Measurements of open-water arctic ocean noise directionality and transport velocity.

Measurements from bottom-mounted acoustic vector sensors, deployed seasonally between 2008 and 2014 on the shallow Beaufort Sea shelf along the Alaskan North Slope, are used to estimate the ambient sound pressure power spectral density, acoustic transport velocity of energy, and dominant azimuth between 25 and 450 Hz. Even during ice-free conditions, this region has unusual acoustic features when compared against other U.S. coastal regions. Two distinct regimes exist in the diffuse ambient noise environment: one with high pressure spectral density levels but low directionality, and another with lower spectral density levels but high directionality. The transition between the two states, which is invisible in traditional spectrograms, occurs between 73 and 79 dB re 1 µPa2/Hz at 100 Hz, with the transition region occurring at lower spectral levels at higher frequencies. Across a wide bandwidth, the high-directionality ambient noise consistently arrives from geographical azimuths between 0° and 30° from true north over multiple years and locations, with a seasonal interquartile range of 40° at low frequencies and high transport velocities. The long-term stability of this directional regime, which is believed to arise from the dominance of wind-driven sources along an east-west coastline, makes it an important feature of arctic ambient sound.

Linguistic and Cultural Adaptation of a Computer-Based Counseling Program (CARE+ Spanish) to Support HIV Treatment Adherence and Risk Reduction for People Living With HIV/AIDS: A Randomized Controlled Trial.

BACKGROUND: Human immunodeficiency virus (HIV) disease in the United States disproportionately affects minorities, including Latinos. Barriers including language are associated with lower antiretroviral therapy (ART) adherence seen among Latinos, yet ART and interventions for clinic visit adherence are rarely developed or delivered in Spanish. OBJECTIVE: The aim was to adapt a computer-based counseling tool, demonstrated to reduce HIV-1 viral load and sexual risk transmission in a population of English-speaking adults, for use during routine clinical visits for an HIV-positive Spanish-speaking population (CARE+ Spanish); the Technology Acceptance Model (TAM) was the theoretical framework guiding program development. METHODS: A longitudinal randomized controlled trial was conducted from June 4, 2010 to March 29, 2012. Participants were recruited from a comprehensive HIV treatment center comprising three clinics in New York City. Eligibility criteria were (1) adults (age ≥18 years), (2) Latino birth or ancestry, (3) speaks Spanish (mono- or multilingual), and (4) on antiretrovirals. Linear and generalized mixed linear effects models were used to analyze primary outcomes, which included ART adherence, sexual transmission risk behaviors, and HIV-1 viral loads. Exit interviews were offered to purposively selected intervention participants to explore cultural acceptability of the tool among participants, and focus groups explored the acceptability and system efficiency issues among clinic providers, using the TAM framework. RESULTS: A total of 494 Spanish-speaking HIV clinic attendees were enrolled and randomly assigned to the intervention (arm A: n=253) or risk assessment-only control (arm B, n=241) group and followed up at 3-month intervals for one year. Gender distribution was 296 (68.4%) male, 110 (25.4%) female, and 10 (2.3%) transgender. By study end, 433 of 494 (87.7%) participants were retained. Although intervention participants had reduced viral loads, increased ART adherence and decreased sexual transmission risk behaviors over time, these findings were not statistically significant. We also conducted 61 qualitative exit interviews with participants and two focus groups with a total of 16 providers. CONCLUSIONS: A computer-based counseling tool grounded in the TAM theoretical model and delivered in Spanish was acceptable and feasible to implement in a high-volume HIV clinic setting. It was able to provide evidence-based, linguistically appropriate ART adherence support without requiring additional staff time, bilingual status, or translation services. We found that language preferences and cultural acceptability of a computer-based counseling tool exist on a continuum in our urban Spanish-speaking population. Theoretical frameworks of technology's usefulness for behavioral modification need further exploration in other languages and cultures. TRIAL REGISTRATION: ClinicalTrials.gov NCT01013935; https://clinicaltrials.gov/ct2/show/NCT01013935 (Archived by WebCite at http://www.webcitation.org/6ikaD3MT7).

Acoustic vector sensor beamforming reduces masking from underwater industrial noise during passive monitoring.

Masking from industrial noise can hamper the ability to detect marine mammal sounds near industrial operations, whenever conventional (pressure sensor) hydrophones are used for passive acoustic monitoring. Using data collected from an autonomous recorder with directional capabilities (Directional Autonomous Seafloor Acoustic Recorder), deployed 4.1 km from an arctic drilling site in 2012, the authors demonstrate how conventional beamforming on an acoustic vector sensor can be used to suppress noise arriving from a narrow sector of geographic azimuths. Improvements in signal-to-noise ratio of up to 15 dB are demonstrated on bowhead whale calls, which were otherwise undetectable using conventional hydrophones.

HIV infection and microbial diversity in saliva.

