Efficacy of auto-trilevel positive airway ventilation on patients with both obesity hypoventilation and moderate to severe obstructive sleep apnea syndromes

Abstract

Objective To observe the efficacy of auto-trilevel positive airway pressure (Auto-trilevel PAP) ventilation on patients with both obesity hypoventilation syndrome (OHS) and moderate to severe obstructive sleep apnea syndromes (OSAS) by comparison of fixed bilevel positive airway pressure (BiPAP) ventilation.Methods 17 patients with both OHS and moderate to severe OSAS were recruited.Three different positive airway pressure (PAP) modes issued by the ventilators (SOMNOvent auto-S,Weinmann Inc,Germany) were used for 8 hours per night with each mode at each night and two nights’interval without any treatment among different modes.In mode one,the EPAP issued by BiPAP was titrated as the Minimal positive pressure for disappearance of snoring.The same inspiratory positive airway pressure (IPAP) titrated by PaCO2 in mode 1 was used in mode 2 and 3 as well.However,the EPAP issued by BiPAP in mode 2 was 3 cm H2O higher than that in mode 1.In mode 3 with autotrilevel PAP,the beginning of EPAP was set the same as that in mode 1 while the end of EPAP (EEPAP) was automatically adjusted to elevate based on upper airway patency condition.Comparisons were made for parameters before and after treatment as well as among different ventilation modes. The following parameters were compared such as nocturnal apnea hypopnea index (AHI),Minimal SpO2 (MiniSpO2),arousal index,sleep efficiency,morning PaCO2 and daytime ESS.Results Compared with the parameters before ventilation therapies,there was a significant decrease in nocturnal AHI,arousal index,morning PaCO2 and daytime ESS,but a significant increase in nocturnal MiniSpO2 and sleep efficiency caused by all three modes of ventilation (all P ＜0.01).Comparison among three modes demonstrated that with the same IPAP,the mode 3 could result in the lowest arousal index,daytime ESS and the highest sleep efficiency.Comparison between mode 1 and 2 revealed there was a statistically lower AHI but higher MiniSpO2 and morning PaCO2 in mode 2 (all P ＜0.01).Compared with mode 1,in mode 3 there was a lower AHI,higher MiniSpO2 (all P ＜0.01 ),but no significant difference in morning PaCO2 at the end of therapy.Compared with mode 2,in mode 3 there was a significant lower morning PaCO2 ( P ＜0.01),but no significant difference in AHI and MiniSpO2.Conclusions Auto-trilevel PAP ventilation is superior over fixed BiPAP ventilaiton for treatment of OHS with coexisting moderate to severe OSAS,since this novel PAP mode can achieve a higher efficacy in simultaneous removal of residual apnea hypopnea events and correction of hypercapnia as well as in achieving a higher sleep quality and lower daytime sleepiness. Key words: Obesity hypoventilation syndrome; Obstructive sleep apnea syndrome; Positive airway pressure ventilation