Faculty Bibliography

STUDY OBJECTIVES: To evaluate the validity of the Apnea Risk Evaluation System (ARES) Unicorder, a self-applied, limited-channel portable monitoring device for the evaluation of sleep disordered breathing (SDB). DESIGN: Prospective study with blinded analysis. SETTING: Sleep disorder center, academic institution. PARTICIPANTS: Eighty patients with suspected obstructive sleep apnea hypopnea syndrome (OSAHS) and 22 volunteers. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Subjects used the ARES Unicorder at home for 2 nights using only written instructions. Within 2 weeks, they returned to the laboratory for full nocturnal polysomnography (NPSG) with simultaneous monitoring with the Unicorder. NPSGs were scored manually to obtain an apnea-hypopnea index based on Medicare guidelines (AHI4%) and a respiratory disturbance index (RDI). ARES studies were autoscored and reviewed to obtain indices based on equivalent definitions i.e., AHI4%(ARES) and apnea hypopnea (events with 1% desaturation) index (AHI1%(ARES)). Indices from the NPSG were compared to the in-lab ARES and in-home ARES indices using mean differences and the intraclass correlations (ICC). For the in-lab comparison, there was high concordance between AHI4%(NPSG) and AHI4%(ARES) (ICC = 0. 96, mean difference = 0.5/hour) and RDI(NPSG ) and AHI1%(ARES) (ICC =0.93, mean difference = 3.2/hour). For NPSG versus In-Home ARES comparison, there was good concordance between AHI4%(NPSG) and AHI4%(ARES) (ICC = 0.8, mean difference = 4.1/ hour) and RDI(NPSG) and AHI1%(ARES) (ICC = 0.8 mean difference = 8.6/hour). The diagnostic sensitivity of in-lab ARES for diagnosing SDB using an RDI cut-off of 15 per hour was 95% and specificity was 94%, with a positive likelihood ratio (LR+) =17.04, and negative likelihood ratio (LR-) = 0.06. For in-home ARES data the sensitivity was 85% and specificity 91% (LR+ = 9.34, LR- = 0.17). There was good agreement between the manually scored NPSG SDB indices and the autoscoring ARES algorithm. CONCLUSIONS: ARES Unicorder provides acceptably accurate estimates of SDB indices compared to conventional laboratory NPSG for both the simultaneous and in-home ARES data. The high sensitivity, specificity, and positive and negative likelihood ratios obtained in the group we studied supports the utility of an ambulatory limited-monitoring approach not only for diagnosing sleep disordered breathing but also to rule out SDB in suitably selected groups.

This paper presents a series of experiments, both in patients and computer models, investigating the transition from acute to chronic hypercapnia in OSA. The data demonstrate that acute hypercapnia during periodic breathing occurs due to either reduction in magnitude of inter-event ventilation and/or reduction in inter-event ventilatory duration relative to duration of the preceding event. The transition between acute hypercapnia during sleep and chronic sustained hypercapnia during wakefulness may be determined by an interaction between respiratory control and renal handling of HCO3-.

The relationship between chewing gum and short-term learning was investigated as prior studies had reported conflicting results. Incoming 1st-yr dental students were assigned by stratified randomization to either a group who chewed gum during lectures and examinations or a group that did not chew gum. The research subjects listened to a taped lecture on dental anatomy and then completed 2 examinations: a test of specific knowledge which was a multiple-choice test on the dental anatomy lecture material; and a test of generalized knowledge which was a standardized reading comprehension exam. Statistical analysis of the results showed that in a group of graduate students with a history of high academic performance, there was no difference in learning between research subjects who chewed gum compared with those who did not chew gum, as measured by performance on either test

PURPOSE: To test the relationship between nurses' perceptions of the geriatric nurse practice environment (GNPE) and perceptions of geriatric-care delivery, and geriatric nursing knowledge. DESIGN: A secondary analysis of data collected by the New York University Hartford Institute Benchmarking Service staff using a retrospective, cross-sectional, design. METHODS: Responses of 9,802 direct-care registered nurses from 75 acute-care hospitals in the US that administered the GIAP (Geriatric Institutional Assessment Profile) from January 1997 to December 2005 were analyzed using linear mixed effects modeling to explore associations between variables while controlling for potential covariates. FINDINGS: Controlling for hospital and nurse characteristics, a positive geriatric nurse practice environment was associated with positive geriatric care delivery (F=4,686, p<.0001) but not geriatric nursing knowledge. The independent contribution of all three dimensions of the geriatric nurse practice environment (resource availability, institutional values, and capacity for collaboration) influences care delivery for hospitalized older-adult patients. CONCLUSIONS: Organizational support for geriatric nursing is an important influence upon quality of geriatric care. CLINICAL RELEVANCE: Hospitals that utilize an organizational approach addressing the multifaceted nature of the GNPE are more likely to improve the hospital experience of older adults.

The dietary and environmental agent, 6-nitrochrysene (6-NC) is a powerful mammary carcinogen and mutagen in rats. It is known to be metabolized by ring-oxidation, nitro-reduction and a combination of the two pathways. In order to determine the ultimate mutagenic metabolites, we have compared the previously determined mutational profile of 6-NC in rat mammary gland [T. Boyiri, et al. (2004) Carcinogenesis, 25, 637-643] with that of five of its known metabolites in the cII gene of lacI mammary epithelial cells in vitro. In vivo, 6-NC gives rise to three major mutations, AT > GC, AT > TA and GC > TA (in decreasing order) which comprise >70% of the mutations. The metabolite whose mutational profile was most similar to that of 6-NC in vivo was trans-1,2-dihydroxy-1,2-dihydro-N-hydroxy-6-aminochrysene (1,2-DHD-6-NHOH-C) which arises from both ring-oxidation and nitro-reduction. However, metabolites arising from either ring-oxidation or nitro-reduction alone exhibited some similarities to mutational profile of 6-NC. These results, taken in conjunction with previous data showing that the major DNA adducts in mammary tissue of rats treated with 6-NC are products of the reaction of 1,2-DHD-6-NHOH-C with guanine and adenine, make a strong case that 1,2-DHD-6-NHOH-C is the ultimate genotoxic metabolite from 6-NC.

