Version May 2024
INTRODUCTION — Noninvasive ventilation (NIV) refers to the delivery of positive pressure ventilation through a noninvasive interface (eg, nasal mask or pillows, face mask, or mouthpiece), rather than an invasive interface (ie, endotracheal tube, tracheostomy).
Noninvasive positive pressure ventilation is commonly used to assist ventilation in patients with chronic respiratory insufficiency due to a variety of chronic neuromuscular and chest wall diseases. The practical aspects of initiating NIV in this population are discussed here. Selecting suitable patients for chronic NIV use, follow-up of chronic NIV during the adaptation phase, and aspects of NIV use in acute respiratory failure are provided separately.
●(See "Noninvasive ventilation in adults with acute respiratory failure: Benefits and contraindications".)
●(See "Noninvasive ventilation in adults with acute respiratory failure: Practical aspects of initiation".)
INITIAL SELECTION OF NONINVASIVE VENTILATION COMPONENTS — Once the decision is made to initiate nocturnal NIV, certain preparative steps improve patient acceptance and success (algorithm 1 and algorithm 2 and algorithm 3). These include the following:
●Initiating NIV in an appropriate location (eg, home, sleep laboratory, or hospital). (See 'Timing (daytime or nocturnal)' below and 'Site and ancillary staff' below.)
●Selecting and fitting an appropriate mask. (See 'Interfaces (masks)' below.)
●Selecting a ventilator device and mode of ventilation. (See 'Ventilators' below.)
The overall goal is to provide NIV at a level that is comfortable for the patient and maximizes or normalizes nocturnal alveolar ventilation ("the best level of NIV is one that the patient tolerates").
Patient selection for NIV is discussed separately. (See "Noninvasive ventilation in adults with chronic respiratory failure from neuromuscular and chest wall diseases: Patient selection and alternative modes of ventilatory support".)
Timing (daytime or nocturnal) — In most patients, we initiate NIV for nocturnal use (ie, during sleep). However, the initial trial is often begun during daytime hours while the patient is awake so they can be acclimated to the procedure before using it during sleep, unless the patient is an inpatient or in a sleep laboratory. (See 'Initial trial' below and 'Site and ancillary staff' below.)
In patients with severe chronic respiratory failure, there may be an additional need for several hours of NIV while awake with breaks for select periods (eg, meals).
In those with progressive disease, the need for NIV may slowly advance to a point where NIV is required for almost 24 hours a day. NIV at this level may be maintained for a significant length of time, at which point we typically discuss and make a decision regarding the inevitable need for tracheostomy. (See "Tracheostomy: Rationale, indications, and contraindications".)
The rationale for nocturnal NIV is that patients with chronic respiratory failure from neuromuscular and chest wall disorders have worsening alveolar hypoventilation during sleep compared with ventilation when awake. In addition, nocturnal NIV has the potential to prevent further deterioration of sleep quality in this population.
Site and ancillary staff — In the US, the initial process of applying NIV usually takes two to four hours and occurs mostly in an outpatient setting. Choosing among these settings depends upon several factors including the severity of respiratory failure, preferences of the patient, and presence of any suspected or actual coexisting sleep disorder. Regardless of the setting, appropriate use of NIV is dependent upon expert staff who ensure the provision of a comfortable snug-fitting interface with minimal air leaks, appropriate initial settings, and follow-up that comprises several visits, frequent check-ins, and adjustment in settings (if needed).
●Outpatient setting – For most patients with chronic respiratory failure due to neuromuscular or chest wall diseases, we initiate NIV as an outpatient. Patients best suited to outpatient initiation include those with mild or early respiratory failure who are not anxious and in whom no sleep disorder is suspected.
An initial trial can occur in the home, clinician's office, or medical supply company office. Most often this will occur in the patient's home with the assistance of therapists from a durable medical equipment company. Education and a brief trial of NIV is commenced during daytime hours under the direct supervision of skilled personnel (eg, respiratory therapist or nurse).
Once an interface and ventilator is selected and the patient is comfortable, an NIV trial with titration of settings is then begun. (See 'Interfaces (masks)' below and 'Ventilators' below and 'Initial trial' below.)
There is a paucity of data that supports this approach. One study reported a similar improvement in gas exchange and quality of life among patients who had NIV initiated at home using telemonitoring compared with patients who had NIV initiated as an inpatient [1].
