Piezoelectric rubber sheet sensor: a promising tool for home sleep apnea testing.

PURPOSE: This study aimed to develop an unobtrusive method for home sleep apnea testing (HSAT) utilizing micromotion signals obtained by a piezoelectric rubber sheet sensor. METHODS: Algorithms were designated to extract respiratory and ballistocardiogram components from micromotion signals and to detect respiratory events as the characteristic separation of the fast envelope of the respiration component from the slow envelope. In 78 adults with diagnosed or suspected sleep apnea, micromotion signal was recorded with a piezoelectric rubber sheet sensor placed beneath the bedsheet during polysomnography. In a half of the subjects, the algorithms were optimized to calculate respiratory event index (REI), estimating apnea-hypopnea index (AHI). In the other half of subjects, the performance of REI in classifying sleep apnea severity was evaluated. Additionally, the predictive value of the frequency of cyclic variation in heart rate (Fcv) obtained from the ballistocardiogram was assessed. RESULTS: In the training group, the optimized REI showed a strong correlation with the AHI (r = 0.93). Using the optimal cutoff of REI ≥ 14/h, subjects with an AHI ≥ 15 were identified with 77.8% sensitivity and 90.5% specificity. When applying this REI to the test group, it correlated closely with the AHI (r = 0.92) and identified subjects with an AHI ≥ 15 with 87.5% sensitivity and 91.3% specificity. While Fcv showed a modest correlation with AHI (r = 0.46 and 0.66 in the training and test groups), it lacked independent predictive power for AHI. CONCLUSION: The analysis of respiratory component of micromotion using piezoelectric rubber sheet sensors presents a promising approach for HSAT, providing a practical and effective means of estimating sleep apnea severity.

[A Thrombus in the Right Atrium Associated with Pyogenic Liver Abscess].

Hepatic abscesses are divided into bacterial and amoebic types. Although the prognosis of bacterial liver abscesses has improved owing to progress in drainage techniques and antimicrobial agents, poor outcomes remain common. While there have been some reports of amoebic liver abscesses complicated by thrombosis, bacterial liver abscesses and subsequent thrombus in the right atrium are very rare. We herein report the case of an 82-year-old man. He had suffered acute obstructive suppurative cholangitis 10 months previously, and bile culture yielded Enterococcus faecalis. In the present case, a right atrial thrombus caused by a bacterial liver abscess was observed and the causative organism was thought to be Enterococcus faecalis, for which was detected in a blood culture was positive. The patient was successfully treated with hepatic abscess drainage and surgical right atrial thrombectomy under cardiopulmonary bypass with a beating heart.