Noninvasive Positive Pressure Ventilation (NPPV)

Noninvasive positive pressure ventilation is a method of supporting breathing without inserting an endotracheal tube or creating a tracheostomy. Positive pressure is delivered through an external interface, such as a nasal, oronasal, full-face, total-face, or helmet-style device.

The therapy can improve oxygenation, increase ventilation, reduce respiratory muscle workload, and help selected patients avoid invasive mechanical ventilation. Its success depends on careful patient selection, appropriate pressure settings, proper mask fit, close monitoring, and early recognition of treatment failure.

What Is Noninvasive Positive Pressure Ventilation?

Noninvasive positive pressure ventilation (NPPV) provides respiratory support while preserving the patient’s natural airway. It is also frequently called noninvasive ventilation (NIV).

During invasive mechanical ventilation, gas is delivered through an endotracheal or tracheostomy tube. With NPPV, the ventilator connects to an external interface placed over the nose, mouth, or face.

Because an artificial airway is not used, the patient may retain the ability to:

• Speak
• Swallow
• Cough
• Clear secretions
• Communicate with caregivers
• Eat or drink during scheduled breaks

However, the natural airway is not protected from aspiration. The patient must therefore remain capable of controlling the upper airway, managing secretions, and maintaining adequate spontaneous breathing.

The major purposes of NPPV are to:

• Reduce the work of breathing
• Rest fatigued respiratory muscles
• Improve tidal volume
• Increase alveolar ventilation
• Lower an elevated arterial carbon dioxide level
• Increase functional residual capacity
• Recruit collapsed alveoli
• Improve oxygenation
• Prevent or delay endotracheal intubation

NPPV is used in acute respiratory failure, chronic hypoventilation, sleep-related breathing disorders, neuromuscular weakness, restrictive thoracic conditions, and selected post-extubation situations.

How Noninvasive Ventilation Works

Gas moves into the lungs when pressure at the airway opening is greater than pressure inside the respiratory system. NPPV creates this pressure difference without requiring an artificial airway.

The amount of support delivered depends on several factors, including:

• Inspiratory pressure
• Expiratory pressure
• Patient effort
• Lung compliance
• Airway resistance
• Respiratory rate
• Inspiratory time
• Mask leakage
• Patient-ventilator synchrony

Note: Two common forms of noninvasive positive-pressure support are continuous positive airway pressure and bilevel positive airway pressure.

Continuous Positive Airway Pressure

Continuous positive airway pressure (CPAP) provides one constant pressure throughout inspiration and expiration.

The patient must breathe spontaneously because CPAP does not provide a separate inspiratory boost. It does not directly increase tidal volume in the same way that pressure support does.

CPAP mainly improves oxygenation by:

• Increasing functional residual capacity
• Preventing alveolar collapse
• Recruiting unstable lung units
• Reducing intrapulmonary shunting
• Keeping the upper airway open
• Increasing end-expiratory lung volume

CPAP is commonly used for:

• Obstructive sleep apnea
• Cardiogenic pulmonary edema
• Atelectasis
• Reduced functional residual capacity
• Upper-airway obstruction during sleep
• Selected cases of acute hypoxemia

Positive pressure may also decrease left ventricular afterload, which can improve cardiac performance in selected patients with acute heart failure.

Because CPAP does not provide direct ventilatory assistance, it may be inadequate for patients with severe respiratory muscle weakness, progressive fatigue, apnea, or significant carbon dioxide retention.

Bilevel Positive Airway Pressure

Bilevel positive airway pressure (BiPAP) provides two different pressure levels during the respiratory cycle:

• Inspiratory positive airway pressure
• Expiratory positive airway pressure

Inspiratory positive airway pressure, or IPAP, is the higher pressure delivered during inspiration. It assists the patient’s inspiratory effort and can increase tidal volume.

Expiratory positive airway pressure, or EPAP, is the lower pressure maintained during expiration. It functions similarly to positive end-expiratory pressure.

Effects of IPAP

IPAP primarily supports ventilation. Increasing IPAP can:

• Increase tidal volume
• Improve minute ventilation
• Reduce PaCO₂
• Reduce respiratory muscle workload
• Improve respiratory acidosis
• Decrease the effort required to inhale

Effects of EPAP

EPAP primarily supports oxygenation and airway stability. Increasing EPAP can:

• Prevent alveolar collapse
• Increase functional residual capacity
• Recruit unstable alveoli
• Improve oxygenation
• Reduce intrapulmonary shunting
• Maintain upper-airway patency
• Reduce obstructive apnea events

Pressure Support

The difference between IPAP and EPAP represents the pressure-support level.

For example:

• IPAP: 12 cm H₂O
• EPAP: 5 cm H₂O
• Pressure support: 7 cm H₂O

A larger difference between IPAP and EPAP generally produces greater inspiratory assistance and a larger tidal volume. If ventilation is inadequate, IPAP may be increased while EPAP remains unchanged. This widens the pressure difference and usually improves carbon dioxide removal.

If oxygenation is inadequate, EPAP may be increased. However, raising EPAP without raising IPAP decreases the pressure-support level. This may reduce tidal volume.

For that reason, IPAP is often increased by the same amount when EPAP is increased. Changing settings from 10/5 to 12/7 cm H₂O raises the baseline pressure while preserving 5 cm H₂O of pressure support.

Benefits of Noninvasive Positive Pressure Ventilation

When used successfully, NPPV can provide many benefits compared with invasive mechanical ventilation.

