Auto-trilevel Versus Bilevel Positive Airway Pressure Ventilation For Treating Overlap Syndrome With Hypercapnia

Background and objective Although bilevel positive airway pressure?BiPAP?therapy is the treatment of choice for overlap syndrome?OS?,there is still a portion of OS patients in whom residual apnea events and hypercapnia could not been simultaneously avoided during the BiPAP therapy.The aim of this study was to investigate whether auto-Trilevel positive airway pressure?auto-TriPAP?therapy with auto-adjusting end expiratory positive airway pressure?EEPAP?can serve as a better alternative for these patients.Patients and MethodsFrom December of 2013 to July of 2016,we recruited 32 hypercapnic OS patients with their pulmonary diseases?COPD?at stable stage and coexisting moderate-to-severe obstructive sleep apnea hypopnea syndrome?OSAHS?..We compared three different types of positive airway pressure?PAP?modes from the Auto-trilevel ventilators?Prisma25ST,Weinmann Inc,Germany?.During comparison each PAP mode was used as 8 hours per night followed by two nights'interval without any treatment as washout period among different PAP modes.In mode 1,the EPAP was titrated as the minimal PAP for snoring removal.On one hand,the inspiratory positive airway pressure?IPAP?was pursued the same from mode 1-3 as the minimal pressure to keep end tidal CO₂?ETCO₂??45 mmHg for each patient.On the other hand,the EPAP in mode 2 purposely maintained 3cmH₂O higher than that in mode 1.In mode 3 Auto-triPAP was used with the EPAP at two different levels,i.e.,the beginning of EPAP was the same as that in mode 1 but the EEPAP was automatically adjusted to elevate at a range of?4cmH2O based on nasal airflow wave measuement.We compared the effects of three PAP modes on parameters before,during or following treatment as well as among different PAP treatment modes.The observed parameters included apnea hypopnea index?AHI?,arousal index?AI?,minimal SpO₂?miniSpO₂?,sleep structure and efficiency during sleep,In addition,morning PaCO₂ following PAP treatment and daytime Epworth sleepiness score?ESS?were also recorded and compared.Results Compared with the parameters before PAP therapies,there was a signi ficant decrease in nocturnal AHI,arousal index,morning PaCO₂ and daytime ESS,but a significant increase in nocturnal miniSpO₂ and sleep efficiency cau sed by all three PAP modes?all P<0.01?.Comparison among three differrent PAP modes revealed that when IPAP was kept unchanged,during mode 3 tr eatment,arousal index and daytime ESS were the lowest and the sleep efficie ncy was the highest.Compared with mode 1,it was detected that a)AHI wa s lower but miniSpO₂ was higher in both mode 2 and 3?all P<0.05?;b)mor ning PaCO₂ was higher in mode 2?P<0.05?but no significant changes in mo de 3.Although no significant difference in AHI and miniSpO₂ was detected b etween mode 2 and mode 3?all P>0.05?,the morning PaCO₂ was lower in mode 3 than in mode 2?P<0.05?.Conclusion Auto-TriPAP therapy was superior over conventional BiPAP ventilaiton for treatment of hypercapnic OS with coexisting moderate to severe OSAS,since Auto-TriPAP could lead to a higher efficacy in synchronized elimination of residual apnea events and hypercapnia as well as in obtaining a better sleep quality and reduced daytime sleepiness.