Non-Invasive Ventilation (NIV)


  • Non-invasive ventilation (NIV) is the application of respiratory support via a sealed face-mask, nasal mask, mouthpiece, full face visor or helmet without the need for intubation
  • In the modern era it implies the application of positive airway pressure, however some classifications include the application of a negative-pressure generator to the chest (‘iron lung’) as NIV
  • Positive pressure ventilatory support may be with CPAP or bi-level modes and delivered by a range of ventilators from specifically designed devices to full-service ICU ventilators
  • NIV decreases resource utilisation compared with invasive ventilation and avoids the associated complications.
  • Patient selection and a well-designed clinical protocol are important to avoid delaying intubation in patients who are not suitable for and/or failing NIV


Negative pressure (cyclical)

  • iron lung chest box
  • used for COPD, neuromuscular disease

Positive pressure (non-cyclical)

  • continusous positive airway pressure (CPAP)
  • used for acute pulmonary edema, asthma, obstructive sleep apnoea (OSA)

Positive pressure (cyclical)

  • Bilevel positive airway pressure (BIPAP), inspiratory positive airway pressure (IPAP), pressure support ventilation (PSV) and positive pressure ventilation (PPV)
  • used for COPD, weaning, asthma, neuromuscular disease

Positive and negative pressure (cyclical)

  • cough assist
  • used for neuromuscular disease


NIV can reverse many of the physiological and mechanical derangements associated with respiratory failure:

  • augmentation of alveolar ventilation, helps reverse acidosis and hypercapnoea
  • alveolar recruitment and increased FiO2, helps reverse hypoxia
  • reduction in work of breathing and respiratory effort/ fatigue
  • stabilisation of chest wall in the presence of chest trauma/surgery
  • reduction in left ventricular afterload, improves LV function
  • counterbalances the respiratory workload and/or reduces respiratory muscle effort, helps maintain alveolar ventilation and prevents exhaustion


Primarily for hypercapnea

  • acute exacerbation of COPD – decrease work of breathing and unload respiratory muscles
  • post extubation acute respiratory failure — planned strategy in selected patients
  • Obstructive sleep apnoea / Obesity hypoventilation syndrome
  • cystic fibrosis — e.g. bridge to transplant
  • patients awaiting lung transplantation
  • acute asthma (see Non-Invasive Ventilation and Asthma)

Primarily for hypoxaemia

  • cardiogenic pulmonary oedema – alveolar recruitment, decreased afterload, decreased work of breathing
  • post operative respiratory failure – in selected patients
  • post-traumatic respiratory failure — rib fractures
  • respiratory failure in AIDS and other immunosuppressed states
  • patient not candidates for intubation/ treatment limitation orders who may qualify for HDU admission or admission to respiratory care units
  • Pre-oxygenation prior to intubation

In reality, NIV is often used for a combination (to varying extents) of hypoxaemia, hypercapnia and respiratory weakness regardless of the underlying diagnosis


  • Younger age
  • Unimpaired conscious state
  • Moderate rather than severe hypercarbia
  • Rapid improvement in physiological parameters


  • Cardiac / respiratory arrest
  • Inability to protect airway – poor cough, excessive/ inability to clear secretions, decreased conscious state/ coma
  • upper airway obstruction
  • untreated pneumothorax
  • marked haemodynamic instability (e.g. shock, ventricular dysrhythmias, severe acute myocardial ischaemia GI bleeding)
  • Following upper GI surgery (some debate about this)
  • Maxillofacial surgery
  • base of skull fracture (risk of pneumocephalus)
  • patient refusal
  • staff inexperience
  • Intractable vomiting


Starting NIV

  • patient reassurance
  • well fitted mask with straps (nasal, full face or helmet)
  • set appropriate FiO2
  • time or flow cycled
  • start at low pressures e.g. 10/5 cmH2O or CPAP 5 cmH20
  • increase pressures by 2-3 cmH20 every 5 minutes until satisfactory response (up to 15-17 max)
  • reassess after 60 minutes plus ABG

Weaning NIV

  • typical approach is trial periods off NIV during the day (e.g. 1 hour off and 2 hours) with overnight rest on NIV
  • if patient condition markedly improves NIV can be stopped abruptly
  • monitor closely for respiratory fatigue or deterioration

The use of NIV for preventing post-extubation respiratory failure is discussed in the CC entry titled Non-Invasive Ventilation for Weaning.


  • pressure ulcers/necrosis (nasal bridge)
  • facial or ocular abrasions
  • claustrophobia/anxiety
  • agitation
  • air swallowing with gastric/ abdominal distension, potentially leading to vomiting and aspiration
  • hypotension if hypovolaemic
  • aspiration
  • oronasal mucosal dryness
  • raised ICP
  • increased intraocular pressure
  • impaired communication
  • impaired nutrition


Summary of evidence for the use of NIV:

  • APO – studies show decreased intubation rate and faster time to resolution of respiratory failure and reduction in mortality and hospital length of stay
  • COPD – RCTs and Cochrane review (14 RCTs) showed significant improvement in intubation rates, complications, length of hospital stay and mortality rates for NIV compared with invasive ventilation
  • Immunocompromised – – 2 studies, one looking at solid organ transplant recipients and one looking at patients with haematological malignancy showed benefit with NIV, i.e. fewer intubations, complications and reduced ICU and hospital mortality
  • Asthma – probably beneficial but limited evidence
  • Rib fractures – fewer episodes of pneumonia but no mortality benefit and limited evidence

