Some practitioners may be hesitant to try managing mechanical ventilation in the cuff deflation condition, concerned that adequate ventilation cannot be maintained.  In a study done on “unweanable” patients with mechanical ventilation with neuromuscular disease, Bach reported that 91 out of 104 patients were adequately ventilated with either the cuff deflated or with cuffless tracheostomy tubes (Bach & Alba, 1990).  Pediatric patients are typically ventilated with cuffless tracheostomy tubes in order to reduce complications of inflated cuffs.

The cuff may be deflated when an individual is on mechanical ventilation in order to allow for speech and improved swallowing. The term used to describe speech when the cuff is fully or partially deflated is termed “leak speech.”  Speech is primarily available on the inspiratory cycle as this is the phase when the ventilator primarily delivers air.  . With the conventional volume-control mode, patients use the pressures and flows provided by the ventilator to speak. Ventilator-supported speech is therefore mainly produced during the inspiratory phase of the ventilator cycle and can only be continued during the initial part of the expiratory phase, as it stops when the tracheal pressure falls below the threshold value allowing speech.

When cuff deflation is performed with volume modes, the airflow used to ventilate the patient is partly being used for speech.  Ventilator changes may improve tolerance of cuff deflation for those on mechanical ventilation. 

After step six in the above protocol, assess the patient for possible ventilator changes.  A physician order is required prior to ventilator changes.  

 Volume:  The patient may not receive the pre-set tidal volume when the cuff is deflated.  Tidal volume may need to be increased in order to compensate for the loss of volume that occurs through the upper airway during cuff deflation.  Excessive tidal volume may lead to barotrauma, particularly in those with high peak inspiratory pressures to begin with.  Increasing tidal volume should be done slowly with no more than 400ml of additional volume provided.  

I:E Ratio:  The I:E ratio is the ratio of inspiration to expiration.  Increasing the inspiratory time can be achieved by lengthening the set inspiratory time (iTime) or lowering the inspiratory flow rate.  Increasing the amount of time of inspiration can provide longer speech (syllables per minute)(Hoit et al, 2003) and may also improve patient comfort. This may help the patient to coordinate voice with the ventilator.  

Positive End Expiratory Pressure (PEEP):  If the PEEP is set to zero than most of the exhaled gas will exit through the ventilator circuit rather than through the upper airway, resulting in limited ability to speak during expiration.  When PEEP is set on the ventilator then there is an increased likelihood that gas will flow through the upper airway, which increases speaking rate.  When PEEP was added (5 to 10 cm H(2)O), speaking time was 25% longer and obligatory pauses were 21% shorter (Hoit et al, 2003).   Patients are able to speak but on inspiration and expiration when changes to inspiratory time and PEEP were made.  This is different than normal speech, which occurs on exhalation only.  High PEEP levels may result in hyperinflation, but is easily adjustable to patient tolerance. 

Bilevel Positive Pressure Ventilation (BPPV) combines PEEP and Pressure Support Ventilation (PSV), thus providing an increase in Ti and tidal Volume (iV) during leak speech, which allows the combination of beneficial effects on speech production of adding PEEP and changing iTime without manual adjustments.  Most pressure-support devices, terminate inspiration when inspiratory flow falls below a set percentage of the inspiratory peak flow. Patients subjectively felt more comfortable speaking on BPPV than ACV (Prigent, H et al, 2003).