●Sleep laboratory – For patients with suspected or known concomitant obstructive sleep apnea (OSA) or other sleep disorder, we suggest in-laboratory polysomnography with NIV titration. The rationale for this approach is that polysomnography is required to ensure elimination of apneas, hypopneas, and respiratory-related arousals from the underlying sleep disorder, and also to augment ventilation associated with chronic hypoventilation from the underlying neuromuscular or chest wall disorder.
However, if in-laboratory polysomnography is not readily available, the laboratory lacks the appropriate experience of adjusting ventilation for neuromuscular disease, or the patient has a preference for avoiding the sleep laboratory (eg, some patients with advanced neuromuscular disease have difficulty adapting to an in-laboratory environment), then initiation of NIV should not be delayed while waiting for a sleep study. In such cases, NIV may be initiated in the outpatient or inpatient setting, and subsequently be evaluated in the laboratory or home setting if problems are encountered (eg, poor efficacy, residual sleepiness). (See "Noninvasive ventilation in adults with chronic respiratory failure from neuromuscular and chest wall diseases: Adaptation and follow-up after initiation".)
Our approach varies from that of the 2011 NIV Titration Task Force of the American Academy of Sleep Medicine (AASM). The AASM recommended that in most patients with neuromuscular disorders (even if an underlying sleep disorder is not suspected), the initial titration of NIV should occur in a sleep laboratory, rather than at home, to optimize pressure settings in addition to comfort [2]. Their rationale is that titration in the laboratory with careful analysis of effort and flow, and adjustment of trigger sensitivity, rise time and inspiratory time may help mitigate patient-ventilator asynchrony that may occur when patients with neuromuscular disease are initially placed on NIV [3]. However, this recommendation is based on expert opinion, and evidence is lacking to demonstrate the superiority of this approach over home initiation.
Positive airway titration modules for OSA without associated chronic hypoventilation are described separately. (See "Titration of positive airway pressure therapy for adults with obstructive sleep apnea".)
●In-hospital setting – In Europe, in-hospital initiation has been preferred by many clinicians. In the US, this is uncommonly practiced. One small, randomized trial found no advantage of initiation during a few days of hospitalization compared with initiation at home with frequent visits from trained nurses [4].
Interfaces (masks) — In most patients with chronic respiratory failure from neuromuscular and chest wall disorders in whom NIV is chosen, a nasal mask is the preferred interface (picture 1). (See 'Nasal interfaces' below.)
Templates are available to assist with mask sizing. In general, we select the smallest mask that fits comfortably.
An important aspect of mask fitting is setting the strap tension. Generally, we select the least amount of strap tension that does not allow excessive leak but protects the skin from irritation and breakdown.
If nasal masks are not suitable or cannot be tolerated, several alternatives are available. (See 'Oronasal masks' below and 'Full-face masks' below and 'Mouthpieces' below and 'Interfaces not used (helmet)' below.)
Nasal interfaces — In patients with chronic respiratory failure from neuromuscular and chest wall diseases, NIV is preferably delivered via a standard nasal mask. If a standard nasal mask is not tolerated, nasal pillows are an alternative:
●Standard nasal mask – We prefer standard nasal masks for chronic NIV applications since they can effectively deliver nocturnal NIV and are generally well tolerated by patients with neuromuscular or chest wall disorders.
Standard nasal masks are clear plastic dome-shaped devices that fit over the entire nose and have a soft rubber or silicone cuff to maintain an air seal (picture 1).
Most patients successfully adapt to standard nasal masks. However, some masks are uncomfortable because of poor fit (eg, nasal or facial deformity) or excessive mask pressure on the nose. In such patients, alternatives include "gel masks" that use a soft gel or foam in the sealing gasket or "minimasks" that seal underneath the nose and cover only the entrance of the nares .
Issues with mask intolerance are more commonly encountered during the adaptation phase than during the initiation phase. Further details regarding mask intolerance during adaptation are provided separately. (See "Noninvasive ventilation in adults with chronic respiratory failure from neuromuscular and chest wall diseases: Adaptation and follow-up after initiation", section on 'Mask (interface) intolerance'.)
