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Troubleshooting problems with noninvasive positive pressure ventilation

Nicholas S Hill, MD
Naomi R Kramer, MD
Section Editors
Talmadge E King, Jr, MD
Polly E Parsons, MD
Deputy Editor
Geraldine Finlay, MD


Noninvasive positive pressure ventilation (NPPV) is now commonly used, especially at night, to assist ventilation in patients with a variety of neuromuscular and chest wall diseases. Most patients have some difficulty adapting to nocturnal use of NPPV, although occasional patients adapt within days. Facilitating adjustment to NPPV is important as regular use of NPPV has been shown to lengthen survival in patients with neuromuscular disease [1]. In addition, greater than four hours of use per night has been associated with increased CO2 responsiveness and lower partial pressure of carbon dioxide (PaCO2) levels when compared to less than four hours per night [2].

Approaches to resolving the most common side effects of NPPV and to addressing failure of NPPV to improve gas exchange are reviewed here. The indications for and the initiation of nocturnal and daytime NPPV are discussed separately. (See "Practical aspects of nocturnal noninvasive ventilation in neuromuscular and chest wall disease" and "Continuous noninvasive ventilatory support for patients with respiratory muscle dysfunction" and "Types of noninvasive nocturnal ventilatory support in neuromuscular and chest wall disease".)


Mask discomfort is the most commonly encountered problem for patients adapting to noninvasive positive pressure ventilation (NPPV) [3]. The practitioner should ensure that mask fit is optimal and that minimal strap tension is used to control air leaking. Trials with different types of interfaces may help, such as the "bubble" mask, gel masks, nasal "pillows," custom-fit masks, or even oronasal masks or mouthpieces. The patient should not be forced to use the mask for more time than can be tolerated, and should be encouraged to attempt adaptation for at least several weeks or months before giving up. Adaptation can include wearing the mask for brief, but progressively longer, periods while watching TV or participating in another distracting activity. Despite these efforts, a minority of patients may be unable to tolerate the sensation of a foreign body strapped to the face, and alternative noninvasive ventilators should be tried. The helmet interface should not be used. (See "Types of noninvasive nocturnal ventilatory support in neuromuscular and chest wall disease".)


Both nasal congestion and dryness occur commonly during noninvasive positive pressure ventilation (NPPV), sometimes in the same patient. These complaints tend to be seasonal (dryness worse during the winter months) and should be treated symptomatically.

In-line heated humidification has become standard and has reduced the nasal dryness problem [4]. Both the warmth and increased humidity tend to enhance comfort with the airflow. The heated humidifier may also decrease nasal resistance to airflow, which is helpful for patients with concomitant obstructive sleep apnea [5]. The heater may be adjusted to increase and decrease the humidity of the incoming air as needed depending on the local environmental conditions, the pressures at which the ventilator is set, and patient preference [6]. Pass-over humidifiers (in which the gas passes over the surface of water) are most often used with pressure-limited ventilators, in order to avoid the drop in pressure that could occur with pass-through humidifiers (in which the gas is bubbled through water). Insulation around the tubing or heated wires within (heated tubing) may also help decrease condensation inside the tube, known as "rain-out." Condensation in the tube seems to be particularly problematic in cold climates where the indoor temperatures are often lower at night.

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Literature review current through: Nov 2017. | This topic last updated: May 31, 2016.
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