Continuum of non-invasive ventilation therapy


SectionRecommendationGrade of recommendation


Assessment of mask fit, interface type, head strap tightness, skin integrity of mask contact point, ventilation synchrony and degree of mask leak are to be completed each time the interface is adjusted and at least second hourly (1, 2).



Interventions to prevent pressure injury secondary to the interface are to be implemented on commencement of NIV.



When deterioration in skin integrity is identified, immediate strategies are to be employed to reduce further injury (1,3).


The evidence review for these recommendations was current to December 2012. Clinicians are advised to check the literature as research may have been published that change these recommendations .

The frequency of NIV use in the management of patients with acute respiratory failure has increased over the past decade. One of the factors that have been identified in contributing to the successful application of NIV and patient compliance is the choice of a suitable interface (4).

There are four types of mask interfaces available for use with NIV:

  • oro-nasal mask
  • nasal mask
  • total face mask (TFM)
  • helmet.

A practice survey audit of NSW ICUs in late 2012 revealed that of the 39 units surveyed, all used the oro-nasal mask, 13 used the TFM, three used nasal masks and only one used the helmet.

Mask (or interface) intolerance may be attributed to several factors:

  • discomfort, claustrophobia or poor fit
  • excessively tightened straps
  • excessive air leak
  • patient ventilator asynchrony
  • skin breakdown, especially on the bridge of the nose
  • oronasal dryness.

The oronasal mask covers the nose and mouth and is commonly used and associated with the successful delivery of NIV. They allow mouth breathing and reduce air leaks (5). However, they may cause patient discomfort, skin breakdown, and air leak due to poor fit over the bridge of the nose or mandible. In addition, they interfere with speech, eating and expectoration (4).

The nasal mask covers the nose only. These masks are associated with less reliable delivery of set pressures as they permit more air leakage through the mouth (5).

Total face masks are larger and cover the whole face. The air seal created around the perimeter of the face eliminates some of the air leak. It also prevents pain and skin damage to the bridge of the nose. Some of its limitations include claustrophobia, increased oronasal dryness and these masks can be difficult to fit and may be associated with greater patient intolerance (6).

The helmet is a special interface device designed to contain the head of the patient completely and it provides a seal all around the patient’s neck. The helmet may have several advantages compared to other interfaces. It allows relatively free movement of the head while maintaining a good seal without compression on the face or head.  The lack of pressure points on the face avoids the main complications associated with the use of a face mask: intolerance, pain and skin necrosis (7). However, concerns in relation to use of helmets with hypercapnic patients include less efficient correction of PaCO2 (8) and increased patient ventilator asynchrony compared with face masks (9).

Oronasal masks are generally preferred to other interfaces when initiating NIV in patients with acute respiratory failure (10). Although nasal masks may be more comfortable for some patients (11) and have been associated with less claustrophobia, however the rate of NIV failure appears to be higher, most likely due to mouth leaks (12). Pressure injuries, especially over the nasal bridge, occur with both types of mask. Even with prophylactic dressings, around 50% of patients will still develop pressure injuries (3).

When using simple bilevel devices and single limb ventilator circuits, the interface used needs to have a low dynamic dead space to prevent CO2 rebreathing. This can be achieved by ensuring that the intentional leak ports are positioned within the mask itself rather than between the mask and tubing (13, 14).

Practice point 1 - Preventing pressure injury

Prior to commencement of NIV or as soon as practicable, proactive pressure injury prevention measures should be taken. These include use of specialist devices to prevent tubing (e.g. a nasogastic tube) from being pressed into the skin and the use of protective interfaces such as a hydrocolloid dressing. When deterioration in skin integrity is identified, additional strategies need to be implemented to minimise further injury. These may include: changing the interface (consider full face mask) (6), and repositioning of the interface so as to ensure the mask is not pressing on the bridge of the nose or that the straps are not pressing into the skin.

Initiation and titration of therapy

SectionRecommendationGrade of recommendation


a) Initial settings for bi-level positive airway pressure (BPAP): inspiratory positive airway pressure (IPAP) of 10cmH2O and expiratory positive airway pressure (EPAP) of 4-5cmH2O= pressure support (PS) level of 5-6cm H2O (1, 15).

b) Initial settings for continuous positive airway pressure (CPAP): 5cm H20 (1, 15)



Increases to IPAP of 2-5cmH2O can be undertaken every 10 minutes or as clinically indicated until therapeutic response is achieved. The maximum IPAP should not exceed 20 – 23 cmH2O (1).



The target tidal volume of 6-8mls/kg (ideal body weight) is the target for all adult patients (2).



Optimal non-invasive positive pressure ventilation (NIV) is the lowest pressure and lowest Fi02 that achieve Sa02 of 90% or Pa02 of 60mmHg without further clinical deterioration (16).


The evidence review for these recommendations was current to December 2012. Clinicians are advised to check the literature as research may have been published that change these recommendations .