Potential advantages include:

• Avoidance of airway trauma from intubation
• Reduced need for sedation
• Lower risk of ventilator-associated pneumonia
• Preservation of natural airway defenses
• Improved communication
• Preservation of swallowing during breaks
• Reduced duration of mechanical ventilation
• Lower intubation rates
• Shorter intensive care stays
• Shorter hospital stays
• Lower treatment costs
• Greater patient comfort in selected cases

NPPV may also be used intermittently, allowing breaks for meals, skin care, airway clearance, hydration, communication, and oral hygiene.

These advantages do not mean NPPV is always safer than intubation. In an unsuitable patient, delayed invasive ventilation can lead to worsening respiratory failure, aspiration, cardiac arrest, or difficult emergency airway management.

Common Indications for NPPV

The strongest evidence for acute NPPV is found in patients with acute exacerbations of chronic obstructive pulmonary disease and acute cardiogenic pulmonary edema.

Other applications include chronic hypoventilation, sleep-related breathing disorders, neuromuscular weakness, and selected cases of post-extubation support.

COPD Exacerbation

An acute exacerbation of chronic obstructive pulmonary disease is one of the most established indications for bilevel NPPV.

During an exacerbation, worsening airflow obstruction may cause:

• Air trapping
• Dynamic hyperinflation
• Increased intrinsic PEEP
• Respiratory muscle fatigue
• Increased work of breathing
• Reduced tidal volume
• Alveolar hypoventilation
• Elevated PaCO₂
• Respiratory acidosis

Bilevel ventilation helps unload the respiratory muscles and improve effective ventilation.

Expected benefits include:

• Increased tidal volume
• Reduced respiratory rate
• Decreased accessory-muscle use
• Lower PaCO₂
• Rising pH
• Improved comfort
• Reduced dyspnea
• Reduced need for intubation

A suitable patient generally remains awake, cooperative, spontaneously breathing, and able to protect the airway.

The goal in a patient with chronic carbon dioxide retention is not always to normalize PaCO₂. Treatment commonly focuses on improving pH, reducing respiratory distress, and returning ventilation closer to the patient’s baseline.

Acute Cardiogenic Pulmonary Edema

Acute cardiogenic pulmonary edema is another major indication for noninvasive positive-pressure support.

Fluid accumulation and alveolar collapse can produce severe hypoxemia, tachypnea, and respiratory distress. Positive pressure can:

• Recruit fluid-filled or collapsed alveoli
• Increase functional residual capacity
• Improve oxygenation
• Reduce venous return
• Decrease left ventricular afterload
• Reduce the work of breathing

CPAP is often selected when hypoxemia is the main problem and the patient is ventilating adequately.

Bilevel ventilation may be preferred when pulmonary edema is accompanied by:

• Hypercapnia
• Respiratory acidosis
• Low tidal volume
• Respiratory muscle fatigue
• Inadequate ventilation

Note: Excessive pressure can reduce venous return and cardiac output. Blood pressure and mental status should therefore be monitored closely.

Obstructive Sleep Apnea

Obstructive sleep apnea occurs when the upper airway repeatedly collapses during sleep while respiratory effort continues.

CPAP acts as a pneumatic splint that holds the upper airway open.

Common findings associated with obstructive sleep apnea include:

• Loud snoring
• Witnessed apnea
• Daytime sleepiness
• Morning headaches
• Restless sleep
• Fatigue
• Obesity
• Increased neck circumference
• Hypertension

CPAP is often the preferred treatment when airway obstruction is the primary problem.

Bilevel support may be used when the patient:

• Cannot tolerate continuous pressure
• Requires a lower expiratory pressure
• Has persistent hypoventilation
• Retains carbon dioxide
• Has obesity-hypoventilation syndrome
• Has overlapping neuromuscular or restrictive disease

Obesity-Hypoventilation Syndrome

Obesity-hypoventilation syndrome involves obesity, sleep-related breathing abnormalities, and chronic daytime hypoventilation.

Patients may experience:

• Daytime hypercapnia
• Hypoxemia
• Morning headaches
• Excessive sleepiness
• Reduced concentration
• Poor sleep quality
• Right-sided heart strain
• Increased work of breathing

Note: Bilevel NPPV can improve nocturnal ventilation and reduce carbon dioxide retention. Some patients improve with CPAP when upper-airway obstruction is the dominant problem, while others require bilevel support.

Neuromuscular Disorders

Neuromuscular diseases may weaken the diaphragm and other respiratory muscles.

Conditions that may require long-term NPPV include:

• Amyotrophic lateral sclerosis
• Muscular dystrophy
• Spinal muscular atrophy
• High spinal cord injury
• Myasthenia gravis
• Other progressive neuromuscular disorders

Sleep-related hypoventilation may develop before daytime respiratory failure becomes obvious.

Possible symptoms include:

• Morning headaches
• Orthopnea
• Frequent nighttime awakening
• Daytime fatigue
• Reduced concentration
• Weak cough
• Recurrent respiratory infections
• Excessive sleepiness
• Unrefreshing sleep

Nocturnal NPPV can rest the respiratory muscles, improve ventilation, reduce symptoms, and prolong survival in selected neuromuscular conditions.

The ability to clear secretions remains important. Patients with weak cough may require cough-assist therapy, suctioning, manually assisted cough, or other airway-clearance techniques.

Restrictive Thoracic Disorders

Restrictive thoracic disorders can limit chest expansion and reduce tidal volume.

