Non - Invasive Ventilation
A form of ‘closed circuit’ ventilation, usually delivered via sealed face mask, to provide positive pressure ventilatory support in select spontaneously-breathing patients with respiratory failure, whilst avoiding additional risks of intubation and invasive ventilation.
Indications
Hypoxaemic Respiratory Failure (SaO2 < 88, [PaO2 < 60 mmHg])
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Acute pulmonary oedema
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immunocompromised patients with severe pneumonia / Acute lung injury
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Chest trauma
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Improves work of breathing
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Hypercapnoeic Respiratory Failure (PaCO2 > 60 mmHg, pH < 7.32)
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Exacerbation of COPD
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Exacerbation of severe asthma
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Improves work of breathing
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Neuromuscular disorders
Cautions
Confirmed or suspected COVID-19 Patients
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NIV is an aerosol-generating procedure
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NIV should not be commenced in this patient group except with express consultant permission
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These patients require early intubation
Agitation/Intolerance
Vomiting
Recent upper GI surgery
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Clarify with surgical team first
Haemodynamic instability
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Discuss with intensivist first
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NIV may improve or worsen haemodynamics
Contraindications
Severe hypoxic respiratory failure that requires emergent intubation
Severe hypercapnoeic respiratory failure that requires emergent intubation
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pH < 7.1
Altered conscious state / inability to maintain patent airway
Excessive respiratory secretions
Severe refractory vomiting/haematemesis
Facial surgery/ orofacial abnormalities
Pneumothorax
ARDS
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High failure rate
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Harm associated with delay to intubation
When To Use
How To Use
Initial Settings:
CPAP
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APO - start with CPAP (EPAP) 10 cmH2O, FiO2 100%
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Asthma - start with CPAP (EPAP) 5 cmH2O, FiO2 50%
BiPAP
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Use for COPD, neuromuscular disease, chest trauma, pneumonia/acute lung injury in the immunocompromised
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Initial pressure settings:
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5 cmH2O PEEP (EPAP)
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5 cmH2O Pressure Support (PS)
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Note: Ward NIV uses IPAP and EPAP where IPAP = EPAP + pressure support. For example, 5 PEEP/5 PS = 5 EPAP and 10 IPAP
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ICU ventilators/nomenclature distinguishes PEEP and pressure support as seperate pressures where PS is value ABOVE PEEP
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FiO2 setting
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Normal lungs - titrate FiO2 to SpO2 > 92%
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Chronic obstructive lung disease - titrate FiO2 to SpO2 88 - 92%
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Adjusting Settings:
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Assess response by improvement in:
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pH
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PCO2
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SpO2
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PaO2
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Respiratory rate
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Work of breathing
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Oxygenation issues
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Increase PEEP by 1 - 2 cmH2O; max PEEP 8 - 10 cmH2O
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Increase FiO2
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Any increasing oxygen requirements must be flagged to the ICU registrar/consultant
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Ventilation issues
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Ensure good seal/minimal air leak
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Assess synchrony
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Assess NIV compliance
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Increase pressure support by 2 cmH2O; max PS = 15 cmH2O above PEEP
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Any worsening ventilation must be flagged to the ICU registrar/consultant
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Complications
Complications
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Mask intolerance
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Gastric insufflation
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Reflux
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Pressure injuries on face
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Airway dryness, inspissated secretions
Signs of Failure
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Progressive respiratory distress
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Rising respiratory rate
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Persistent tachypnoea
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Worsening pH, PCO2, SpO2, PO2 despite NIV (1 - 2 hours)
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Deteriorating conscious state
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Mucous plugging
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Aspiration
Author: Dr. Hector-Jack Cheung, Peer Reviewer: Dr. James Douglas Date: 22/03/20