannulae?

A

mild hypoxaemia, not critically ill

12
Q

what are the negatives of nasal cannulae?

A
  • can’t provide humified oxygen

- can cause bleeding, crusting

13
Q

simple face mask - hudson mask?

A
  • delivers 30-60% oxygen
  • flow rate 5-10L/min
  • mixing of oxygen, room air and exhaled air in mask
  • used less often
14
Q

what are the negatives of uncontrolled masks?

A

can’t fix oxygen intake

15
Q

non-rebreathe masks?

A
  • delivers 85-90% oxygen with 15L flow rate

- bag: one way valve stops mixing with room air and patient rebreathing expired air

16
Q

what are the uses of non-rebreathe masks?

A

acutely unwell patients - step them down as soon as possible

17
Q

venturi mask?

A
  • controlled oxygen

- venturi valve allows delivery of a fixed concentration of oxygen

18
Q

what do the different colours mean in venturi masks?

A
  • blue = 2-4L/min, 24% oxygen
  • white = 4-6L/min, 28% oxygen
  • yellow = 8-10L/min, 35% oxygen
  • red = 10-12L/min, 40% oxygen
  • green = 12-15L/min, 60% oxygen
19
Q

when do you usually use oxygen to treat patients?

A
  • acutely hypoxaemic patients
  • chronically hypoxaemic COPD patients with acute exacerbation
  • chronically hypoxaemic COPD patients who are stable
  • palliative use in advanced malignancy (stats <90%)
20
Q

what are the target oxygen saturations?

A
  • normal young adult = 96-98%
  • over 70s = 94-98%
  • most patients = 94-98%
  • those at risk of hypercapnia = 88-92%
21
Q

what is hypercapnia?

A

high carbon dioxide levels

22
Q

who is at risk of hypercapnia if given a high dose of oxygen?

A
  • chronic hypoxic lung disease (COPD, bronchiectasis/cystic fibrosis)
  • chest wall disease: kyphoscoliosis, throacoplasty
  • neuromuscular disease
  • obesity-related hypoventilation
23
Q

how to assess response to treatment?

A
  • arterial blood gases, check frequently
  • pO2 <10
  • pCO2 falling from peak or maintained <6.0
  • pH increasing/maintained >7.35
  • if not improving may need non-invasive ventilation
24
Q

who can not use nasal cannulae?

A
  • potentially dangerous as actual inspired oxygen percentage varies according to the patients respiratory characteristics
  • uncontrolled therapy
25
Q

how do you prescribe oxygen?

A
  • in-hospital oxygen should be prescribed on the drug chart
  • state: 1) target oxygen saturation range 2) the delivery device 3) the ‘dose’ - flow rate or percentage of inspired oxygen
  • patients may carry an oxygen treatment card with their recommended oxygen saturations/prescriptions
26
Q

when would you consider long term oxygen treatment (LTOT)?

A
  • for some patients with COPD

- specialist assessment: in patients stable state, no sooner than 4 weeks after an exacerbation

27
Q

what are the indicators for long term oxygen treatment?

A
  • COPD patients with pO2 <7.3kPa
    OR
  • COPD patients with pO2 7.3<8kPA and secondary polycythaemia, nocturnal hypoxemia, peripheral oedema/evidence of right ventricular failure or evidence of pulmonary hypertension
28
Q

what is long term oxygen treatment?

A
  • provided from an oxygen concentrator
  • regional concentrator supply service
  • O2 treatment for >15 hours per day
29
Q

what are the benefits of long term oxygen treatment?

A
  • 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
30
Q

portable oxygen?

A
  • may improve breathlessness in some patients
  • may extend the duration of LTOT
  • but most patients breathlessness is not due to low pO2, weight of cylinders, duration of supply
31
Q

what is apnoea?

A

cessation of airflow for 10 seconds or longer

32
Q

what is central?

A

respiratory control centre - no respiratory effort

33
Q

what is obstructive?

A

collapse of pharyngeal airway during sleep

34
Q

what is OSA?

A

5 or more obstructive apnoeas per house

35
Q

what is hypopnea?

A

reduction in airflow by 50% accompanied by desaturation of 4% and/or arousal from sleep

36
Q

what are the risk factors for sleep apnoea?

A
  • male sex
  • obesity
  • neck circumference (43cm men & 41cm women)
  • family history of OSAHS
  • smoking
  • alcohol/sedative use
  • craniofacial abnormalities
  • pharyngeal abnormalities
  • some medial conditions
  • sleeping supine
37
Q

what happens in sleep apnoea?

A
  • sleep
  • relaxation of muscles/tissues surrounding pharyngeal airway
  • collapse and obstruction of the airway, snoring
  • apnoea
  • arousal
  • muscle tone returns, airway clears
  • resumption of breathing
    REPEAT CYCLE
38
Q

what are the clinical features of sleep apnoea?

A
  • snoring
  • nocturnal chocking/waking with a start
  • unrefreshing/restless sleep
  • morning dry mouth
  • morning headaches
  • excessive daytime sleepiness: difficulty concentrations, mood changes, sleeping at inappropriate times
  • nocturia
  • complications: cor pulmonale and secondary polycythaemia
39
Q

how do you diagnose sleep apnoea?

A
  • uses apnoea/hypopnea index (AHI)
  • AHI = apnoeas + hypopneas / total sleep time in hours
  • mild: AHI 5-14 per hour (+symptoms/signs)
  • moderate: AHI 15-30 per hour
  • severe: AHI more than 30 per hour
  • or oxygen desaturation index
40
Q

what are the consequences of OSA?

A
- increased risk of accidents
association with:
- hypertension
- type 2 diabetes
- ischemic heart disease
- heart failure
- cerebrovascular disease/stroke
- cardiac arrhythmias
- death
41
Q

what are the goals for managing sleep apnoea?

A
  • resolve signs and symptoms of OSA
  • improve sleep quality
  • normalise: apnoea-hypopnea index, oxyhaemoglobin saturation level
  • multidisciplinary approach needed
  • patient education
  • mandibular advancement devices
  • surgery
  • continuous positive airway pressure (CPAP)
42
Q

when do you use CPAP?

A
  • patients with mild OSAHS and additional co-morbidities
  • patients with mild OSAHS and high risk profession
  • patients with moderate/severe OSAHS regardless of symptoms
  • but not patients with mild OSAHS no additional risk factors who aren’t excessively sleepy
43
Q

what are the benefits of CPAP?

A
  • symptoms resolve
  • decreased apnoea/hypopnoea
  • decreased daytime sleepiness
  • decreased risk of road accidents
  • increased quality of life
  • normalises BP
44
Q

what are the problems with CPAP?

A
  • adherence an issue
  • airway drying/irritation (can humidity)
  • mask problems (air lead, comfort)
  • normally life long treatment