Examples include:

• Severe kyphoscoliosis
• Chest-wall deformities
• Post-polio syndrome
• Restrictive neuromuscular conditions
• Severe obesity
• Certain congenital skeletal abnormalities

Note: Nocturnal NPPV may improve ventilation, reduce carbon dioxide retention, and decrease symptoms of chronic hypoventilation.

Immunocompromised Patients

Selected immunocompromised patients with pulmonary infiltrates and respiratory distress may benefit from NPPV.

Avoiding intubation may reduce the risk of invasive-airway complications and infection. However, these patients can deteriorate rapidly.

NPPV should be stopped and invasive ventilation considered if the patient develops:

• Worsening hypoxemia
• Progressive respiratory distress
• Hemodynamic instability
• Declining consciousness
• Inability to manage secretions
• Severe fatigue

Asthma, Pneumonia, and Acute Hypoxemic Failure

NPPV may be attempted in selected cases of:

• Severe asthma
• Community-acquired pneumonia
• Postoperative respiratory failure
• Acute hypoxemic respiratory failure
• Acute lung injury
• Acute respiratory distress syndrome

Success is less predictable in these conditions than in COPD exacerbation or cardiogenic pulmonary edema. Patients with pneumonia or ARDS may initially appear stable and then deteriorate quickly. A trial should only be performed in a closely monitored setting with immediate access to intubation equipment and trained personnel.

Note: Persistent or worsening hypoxemia despite high oxygen concentrations and appropriate pressure settings is a major warning sign.

Post-Extubation Support

NPPV may be used during liberation from invasive mechanical ventilation.

Selected patients with COPD may be extubated directly to noninvasive support when they have difficulty completing a spontaneous breathing trial but are otherwise appropriate for extubation.

Preventive NPPV may also reduce reintubation risk in selected high-risk patients.

Potential high-risk features include:

• COPD
• Chronic hypercapnia
• Heart failure
• Weak cough
• Advanced age
• Prolonged mechanical ventilation
• Repeated failed spontaneous breathing trials

Note: Routine use after post-extubation respiratory failure has already developed may delay needed reintubation. When a patient worsens after extubation, the clinician must identify the cause and determine whether noninvasive support is likely to reverse the problem.

Palliative and Do-Not-Intubate Use

NPPV may be used in patients who do not wish to receive invasive mechanical ventilation.

The treatment goal should be clearly defined.

Possible goals include:

• Reversing a treatable episode without intubation
• Prolonging life while respecting treatment limitations
• Relieving dyspnea
• Reducing respiratory muscle fatigue
• Supporting communication with family
• Providing comfort near the end of life

Note: The interface may cause discomfort or anxiety. Treatment should be continued only when it is consistent with the patient’s goals and provides meaningful benefit.

Patient Selection

Appropriate patient selection is one of the strongest predictors of NPPV success.

A suitable patient should generally:

• Be breathing spontaneously
• Have an adequate respiratory drive
• Remain awake or easily arousable
• Cooperate with treatment
• Follow instructions
• Protect the airway
• Manage secretions
• Have an adequate cough
• Tolerate the interface
• Remain reasonably hemodynamically stable
• Have a condition expected to respond to positive pressure

Clinical findings that may support an NPPV trial include:

• Moderate to severe dyspnea
• Accessory-muscle use
• Paradoxical breathing
• Respiratory rate of at least 25 breaths per minute
• Hypercapnia
• Respiratory acidosis
• Low tidal volume
• Increased work of breathing
• Significant hypoxemia
• Signs of respiratory muscle fatigue

Note: NPPV is more likely to succeed when treatment begins before severe exhaustion, profound acidosis, shock, or altered mental status develops.

Contraindications and Exclusion Criteria

NPPV should not delay immediate airway management.

Major contraindications include:

• Respiratory arrest
• Cardiac arrest
• Apnea
• Inability to protect the airway
• Severe aspiration risk
• Active vomiting
• Copious secretions
• Inability to clear secretions
• Severe hemodynamic instability
• Uncontrolled arrhythmias
• Severe agitation
• Lack of cooperation
• Upper-airway obstruction
• Facial trauma
• Facial burns
• Recent facial surgery
• Abnormal facial anatomy preventing a seal
• Severe deterioration requiring immediate intubation

A severely reduced pH is associated with a higher risk of failure. A pH below approximately 7.20 is a major warning sign, although the overall clinical condition is more important than any single number.

Note: NPPV should be stopped when the patient no longer meets the requirements for safe noninvasive support.

Types of Interfaces

The interface has a major effect on comfort, leakage, pressure delivery, synchrony, and treatment success.

Nasal Mask

A nasal mask covers the nose only.

Advantages include:

• Less facial coverage
• Improved communication
• Easier coughing
• Reduced claustrophobia
• Greater comfort during long-term use

Disadvantages include:

• Mouth leakage
• Reduced pressure delivery
• Nasal dryness
• Nasal congestion
• Pressure injury
• Reduced effectiveness during acute distress

Note: Nasal masks are often suitable for stable patients, long-term home use, and obstructive sleep apnea.

Oronasal Mask

An oronasal mask covers both the nose and mouth. It is commonly preferred during acute respiratory failure because distressed patients frequently breathe through the mouth.

Advantages include:

• Reduced mouth leakage
• More reliable pressure delivery
• Better support at higher pressures
• Improved effectiveness during acute distress

Disadvantages include:

• Claustrophobia
• Difficulty communicating
• Skin pressure
• Aspiration risk during vomiting
• Reduced access to the mouth

Total-Face Mask

A total-face mask covers most or all of the face. It distributes pressure across a larger surface and may reduce pressure on the nasal bridge.