An initial inspiratory positive pressure (IPAP) of 10cmH20 and expiratory positive airway pressure (EPAP) of 4-5 cmH20 should be used (1, 2, 15, 16). Note that IPAP-EPAP=Pressure support (PS) level.  A tidal volume of 6-8ml/kg should be aimed for (2).

Practice point 2 - Bilevel positive airway pressure settings and pressure support

On many bilevel positive airway pressure specific ventilators IPAP - EPAP= PS.  However if using an invasive ventilator in NIV mode the PS level may be above PEEP meaning that PEEP + PS = IPAP (Peak Inspiratory Pressure). It is important to be familiar with the ventilator used at the individual site to ensure that the patient receives the required pressure support level.

IPAP should be increased by 2-5cm increments at a rate of approximately 5 cmH20 every ten minutes or as clinically indicated with a usual pressure target of 20 cmH20 or either a therapeutic response is achieved (1) or patient tolerability has been reached (2).

Acutely ill patients are to be under direct visual observation by appropriately qualified staff. At a minimum, qualified nursing staff must be present at the bedside to provide continuous monitoring and visual observation of the patient’s tolerance of NIV until the patient is stable (1, 2, 15, 16). Patients at high risk of adverse complications, including patients who have a decreased level of consciousness secondary to raised CO2 level or those who are confused and hypoxic, are to remain under constant direct observation until their condition has improved.

Optimal NIV (therapeutic response) is defined as the lowest pressure level of NIV and lowest FiO2 which maintains SaO2 at 90% or PaO2 60 mmHg without further deterioration of any clinical parameters (16).


SectionRecommendationGrade of recommendation


All NIV circuits are to be actively humidified (17).



Heat moisture exchangers (HMEs) are not recommended for NIV (17).



Gas temperatures during NIV are to be based on patient comfort (17).


The evidence review for these recommendations was current to December 2012. Clinicians are advised to check the literature as research may have been published that change these recommendations .

The natural human airway heats and humidifies inspired gas, reaching a temperature of 37°C and 100% relative humidity. NIV increases demand on the normal airway. Demand can manifest itself by increasing heat and water loss resulting in drying of the respiratory mucosa leading to respiratory compromise. This may manifest itself as increased mucus viscosity, difficulty in sputum clearance, sputum retention, increase airway resistance, decreased pulmonary compliance and atelectasis (18). The gas required to deliver NIV combines both entrainment of room air containing ambient humidity and pipeline supplemental oxygen, which is dry gas. Ventilation machines with an inbuilt oxygen blender mix both the ambient and pipeline gas delivered through the circuit. The success of NIV depends on the patient‘s tolerance of therapy and level of comfort (19). To aid success inline humidification will complement and enhance normal airway humidification.

There are two inline humidification circuits available for consideration. Heat and moisture exchangers (HME) provide passive humidification and heated humidification provides active humidification. Critical care areas have extensive experience with HMEs as they have been used for the delivery of humidification for invasive ventilation. They are used because of their simplicity and low cost (20). However it must be accepted that when HMEs are placed inline they increase dead space within the circuit. This dead space can increase resistance to flow and increase the patient’s work of breathing (WOB) (21). For the delivery of NIV an increase in work of breathing may decrease patient compliance to therapy (22). In addition, mask and mouth leak can occur when using HMEs. This may render the HME less efficient as the purpose of an HME is to capture expired tidal volume moisture so it is not lost to atmosphere (21). It is worth noting that Boyer (23) found no differences in respiratory outcomes, including respiratory rate, end tidal CO2, minute ventilation, oxygen saturation, ABG and comfort perception when comparing active and passive humidification.

Heated humidification (HH) requires the movement of gas through a heated water chamber. This results in the delivery of increased humidity during NIV therapy to decrease airway resistance, improve ventilation and improve the removal of secretions.(18). The advantage of this is twofold: first, continuous humidification can be delivered even in the event of mask and/or mouth leaks and second, temperature adjustments can be made to improve patient comfort and thereby increase patient tolerance. It is worth highlighting that studies by Holland (18) found that as IPAP is increased relative humidity is reduced although at higher humidifier temperatures this was less significant.

Grading of recommendations

Grade of recommendation



Body of evidence can be trusted to guide evidence


Body of evidence can be trusted to guide practice in most situations


Body of evidence provides some support for recommendation/s but care should be taken in its application


Body of evidence is weak and recommendation must be applied with caution


Consensus was set as a median of ≥ 7

Grades A–D are based on NHMRC grades (24)