●Nasal pillows or cradle – Nasal pillows (or prongs) or a nose cradle may be preferred by patients who are unable to tolerate a nasal mask due to nasal discomfort (or ulceration). Nasal pillows consist of soft rubber cones that are inserted directly into the nostrils, thereby exerting no pressure on the nasal bridge (picture 2 and picture 3).
One issue that can occur with nasal masks is air leak via the mouth (eg, patients with mouth weakness). If this is noted during the initial trial, a chin strap may be placed to facilitate mouth closure and improve the delivery of positive pressure to the lungs. (See 'Interface and strap tension' below.)
Oronasal masks — For patients with significant air leak in whom a chin strap is not helpful, we consider an oronasal mask (ie, a mask that covers the nose and mouth (picture 4)).
However, in patients with neuromuscular weakness, certain safety issues are a concern. Upper extremity strength needs to be sufficient to allow the patient to access quick-release straps for rapid removal of the mask in the event of an emergency (eg, vomiting, secretion buildup) or power failure. We also ensure that an oronasal mask with an anti-asphyxia valve is used. An anti-asphyxia valve opens in the event of blower device failure; without an anti-asphyxia valve, rebreathing could occur and asphyxiate the patient.
Oronasal masks are the interfaces that are most often used to administer NIV in patients with acute respiratory failure since adequate ventilation can be readily achieved due to reduced leak via the mouth. In patients with chronic respiratory failure due to neuromuscular disease, oronasal masks are less well tolerated than nasal masks because they cover both the nose and mouth, are associated with greater sense of claustrophobia, and interfere with speech [5]. (See "Noninvasive ventilation in adults with acute respiratory failure: Practical aspects of initiation", section on 'Interface (mask)'.)
Full-face masks — Full-face masks that cover the entire face with the upper border going across the forehead and the lower border between the chin and lower lip spare the bridge of the nose and allow mouth breathing. They may also allow vocalization to a greater degree than standard oronasal masks. Thus, in some patients who have problems with nasal comfort or obtaining a good seal with the standard oronasal mask, or for patients who have a strong preference for vocalization, we consider a full-face mask. Similar to oronasal masks, concerns regarding cautious use in patients with upper extremity weakness also applies. (See 'Oronasal masks' above.)
Mouthpieces — Mouthpiece interfaces cover the mouth only (picture 5) [6]. Mounting the ventilator on a wheelchair and suspending the mouthpiece on a gooseneck stand allow the patient to remain mobile and simultaneously have access to positive pressure as needed (also called "sip and puff" ventilation). A mouthpiece can also be strapped onto the face for use during sleep, although many patients switch to a nasal (or oronasal) mask at night. Safety issues for those who use a nocturnal oronasal mask are discussed above. (See 'Oronasal masks' above.)
Some mouthpieces are designed to be expectorated, but with strapped-on mouthpieces in patients with quadriplegia, anti-asphyxia valves should be in place to prevent rebreathing in the event of ventilator failure. (See 'Oronasal masks' above.)
Interfaces not used (helmet) — We do not use helmet interfaces. A helmet is a transparent hood that covers the entire head and face, the base of which is linked to a soft collar that seals the helmet around the neck and is usually secured by soft straps under the axillae (figure 1). Although sometimes used in acute respiratory failure [7-14], we prefer not to use helmets in patients with chronic respiratory failure due to the risk of carbon dioxide rebreathing, a phenomenon thought to be due to poor gas flow inside the helmet [15,16]. Additionally, helmet NIV has been shown to be less effective in reducing the work of breathing compared with a standard face mask [17] and can cause delays with ventilator triggering and cycling. Data describing its potential efficacy in patients with acute respiratory distress syndrome are discussed separately. (See "Acute respiratory distress syndrome: Ventilator management strategies for adults", section on 'Selecting invasive versus noninvasive ventilation'.)
Ventilators — In patients with chronic respiratory failure from neuromuscular or chest wall disorders, we suggest positive pressure ventilation delivered through a pressure-limited device. Volume-limited ventilators are an alternative for those who do not tolerate pressure-limited devices or need an assured volume.
For patients who cannot tolerate pressure- or volume-limited ventilation or who need more prolonged or intermittent support during the day, we consider using a hybrid ventilator. Hybrid devices have sophisticated alarms and monitoring and can deliver volume-assured pressure support (VAPS) that automatically modulates pressure to achieve a target tidal volume.