It may be useful when:

• A standard mask causes pressure injury
• Facial discomfort limits treatment
• Large leaks persist
• The patient cannot tolerate an oronasal mask

Nasal Pillows

Nasal pillows rest at the nostrils. They reduce facial contact and may be useful for long-term therapy.

Possible limitations include:

• Nasal irritation
• Dryness
• Nosebleeds
• Limited pressure tolerance
• Leakage
• Reduced effectiveness during severe acute failure

Helmet Interface

A helmet surrounds the patient’s head and seals around the neck. Potential advantages include reduced facial pressure and improved tolerance.

However, helmets have a large internal volume and different flow characteristics. They may affect carbon dioxide clearance, triggering, pressurization, noise, and synchrony. Ventilator settings should not be assumed to have the same effects as they would with a tightly fitting face mask.

Pediatric Interfaces

Pediatric patients may require nasal masks, nasal prongs, nasal pillows, nasal-oral masks, or custom interfaces. Infants and young children may be difficult to fit because standard masks may not match their facial dimensions.

Long-term pressure on the developing face may contribute to midface or maxillary changes. Interface fit, pressure points, and facial growth should be reassessed regularly.

Mask Fitting and Leak Management

The mask should produce an adequate seal without excessive strap tension.

Overtightening can cause:

• Nasal-bridge injury
• Skin breakdown
• Pain
• Anxiety
• Claustrophobia
• Facial pressure
• Poor tolerance

The mask may initially be held gently against the face while low pressure is applied. Once the patient becomes comfortable, the straps can be secured.

Air leakage can:

• Reduce delivered pressure
• Lower tidal volume
• Interfere with triggering
• Cause premature or delayed cycling
• Increase patient-ventilator asynchrony
• Dry the eyes
• Increase noise
• Reduce comfort
• Prevent adequate ventilation

Corrective actions include:

• Repositioning the mask
• Adjusting strap tension
• Selecting a different size
• Changing the interface type
• Inspecting tubing connections
• Correcting mouth leakage
• Adjusting trigger or cycle settings
• Using a chin strap with a nasal interface

Note: A minor leak may be acceptable if the patient remains comfortable and receives adequate ventilation and oxygenation.

Initial NPPV Settings

Initial settings should be individualized according to the patient’s condition, body size, gas exchange, comfort, and response.

A common starting point for acute bilevel support is:

• IPAP: 8 to 10 cm H₂O
• EPAP: 4 to 5 cm H₂O
• Backup rate: approximately 10 breaths per minute when needed
• Supplemental oxygen adjusted to the target saturation

For an acute COPD exacerbation, settings may begin near 10/5 cm H₂O and then be increased gradually.

Low initial pressures may improve tolerance. Pressure is then adjusted according to:

• Tidal volume
• Respiratory rate
• Accessory-muscle use
• Dyspnea
• Oxygen saturation
• PaCO₂
• pH
• Patient comfort
• Mask leakage

Adjusting Ventilation

Ventilation is mainly controlled by the pressure difference between IPAP and EPAP.

Signs of inadequate ventilation include:

• Low tidal volume
• Rising PaCO₂
• Persistent respiratory acidosis
• High respiratory rate
• Severe accessory-muscle use
• Poor chest expansion
• Continued dyspnea

IPAP is usually increased to improve ventilation. A common target tidal volume is approximately 6 to 8 mL/kg, although tidal volume should be interpreted with caution because mask leaks can affect displayed values.

IPAP should remain within a range that the patient can tolerate. Pressures above approximately 20 to 25 cm H₂O may increase:

• Mask leakage
• Gastric insufflation
• Abdominal distention
• Discomfort
• Aspiration risk

Adjusting Oxygenation

Oxygenation is primarily managed through:

• Supplemental oxygen
• EPAP
• Lung recruitment
• Treatment of the underlying condition

FiO₂ is usually adjusted first when oxygen saturation is low. EPAP may then be increased when additional alveolar recruitment or airway stabilization is needed.

When EPAP is increased, IPAP may also need to be increased to preserve pressure support.

For example:

• Initial setting: 10/5 cm H₂O
• Adjusted setting: 12/7 cm H₂O

Note: The pressure-support level remains 5 cm H₂O, while the higher expiratory pressure may improve oxygenation.

Timing and Backup Rate

Some bilevel devices allow the clinician to set:

• Backup respiratory rate
• Inspiratory time
• Trigger sensitivity
• Cycling sensitivity
• Rise time

A backup rate is useful when the patient’s respiratory drive is unreliable or when apnea may occur. The inspiratory-to-expiratory relationship should allow sufficient expiratory time, particularly in obstructive lung disease.

Patients with COPD may require a longer expiratory phase to reduce air trapping. An inspiratory-to-expiratory ratio near 1:3 or lower may be appropriate in some cases.

Monitoring During NPPV

The first one to two hours are especially important.

The clinician should monitor:

• Respiratory rate
• Heart rate
• Blood pressure
• Oxygen saturation
• Mental status
• Accessory-muscle use
• Breathing pattern
• Chest movement
• Tidal volume
• Minute ventilation
• Mask leak
• Patient comfort
• Skin condition
• Breath sounds
• Secretion clearance
• Patient-ventilator synchrony

Arterial blood gases may be obtained to evaluate:

• pH
• PaCO₂
• PaO₂
• Bicarbonate
• Response to treatment

Note: Capnography or transcutaneous carbon dioxide monitoring may also be useful in selected patients.

Signs of NPPV Success

Clinical improvement should occur relatively early in acute respiratory failure.

