4(b) Weaning Flashcards
What is weaning?
• Reducing the amount of ventilatory support
– Generally refers to pump support, though also wean O2
support
What are the weaning criteria
• Medical stability – CXR improved, infective/inflammatory
markers returned to normal, high P/F ratio on minimal
ventilator settings
• Resolution of underlying problem eg improved cardiac
function / sepsis
• pH and BE normal or near norms
• Adequate spontaneous respiratory effort
• Patient understands and follows commands
• Minimal secretions/sputum load
• Voluntary inspiratory effort
Why patients fail to wean
• Mismatch of ventilatory needs and neuro‐musckuloskeletal
capacity
• Cardiovascular dysfunction
• “Stealing theory”
What factors influence wheaning
Energy supply
Energy demands
Neuromuscular competence
How does energy supply affect weaning
Energy supply
– Nutrition: intake, catabolic state
– O2 supply: Hb, circulating blood volume
– O2 utilisation: sepsis inhibited
How does energy demands affect weaning?
• Energy demands – Efficiency • CO2: fever, agitation, burns • VD/VT: PE, hyperinflation – Resistive load (Raw) • Secretions • Bronchoconstriction – Lung elastic load • Atelectasis • Consolidation – Chest wall elastic load • Abdominal distention
How does neuromuscular competence affect weaning?
• Neuromuscular competence – Drive • Sleep deprivation – Neuromuscular transmission • Reversible vs permanent – Muscle weakness • Disuse atrophy • Critical illness weakness • Psychogenic
Critical illness weakness
• Critical illness polyneuromyopathy (sepsis, steroids, neuromuscular blocking agents. Not just deconditioned)
• Weakness of extremities
• Facial muscles are usually spared
• Loss of tendon reflexes
• EMGs ‐ fibrillations and positive sharp waves
• Nerve conduction studies ‐ reduced compound
muscle and sensory nerve action potentials
How to maximise ventilatory capacity for successful weaning
Maximise ventilatory capacity – Positioning – Nutrition – Rest – Oxygenation – Correct metabolc abnormalities – Treat sepsis – Improve cardiac function
How to minimise ventilatory load for weaning
Minimise ventilatory load – Secretion clearance – Treat bronchospasm and pulmonary oedema – Correct for hyperinflation/gas trapping
What is uncomplicated weaning
Uncomplicated weaning (< 24 hr) • dec. set RR enough to allow for spontaneous respiratory efforts • dec. PEEP to 5 • dec. PS to 10 • dec. FIO2 to 0.3 or less • Satisfactory CXR and ABGs
Role of physiotherapist during weaning
• Minimise airway resistance • Maximise lung compliance • Minimise impedence to chest wall movement • Optimise respiratory muscle mechanics • Prevent peripheral deconditioning • Reassurance and minimising demand during weaning trials • ? Respiratory muscle training
Respiratory muscle training
• No consensus on IMT – May depend on patient pathology • COPD • Non‐COPD pulmonary pathology • Neuromuscular • Importance of EMT
Methods of weaning
- Weaning protocols
- Airway support/CPAP mode
- Extubation/decannulation onto NIV
- Tracheostomy
- Spontaneous breathing trials
- Weaning protocols
- Airway support/CPAP mode
- Extubation/decannulation onto NIV
- Tracheostomy
- Spontaneous breathing trials
How does trache help weaning and things to note
• Tracheostomy – Reduced dead space – Decreased need for sedation / more comfortable – Easier to communicate – Humidification is very important – Unfavourable consequences