Importantly, regardless of whether a volume- or pressure-limited device is used, the initial priority should be to achieve patient comfort and acceptance rather than any particular level of improvement in gas exchange.
Pressure- or volume-limited ventilators — While in the past portable volume-limited ventilators were used to deliver NIV, most practitioners now prescribe portable pressure-limited ventilators for chronic ventilatory support of patients with respiratory failure due to neuromuscular or chest wall disorders for reasons of convenience, comfort, and portability. These devices generally lack sophisticated alarms or internal batteries and are best suited for patients requiring nocturnal assistance only, but can be used to provide continuous (day and night) ventilator support if needed. However, if used to provide ventilation for prolonged periods (eg, 24 hours), we prefer that they be equipped with alarms to detect loss of function.
●Pressure-limited ventilators – Portable pressure-limited ventilators that deliver bilevel positive airway pressure (bilevel PAP) are the ventilator device of choice (figure 2).
Pressure-limited ventilators deliver both a preset inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP); the difference between the two determines the delivered tidal volume (algorithm 1 and algorithm 2 and algorithm 3). Bilevel PAP resembles pressure support ventilation on standard critical care ventilators [18]. Initial settings are discussed below. (See "Modes of mechanical ventilation", section on 'Pressure support' and "Modes of mechanical ventilation", section on 'Bilevel positive airway pressure' and 'Initial settings' below.)
One advantage of pressure-limited ventilation is its ability to maintain inspiratory airflow on a breath-by-breath basis to compensate for air leaks, which are common with NIV, particularly when it is administered via a nasal mask [19]. Pressure-limited ventilators have sensitive flow triggers for cycling between inspiratory and expiratory pressures, matching patient breathing efforts closely. However, the presence of large air leaks may also impair the ability of pressure-limited ventilators to sense patient inspiratory or expiratory flows, leading to asynchrony.
Most devices also provide a spontaneous (S)-, timed (T)-, or spontaneous/timed (S/T) backup mode; the S/T mode is most commonly used. The use of a backup respiratory rate that approximates the patient's spontaneous breathing rate assures ventilator inspiratory triggering during large leaks or potential periods of apnea.
●Volume-limited ventilators – Volume-limited ventilators deliver a set tidal volume and positive end-expiratory pressure (PEEP). The assist-control mode is typically used for volume-cycled ventilators and a backup rate is set close to the spontaneous rate of the patient.
In contrast with pressure-limited ventilators, volume-limited ventilators are not able to make breath-to-breath adjustments; in order to compensate for air leaks, the tidal volume must be manually increased. Initial settings are discussed below. (See 'Initial settings' below and "Modes of mechanical ventilation", section on 'AC'.)
Studies that have directly compared pressure- and volume-limited ventilators have found similar efficacies in terms of supporting gas exchange and patient adherence [20-22]. However, pressure-limited ventilators are generally perceived by patients as being more comfortable while volume-limited ventilators may induce more gastrointestinal side effects [23-25].
Hybrid ventilators — Hybrid ventilators are capable of delivering several modes of ventilation (eg, volume- or pressure-limited ventilation) as well as mouthpiece ventilation and have both invasive and noninvasive applications.
We consider a hybrid ventilator for patients with high levels of ventilator dependency (up to 24 hours daily) since they have sophisticated alarm systems and have internal batteries in the event of power failure.
Hybrid ventilators may also be required when patients need a more complex form of ventilation such as average volume-assured pressure support (AVAPS) and intelligent volume-assured pressure support (iVAPS); these modes of ventilation target an average minute volume determined by setting a target tidal volume and backup rate. Both modes have algorithms that adjust inspiratory pressure to assure the target volumes are met.
A small, single-blind, randomized study reported that AVAPS was comparable with pressure support ventilation in terms of effects on sleep, but minute ventilation was slightly greater with AVAPS [26]. AVAPS may also lower the partial pressure of carbon dioxide (PaCO2) more rapidly than standard bilevel PAP in patients with hypercapnic respiratory failure [27]. However, superiority in outcomes assessing subjective or functional responses, health care utilization, or survival has not been shown.
INITIAL TRIAL
Patient position — Patients should be comfortable in a chair or bed and positioned at a 30-degree angle or more, regardless of the location (eg, at home, hospital, or sleep laboratory). (See 'Site and ancillary staff' above.)