Signs of success include:

• Reduced respiratory rate
• Lower heart rate
• Improved comfort
• Reduced accessory-muscle use
• Improved chest movement
• Increased tidal volume
• Improved oxygen saturation
• Rising pH
• Falling PaCO₂
• Improved mental status
• Stable blood pressure
• Better patient-ventilator synchrony

Note: The ventilator functioning normally does not prove that treatment is successful. The patient’s clinical condition and gas exchange must improve.

Signs of NPPV Failure

Failure must be identified promptly.

Warning signs include:

• Worsening respiratory distress
• Persistent tachypnea
• Increasing accessory-muscle use
• Declining tidal volume
• Rising PaCO₂
• Worsening respiratory acidosis
• Refractory hypoxemia
• Declining consciousness
• Agitation or somnolence
• Hemodynamic instability
• Severe arrhythmias
• Inability to clear secretions
• Repeated vomiting
• Aspiration
• Poor mask tolerance
• Severe patient-ventilator asynchrony

If these findings persist despite correction of mask fit, leakage, oxygen delivery, and pressure settings, intubation should be considered promptly.

Delayed intubation may worsen outcomes, particularly in pneumonia, ARDS, severe hypoxemia, and rapidly progressive respiratory failure.

Common Complications

Most NPPV complications are minor, but serious complications can occur.

Common problems include:

• Mask discomfort
• Skin redness
• Pressure ulcers
• Nasal-bridge injury
• Claustrophobia
• Eye irritation
• Dry mouth
• Nasal dryness
• Nasal congestion
• Sinus discomfort
• Ear pain
• Gastric distention
• Abdominal discomfort
• Air leakage
• Sleep disruption

Serious complications include:

• Aspiration
• Pneumothorax
• Hypotension
• Severe gastric insufflation
• Delayed intubation
• Asphyxiation if gas flow fails with certain interfaces

Preventing Skin Injury

The bridge of the nose, cheeks, chin, and other pressure points should be inspected frequently.

Preventive strategies include:

• Avoiding excessive strap tension
• Repositioning the mask
• Alternating interface types
• Using protective skin barriers
• Applying hydrocolloid dressings
• Selecting a better-fitting mask
• Scheduling short breaks
• Keeping the skin clean and dry

Note: Persistent redness that does not resolve may indicate developing pressure injury.

Humidification During NPPV

High flow, air leakage, and prolonged use can cause dryness and thick secretions.

Heated humidification may improve:

• Nasal comfort
• Oral comfort
• Secretion clearance
• Treatment tolerance
• Long-term adherence

A heat-moisture exchanger is generally not recommended during NPPV because it adds dead space and resistance. It may contribute to carbon dioxide retention and increase the work of breathing.

Note: Humidification systems should be monitored for condensation that could interfere with the circuit or ventilator.

Gastric Distention and Aspiration Risk

Positive pressure may force gas into the stomach, particularly at higher inspiratory pressures.

Gastric distention can cause:

• Discomfort
• Reduced diaphragmatic movement
• Nausea
• Vomiting
• Increased aspiration risk

Note: The patient should be monitored for abdominal distention and nausea. Active vomiting is generally a contraindication to continued NPPV because the mask may interfere with rapid airway clearance.

Patient-Ventilator Asynchrony

Patient-ventilator asynchrony occurs when the ventilator does not match the patient’s breathing effort.

Common causes include:

• Excessive air leakage
• Poor trigger sensitivity
• Inappropriate cycling
• Incorrect inspiratory time
• Inadequate pressure support
• Excessive pressure support
• Mask discomfort
• Air trapping
• Weak inspiratory effort

Signs include:

• Missed triggers
• Double triggering
• Premature cycling
• Delayed cycling
• Visible distress
• Irregular chest movement
• Continued accessory-muscle use

Note: Correcting the leak is often the first step. Trigger, cycle, rise-time, pressure, and inspiratory-time settings may then be adjusted.

Weaning From NPPV

Weaning begins when the underlying condition has improved and the patient can maintain adequate breathing with less support.

Possible readiness findings include:

• Respiratory rate below 25 breaths per minute
• Heart rate below 110 beats per minute
• Reduced accessory-muscle use
• Improved mental status
• Stable blood pressure
• Compensated pH
• Acceptable PaCO₂
• Oxygen saturation above 90%
• FiO₂ below 50%
• IPAP below approximately 15 cm H₂O
• EPAP below approximately 10 cm H₂O

Weaning may involve:

• Lowering IPAP
• Lowering EPAP
• Reducing FiO₂
• Extending daytime breaks
• Removing support during meals
• Continuing support during sleep
• Assessing gas exchange off therapy

Note: Some patients receive one additional night of support after successful daytime withdrawal. Weaning is complete when ventilation, oxygenation, mental status, and work of breathing remain acceptable without assistance.

Pediatric Considerations

NPPV can be used in children with acute and chronic respiratory disorders.

Possible indications include:

• Neuromuscular weakness
• Restrictive chest-wall disease
• Congenital central hypoventilation
• Advanced cystic fibrosis
• Obesity-hypoventilation syndrome
• Obstructive sleep apnea
• Myelomeningocele
• Chronic respiratory failure
• Bridge to transplantation

Children may have difficulty understanding the treatment and may become frightened or agitated.

