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Flashcards in Respiratory Failure Deck (29)
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1
Q

Definition of respiratory failure.

A

PaO2 < 8kPa

2
Q

Subdivisions of respiratory failure.

A

Type 1 respiratory failure

Type 2 respiratory failure

3
Q

Define type 1 RF.

A

Hypoxia -> < 8kPa PaO2

with a normal or low PaCO2.

4
Q

Main causes of type 1 RF.

A

V/Q mismatch

Hypoventilation

Abnormal diffusion

Right to left cardiac shunts

5
Q

Examples of V/Q mismatches.

A

Pneumonia

Pulmonary oedema

PE

Asthma

Emphysema

Pulmonary fibrosis

ARDS

6
Q

Define type 2 RF.

A

Defined as hypoxia PaO2 < 8 kPa and hypercapnia of PaCO2 > 6 kPa.

Caused by alveolar hypoventilation with or without V/Q mismatch.

7
Q

Causes of type 2 RF.

A

Pulmonary disease like asthma, COPD, pneumonia, end-stage pulmonary fibrosis and obstructive sleep apnoea.

Reduced resp drive like sedatives, CNS tumour or trauma.

Neuromuscular disease like cervical cord lesion, diaphragmatic paralysis, poliomyelitis, myasthenia gravis, Guillain-Barré syndrome.

Thoracic wall disease like flail chest or kyphoscoliosis.

8
Q

Clinical features of hypoxia.

A

Dyspnoea

Restlessness

Agitation

Confusion

Central cyanosis

Tachycardia

Long-standing;

Polycythaemia

Pulmonary hypertension

Cor pulmonale

9
Q

Clinical features of hypercapnia.

A

Headache

Peripheral vasodilation

Tachycardia

Bounding pulse

Tremor/flap - asterixis

Papilloedema

Confusion

Drowsiness

Coma

10
Q

Investigations in respiratory failure.

A

Blood tests like FBC, U&Es, CRP and ABG.

Pulse oximetry

Capnography

CXR

Microbiology like sputum and blood cultures if indicated.

Spirometry

PaO2/FiO2 ratio

CXR

11
Q

Clinical features of acute respiratory distress/failure.

A

Tachypnoea (respiratory rate >24 breaths per minute in adults)

Use of accessory breathing muscles

Cyanosis

Tachycardia

Intercostal recession

Sweating

Pulsus paradoxus

Inability to speak and unwillingness to lie flat

12
Q

Management of type 1 RF.

A

Treat the underlying cause.

Give O2 24-60% by facemask

Assisted ventilation if PaO2 < 8kPa despite 60% oxygen

13
Q

Management of type 2 RF.

A

Remember there might be only a hypoxic drive causing tachypnoea.

Treat underlying cause

Controlled oxygen therapy starting at 24% O2. The oxygen therapy should be given with care. However remember that severe hypoxaemia is more dangerous that severe hypercapnia.

Recheck ABG after 20 min -> If PaCO2 is steady or lower then increase O2 to 28%.
If PaCO2 has risen > 1.5kPa and the patient is still hypoxic consider assisted ventilation like NIPPV.

If this fails consider intubation and ventilation.

14
Q

What is capnograph?

A

A continuous breath-by-breath analysis of the expired carbon dioxide concentration.

15
Q

What is capnography used for?

A

Confirm tracheal intubation

Continuously monitor end-tidal PCO2 to assess effectiveness of ventilation.

Detect acute airway problems

Detect acute alterations in cardiorespiratory function.

16
Q

What can happen if you give too much oxygen apart from CO2 retention?

A

Oxygen toxicity where hyperoxia causes pulmonary dmaage due to oxygen free radical and oxidative damage to the lung tissue.

17
Q

Give examples of techniques for respiratory support.

A

Controlled mechanical ventilation (CMV)

Synchronised intermittent mandatory ventilation (SIMV)

Pressure support ventilation (PSV)

Biphasic positive airway pressure (BiPAP)

Non-invasive ventilation (NIV)

Continuous positive airway pressure (CPAP)

Extracorporal techniques

18
Q

What does NIV encompass?

A

Nasal mask/cannula

Face mask

Hood

19
Q

What does CPAP encompass?

A

Mask

Hood

High-flow nasal prongs

20
Q

Indications for mechanical ventilation.

A

Acute respiratory failure with signs of severe respiratory distress.

Acute ventilatory failure like MG, GB-syndrome, high spinal cord injury when vital capacity has fallen to 10ml/kg or less.

Post-OP ventilation in high-risk patients

Head injury to avoid hypoxia or hypercarbia

Trauma to chest or high spinal cord

Severe left ventricular failure with pulmonary oedema

Coma with airway compromise or breathing difficulties.

21
Q

Complications of tracheal intubation.

A

Trauma to upper airways

Tube goes into oesophagus

Tube in one or other main bronchus - need to be in both.

Migration of tube out of trachea

Leaks around tube

Obstruction of tube

Sinusitis

Mucosal oedema and ulceration

Laryngeal injury

Tracheal narrowing and fibrosis

Tracheomalacia

22
Q

Complications of tracheostomy.

A

Death, pneumothorax, haemorrhage, hypoxia, hypotension, cardiac arrhythmias, subcut emphysema

Mucosal ulceration, erosion of tracheal cartilages, erosion of innominate artery, stomal infection, pneumonia

Failure of stoma to heal, tracheal granuloma, treacheal stenosis, collapse of tracheal rings at level of stoma, cosmetic factors.

23
Q

General complications associated with mechanical ventilation.

A

Disconnection, failure of gas or power supply.

CVS complications - pulmonary HTN -> fall in cardiac output.

Respiratory complications like venilator-associated pneumonia and tension pneumothorax.

24
Q

Types of controlled mechanical ventilation.

A

Volume-controlled ventilation

Pressure-controlled ventilation

25
Q

How is oxygen delivered in CPAP?

A

a tightly fitting face mask or a hood

26
Q

Indications for NIV.

A

Acute exacerbation of COPD (H+ > 44nmol/L or pH < 7.35)

Cardiogenic pulmonary oedema

Chest wall deformity/neuromuscular disease

Obstructive sleep apnoea

Severe pneumonia

Asthma

Weaning patients from invasive ventilation

27
Q

Contraindications of NIV.

A

Facial or upper airway surgery

Reduced conscious level

Inability to protect the airways.

28
Q

What is a venturi mask?

A

A mask providing precise percentage or fraction of O2 (FiO2) at high flow rates.

This is what you can use in COPD and start off at 24% to 28%.

29
Q

When to consider ABGs.

A

Any unexpceted deterioration in an ill patient.

Anyone iwth an acute exacerbation of a chronic chest condition

Anyone with impaired cosncioussness or impair resp effort.

Signs of CO2 retention such as bounding pulse, drowsy, tremor, headache.

Cyanosis, confusion and visual hallucinations

To validate measurements from transcutaneous pulse oximetry.