Summary of evidence against the use of NIV:

  • Use as rescue strategy for failed extubation – delays time to re-intubation. May be of benefit as part of weaning strategy and planned intervention post extubation especially in COPD patients
  • ARDS – not recommended as first line therapy

Cardiogenic Pulmonary Oedema

  • improves respiratory function using above mechanisms
  • also allows for redistribution of extravascular lung water back into interstitial space through recruitment and surfactant production
  • e.g. CPAP at ~ 10cmH2O
  • BIPAP increased risk of MI in one study, but not born out
  • over 20 RCTs show improvements in:

-> respiratory failure -> need to intubate -> hospital LOS -> survival -> duration of respiratory support (MV vs NIV)

Chronic Obstructive Pulmonary Disease

  • often respond to both CPAP but also need BIPAP
  • over 14 RCTs show improvements in:

-> hypercapnic respiratory failure -> intubation rates -> hospital mortality -> nosocomial pneumonia


  • CPAP 5cmH2O and BiLevel

-> significant increase in FEV1 -> significant decrease in hospital admission rates


  • little supportive evidence for NIV

-> high failure rates

Pneumonia and the Immunocompromised

  • MV is associated with high morbidity and mortality in these patients
  • thus may benefit from a reduction in intubation and MV

Post-operative and Post-traumatic Acute Respiratory Failure

  • CPAP improves oxygenation and respiratory rate in general surgical and cardiothoracic patients with mild hypoxaemia.
  • outcome data is less clear

NIV-assisted Weaning

  • COPD patients respond well if used as a prophylactic measure, can be used for rescue but must not delay intubation if indicated
  • not so clear cut for other patients

Sleep Apnoea Syndromes

  • CPAP can reverse the chronic changes associated with chronic hypoxia
  • if there is a central component, BiLevel or controlled ventilation can be used until can be weaned to CPAP

Chronic Hypoventilation Syndromes

  • neuromuscular disease
  • no real benefit in stable COPD

Blunt chest injury

  • beneficial for prevention of respiratory failure, evidence unclear for rescue


  • Role of NIV in the critically ill includes APO and respiratory failure in COPD and immunosuppressed patients
  • Use NIV as a planned strategy post-extubation in selected patients and as ventilatory support for patients with respiratory failure and treatment directives limiting care
  • Avoid the use of NIV to delay or withhold intubation in those who need it

CCC Ventilation Series

Journal articles

  • Duggal A, Perez P, Golan E, Tremblay L, Sinuff T. The safety and efficacy of noninvasive ventilation in patients with blunt chest trauma: a systematic review. Crit Care. 2013 Jul 22;17(4):R142. [Epub ahead of print] PubMed PMID: 23876230.
  • Esquinas Rodriguez AM, Scala R, Soroksky A, BaHammam A, de Klerk A, Valipour A, Chiumello D, Martin C, Holland AE. Clinical review: humidifiers during non-invasive ventilation–key topics and practical implications. Crit Care. 2012 Feb 8;16(1):203. doi: 10.1186/cc10534. Review. PubMed PMID: 22316078; PubMed Central PMCID: PMC3396215.
  • Garpestad E, Brennan J, Hill NS. Noninvasive ventilation for critical care. Chest. 2007 Aug;132(2):711-20. Review. PubMed PMID: 17699147. [Free Full Text]
  • Keenan, S. et.al. (2011). Clinical practice guidelines for the use of noninvasive positive-pressure ventilation and noninvasive continuous positive airway pressure in the acute care setting. Canadian Medical Association Journal. PMID: 21324867
  • McNeill GBS, Glossop AJ. Clinical applications of non-invasive ventilation in critical care Contin Educ Anaesth Crit Care Pain (2012) 12 (1): 33-37. doi: 10.1093/bjaceaccp/mkr047 [Free Full Text]
  • Nava S, Hill N. Non-invasive ventilation in acute respiratory failure. Lancet. 2009 Jul 18;374(9685):250-9. doi: 10.1016/S0140-6736(09)60496-7. Review. PubMed PMID: 19616722.
  • Nava S, Navalesi P, Carlucci A. Non-invasive ventilation. Minerva Anestesiol. 2009 Jan-Feb;75(1-2):31-6. Epub 2008 Apr 19. Review. PubMed PMID: 18421257.
  • Ram FS, Picot J, Lightowler J, Wedzicha JA. Non-invasive positive pressure ventilation for treatment of respiratory failure due to exacerbations of chronic obstructive pulmonary disease. Cochrane Database Syst Rev. 2004;(3):CD004104. Review. PubMed PMID: 15266518.
  • Vital FM, Ladeira MT, Atallah AN. Non-invasive positive pressure ventilation (CPAP or bilevel NPPV) for cardiogenic pulmonary oedema. Cochrane Database Syst Rev. 2013 May 31;5:CD005351. doi: 10.1002/14651858.CD005351.pub3. PubMed PMID: 23728654.

FOAM and web resources

Last update: [last-modified]

Critical Care


Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

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