Other pediatric concerns include:

• Immature airway-protective reflexes
• Gastroesophageal reflux
• Small facial dimensions
• Poor mask fit
• Mouth leakage
• Retained secretions
• Nasopharyngeal obstruction
• Developing facial structures
• Limited ability to report discomfort

Family involvement, gradual introduction, distraction, reassurance, and careful interface selection may improve tolerance. The child should be monitored closely for worsening fatigue, altered consciousness, persistent agitation, reduced tidal volume, and deteriorating gas exchange.

Immediate access to intubation equipment and trained personnel is essential during treatment of acute pediatric respiratory failure.

Noninvasive Positive Pressure Ventilation Practice Questions

1. What is noninvasive positive pressure ventilation?
Noninvasive positive pressure ventilation is a method of supporting breathing through an external interface without inserting an endotracheal or tracheostomy tube.

2. What is another common abbreviation for noninvasive positive pressure ventilation?
It is commonly abbreviated as NPPV or NIV.

3. What is the primary purpose of NPPV?
The primary purpose is to improve ventilation, oxygenation, or both while reducing the work of breathing and potentially avoiding intubation.

4. What types of interfaces may be used to deliver NPPV?
Interfaces may include nasal masks, oronasal masks, full-face masks, total-face masks, nasal pillows, mouthpieces, and helmets.

5. How does CPAP differ from bilevel positive pressure ventilation?
CPAP provides one continuous pressure throughout the respiratory cycle, while bilevel ventilation provides separate inspiratory and expiratory pressures.

6. What is inspiratory positive airway pressure?
Inspiratory positive airway pressure, or IPAP, is the higher pressure delivered during inspiration to increase tidal volume and support ventilation.

7. What is expiratory positive airway pressure?
Expiratory positive airway pressure, or EPAP, is the lower pressure maintained during expiration to prevent airway and alveolar collapse.

8. How is pressure support calculated during bilevel ventilation?
Pressure support is calculated by subtracting EPAP from IPAP.

9. What is the pressure support when IPAP is 14 cm H₂O and EPAP is 6 cm H₂O?
The pressure support is 8 cm H₂O.

10. Which NPPV setting is primarily adjusted to improve ventilation?
IPAP is primarily adjusted to increase tidal volume, improve alveolar ventilation, and lower PaCO₂.

11. Which NPPV setting is primarily adjusted to improve oxygenation?
EPAP is primarily adjusted to recruit alveoli, increase functional residual capacity, and improve oxygenation.

12. Why may IPAP need to be increased when EPAP is raised?
IPAP may need to be increased by the same amount to maintain the existing pressure-support level and prevent a reduction in tidal volume.

13. What are two major acute indications for NPPV?
Two major acute indications are COPD exacerbation with hypercapnic respiratory failure and acute cardiogenic pulmonary edema.

14. How does NPPV help a patient with an acute COPD exacerbation?
It reduces respiratory muscle workload, increases tidal volume, improves alveolar ventilation, lowers PaCO₂, and helps correct respiratory acidosis.

15. How does positive airway pressure help in cardiogenic pulmonary edema?
It recruits collapsed or fluid-filled alveoli, improves oxygenation, decreases venous return, and reduces left ventricular afterload.

16. When may bilevel ventilation be preferred over CPAP in cardiogenic pulmonary edema?
Bilevel ventilation may be preferred when the patient also has hypercapnia, respiratory acidosis, or inadequate ventilation.

17. What characteristics make a patient a suitable candidate for NPPV?
A suitable patient is generally awake, cooperative, spontaneously breathing, hemodynamically stable, and able to protect the airway and manage secretions.

18. Why is the ability to protect the airway important during NPPV?
NPPV does not provide an artificial airway, so the patient must be able to prevent aspiration and clear secretions.

19. Why is respiratory arrest a contraindication to NPPV?
A patient in respiratory arrest requires immediate airway control and invasive mechanical ventilation.

20. Why are copious secretions a concern during NPPV?
Copious secretions may obstruct airflow and cannot be suctioned as easily because there is no direct artificial airway access.

21. Why is active vomiting a contraindication to NPPV?
Active vomiting increases the risk of aspiration because the mask may interfere with rapid airway clearance.

22. Which mask is commonly preferred during acute respiratory failure?
An oronasal mask is commonly preferred because acutely distressed patients often breathe through the mouth.

23. What is a common disadvantage of using a nasal mask?
A common disadvantage is mouth leakage, which can reduce delivered pressure and tidal volume.

24. How can excessive mask strap tension affect the patient?
It can cause discomfort, skin irritation, pressure ulcers, anxiety, and injury over the bridge of the nose.

25. What findings suggest that NPPV is working successfully?
Signs of success include a lower respiratory rate, reduced accessory-muscle use, improved comfort, better oxygenation, rising pH, and falling PaCO₂.

26. What findings may indicate that NPPV is failing?
Signs of failure include worsening respiratory distress, persistent tachypnea, declining consciousness, refractory hypoxemia, rising PaCO₂, and worsening acidosis.

27. Why should NPPV not delay endotracheal intubation?
Delaying intubation in a deteriorating patient can allow respiratory failure to progress and increase the risk of serious complications.

28. During which period is monitoring especially important after NPPV is initiated?
Monitoring is especially important during the first one to two hours of treatment.

29. Which vital signs should be monitored during NPPV?
Respiratory rate, heart rate, blood pressure, and oxygen saturation should be monitored closely.

30. Which blood gas changes indicate improvement in hypercapnic respiratory failure?
A rising pH and falling PaCO₂ indicate improving ventilation and respiratory acidosis.

31. What is a common initial bilevel setting for an adult with an acute COPD exacerbation?
A common starting point is an IPAP of 10 cm H₂O and an EPAP of 5 cm H₂O.

