Principles of Oxygen Therapy and Sleep Apnoea Flashcards
When would a Nasal Cannulae be used to deliver oxygen?
- delivering less flow rate
- delivers 24-40% O2
- mild hypoxaemia
- not critically ull
- flow rate 1-4L/min
What are advantages of a Nasal Cannulae
- able to speak
- able to eat
- less claustrophobic
What disadvantages are there to nasal cannulae?
- drying of nasal cavity
When would an uncontrolled mask (hudson mask) be used?
- deliver medium to high flw rate
- 5-10L/min
- 30-60% O2 delivered
- less drying
When would a rebreathe uncontrolled mask be used?
- high oxygen saturation 85-90%
- high flow rate 12L/min
- very unwell patients
- COPD
When would oxygen be given as a treatment?
- acutely hypoxaemic patients
- reduced oxygen saturations
- acutely unwell patients that show signs of further deterioration
What are is the target oxygen saturations?
- Young adult: 96%-98%
- Over 70yrs: 94-98%
- Those at risk of hypercapnic respiratory failure: 88-92%
What is the treatment for acute breathlessness with hypoxemia?
- Maximal oxygen treatment
- High flow uncontrolled mask (first-line treatment)
- Alter flow and delivery device when stable
Target SpO2 = 94-98%
Who is at risk of hypercapnia if given a high dose of oxygen?
- Chronic hypoxic lung disease: COPD, Bronchiectasis/ Cystic fibrosis
- Chest wall disease: Kyphoscoliosis, Thoracoplasty
- Neuromuscular disease
- Obesity-related hypoventilation
What is hypercapnia?
- CO2 retention
What is seen in chronically hypoxaemic patients with COPD who have acute exacerbation?
- They have increasingly worsening breathing
- the exacerbation may be a viral or bacterial infection or an episode of heart failure (inadequate perfusion)
What can untreated hypoxaemic patients develop?
- pulmonary hypertension
- right ventricular failure
- right ventricular hypertrophy
- secondary polycythaemia (raised Haemoglobin)
When would a patient have Long Term Oxygen Therapy (LTOT)?
- some COPD patients
- pO2 <7.3kPa
or - pO2 7.3<8kPA and, secondary polycythamia, nocturnal hypoxemia, peripheral oedema/ evidence of RV failure. evidence of pulmonary hypertension
- pO2 <7.3kPa
What are the benefits of Long term Oxygen Therapy (LTOT)?
- Improved long term survival
- Prevention of deterioration in pulmonary hypertension cases
- Reduction of polycythaemia (raised Hb)
- Improved sleep quality
- Increased renal blood flow
- Reduction in cardiac arrhythmias
- Improved quality of life
What is LTOT
Long term oxygen therapy
What is sleep apnoea and obstructive sleep apnoea?
- cessation of airflow for 10 or more seconds
- the collapse of the pharyngeal airway during sleep
What are pathophysiological presentation from the pharynx that increases its tendency to collapse
- Decreased upper airway (UA) neuromuscular tone
- Decreased UA caliber
- Increased UA resistance
- INcreased pharyngeal compliance
What regions contribute to the pathophysiological presentation to sleep apnoea?
- Nasal pathology: polyps, deviated septum
- Enlarged Tonsils
- Abnormal chin: micrognathia, retrognathia
- The increased soft tissue at the neck: obesity, hypothyroidism
What are some clinical features of sleep apnoea
- snoring
- nocturnal choking
- unrefreshing/ restless sleep
- Excessive daytime sleepiness
- Morning dry mouth
- Morning headaches
- Nocturia ( waking up in the night to urinate)
What Investigations can be done for sleep apnoea ?
- Nocturnal oximetry
- Polysomnography (PSG) (sleeping with sensors)
- Epworth Sleepiness Scale
What other pathologies is Sleep Apnoea associated with?
- Hypertension
- Type 2 diabetes
- Ischaemic heart disease
- Heart failure
- Cerebrovascular disease/stroke
- Cardiac arrhythmias
- Death
What are some risk factors for Sleep Apnoea
- Males
- Obesity
- Neck circumference greater than 43cm
- Family History of OSAHS
- Smoking
- Alcohol
- Craniofacial abnormalities
- Pharyngeal abnormalities
- Sleeping supine
- Hypothyroidism, Acromegaly, Pregnancy
How is Sleep Apnoea diagnosed?
Using the Apnoea/hypopnea Index (AHI)
apnoeas+hypopnoeas/ total sleep time in hours
- Mild: AHI 5-14 per hour (along with symptoms and signs)
- Moderate: AHI 15-30 per hour
- Severe: AHI > 30 per hour
How can Sleep Apnoea be managed?
> Weight loss
- avoid sleeping supine
- avoid alcohol
Treat contributing problems i.e hypothyroidism
Review medications, sedating drugs and drugs causing weight gain
- Mandibular advancement devices
- Continuous Positive Airway Pressure (CPAP)
