Dysphagia Knowledge Hub — 吞嚥困難知識庫

Passy Muir Valve for Tracheostomy Patients with Dysphagia

The Passy Muir Valve (PMV) is a one-way speaking valve placed on the hub of a tracheostomy tube that has been widely adopted in the management of tracheostomised patients with dysphagia. First described by David Muir in the 1980s, the PMV opens on inhalation and closes during exhalation, redirecting airflow through the upper airway and restoring many of the physiological conditions necessary for safe swallowing. For speech-language therapists (SLTs) working in acute, rehabilitation, and long-term settings in Hong Kong and internationally, understanding PMV candidacy, application protocols, and limitations is essential clinical competency.

Mechanism: Restoring Subglottic Pressure

In a patient breathing through an uncuffed or deflated-cuff tracheostomy tube, exhaled air bypasses the upper airway entirely, exiting through the tracheostomy stoma. The consequences for swallowing are significant. Subglottic air pressure — the positive pressure that builds below the vocal folds during the swallowing sequence — is eliminated. This pressure normally contributes to laryngeal elevation, vocal fold adduction, and cough strength. Its loss correlates with increased aspiration risk, reduced laryngeal sensation (partly driven by lack of airflow over sensory mucosa), and impaired protective cough reflexes.

When the PMV is in place and the tracheostomy cuff is fully deflated, exhaled air is redirected upward through the larynx and pharynx. This restores subglottic pressure, improves laryngeal adduction, and re-establishes airflow-dependent sensory feedback. Lichtman et al. (1995) demonstrated that PMV use significantly reduced aspiration events on VFSS in tracheostomised patients, a finding replicated in subsequent studies. Elpern et al. (2000) reported reduced aspiration and improved swallowing efficiency with PMV use in a ventilator-dependent cohort.

Candidacy Criteria

Not every tracheostomised patient is a PMV candidate. A structured assessment protocol — typically led by SLT in collaboration with respiratory therapy and nursing — should determine readiness.

Essential prerequisites:

Supporting factors favourable to PMV use:

Cuff deflation tolerance is the single most important screening step. In patients with significant respiratory compromise, cuff deflation may not be safely achievable, and the PMV trial is deferred. Occupational and physiotherapy colleagues should be consulted regarding positioning and secretion management before the trial.

Speaking Valve vs. Swallowing PMV: Clinical Distinctions

The PMV is primarily described as a “speaking valve,” but its swallowing benefits are mechanistically distinct from phonation benefits and should be assessed separately.

For communication, the PMV allows exhaled air to pass the vocal folds, enabling voice production. This is often the initial clinical goal and is used to gauge tolerance.

For swallowing, the restored subglottic pressure and laryngeal sensory feedback are the relevant mechanisms. Patients may demonstrate improved swallowing on FEES or VFSS even before phonation is clear, because the swallowing improvements rely on pressure dynamics rather than voluntary phonation control.

SLTs should assess swallowing with the PMV in place on FEES or VFSS rather than inferring swallowing safety solely from phonation quality. Clinical swallowing examination with PMV in situ provides useful information but cannot substitute for instrumental assessment in high-risk patients.

Trial Protocol

A stepwise PMV trial should be conducted in a monitored environment with resuscitation equipment available. The standard protocol involves:

  1. Ensure full cuff deflation and confirm by audible airflow around the tube or manometry
  2. Apply PMV; monitor SpO2, respiratory rate, and work of breathing continuously
  3. Begin with 5–10 minutes of rest breathing with PMV; extend incrementally if tolerated
  4. Once tolerance at rest is established, progress to phonation tasks
  5. Progress to swallowing trials under SLT supervision, using FEES where available
  6. Document tolerance time, SpO2 nadir, cough strength, phonation quality, and swallowing observations
  7. If tolerated, increase wear time across subsequent sessions toward continuous daytime use

In ventilator-dependent patients, a dedicated inline PMV (Passy Muir 007 or equivalent) is used with the ventilator circuit. Respiratory therapist involvement is mandatory in this context. Expiratory tidal volume alarms require adjustment.

Contraindications

Absolute contraindications include: inflated tracheostomy cuff during valve use, severe upper airway obstruction, bilateral vocal fold fixation in the adducted position, and thick foam-cuffed tracheostomy tubes incompatible with full deflation. Relative contraindications include: markedly impaired consciousness, haemodynamic instability, copious tenacious secretions, and severe aspiration of secretions at baseline.

FEES with PMV in Place

Fibreoptic endoscopic evaluation of swallowing (FEES) conducted with the PMV in place provides direct visualisation of laryngeal and pharyngeal function under conditions that approximate normal breathing mechanics. Langmore (2003) and subsequent authors have highlighted the importance of assessing patients both with and without the PMV to document valve effect. Key observations include changes in secretion management, laryngeal adduction during swallowing, penetration-aspiration scale scores, and residue patterns.

In Hong Kong’s public hospital system, FEES is available in most speech therapy departments of regional hospitals. PMV trials with concurrent FEES are performed in select centres including Queen Mary Hospital and Prince of Wales Hospital.

Weaning from Tracheostomy

PMV use is an integral component of tracheostomy decannulation pathways. Successful tolerance of full-day PMV wear, combined with adequate secretion management and swallowing safety, contributes to the clinical decision to trial tracheostomy tube downsizing and ultimately decannulation. Mitchell et al. (2013) described a systematic decannulation protocol in which PMV tolerance was one of the five key criteria assessed. In the HK context, decannulation decisions typically involve a multidisciplinary team including ENT, respiratory medicine, SLT, and nursing.

HK Availability and Practical Considerations

PMVs are available through authorised medical device suppliers in Hong Kong and are stocked in most public hospital supplies chains. The standard PMV 2020 (aquamarine) and PMV 007 (ventilator model) are the most commonly used models. Caregivers of home-tracheostomised patients can obtain PMVs on prescription through hospital outpatient channels. Community nurses and caregivers require training in valve application, cleaning, and emergency removal before home use.

The PMV should be cleaned daily with mild soap and water (not autoclaved) and replaced every three to six months or earlier if the one-way mechanism becomes sluggish. Proper cleaning protocols should be documented in the patient’s home care plan.

Summary

The Passy Muir Valve represents one of the most evidence-supported interventions for tracheostomised patients with dysphagia, addressing both communication and swallowing safety through restoration of subglottic pressure and upper airway airflow. Appropriate candidacy screening, stepwise trial protocols, and instrumental assessment with FEES or VFSS are essential components of best practice. SLTs in Hong Kong should be familiar with both the mechanism and the practical logistics of PMV implementation across acute and community settings.

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