32. Why are low pressures often used when NPPV is first applied?
Low pressures help the patient become accustomed to the mask and reduce anxiety, discomfort, and intolerance.

33. How should the patient generally be positioned when NPPV is initiated?
The patient should usually be placed upright or in a high semi-Fowler’s position.

34. Why may an inspiratory-to-expiratory ratio near 1:3 be helpful in COPD?
A longer expiratory phase allows more time for exhalation and may reduce air trapping.

35. What tidal volume may be targeted during bilevel ventilation?
A tidal volume of approximately 6 to 8 mL/kg may be targeted, depending on the patient’s condition.

36. What may happen if EPAP is increased without changing IPAP?
The pressure-support difference decreases, which may reduce tidal volume and ventilatory assistance.

37. What happens when IPAP and EPAP are increased by equal amounts?
The baseline airway pressure increases while the pressure-support difference remains unchanged.

38. Why are inspiratory pressures above approximately 20 to 25 cm H₂O used cautiously?
Higher pressures may cause gastric insufflation, discomfort, increased leakage, abdominal distention, and aspiration risk.

39. What role does a backup respiratory rate serve during bilevel ventilation?
It allows the machine to deliver breaths when the patient’s spontaneous respiratory rate falls below the set value.

40. Why is CPAP generally inadequate for a patient who is apneic?
CPAP does not provide mandatory breaths, so the patient must generate spontaneous respiratory effort.

41. How does CPAP help treat obstructive sleep apnea?
It acts as a pneumatic splint that prevents the upper airway from collapsing during sleep.

42. When may bilevel support be selected instead of CPAP for sleep-related breathing disorders?
Bilevel support may be selected when hypoventilation, carbon dioxide retention, respiratory muscle weakness, or CPAP intolerance is present.

43. What symptoms may suggest nocturnal hypoventilation?
Symptoms may include morning headaches, poor sleep, daytime fatigue, orthopnea, reduced concentration, and excessive sleepiness.

44. How may long-term NPPV benefit patients with neuromuscular disease?
It may improve nocturnal ventilation, rest weakened respiratory muscles, reduce symptoms, and prolong survival in selected disorders.

45. Why may patients with neuromuscular weakness require airway-clearance assistance?
Weak respiratory muscles may produce an ineffective cough and difficulty removing secretions.

46. What is one concern with prolonged mask use in young children?
Prolonged pressure from the mask may affect midface or maxillary growth.

47. Why may custom interfaces be required for infants or young children?
Commercial interfaces may not fit their small facial dimensions or craniofacial anatomy properly.

48. What is a possible advantage of a total-face mask?
It distributes pressure over a larger area and may reduce injury to the bridge of the nose.

49. What is a possible disadvantage of a helmet interface?
Its large internal volume may affect triggering, pressurization, carbon dioxide clearance, and patient-ventilator synchrony.

50. How can air leaking toward the eyes affect the patient?
It can cause eye dryness, irritation, discomfort, and reduced tolerance of treatment.

51. Why may heated humidification be added during NPPV?
Heated humidification can reduce nasal and oral dryness, improve comfort, and help prevent thick secretions.

52. Why is a heat-moisture exchanger generally avoided during NPPV?
It adds dead space and resistance, which may increase PaCO₂ and the work of breathing.

53. What can cause patient-ventilator asynchrony during NPPV?
Common causes include excessive leakage, poor trigger sensitivity, incorrect cycling, air trapping, and inappropriate pressure settings.

54. What is a missed trigger during NPPV?
A missed trigger occurs when the patient makes an inspiratory effort but the ventilator fails to deliver support.

55. What should be checked first when severe mask leakage develops?
The clinician should check mask position, strap tension, interface size, tubing connections, and mouth leakage.

56. How may mouth leakage with a nasal mask be reduced?
A chin strap may be used, or the patient may be switched to an oronasal mask.

57. What is one advantage of nasal pillows?
They reduce facial contact and may be more comfortable for some long-term users.

58. What is one limitation of nasal pillows?
They may not tolerate high pressures well and can cause nasal irritation, dryness, or leakage.

59. Why should the bridge of the nose be inspected frequently?
It is a common site for pressure-related redness, ulceration, and skin breakdown.

60. How can pressure injury from a mask be reduced?
Pressure injury may be reduced by loosening straps, changing mask type, using protective dressings, and scheduling brief breaks.

61. Why can NPPV cause hypotension?
Positive intrathoracic pressure can reduce venous return and decrease cardiac output.

62. What serious pulmonary complication can occur with excessive positive pressure?
A pneumothorax can occur if positive pressure leads to alveolar overdistention and air leakage.

63. Why is severe hemodynamic instability a contraindication to NPPV?
Positive pressure may further reduce cardiac output and worsen blood pressure.

64. What is the role of FiO₂ during NPPV?
FiO₂ is adjusted to provide supplemental oxygen and achieve the desired oxygen saturation.

65. Why should oxygen therapy be carefully titrated in some patients with COPD?
Excessive oxygen may worsen carbon dioxide retention in susceptible patients.

66. What is the usual treatment goal for chronic hypercapnia during an acute COPD exacerbation?
The goal is generally to improve pH and respiratory distress rather than force PaCO₂ to a completely normal value.

67. Why may pneumonia increase the risk of NPPV failure?
Pneumonia may cause severe hypoxemia, secretion burden, and rapidly progressive respiratory failure.

68. Why must patients with ARDS be monitored closely during an NPPV trial?
They may deteriorate rapidly and require invasive ventilation if oxygenation does not improve.