Baseline measurements, oxygenation, and gas exchange monitoring — The following is a reasonable approach:
●Oxygen monitoring – For patients in a monitored setting, we obtain baseline vital signs and monitor pulse oximetry throughout the trial. For patients in a non-monitored setting, only peripheral pulse oximetry is measured.
●Carbon dioxide monitoring – There is a lack of consensus on whether and how to monitor carbon dioxide levels during initiation.
•We prefer to measure transcutaneous carbon dioxide (tcCO2) levels, if feasible.
•Arterial blood gas (ABG) or a venous blood gas analysis at the beginning and end of the trial are an alternative to tcCO2. If ABG analysis has typically been done as part of the diagnostic evaluation, it does not need to be repeated prior to the NIV trial.
•We do not advocate using end-tidal partial pressure of carbon dioxide (PETCO2) measurements via the mask, since they are less reliable due to leaks and dilution of expired gas, which underestimate the actual arterial carbon dioxide tension (PaCO2) [28]. If, however, PETCO2 is used, it must be measured off of NIV (eg, beginning and end of the trial).
Evidence is lacking on how to apply this information, but we choose settings that reduce PaCO2 by approximately 5 mmHg compared with the baseline measurement to assure augmentation of ventilation.
Initial settings — The goal of initial settings is to provide a modest amount of ventilatory support while allowing the patient to become acclimated to NIV (algorithm 1 and algorithm 2 and algorithm 3). Typically, patients are started on bilevel positive airway pressure (bilevel PAP) ventilation delivered via a standard nasal mask. Volume-cycled ventilation and average or intelligent volume-assured pressure support ventilation (AVAPS, iVAPS) are less commonly used initial modes and are more likely to be used if bilevel PAP ventilation fails or is poorly tolerated. To improve acceptance, we prefer to initiate NIV using low initial pressures, which can then be subsequently increased to a desired level once the patient becomes acclimated. The settings and titration modules provided in the algorithm are suggested as an initial guide only (algorithm 2); for comfort, some patients may even need lower than usual initial settings.
For all modes, a backup respiratory rate is usually set at two to four breaths per minute below the patient's spontaneous rate. This is particularly important in patients with neuromuscular disease who have weak respiratory muscles and therefore may not be capable of spontaneously triggering the ventilator reliably while asleep.
We also find it helpful to set a high trigger sensitivity, which makes it easier for the patient to transition from exhalation to inhalation.
For the same reason, we generally set a longer than usual inspiratory time for patients with neuromuscular disorders (ie, 33 to 50 percent of the total respiratory cycle time). In contrast, patients with concomitant airway obstruction usually prefer a shorter inspiratory time and longer time for exhalation. Patients with chest wall disorders may not need adjustment in the trigger sensitivity or inspiratory time.
Humidification — Heated humidification is now considered standard on most NIV devices to enhance comfort by decreasing dryness in the upper airway. Humidification may also decrease nasal resistance [29]. Troubleshooting problems with condensation due to humidification is discussed separately. (See "Noninvasive ventilation in adults with chronic respiratory failure from neuromuscular and chest wall diseases: Adaptation and follow-up after initiation", section on 'Nasal congestion or dryness'.)
Adjustments during the trial — Once the initial pressures or volumes have been set, we begin the NIV trial and encourage the patient to relax and "let the ventilator do the breathing."
Several adjustments may need to be performed to both the equipment and settings so that ventilation and tolerance can be maximized. In general, we make these adjustments on clinical grounds, relying on patient-targeted symptom relief and comfort.
When the patient is being monitored in the sleep laboratory (ie, with polysomnography and capnography), additional targets include elimination of any apneas, hypopneas, and respiratory-related arousals from OSA, as well as augmentation of ventilation associated with chronic hypoventilation from the underlying neuromuscular or chest wall disorder. (See "Mode selection for positive airway pressure titration in adult patients with central sleep apnea syndromes" and "Titration of positive airway pressure therapy for adults with obstructive sleep apnea".)
Provide reassurance — For every patient, we provide encouragement and reassurance during the trial, explaining every step carefully.
For patients who are anxious about NIV, we sometimes initiate the trial during the daytime using a diversion, such as watching television, which can facilitate adaptation.
