O2 therapy and sleep apnoea Flashcards
Describe 4 sources of oxygen
- Oxygen cylinders- widely available, expensive, vary in size
- Wall supply- in hospital only, 100% O2
- Oxygen concentrators- Mains operators, home, [O2} >90%
- Liquid Oxygen
How do target oxygen saturations differ in healthy people to those at risk of hypercapnia?
Normal : >96%
Those at risk: 88-92%
Acute hypoxaemia can lead to acute cardiac dysrhythmia and organ failure. What is the treatment?
Max O2 treatment and high flow uncontrolled mask
Alter flow when stable
Target: 94-98%
Maintain airway, enhance circulation, avoid respiratory depressants, establish cause
Which categories of people are at risk of developing hypercapnia if given high dose of oxygen?
Chronic hypoxic lung disease - COPD, bronchiectasis/ cystic fibrosis
Chest wall disease- kyphoscoliosis, thoracoplasty
Neuromuscular disease
Obesity hypoventilation
How would you treat a chronically hypoxaemic patient with COPD who has acute exacerbation?
Beware: if you over correct O2 you may decrease respiratory drive as body-which is usually good at compensating - isn’t triggered anymore. This leads to CO2 retention, worsening acidosis, narcosis, death
Treatment: modest oxygenation whilst preventing CO2 retention. Deliver oxygen by fixed percentage Venturi O2 mask.
Monitor by doing frequent blood gases
Aim for 88-92%
If no improvement, non-invasive ventilation
Why wouldn’t you use nasal cannulae to administer O2 to treat chronically hypoxaemic patient with COPD with a cute exacerbation?
Potentially dangerous and actual inspired O2 varies according to patients respiratory characteristics
Uncontrolled
When prescribing O2 which factors need to be considered?
Target O2 saturation
Deliveyr device
Dose (O2 concentration, flow rate)
Some patients have O2 treatment card which details all this information
If untreated, what might happen to chronically hypoxaemic patients?
Pulmonary arterial hypertension
Right ventricle hypertrophy
RV failure
What is LTOT?
When is Long term oxygen therapy indicated?
Provided from O2 concentrator for >15hrs/day
Improves long term survival, prevention of deterotiation of pulmonary hypertension, decreases polycythaemia, improves sleep and renal blood flow and reduces heart arrhythmias
COPD with pO2 <7.3kPa
COPD with pO2 >7.3kPa and:
- secondary polycythaemia
- nocturnal hypoxaemia
- peripheral oedema
- evidence of pulmonary hypertension
What is the definition of apnoea?
Describe different types
Cessation of airflow for >10s
Central: no respiratory effort caused by respiratory control centre
Obstructive: collapse of pharyngeal airway during sleep
OSA: >5 obstructive apnoeas per hour
Hypopnoea: Reduction in airflow by 50% accompanied by desaturation of 4% and/or arousal from sleep
Describe the risk factors for sleep apnoea
More men then women
Obesity Smoking Large neck Alcohol Craniofacial abnormalities Pharnygeal abnormalities Hypothyroidism, acromegaly, pregnancy
What happens in sleep apnoea?
Sleep
Relaxation of muscles/tissues surrounds pharyngeal airway
Collapse and obstruction of airway-> snoring
Apnoea or hypopnoea(partial collapse)
Arousal
Muscle tone returns- airway clears
Resumption of breathing
Outline some clinical features of sleep apnoea
Snoring Nocturnal choking/waking Unrefreshing sleep Morning dry mouth Excessive daytime sleepiness Nocturnia
Which factors could lead to a tendency of pharyngeal collapse?
Decreased upper airway neuromuscular tone
Decreased upper airway caliber
Increased upper airway resistance
Increased pharyngeal compliance
Which complications might arise from/cause sleep apnoea?
Cor pulmonale
Secondary polycythaemia
