Effect of mouth leak on effectiveness of nasal bilevel ventilatory assistance and sleep architecture

Abstract

Mouth leak is common during nasal ventilatory assistance, but its effects on ventilatory support and on sleep architecture are unknown. The acute effect of sealing the mouth on sleep architecture and transcutaneous carbon dioxide tension (Ptc,CO 2 ) was tested in 9 patients (7 hypercapnic) on longterm nasal bilevel ventilation with symptomatic mouth leak.Patients slept with nasal bilevel ventilation at their usual settings on two nights in random order. On one night, the mouth was taped closed. Nocturnal nasal bilevel ventilatory support has become an important and successful therapy for respiratory failure during sleep [1±3]. At present, nasal masks are more common than mouthpieces, mouth-nose masks or full face masks (perhaps because of issues related to comfort, fit and deadspace) but a major practical problem is escape of air via the mouth, as has been well documented for nasal continuous positive airway pressure (CPAP) [4,5].In the only study to date to directly measure the effect of mouth leaks on effectiveness of ventilatory support, CAR-REY et al.[6] investigated the effect of voluntary mouth opening on diaphragm electromyogram (EMG) activity during awake nasal intermittent positive pressure ventilation in 5 subjects. With the mouth closed, diaphragm EMG dropped to 15% of unassisted control, but with the mouth open, returned to 98% of unassisted control, implying complete loss of ventilatory support.Mouth leak is ubiquitous during noninvasive ventilatory support in sleep. BACH et al. [7] demonstrated that during nasal intermittent positive pressure ventilation (NIPPV), severe leak (>33% of tidal volume escaping) was present for a median of 55% of sleep time, and was associated with 7.5 desaturations (of at least 4%) per hour of sleep.MEYER et al. [8] found severe mouth leak during most of sleep time and 100% of slow wave sleep.Mouth leak could lead to severe sleep fragmentation, either directly via airway irritation, or indirectly via a reduction in effectiveness of ventilation as discussed above. In the study by BACH et al. [7], there were a total of 34 arousals . h -1 and 74% of desaturations were terminated by either an arousal or a lightening of sleep stage. The authors concluded that leak was reducing ventilatory effectiveness and causing desaturation, and that arousal reversed the leak and desaturation. Similarly, in the study of MEYER et al. [8] there were 46 arousals . h -1 in stages I-II nonrapid eye movement (NREM) sleep, associated in time with mouth leak. However, association in time does not establish causality, and it is not known whether preventing the mouth leak would improve sleep quality.The purpose of the present paper was to directly assess the effect of mouth leak on sleep architecture and transcutaneous carbon dioxide tension (Ptc,CO 2 ) during nasal bilevel ventilatory support, by preventing the leak. To do this, the authors measured the first-night effect of taping the mouth closed, on sleep architecture and Ptc,CO 2 in patients already on long-term nasal bilevel venti...

Leak Profile Inspection During Nasal Continuous Positive Airway Pressure

“…The leaks may be due to mask fit problems or, with nasal CPAP, mouth leaks, which have been polysomnographically documented to occur more often in patients with frequent mouth breathing during sleep. 23 This phenomenon correlates with worse adherence to nasal CPAP. 23 Large leaks can compromise CPAP's effectiveness in treating OSA.…”

“…23 This phenomenon correlates with worse adherence to nasal CPAP. 23 Large leaks can compromise CPAP's effectiveness in treating OSA. When the CPAP machine reads breath-by-breath signals to either trigger ventilatory assis- tance or modify the pressure at expiration, leak can render these "intelligent" or "triggered" algorithms ineffective and even disrupt sleep.…”

Intra-Hospital Transport of Patients on Non-Invasive Ventilation: Review, Analysis, and Key Practical Recommendations by the International NIV Committee

“…In any case, this policy must be matched with features and configurations of the ventilator system adopted for the transport. Considering that the simplest ventilator circuit should generally be given precedence for transport (25), if the patient is shifted from a dual-limb to a single-limb circuit, as previously mentioned, there might be the need to switch from a non-vented to a vented mask or to insert a proper exhalation valve (18,26,27). In this regard, it is important to consider that some single-limb circuit ventilators are tested to work with their specific brand of masks in order to guarantee full CO 2 rebreathing prevention.…”

Can We Improve Sleep Quality by Changing the Way We Ventilate Patients?

“…Major causes of sleep disturbance associated with mechanical ventilation include patient-ventilator asynchronies [16], central apneas due to overventilation [17], and inadequate ventilatory support due to improper settings or air leaks leading to increased respiratory effort [18]. Therefore, there is a renewed interest in finding novel ways of adequately ventilating patients while minimizing sleep disturbance.…”