69. How may NPPV be used during liberation from invasive ventilation?
Selected patients may be extubated directly to noninvasive support to continue ventilatory assistance.

70. Why may routine rescue NPPV after post-extubation failure be harmful?
It may delay necessary reintubation while respiratory failure continues to worsen.

71. What is prophylactic post-extubation NPPV?
It is noninvasive support started immediately after extubation in selected high-risk patients to help prevent respiratory failure.

72. How may NPPV help a patient with restrictive chest-wall disease?
It can increase tidal volume, improve nocturnal ventilation, and reduce carbon dioxide retention.

73. What is one possible palliative use of NPPV?
It may reduce dyspnea and respiratory muscle fatigue in a patient who does not want intubation.

74. Why should treatment goals be established before palliative NPPV begins?
The care team must determine whether the goal is recovery, life prolongation without intubation, or relief of discomfort.

75. What findings may indicate readiness to begin weaning from NPPV?
Readiness may be suggested by stable vital signs, reduced work of breathing, improved pH, adequate oxygenation, and lower pressure requirements.

76. How is NPPV commonly reduced during the weaning process?
Support may be reduced by lowering pressure levels, extending time off the device, and limiting use to sleep or periods of fatigue.

77. Why are daytime breaks useful during NPPV weaning?
They allow the patient to eat, drink, perform oral care, clear secretions, and demonstrate independent breathing.

78. When is weaning from NPPV considered complete?
Weaning is complete when the patient maintains adequate ventilation, oxygenation, mental status, and work of breathing without support.

79. What does functional residual capacity represent?
Functional residual capacity is the amount of gas remaining in the lungs after a normal passive exhalation.

80. How does EPAP increase functional residual capacity?
EPAP prevents premature alveolar closure and maintains more gas in the lungs at the end of expiration.

81. What effect can NPPV have on respiratory muscle fatigue?
It can unload the respiratory muscles by reducing the effort needed to generate an adequate breath.

82. Why must a patient have spontaneous respiratory effort during most forms of NPPV?
The patient usually needs to initiate breaths so the ventilator can detect and support each inspiratory effort.

83. What does trigger sensitivity control during bilevel ventilation?
Trigger sensitivity determines how much patient effort is required for the ventilator to begin inspiratory support.

84. What may happen if trigger sensitivity is not sensitive enough?
The patient may have to work harder to trigger breaths, resulting in missed efforts and increased respiratory workload.

85. What may occur if trigger sensitivity is set too sensitive?
The ventilator may auto-trigger because of leaks, movement, or circuit disturbances rather than true patient effort.

86. What does cycling refer to during pressure-supported NPPV?
Cycling is the transition from inspiratory pressure to expiratory pressure.

87. How can delayed cycling affect a patient with obstructive lung disease?
It can prolong inspiration, shorten expiratory time, and contribute to air trapping and discomfort.

88. What is rise time during bilevel ventilation?
Rise time is the speed at which pressure increases from EPAP to IPAP at the beginning of inspiration.

89. How may a rise time that is too slow affect the patient?
It may fail to meet inspiratory flow demand and increase the sensation of air hunger.

90. How may a rise time that is too fast affect the patient?
It may cause discomfort, excessive flow, leakage, or poor synchrony.

91. Why should secretion clearance be assessed repeatedly during NPPV?
Retained secretions can obstruct airflow, impair gas exchange, increase infection risk, and lead to treatment failure.

92. What may declining mental status indicate during NPPV?
It may indicate worsening hypercapnia, hypoxemia, fatigue, or inability to protect the airway.

93. Why is an adequate cough important for a patient receiving NPPV?
An effective cough helps remove secretions despite the absence of direct airway access for suctioning.

94. How can NPPV support a patient with central sleep-related hypoventilation?
Bilevel ventilation with a backup rate can provide inspiratory assistance when respiratory drive becomes inadequate.

95. Why may an oronasal mask increase aspiration concerns?
It covers the mouth and may interfere with rapid clearance if the patient vomits.

96. What safety concern exists if gas flow or electrical power fails while using some full-face interfaces?
The patient may rebreathe exhaled gas or experience inadequate airflow unless appropriate valves and alarms are present.

97. Why is treatment response more important than the initial NPPV settings alone?
The same settings can produce different effects depending on patient effort, lung mechanics, leakage, and disease severity.

98. What does improved patient-ventilator synchrony look like clinically?
The ventilator supports each effort smoothly, chest movement is coordinated, leakage is controlled, and respiratory distress decreases.

99. Why should alarm limits be appropriately set during NPPV?
Alarms help identify apnea, disconnection, excessive leakage, inadequate ventilation, and other potentially dangerous problems.

100. What factors are most important for successful NPPV treatment?
Success depends on proper patient selection, a suitable interface, correct settings, close monitoring, effective secretion management, and prompt recognition of failure.

Final Thoughts

Noninvasive positive pressure ventilation can improve ventilation, oxygenation, and respiratory comfort while avoiding an artificial airway. It is most effective in carefully selected patients, particularly those with acute COPD exacerbations, cardiogenic pulmonary edema, sleep-related hypoventilation, neuromuscular weakness, and selected chronic respiratory disorders.

Success depends on a cooperative patient, an effective mask seal, appropriate pressure adjustments, frequent reassessment, and clear criteria for escalation.

NPPV should produce measurable clinical improvement soon after initiation. When respiratory distress, gas exchange, hemodynamics, or mental status continue to worsen, invasive ventilation should not be delayed.