Obstructive pressure peak: a new method for differentiation of obstructive and central apneas under auto-CPAP therapy

Significance of vaspin in obstructive sleep apnea-hypopnea syndrome

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a commonly-diagnosed chronic sleep disorder. It is considered to be an important independent risk factor in the development of insulin resistance (IR). Patients with OSAHS exhibit a variety of metabolic disorders, including obesity and metabolic syndrome. Visceral adipose tissue-derived serpin (vaspin) is an adipokine that is considered to be a link between obesity and IR. The present study aimed to evaluate the levels of plasma vaspin in patients with OSAHS and examine their potential correlation with sleep characteristics. A total of 20 healthy male subjects and 42 male patients with OSAHS were selected, and patients were divided into mild (n=22) and severe (n=20) OSAHS groups. The 20 patients in the severe OSAHS group received nasal continuous positive airway pressure (nCPAP) treatment for 2 months. Venous blood samples were drawn from all patients in a fasting state prior to and subsequent to nCPAP treatment, which were used to measure the levels of biochemical indicators. The sleep parameters and serologic index changes were compared prior to and following treatment. The values of contractive pressure (SBP), neck circumference (NC), waist circumference (WC), waist-to-hip ratio (WHR), body mass index (BMI) and hip circumference (HC) in the two OSAHS groups were significantly increased compared with those in the control group. In addition, the levels of vaspin in OSAHS patients were markedly increased and vaspin was revealed to be positively associated with fasting blood sugar, fasting insulin, triglycerides, homeostasis model assessment-IR, apnea-hypopnea index (AHI), NC, WC, BMI and WHR (P<0.05). After 2 months of nCPAP treatment, the SBP and AHI were significantly reduced. In conclusion, vaspin may have an important role in OSAHS patients with IR and treatment using nCPAP may improve the condition of OSAHS patients.

All APAPs Are Not Equivalent for the Treatment of Sleep Disordered Breathing: A Bench Evaluation of Eleven Commercially Available Devices

STUDY OBJECTIVES

This study challenged on a bench-test the efficacy of auto-titrating positive airway pressure (APAP) devices for obstructive sleep disordered breathing treatment and evaluated the accuracy of the device reports.

METHODS

Our bench consisted of an active lung simulator and a Starling resistor. Eleven commercially available APAP devices were evaluated on their reactions to single-type SDB sequences (obstructive apnea and hypopnea, central apnea, and snoring), and to a long general breathing scenario (5.75 h) simulating various SDB during four sleep cycles and to a short scenario (95 min) simulating one sleep cycle.

RESULTS

In the single-type sequence of 30-minute repetitive obstructive apneas, only 5 devices normalized the airflow (> 70% of baseline breathing amplitude). Similarly, normalized breathing was recorded with 8 devices only for a 20-min obstructive hypopnea sequence. Five devices increased the pressure in response to snoring. Only 4 devices maintained a constant minimum pressure when subjected to repeated central apneas with an open upper airway. In the long general breathing scenario, the pressure responses and the treatment efficacy differed among devices: only 5 devices obtained a residual obstructive AHI < 5/h. During the short general breathing scenario, only 2 devices reached the same treatment efficacy (p < 0.001), and 3 devices underestimated the AHI by > 10% (p < 0.001). The long scenario led to more consistent device reports.

CONCLUSION

Large differences between APAP devices in the treatment efficacy and the accuracy of report were evidenced in the current study.