In recent years, many studies have found that in the process of using CPAP to treat OSA, when the optimal therapeutic pressure point is reached or close to, central apnea will appear after obstructive respiratory events are basically eliminated. The phenomenon was first called complex sleep apnea syndrome(CompSAS) in 2005.
According to the current definition, CompSAS refers to CSA-based sleep-disordered breathing after OSA titration treatment with CPAP, so the short-term treatment effect of CPAP is not good. However, some studies have shown that after several months to one year of long-term CPAP treatment, most of the CSA can disappear, so the CSA that appears in the CPAP treatment of OSA may be temporary. The emergence of CSA may be related to sleep fragmentation and sleep stage migration caused by the initial titration of CPAP.
There appears to be a turning point during CPAP titration therapy, at which pressure levels are increased to completely clear obstructive events to induce CSA/CSR, and to reduce pressure residual obstructive respiratory events lead to respiratory airflow limitation correlations Arousal, therefore the optimal pressure for positive airway pressure therapy cannot be determined. Although clinical symptoms improved after positive airway pressure therapy, poor sleep quality and daytime fatigue remained.
The pathogenesis of CompSAS is unclear, and research on it is still at the theoretical stage.
Possible reasons are:
The diagnostic criteria of CompSAS are that after titration by CPAP, obstructive respiratory events are cleared and the residual central apnea index (CAI) is ≥ 5 times/h, or a predominantly CSR.
Early recognition of CompSAS is important as it appears in the midst of CPAP therapy and responds poorly to CPAP. compSAS needs to be differentiated primarily from OSA.
The goal of treating CompSAS is primarily to reduce AHI to normal, restore normal sleep architecture and reduce daytime sleepiness, thereby reducing associated complications and improving the patient's quality of life.
Although there is no systematic treatment for CompSAS, noninvasive ventilation remains the most effective and promising treatment for CompSAS. Other treatments include lateral sleep, oxygen therapy, inhaled CO2, increased dead space ventilation, and avoidance of excessive CPAP titration therapy.
There is no accepted and proven treatment for those patients with CompSAS who have had poor results with long-term CPAP therapy. In recent years, there has been increasing research into the use of adaptive servo-ventilation (ASV) in the treatment of CompSAS.