Mouthpiece ventilation (MPV) allows patients with
neuromuscular disease to receive daytime support from a portable
ventilator, which they can disconnect at will, for example, for speaking, eating, swallowing, and coughing. However, MPV carries a risk of underventilation. Our purpose here was to evaluate the effectiveness of daytime MPV under real-life conditions. Eight wheelchair-bound patients who used MPV underwent daytime polygraphy at home with recordings of airflow, mouthpiece pressure, thoracic and abdominal movements, peripheral capillary oxygen saturation (SpO2), and transcutaneous partial pressure of
carbon dioxide (PtcCO2). Times and durations of tasks and activities were recorded. The
Apnea-Hypopnea Index (AHI) was computed. Patient-
ventilator disconnections ≥3 minutes and episodes of
hypoventilation defined as PtcCO2>45 mmHg were counted.
Patient-ventilator asynchrony events were analyzed. The AHI was >5 hour(-1) in two patients. Another patient experienced unexplained 3% drops in arterial
oxygen saturations at a frequency of 70 hour(-1). Patient-
ventilator disconnections ≥3 minutes occurred in seven of eight patients and were consistently associated with decreases in SpO2 and ≥5-mmHg increases in PtcCO2; PtcCO2 rose above 45 mmHg in two patients during these disconnections. The most common type of
patient-ventilator asynchrony was ineffective effort. This study confirms that MPV can be effective as long as the patient remains connected to the mouthpiece. However, transient arterial
oxygen desaturation and
hypercapnia due to disconnection from the
ventilator may occur, without inducing unpleasant sensations in the patients. Therefore, an external warning system based on a minimal acceptable value of minute ventilation would probably be useful.