MPV is a less intrusive form of noninvasive ventilation that uses a portable home mechanical ventilator (HMV) with a single-limb open-circuit and mouthpiece assembly. The individual receives a ventilator-assisted breath as often as needed by self-initiating an inspiratory effort while placing lips firmly around the mouthpiece. A support arm for the single-limb open-circuit is usually necessary to enable proper positioning of the mouthpiece for ease of access for the user.

Individuals with weak inspiratory and expiratory muscles requiring breathing support during the day may benefit from MPV. Weak inspiratory and expiratory muscles are associated with neuromuscular diseases (e.g., amyotrophic lateral sclerosis, muscular dystrophy, post-polio syndrome), spinal cord injury or muscular skeletal conditions (e.g., kyphoscoliosis). MPV is generally recommended for individuals with adequate oropharyngeal muscle strength and reasonably good range of head motion. The individual must be alert, cooperative and able to communicate.

The ultimate goal of MPV is to provide daytime noninvasive breathing support. MPV may:

• Prevent endotracheal tube intubation or tracheostomy thereby reducing the risk of infection;
• Facilitate timely endotracheal tube extubation and/or tracheostomy weaning;
• Improve an individual’s quality of life; and
• Promote an individual’s independence thereby reducing caregiver burden.

Access to MPV enables independent lung volume recruitment (LVR) as the user can sequentially stack ventilator-assisted breaths until maximum insufflation capacity (MIC) is reached. LVR with MPV will:

• Improve cough effectiveness and secretion clearance;
• Increase mechanical compliance and thoracic range of motion;
• Decrease atelectasis; and
• Increase speech volume.

MPV should be initiated when diurnal hypercapnea and/or dyspnea is noted despite optimal nocturnal noninvasive ventilation. MPV may also be initiated in the following clinical scenarios: Post endotracheal tube extubation to minimize the risk of re-intubation;

• To facilitate tracheostomy weaning prior to tracheostomy removal (tracheostomy must be capped). This helps the individual to get used to MPV should noninvasive breathing support be required on a long term basis; and
• Post decannulation with the stoma occluded to minimize risk of tracheostomy re-insertion, especially if daytime breathing support is indicated.

MPV can be initiated in any clinical or home setting with a medically stable, alert, cooperative individual able to communicate.

MPV is possible with a HMV with existing MPV option and/or most traditional volume-cycled pressure/flow-triggered home ventilators. The set up configuration will differ depending on the type of ventilator available.

Bilevel pressure devices and home ventilators in pressure modes are NOT appropriate for MPV. The inspiratory positive airway pressure (IPAP or pressure support) setting, limits LVR and cough efficacy; the expiratory positive airway pressure (EPAP or PEEP) generates a constant flow-by which cannot be minimized to 0 cmH2O and may be a nuisance to user and; in some instance, the device low EPAP alarm cannot be disengaged, enabling a nuisance alarm during MPV.

Clinical Considerations

• A learning period may be necessary for individuals who have been ventilated with an artificial airway for an extended period or who have not used LVR with a modified resuscitation bag (e.g., breath-stacking with LVR bag).
• The individual needs to generate very little effort via the mouthpiece to initiate a ventilator delivered breath.
• With lips placed firmly around the mouthpiece, the individual uses their cheek muscles to draw or “sip” through the mouthpiece, triggering a ventilator-assisted breath that provides as much air volume as needed.
• The individual must be able to close the soft palate, seal the nasopharynx, and open the glottis and vocal cords to allow the ventilator delivered breath to reach the lungs.
• Instruct the individual to accept as much air as possible in to the lungs up to the preset pressure limit. Average high pressure limit ranges from 45 to 70 cmH2O to allow for MIC.
• The individual should feel a satisfying breath volume with every inspiratory effort. The inspiratory volume, flow, time, and rise settings should be adjusted to promote individual comfort.
• Exhalation should occur naturally through the nose or open mouth.
• A filter proximal to the mouthpiece will soften the ventilator circuit constant flow-by and may improve individual comfort.
• A one-way valve proximal to the mouthpiece may be necessary if the individual is unable to exhale through the nose or at the side of the mouth. The one-way valve will alleviate ventilator alarms caused by back-flow (individual exhalation) to the circuit.
• Once the individual is familiar with taking ventilator supported breaths via the mouthpiece, they can start to learn LVR by breath-stacking. This requires taking multiple MPV breaths without exhaling until the lungs are full. LVR with MPV should be followed by gentle exhalation, a breath-hold up to 5 seconds or individual initiated cough effort.
• LVR with MPV should not induce dizziness or chest discomfort.
• Individual and clinician communication is essential when determining alarm settings to ensure safe, comfortable and effective ventilation.

LVR with MPV is recommended as often as required; with a minimum of 2-3 times per day with 3-5 lung stretches per session. If combined with manually assisted cough (MAC) it is best done before meals and at bedtime to minimize risk of refluxed gastric content. MPV is possible with most home mechanical ventilators (HMV). In the following section we describe the how to set up MPV with the following devices and related accessories:

A) HMV with existing MPV option e.g., Trilogy 200; and
B) Traditional volume-cycled pressure/flow-triggered HMV with, and without, a proprietary circuit.

Measure and compare spontaneous Forced Vital Capacity (FVC) and peak cough flow (PCF) with and without LVR-MPV. PCF may further improve with a MAC.

EPAP:	Expiratory Positive Airway Pressure
HMV:	Home Mechanical Ventilation
IPAP:	Inspiratory Positive Airway Pressure
LVR:	Lung Volume Recruitment
LVR bag:	Lung Volume Recruitment with resuscitation bag
MAC:	Manually Assisted Cough
MIC:	Maximum Insufflation Capacity
MPV:	Mouth Piece Ventilation
PCF:	Peak Cough Flow
PEEP:	Positive End Expiratory Pressure
PIF:	Peak Inspiratory Flow
VRBT:	Ventilator-Free Breathing Time
VT:	Tidal Volume