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  2. Vargas F, Thille A, Lyazidi A, Campo FR, Brochard L. Helmet with specific settings versus facemask for noninvasive ventilation. Crit Care Med. 2009;37(6):1921-8.
  3. Weng M-H. The effect of protective treatment in reducing pressure ulcers for non-invasive ventilation patients. Intensive and Critical Care Nursing. 2008;24(5):295-9.
  4. Ozsancak A, Sidhom SS, Liesching TN, Howard W, Hill NS. Evaluation of the total face mask for noninvasive ventilation to treat acute respiratory failure. Chest. 2011;139(5):1034-41.
  5. Kwok H, McCormack J, Cece R, Houtchens J, Hill NS. Controlled trial of oronasal versus nasal mask ventilation in the treatment of acute respiratory failure. Critical care medicine. 2003;31(2):468-73.
  6. Holanda MA, Reis RC, Winkeler GF, Fortaleza SC, Lima JW, Pereira ED. Influence of total face, facial and nasal masks on short-term adverse effects during noninvasive ventilation. J Bras Pneumol. 2009;35(2):164-73.
  7. Patroniti N, Foti G, Manfio A, Coppo A, Bellani G, Pesenti A. Head helmet versus face mask for non-invasive continuous positive airway pressure: a physiological study. Intensive Care Med. 2003;29(10):1680-7.
  8. Taccone P, Hess D, Caironi P, Bigatello LM. Continuous positive airway pressure delivered with a “helmet”: Effects on carbon dioxide rebreathing*. Critical care medicine. 2004;32(10):2090-6.
  9. Navalesi P, Costa R, Ceriana P, Carlucci A, Prinianakis G, Antonelli M, et al. Non-invasive ventilation in chronic obstructive pulmonary disease patients: helmet versus facial mask. Intensive Care Med. 2007;33(1):74-81.
  10. Crimi C, Noto A, Princi P, Esquinas A, Nava S. A European survey of noninvasive ventilation practices. European Respiratory Journal. 2010;36(2):362-9.
  11. Navalesi P, Fanfulla F, Frigerio P, Gregoretti C, Nava S. Physiologic evaluation of noninvasive mechanical ventilation delivered with three types of masks in patients with chronic hypercapnic respiratory failure. Critical care medicine. 2000;28(6):1785-90.
  12. Kwok H, McCormack J, Cece R, Houtchens J, Hill NS. Controlled trial of oronasal versus nasal mask ventilation in the treatment of acute respiratory failure. Crit Care Med. 2003;31(2):468-73.
  13. Schettino G, Altobelli N, Kacmarek RM. Noninvasive positive pressure ventilation reverses acute respiratory failure in select" do-not-intubate" patients. Critical care medicine. 2005;33(9):1976-82.
  14. Saatci E, Miller D, Stell I, Lee K, Moxham J. Dynamic dead space in face masks used with noninvasive ventilators: a lung model study. European Respiratory Journal. 2004;23(1):129-35.
  15. Plant P, Owen J, Elliott M. Early use of non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease on general respiratory wards: a multicentre randomised controlled trial. The Lancet. 2000;355(9219):1931-5.
  16. Cross AM, Cameron P, Kierce M, Ragg M, Kelly AM. Non-invasive ventilation in acute respiratory failure: a randomised comparison of continuous positive airway pressure and bi-level positive airway pressure. Emerg Med J. 2003;20(6):531-4.
  17. Restrepo RD, Walsh BK. Humidification during invasive and noninvasive mechanical ventilation: 2012. Respir Care. 2012;57(5):782-8.
  18. Holland AE, Denehy L, Buchan CA, Wilson JW. Efficacy of a heated passover humidifier during noninvasive ventilation: a bench study. Respir Care. 2007;52(1):38-44.
  19. Oto J, Imanaka H, Nishimura M. Clinical factors affecting inspired gas humidification and oral dryness during noninvasive ventilation. J Crit Care. 2011;26(5):23.
  20. Lellouche F, Pignataro C, Maggiore SM, Girou E, Deye N, Taillé S, et al. Short-Term Effects of Humidification Devices on Respiratory Pattern and Arterial Blood Gases During Noninvasive Ventilation. Respiratory care. 2012;57(11):1879-86.
  21. Branson RD, Gentile MA. Is humidification always necessary during noninvasive ventilation in the hospital? Respir Care. 2010;55(2):209-16.
  22. Jaber S, Michelet P, Chanques G. Role of non-invasive ventilation (NIV) in the perioperative period. Best Pract Res Clin Anaesthesiol. 2010;24(2):253-65.
  23. Boyer A, Vargas F, Hilbert G, Gruson D, Mousset-Hovaere M, Castaing Y, et al. Small dead space heat and moisture exchangers do not impede gas exchange during noninvasive ventilation: a comparison with a heated humidifier. Intensive care medicine. 2010;36(8):1348-54.
  24. NHMRC. Australian Guidelines for the Prevention and Control of Infection in Healthcare. Canberra: Commonwealth of Australia; 2010.


The information on this page is general in nature and cannot reflect individual patient variation. It reflects Australian intensive care practice, which may differ from that in other countries. It is intended as a supplement to the more specific information provided by the doctors and nurses caring for your loved one. ICNSW attests to the accuracy of the information contained here but takes no responsibility for how it may apply to an individual patient. Please refer to the full disclaimer.