A multicentric validation study of a novel home sleep apnea test based on peripheral arterial tonometry.

STUDY OBJECTIVES: This paper reports on the multicentric validation of a novel FDA-cleared home sleep apnea test based on peripheral arterial tonometry (PAT HSAT). METHODS: One hundred sixty-seven participants suspected of having obstructive sleep apnea (OSA) were included in a multicentric cohort. All patients underwent simultaneous polysomnography (PSG) and PAT HSAT, and all PSG data were independently double scored using both the recommended 1A rule for hypopnea, requiring a 3% desaturation or arousal (3% Rule), and the acceptable 1B rule for hypopnea, requiring a 4% desaturation (4% Rule). The double-scoring of PSG enabled a comparison of the agreement between PAT HSAT and PSG to the inter-rater agreement of PSG. Clinical endpoint parameters were selected to evaluate the device's ability to determine the OSA severity category. Finally, a correction for near-boundary apnea-hypopnea index values was proposed to adequately handle the inter-rater variability of the PSG benchmark. RESULTS: For both the 3% and the 4% Rules, most endpoint parameters showed a close agreement with PSG. The 4-way OSA severity categorization accuracy of PAT HSAT was strong, but nevertheless lower than the inter-rater agreement of PSG (70% vs 77% for the 3% Rule and 78% vs 81% for the 4% Rule). CONCLUSIONS: This paper reported on a multitude of robust endpoint parameters, in particular OSA severity categorization accuracies, while also benchmarking clinical performances against double-scored PSG. This study demonstrated strong agreement of PAT HSAT with PSG. The results of this study also suggest that different brands of PAT HSAT may have distinct clinical performance characteristics.

Working memory capacity is decreased in sleep-deprived internal medicine residents.

BACKGROUND: Concerns about medical errors due to sleep deprivation during residency training led the Accreditation Council for Graduate Medical Education to mandate reductions in work schedules. Although call rotations with extended shifts continue, effects on resident sleep-wake times and working memory capacity (WMC) have not been investigated. OBJECTIVES: The objective of this study was to measure effects of call rotations on sleep-wake times and WMC in internal medicine residents. METHODS: During 2 months of an internal medicine training program adhering to ACGME work-hour restrictions (between April 2006 and June 2007), residents completed daily WMC tests, wore actigraphy watches, and logged their sleep hours. This observational study was conducted during a call month requiring 30-hour call rotations every fourth night, whereas the noncall month, which allowed sleep/wake cycle freedom, was used as the control. MAIN OUTCOME MEASURES: Sleep hours per night and WMC testing. RESULTS: Thirty-nine residents completing the study had less sleep per night during their call month (6.4 vs 7.3 h per night noncall, p < 0.001) and sleep per night varied from 3.7 to 10.1 hours. Call rotation caused greater self-assessed sleepiness and reduced WMC recall scores (-2.6/test, p < 0.05), and more math errors occurred when on call (+1.07/test, p < 0.04). Full recovery of WMC did not occur until the fourth day after call. On-call rotation on the first month had a confounding detrimental effect on WMC. CONCLUSION: A month of call rotations reduced overall sleep per night; sleep hours per night were variable, and WMC was adversely affected. Decreased WMC could explain impaired judgment during sleep deprivation, although clinical error rates were not evaluated.

Sleep and critical care.

PURPOSE OF REVIEW: Sleep distortion has been studied as an independent risk factor for morbidity and mortality; however, this role in the ICU patients is unclear. These patients suffer from psychological and physiological stressors and significant disturbance in sleep. We conducted a systematic review of all recent data over the last decade to elaborate the extent and implications of sleep disruption in the ICU. RECENT FINDINGS: Despite adequate data proving that ICU patients have poor quality of sleep over the last three decades, the implications of the sleep distortion in this patient population remains misunderstood. Recently, the Whitehall cohort trial has raised interest in sleep and mortality and substantial data have surfaced regarding prevalence of sleep disturbance in the ICU. SUMMARY: This article discusses the available data on sleep disruption in patients in the ICU and implications with discussion of effects of ventilators and commonly used medications in the ICU. We will conclude with interventions to improve sleep in the intensive care setting.

Identification and treatment of bronchoconstriction induced by a vagus nerve stimulator employed for management of seizure disorder.

We evaluated a 63-year-old woman who developed dyspnea with a sensation of chest tightness that was temporally associated with discharges from a vagus nerve stimulator that had been implanted for the control of intractable seizures. Spirometry demonstrated the development of significant airflow obstruction associated with the firing of the stimulator. Adjustment of the stimulator settings resolved the discharge-associated bronchoconstrictive phenomenon. These findings highlight an important association between vagus nerve stimulators and dyspnea that should be considered in the differential diagnosis of patients with these devices who present with dyspnea and/or chest tightness. The relative importance of vagal stimulation to bronchoconstriction is suggested by the findings.

Shifting care of chronic ventilator-dependent patients from the intensive care unit to the nursing home.

BACKGROUND: Among the most resource intensive and challenging of medical needs is the treatment of patients requiring long-term or chronic mechanical ventilation. Expenditures are significant, and definitions of "successful weaning," are often inconsistent. A weaning program was initiated for patients referred to a stand-alone nursing home ventilator unit. METHODS: Weaning entailed standardized weaning protocols, enhanced socialization, a multidisciplinary approach to care, empowerment of staff to initiate weaning, and aggressive utilization of noninvasive positive pressure ventilation (NPPV) in selected patients. RESULTS: Sixty-eight (67%) of 102 patients were successfully weaned during a six-year period. NPPV facilitated successful weaning in 27 (26%) of 102 patients. Of the 28 chronic ventilator-dependent patients admitted with a neuromuscular etiology for respiratory failure, NPPV was utilized in 73% (8/11) of the successfully weaned patients. Total variable costs per ventilator per patient per day for the years 1998-2000 were $319.79, $302.75, and $297.59. Six-year cost savings for referring hospitals were estimated at $18.5 million. DISCUSSION: Incentives were aligned between the hospital, nursing home, and physicians to develop a financially stable model. Developing an off-site nursing home ventilator unit resulted in significant cost savings to the referring hospitals and positively affected patient flow.

Sleep, sleepiness and school start times: a preliminary study.

BACKGROUND: High school students are reported to be excessively sleepy, resulting in decreased academic performance, increased psycho-social problems and increased risk of morbidity and mortality from accidents. Early school start times have been noted to contribute to this problem. This report attempts to confirm the relationship of early school start times with decreased sleep and increased sleepiness. METHODS: We examined sophomore and junior students in 2 local high schools with different start times and measured the amount of time slept and sleepiness. RESULTS: We found that students at the early start school reported reduced sleep time and more sleepiness than their counterparts at the later starting school. CONCLUSION: Early school start times are associated with student reports of less sleep and increased sleepiness. Further studies in larger groups are recommended in view of the potential significant impact of sleep deprivation in this age group.