Noninvasive Positive Pressure Ventilation

Noninvasive positive pressure ventilation (NIV) delivers ventilatory support through a tight-fitting mask or interface rather than an endotracheal tube, providing the benefits of positive-pressure support while avoiding intubation and its complications. It is a first-line option for selected forms of acute respiratory failure, most clearly the hypercapnic failure of chronic obstructive pulmonary disease exacerbations and cardiogenic pulmonary edema.

Definition

Noninvasive positive pressure ventilation is the delivery of assisted ventilation through a non-invasive interface such as a face or nasal mask, commonly as bilevel support that combines a higher inspiratory pressure to augment ventilation with a lower expiratory pressure to maintain airway and alveolar recruitment, applied without an artificial airway.

Scope

This entry describes the principles of mask-delivered positive-pressure support, the indications best supported by evidence, the importance of patient selection and monitoring, and the relationship of NIV to high-flow nasal oxygen and to intubation. It is a reference and educational topic and is not a source of settings or treatment instructions for individual patients.

Core questions

• How does noninvasive ventilation differ from invasive mechanical ventilation?
• In which forms of acute respiratory failure is NIV most clearly beneficial?
• Why does careful patient selection and monitoring matter so much for NIV?
• How do NIV and high-flow nasal oxygen relate to each other?

Key concepts

• Mask or non-invasive interface
• Bilevel positive airway pressure
• Inspiratory and expiratory positive airway pressure
• Unloading of respiratory muscles
• Avoidance of intubation
• Patient selection and NIV failure
• High-flow nasal oxygen

Mechanisms

NIV applies positive airway pressure through a mask to support breathing without an artificial airway. The inspiratory pressure augments tidal ventilation and unloads the respiratory muscles, lowering the work of breathing and improving carbon dioxide clearance, which is especially valuable in hypercapnic failure; the expiratory pressure counteracts intrinsic positive end-expiratory pressure, helps keep alveoli open, and improves oxygenation. By avoiding intubation, NIV averts the risks of an artificial airway, but it depends on an alert, cooperative patient who can protect the airway and tolerate the interface, and failure of NIV that delays needed intubation can be harmful (Tobin-2013-textbook; Rochwerg-2017-guideline).

Clinical relevance

NIV is a widely used alternative to intubation in selected acute respiratory failure and shapes how clinicians appraise the evidence on respiratory support. This entry explains where the evidence is strongest and why selection matters; it describes concepts and evidence and is not a basis for individual diagnostic or treatment decisions.

Epidemiology

Use of noninvasive ventilation for acute respiratory failure expanded substantially from the 1990s onward, becoming a first-line strategy for chronic obstructive pulmonary disease exacerbations and cardiogenic pulmonary edema, while its role in hypoxemic failure is more variable and carries a higher risk of failure requiring intubation (Rochwerg-2017-guideline; Frat-2015).

Evidence & guidelines

Randomised evidence showed that NIV reduces the need for intubation and improves outcomes in acute exacerbations of chronic obstructive pulmonary disease (Brochard-1995), and professional-society guidelines give strong recommendations for NIV in hypercapnic COPD exacerbations and cardiogenic pulmonary edema while being more cautious in de novo hypoxemic failure (Rochwerg-2017-guideline). A separate trial raised the alternative of high-flow nasal oxygen in hypoxemic failure (Frat-2015). This entry summarises these findings without specifying settings.

History

Noninvasive positive-pressure support grew out of the application of mask ventilation and continuous positive airway pressure, and a landmark 1995 randomised trial demonstrated that NIV reduced intubation and mortality in COPD exacerbations, establishing it as a first-line therapy (Brochard-1995). Subsequent decades extended its use to cardiogenic pulmonary edema and clarified its limits in hypoxemic failure, culminating in international guidelines and in trials exploring high-flow nasal oxygen as an alternative (Rochwerg-2017-guideline; Frat-2015).

Debates

What is the role of NIV in de novo hypoxemic respiratory failure?

Unlike its well-established role in hypercapnic COPD and cardiogenic edema, NIV in hypoxemic failure carries a higher failure rate, and whether it or high-flow nasal oxygen should be preferred, and how to avoid harmful delays to intubation, remains contested.

Key figures

• Laurent Brochard
• Nicholas S. Hill
• Stefano Nava
• Bram Rochwerg

Seminal works

• brochard-1995
• rochwerg-2017-guideline

Frequently asked questions

When is noninvasive ventilation most clearly beneficial?

The strongest evidence supports NIV in hypercapnic respiratory failure from acute exacerbations of chronic obstructive pulmonary disease and in acute cardiogenic pulmonary edema, where it reduces the need for intubation.

Why can noninvasive ventilation fail?

NIV requires a cooperative patient who can protect the airway and tolerate the mask; it may fail when respiratory failure is severe, secretions or aspiration risk are high, or consciousness is impaired, and a failing trial that delays needed intubation can be harmful.