If the patient is very claustrophobic, it may be helpful for them to feel the pressure with their hand first, then hold the mask over their face for a few minutes rather than using the straps right away. This allows the patient to remove and reapply the mask quickly during those first few minutes and gives the patient a sense of control. Once the patient can tolerate the mask, the straps should be attached for effective ventilation.
Although typically avoided, in rare instances when patients have a high level of anxiety, a low dose of benzodiazepine may help ease the initial transition to NIV.
Interface and strap tension — During the trial, the mask and straps are readjusted as needed to reduce leakage of air from the mask, using the least strap tension necessary.
Patients with nasal bridge discomfort may be switched to nasal pillows or cradle. (See 'Nasal interfaces' above.)
In patients with significant air leaks via the mouth, a chin strap may be needed. Alternatively, the patient may be switched to an oronasal mask or, less commonly, a full-face mask, provided there is no significant upper extremity weakness. (See 'Oronasal masks' above and 'Full-face masks' above.)
It is rare during an initial trial that a mouthpiece interface is used. (See 'Mouthpieces' above.)
Further details regarding the patient-device interface are provided separately. (See 'Interfaces (masks)' above and "Noninvasive ventilation in adults with chronic respiratory failure from neuromuscular and chest wall diseases: Adaptation and follow-up after initiation", section on 'Mask (interface) intolerance'.)
Ventilator setting titration — Once ventilation begins on initial settings, we gradually increase ventilator support during the trial (algorithm 1 and algorithm 2 and algorithm 3).
In all patients, titration should target good patient-ventilator synchrony, the alleviation of dyspnea, a reduction in the respiratory rate, and an increase in the tidal volume (if being monitored).
For patients with concomitant OSA who are undergoing their trial in a sleep laboratory, additional attention needs to be paid to eliminating apneas, hypopneas, and respiratory-related arousals from OSA, and to augmenting ventilation (by capnography). (See "Overview of polysomnography in adults".)
Titration varies according to the initial selected mode:
●For patients on bilevel PAP ventilation, we typically increase the IPAP in increments of 1 to 2 cm H2O as tolerated, to a maximum of 20 cm H2O. Using smaller increments (eg, 0.5 cm H2O) may be needed in some patients with neuromuscular disorders as they may be particularly sensitive to or intolerant of large changes in pressure, while other patients may be able to tolerate larger or more rapid increments in pressure.
While the tidal volume (VT) varies with bilevel PAP, we target a delivered VT that ranges between 6 and 10 mL/kg ideal body weight (IBW)/minute, although some devices do not monitor VT. We do not typically titrate EPAP unless the patient has OSA, in which case titration should occur in the sleep laboratory and is dictated by sleep events noted on polysomnography. In such cases, a higher EPAP is typically required to overcome airway obstruction while simultaneously maintaining an adequate pressure difference between IPAP and EPAP for treating concomitant hypoventilation from the neuromuscular or chest wall disorder. (See "Titration of positive airway pressure therapy for adults with obstructive sleep apnea".)
●For patients on volume-controlled ventilation, we increase the set VT in increments of 25 to 50 mL until clinical targets of improved dyspnea, respiratory rate, ventilator synchrony, and an adequate VT between 6 and 10 mL/kg IBW/minute are achieved. PEEP is not generally titrated, unless the patient has OSA, similar to bilevel PAP (see above bullet).
●For patients on AVAPS, we gradually increase the IPAPmin and IPAPmax by 1 to 2 cm H2O and target a level that results in a tidal volume between 6 and 10mL/kg IBW/minute. The EPAP is not typically increased, unless concomitant OSA is present (see first bullet above).
Additional settings can be adjusted to optimize the patient's comfort and interaction with positive pressure ventilators. These include the variables that affect the change from exhalation to inspiration (eg, increasing trigger sensitivity), the duration of inspiratory time, and the parameters that determine the change from inspiration to exhalation (cycle sensitivity). (See 'Initial settings' above.)
Supplemental oxygen is not typically needed in patients whose problem is primarily respiratory muscle weakness in the absence of lung parenchymal disease. However, in patients who are hypoxemic, oxygen is administered to keep peripheral oxygen saturation (SpO2) >90 percent. Useful oxygenation targets in critically ill populations are discussed separately. (See "Overview of initiating invasive mechanical ventilation in adults in the intensive care unit", section on 'Fraction of inspired oxygen'.)
