Romem A; Romem A; Koldobskiy D; Scharf SM. Diagnosis of obstructive sleep apnea using pulse oximeter derived photoplethysmographic signals.

BACKGROUND Circadian rhythm regulates many physiologic and immunologic processes. Disruption of these processes has been demonstrated in acutely ill, mechanically ventilated patients in the ICU setting. Light has not been studied as an entraining stimulus in the chronically mechanically ventilated patient. The purpose of this study was to determine the association of naturally occurring ambient light levels in a long-term acute care (LTAC) hospital with circadian rhythm in patients recovering from critical illness and requiring prolonged mechanical ventilation (PMV). METHODS We performed a prospective observational study of 15 adult patients who were recovering from critical illness and receiving PMV and who were admitted to the ventilator weaning unit at an LTAC hospital. Demographic data were obtained from chart review. Light stimuli in each patient room were assessed using a photometer device placed at eye level. Circadian rhythm was assessed by wrist actigraphy. Cumulative data were obtained from each device for a 48-h period, averaged into 4-h intervals, and analyzed. RESULTS Patients receiving PMV were obese (mean body mass index of 32.7 ± 10.3 kg/m2) and predominantly female (73%) and had an average age of 63.1 ± 14.3 y. Light exposure to this cohort maintained diurnal variation (P < .001) and was significantly different across time periods. Circadian rhythm, as represented by actigraphy, also maintained diurnal variation (P < .001) and was in phase with light. Linear regression of movement and time demonstrated a moderate relationship between light and actigraphy (R2 = 0.56). CONCLUSIONS Despite requiring continued high-level care and a prolonged stay in a medical facility, patients recovering from critical illness and actively weaning from PMV maintain their circadian rhythm in phase with normal diurnal variations of light.

BACKGROUND In this study, we examined the association between 25-hydroxyvitamin D (25(OH)D) concentration and successful weaning from mechanical ventilation in a cohort of ICU survivors requiring prolonged mechanical ventilation. METHODS This was a retrospective cohort study of ICU survivors admitted to a long-term acute care hospital. Demographic data were extracted from medical records, including 25(OH)D concentrations drawn on admission. Subjects were divided into 2 groups based on their 25(OH)D concentrations (deficient, < 20 ng/mL; not deficient, ≥ 20 ng/mL), and associations between 25(OH)D concentration and successful weaning were calculated. RESULTS A total of 183 subjects were studied. A high prevalence of 25(OH)D deficiency was found (61%, 111/183). No association was found between 25(OH)D concentration and weaning from mechanical ventilation. Increased comorbidity burden (Charlson comorbidity index) was associated with decreased odds of weaning (odds ratio of 0.50, 95% CI 0.25– 0.99, P = .05). CONCLUSIONS Vitamin D deficiency is common in ICU survivors requiring prolonged mechanical ventilation. Surprisingly, there was no significant relationship between 25(OH)D concentration and successful weaning. This finding may be due to the low 25(OH)D concentrations seen in our subjects. Given what is known about vitamin D and lung function and given the low vitamin D concentrations seen in patients requiring long-term ventilatory support, interventional studies assessing the effects of 25(OH)D supplementation in these patients are needed.

Background. Recent studies of risks in cardiopulmonary arrest (CPA) have been performed using large databases from a broad mix of hospital settings. However, these risks might be different in a large, urban, academic medical center. We attempted to validate factors influencing outcomes from CPA at the University of Maryland Medical Center (UMMC).Methods. Retrospective chart review of all adult patients who underwent CPA between 2000 and 2005 at UMMC. Risk factors and outcomes were analyzed with appropriate statistical analysis and compared with published results.Results. 729 episodes of CPA were examined during the study period. Surgical patients had better survival than medical or cardiac patients. Intensive care unit' (ICU) patients had poor survival, but there was no difference on monitored or unmonitored floors. Respiratory etiologies survived better than cardiac etiologies. CPR duration and obesity were negatively correlated with outcome, while neurologic disease, trauma, and electrolyte imbalances improved survival. Age, gender, race, presence of a witness, presence of a monitor, comorbidities, or time of day of CPA did not influence survival, although age was associated with differences in comorbidities.Conclusions. UMMC risk factors for CPA survival differed from those in more broad-based studies. Care should be used when applying the results of database studies to specific medical institutions.

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