Comparison between auto-trilevel and bilevel positive airway pressure ventilation for treatment of patients with concurrent obesity hypoventilation syndrome and obstructive sleep apnea syndrome.

PURPOSE: Our study aims to compare the difference in clinical efficacy between auto-trilevel positive airway pressure (auto-trilevel PAP) ventilator and conventional fixed bilevel positive airway pressure (BiPAP) ventilator for obesity hypoventilation syndrome (OHS) patients with coexisting moderate or severe obstructive sleep apnea hypopnea syndrome (OSAHS).

METHODS: Twenty-three OHS patients with moderate or severe OSAHS enrolled between January 2015 and September 2017 underwent ventilation by three different modes of positive airway pressure (PAP) for 8 h per night. A single variable mode was applied at the first night followed by two nights when no PAP therapy was carried out as a washout period between each mode. The inspiratory positive airway pressure (IPAP) decided by PaCO2 was consistently used for modes 1, 2, and 3. In mode 1, the expiratory positive airway pressure (EPAP) issued by BiPAP was decided by the minimal PAP levels for cessation of snoring. However, in mode 2, the EPAP was fixed at 3 cmH2 O higher than this value. With the use of auto-trilevel PAP in mode 3, the EPAP was set to initially match that of mode 1 but the end of EPAP (EEPAP) was automatically regulated to be elevated according to upper airway patency condition. We also compared the following parameters including apnea hypopnea index (AHI), minimal SpO2 (miniSpO2 ), arousal index, and sleep efficiency during sleep; PaCO2 in the morning and Epword sleepiness score (ESS) at daytime were measured prior to and during PAP treatment as well as between three selected PAP modes.

RESULTS: Compared with the parameters before ventilation therapies, all three variable modes of ventilation were associated with a higher nocturnal miniSpO2 and sleep efficiency (all P < 0.01). Among the three variable modes, mode 3 resulted in not only the lowest arousal index and daytime ESS but also the highest sleep efficiency. Compared to mode 1, mode 2 demonstrated a significantly reduced AHI and an elevated miniSpO2 and morning PaCO2 (all P < 0.05), while mode 3 was associated with a decreased AHI, an increased miniSpO2 (all P < 0.05), and no statistical change of PaCO2 following the end of PAP treatment (P > 0.05). Comparison between mode 2 and mode 3 revealed that mode 3 had a significantly lower PaCO2 (P < 0.05), but displayed no remarkable changes of AHI and miniSpO2 (all P > 0.05).

CONCLUSION: Compared to fixed BiPAP ventilation, auto-trilevel PAP ventilation could more effectively correct hypercapnia, achieve lower index of nocturnal apnea and hypopnea, more improved sleep quality, and lower daytime sleepiness score. Auto-trilevel PAP ventilation is therefore more efficacious than conventional BiPAP ventilation in non-invasive ventilation therapy for OHS patients with concurrent moderate or severe OSAHS.