Trial duration — For patients who were started as an outpatient, the NIV trial lasts for one to two hours.
For patients who are staying overnight in the hospital or in a sleep laboratory, NIV can be continued as long as the patient can tolerate it through the night. During this additional time, further adjustments are made to optimize comfort and provide patient and caregiver education before the patient is discharged to use NIV at home.
FOLLOW-UP (ADAPTATION PHASE) — Patients may or may not achieve their desired targets during their NIV trial. Regardless, in most patients, we prescribe NIV at the tolerated settings discovered during the trial.
We instruct patients to use NIV each night for at least a few hours, or as long as possible. Further adjustments are subsequently made during follow-up visits a few weeks later as indicated by symptoms, gas exchange, and patient tolerance. In some patients, a second trial or further titration may need to be performed (eg, in the sleep laboratory or in the hospital setting).
Troubleshooting problems with NIV during this follow-up "adaptation phase" is discussed in detail separately. (See "Noninvasive ventilation in adults with chronic respiratory failure from neuromuscular and chest wall diseases: Adaptation and follow-up after initiation".)
SUMMARY AND RECOMMENDATIONS
●Components – The initial process of applying noninvasive positive pressure ventilation (NIV) to patients with neuromuscular and chest wall disorders involves the following (see 'Initial selection of noninvasive ventilation components' above):
•In most patients, the initial trial occurs in an outpatient setting (eg, office or home), but can also take place in the sleep laboratory (eg, patients with suspected or known obstructive sleep apnea [OSA]), or during a hospital inpatient admission (eg, anxious patients). (See 'Site and ancillary staff' above.)
•Most patients undergo a trial of NIV using a pressure-limited device (figure 2) that delivers bilevel positive airway pressure (bilevel PAP) through a standard nasal mask (picture 1). Other interfaces (eg, nasal pillows, oronasal or full-face mask, mouthpiece) or ventilatory devices (eg, volume-limited or hybrid devices) may be used when patients demonstrate intolerance to the chosen mask or mode of ventilation, respectively (algorithm 1 and algorithm 2 and algorithm 3). The initial trial generally occurs during waking hours with a view to prescribing nocturnal NIV (ie, during sleep), unless the trial occurs in the sleep laboratory or as an inpatient. (See 'Interfaces (masks)' above and 'Ventilators' above.)
●Initial trial – The main goal of the initial trial is to provide a modest amount of ventilatory support while allowing the patient to become acclimated to NIV. (See 'Initial trial' above.)
•Monitoring – Oximetry is generally measured during the initial trial. There is a lack of consensus on whether and how to monitor carbon dioxide levels during initiation. (See 'Baseline measurements, oxygenation, and gas exchange monitoring' above.)
•Initial settings and titration – Initial settings vary depending on the mode selected. Titration during the trial increases the degree of support to target improved symptoms and a tidal volume that ranges between 6 and 10 mL/kg ideal body weight/minute. The appropriate preparatory steps, initial stings, and titration for the selected mode are provided in the algorithms (algorithm 1 and algorithm 2 and algorithm 3). In all modes, expiratory positive airway pressure or positive end-expiratory pressure is not typically titrated (unless the patient has OSA), and a backup respiratory rate is usually set at two to four breaths per minute below the patient's spontaneous rate. (See 'Initial settings' above and 'Ventilator setting titration' above.)
•Trial adjustments – With the patient at 30 degrees or more, the trial begins, and ventilator settings titrated (algorithm 1 and algorithm 2 and algorithm 3). The patient is reassured, and the mask and straps are readjusted as needed to reduce leakage of air from the mask, using the least strap tension necessary. (See 'Adjustments during the trial' above.)
•Trial duration and follow-up – The trial may last one to two hours (outpatient setting) or overnight (inpatient or sleep laboratory setting). In most patients, we prescribe NIV at the tolerated settings discovered during the trial. We instruct patients to use NIV each night for at least a few hours, or as long as possible. Further adjustments are subsequently made during follow-up visits a few weeks later, as indicated by symptoms, gas exchange, and patient tolerance. (See 'Follow-up (adaptation phase)' above and "Noninvasive ventilation in adults with chronic respiratory failure from neuromuscular and chest wall diseases: Adaptation and follow-up after initiation".)
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