In our case study [2], we examined 12 patients with POSA as defined by an overall AHI > 10, a supine AHI > twice non-supine AHI and at least 1 h of sleep supine and non-supine, respectively. All patients received a baseline polysomnography according to standard criteria followed by fitting the vest (Fig. 1) and getting used to it during the day and a second polysomnography at night while wearing the vest.

We could show that the vest eliminated supine posture effectively. AHI was reduced in every single patient with only one patient showing a drop in AHI of less than 50 %. The average AHI dropped from 26.7 ± 11.9 to 7.6 ± 5.1. So was time spent with oxygen saturation below 90 % (from 11.7 ± 11.3 to 1.5 ± 2.1). However, snoring was not reduced to the same extent (from 180 ± 125 to 110 ± 52 min) with an increase of snoring time in 30 % of the cases. Sleep parameters such as sleep efficiency, the amount of sleep stages S1 and S2, slow wave sleep and REM sleep, as well as arousal index remained unchanged. All patients could sleep with the vest but two patients deemed it necessary getting used to. In summary, the supine prevention vest was able to show its efficacy during the first night of use.

However, until today there is only one study comparing a supine prevention vest with CPAP. Permut et al. [3] tested 38 patients with POSA as assessed by a baseline polysomnogram (AHI 13 ± 5) in a randomized crossover design for two consecutive nights. PT as well as CPAP reduced the AHI below 5 in 92 % vs. 97 %. Again there was a between-group difference of the treatment AHI in favor of CPAP (2 vs. 0), which may be considered clinically meaningless. Sleep parameters as well as oxygenation were comparable.

Both studies clearly show that upper airway obstruction and consecutive impaired breathing can be normalized effectively with vests preventing the supine position. Results are even comparable to CPAP treatment. Unfortunately, long-term data was not assessed in either of the studies.

Wenzel and co-workers [4] presented similar short-term results with the same type of vest in 14 patients. In addition, they conducted a structured telephone interview 13.7 ± 15.9 months after the initial fitting of the vest. Only four patients (29 %) continued using the vest daily after the sleep specialist had recommended it. Two among them were initial nonresponders, one a partial responder and one a complete responder. The latter was using the vest for 5 years at the time of the interview. All long-term users experienced a relevant subjective benefit regarding daytime sleepiness with a significant reduction of Epworth Sleepiness Scale from 8.5 ± 6.5. Patients who refused using the vest complained about the uncomfortable posture due to the rigid foam in the back (ten of ten), sleep interruptions (nine of ten), inability to sleep supine being the preferred sleep position (seven of ten), sweating (four of ten), feeling of tightness and hence the lack of subjective benefit. Of this group, three patients each decided to undergo surgery or weight reduction instead. Four patients followed rules of sleep hygiene more consequently as their own decision. Objective long-term data were not collected.

Similarly low subjective adherence rates have been reported with the TBT Oksenberg [5] reported that 19 of 50 (38 %) patients were still using the TBT after 6 months and Bignold [6] found only four long-term users of 67 (6 %) patients responding to a mail-based questionnaire after a follow-up of 2.5 ± 1.0 years. Reasons for interrupting positional treatment in both studies were again uncomfortable and disturbed sleep, back pain, or ineffectivity. Measuring objective compliance as done with CPAP is therefore of major importance when using positional therapy, too.