During sleep, the development of a plateau on the inspiratory airflow/time contour provides a non-invasive indicator of airway collapsibility. Humans recognize this abnormal contour easily, and this study replicates this with an artificial neural network (ANN) using a normalized shape. Five 10 min segments were selected from each of 18 sleep records (respiratory airflow measured with a nasal cannula) with varying degrees of sleep disordered breathing. Each breath was visually scored for shape, and breaths split randomly into a training and test set. Equally spaced, peak amplitude normalized flow values (representing breath shape) formed the only input to a back propagation ANN. Following training, breath-by-breath agreement of the ANN with the manual classification was tabulated for the training and test sets separately. Agreement of the ANN was 89% in the training set and 70.6% in the test set. When the categories of 'probably normal' and 'normal', and 'probably flow limited' and 'flow limited' were combined, the agreement increased to 92.7% and 89.4% respectively, similar to the intra- and inter-rater agreements obtained by a visual classification of these breaths. On a naive dataset, the agreement of the ANN to visual classification was 57.7% overall and 82.4% when the categories were collapsed. A neural network based only on the shape of inspiratory airflow succeeded in classifying breaths as to the presence/absence of flow limitation. This approach could be used to provide a standardized, reproducible and automated means of detecting elevated upper airway resistance.

In this paper we demonstrate the adverse effect of serially observed data sequences containing transient events on the calculation of Cohen's kappa as an index of inter-rater agreement in the detection of these events. We develop and use a Monte-Carlo-based permutation technique to produce an empiric distribution of kappa in the presence of serial dependence. We find that the empiric confidence intervals for kappa tend to be wider than parametrically derived intervals and in the case of longer event lengths, are markedly so. We evaluate the effect of number and length of events, and further, describe and evaluate three permutation methods which match specific rating situations. Finally, we apply these techniques to the measurement of inter-rater agreement for sleep disordered breathing events, a transient event identified during nocturnal polysomnography, for which traditionally computed confidence intervals for kappa are incorrect.

STUDY OBJECTIVES: To develop and demonstrate the utility of measures of sleep continuity based on survival analysis techniques. DESIGN: Retrospective. SETTING: University sleep laboratory. PATIENTS: Anonymous nocturnal polysomnograms from 10 normal subjects, 10 subjects with mild sleep disordered breathing (SDB) (apnea-hypopnea index [AHI], 15-30/hr), and 10 subjects with moderate/severe SDB (AHI > 30/hr). INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Hypnograms were analyzed to measure the lengths of episodes of contiguous sleep and processed using several common survival analysis techniques. Using separate survival curves for each group to describe the durations of continuous epochs of sleep (sleep run lengths), statistically significant differences were found between all groups (p < .001) as well as between the normal and mild SDB groups (p < .001), suggesting differences in the stability of sleep. Using survival regression techniques applied separately to each subject, statistically significant differences were found among all three groups (p < .001) and, more importantly, between the normal and mild SDB groups (p < .005). Similarly, estimation of sleep continuity based on the pooled sleep run data for each group also showed statistically significant differences (normal vs mild, p < .001; Normal vs moderate/severe, p < .001). In addition, the latter technique showed that changes in the "stability" of sleep could be demonstrated as runs progressed. CONCLUSION: Survival curve analysis of the lengths of runs of contiguous sleep provides a potentially useful method of quantifying sleep continuity. The results suggest that sleep becomes more stable as sleep progresses in normal subjects and those with mild SDB and less stable in subjects with moderate/severe SDB.

OBJECTIVES: To examine the physical and mental health characteristics of 120 residents 3 months following their discharge from 1 transferring nursing home to 23 facilities, to compare these characteristics to their pre-transfer status, and to describe resident and family perceptions of the transfer. DESIGN: Secondary analysis of a longitudinal, prospective quasi-experimental intervention and a qualitative description of resident and family views. SETTING: The setting was 23 nursing homes in the Philadelphia metropolitan area. PARTICIPANTS: Participants included 120 nursing home residents and 56 family members. MEASUREMENTS: Minimum Data Set (MDS) and data from the Centers for Medicare and Medicaid Services (CMS) Nursing Home Compare Web site RESULTS: There was a statistically significant increase in the number of residents who fell during the post-transfer (76.9%) compared to the pre-transfer (51.2%) period (P = .0001): 76.3% of those with a history of falling prior to transfer fell during the post-transfer period while 77.4% of those without a history of falling prior to transfer fell. Residents were 3.78 times more likely to fall if they required more than supervision while walking (95% confidence interval [CI] 1.57-9.06) and 2.65 times more likely if they required more than supervision while transferring (95% CI 1.09-6.44). Logistic regression demonstrated that the mobility was also associated with falls (odds ratio 1.15, 95% CI 1.05-1.26). Residents did not demonstrate any other significant physical or mental health changes during the 3 months following the involuntary transfer when compared with their pre-transfer status. Residents and family members clearly voiced their dismay over the process of involuntary relocation. CONCLUSION: Relocation is a stressful event; however, a move to a higher quality care environment does not result in any significant physical or mental health changes. The high incidence of falls post-transfer in both those with and without a fall history points to the need for extra fall precautions in newly admitted residents. In particular, frequent reorientation reminders for the cognitively intact and a high level of staff surveillance for all new residents is indicated during the first few weeks of admission.