Limited information is available about the effects of HIV and subsequent antiretroviral treatment on host-microbe interactions. This study aimed to determine the salivary microbial composition for 10 HIV-seropositive subjects, before and 6 months after highly active antiretroviral therapy (HAART), compared with that for 10 HIV-seronegative subjects. A conventional culture and two culture-independent analyses were used and consistently demonstrated differences in microbial composition among the three sets of samples. HIV-positive subjects had higher levels of total cultivable microbes, including oral streptococci, lactobacilli, Streptococcus mutans, and Candida, in saliva than did HIV-negative subjects. The total cultivable microbial levels were significantly correlated with CD4+ T cell counts. Denaturing gradient gel electrophoresis (DGGE), which compared the overall microbial profiles, showed distinct fingerprinting profiles for each group. The human oral microbe identification microarray (HOMIM) assay, which compared the 16S rRNA genes, showed clear separation among the three sample groups. Veillonella, Synergistetes, and Streptococcus were present in all 30 saliva samples. Only minor changes or no changes in the prevalence of Neisseria, Haemophilus, Gemella, Leptotrichia, Solobacterium, Parvimonas, and Rothia were observed. Seven genera, Capnocytophaga, Slackia, Porphyromonas, Kingella, Peptostreptococcaceae, Lactobacillus, and Atopobium, were detected only in HIV-negative samples. The prevalences of Fusobacterium, Campylobacter, Prevotella, Capnocytophaga, Selenomonas, Actinomyces, Granulicatella, and Atopobium were increased after HAART. In contrast, the prevalence of Aggregatibacter was significantly decreased after HAART. The findings of this study suggest that HIV infection and HAART can have significant effects on salivary microbial colonization and composition.

Evaluation of the similarities and differences in response patterns to the Pediatric Quality of Life Inventory and the Child Oral Health Impact Scores among youth with cleft.

PURPOSE: To examine (a) the pattern of responses to a generic health-related quality of life (HRQL) measure (Pediatric Quality of Life Inventory--PedsQL) and an oral health-related quality of life (OHRQoL) measure (Child Oral Health Impact Profile--COHIP), and (b) the associations of these scores with surgical recommendation status among youth with cleft. METHODS: Cross-sectional data (baseline) regarding clinicians' surgical recommendations and quality of life (QoL) measures were examined from an ongoing observational study on treatment outcomes. Approximately one-third of the racially and geographically diverse sample (N = 1,200; mean = 11.6 years) received surgical recommendations to correct either visible (aesthetic) or invisible (functional) defects. Effect sizes were used to quantify differences in QoL based on surgical recommendation and to compare the sensitivity of the PedsQL and COHIP subscales. Using Pearson coefficients, the scores of those recommended for surgery were compared with those without a surgical recommendation. RESULTS: A moderate correlation (0.52) was found between the total scores on the PedsQL and COHIP (p < 0.0001). Subscale correlations between the QoL measures ranged from 0.19 to 0.48 with the strongest correlation between the PedsQL Emotional (r = 0.47) and COHIP Socioemotional Well-being subscale. The effect size for the COHIP Socioemotional Well-being (0.39) was larger than the PedsQL Social/Emotional (0.07/0.11) subscale (Z = 5.30/Z = 4.64, p < 0.0001, respectively), and the total COHIP (0.31) was significantly greater than the total PedsQL scale (0.15, z = 2.65, p = 0.008). CONCLUSIONS: A significant relationship was found between generic HRQL, OHRQoL, and surgical needs among youth with cleft with the COHIP having larger effect sizes than the PedsQL among surgical groups.

Osteonecrosis of the jaw onset times are based on the route of bisphosphonate therapy.

PURPOSE: Osteonecrosis of the jaw (ONJ) has been reported to be associated with patients receiving bisphosphonate (BP) therapy. There are many reports that suggest that the time of exposure to BPs is a significant risk factor for ONJ and that the greatest risk occurs after dentoalveolar surgery. The aim of this study was to retrospectively investigate the duration of BP therapy and related events before the onset of ONJ based on an intravenous (IV) or oral route of administration. MATERIALS AND METHODS: We conducted a retrospective cohort study of patients referred to our institution to identify the onset of ONJ based on the exposure to BP therapy and associated triggers (ie, dentoalveolar surgery or spontaneous occurrence) based on the route of BP administration. Demographic data (ie, age, gender, and race), medical diagnosis related to BP therapy, and information as to whether the BP therapy was continued at the time of ONJ diagnosis were also collected. RESULTS: We reviewed the records for 114 patients with a history of ONJ. We divided patient cohorts by route of BP administration, with 76 patients having a history of IV BP therapy and 38 patients having a history of oral BP therapy. The overall onset of ONJ was earlier in the IV BP group (median, 3 years) compared with the oral BP group (median, 5 years). There was no statistical difference in the duration to occurrence of ONJ associated with dental extraction compared with spontaneous occurrence for both the IV and oral BP groups. CONCLUSIONS: The median onset of ONJ for patients undergoing IV BP therapy occurs earlier than the median onset for patients undergoing oral BP therapy, and there was no difference in onset occurring spontaneously and after dental extraction. The significance of these findings suggests that patients who receive IV BP therapy should be closely evaluated after the initiation of BP therapy. The lack of evidence suggesting greater onset after dental extraction may provide clinical support for dentoalveolar surgery that is indicated for patients with a history of BP therapy. Research focusing on the clinical circumstances and physiologic events during early antiresorptive therapy may provide insight as to the critical risk factors.

Irregular respiration as a marker of wakefulness during titration of CPAP.

STUDY OBJECTIVES: Regularity of respiration is characteristic of stable sleep without sleep disordered breathing. Appearance of respiratory irregularity may indicate onset of wakefulness. The present study examines whether one can detect transitions from sleep to wakefulness using only the CPAP flow signal and automate this recognition. DESIGN: Prospective study with blinded analysis SETTING: Sleep disorder center, academic institution. PARTICIPANTS: 74 subjects with obstructive sleep apnealhypopnea syndrome (OSAHS) INTERVENTIONS: n/a. MEASUREMENTS AND RESULTS: 74 CPAP titration polysomnograms in patients with OSAHS were examined. First we visually identified characteristic patterns of ventilatory irregularity on the airflow signal and tested their relation to conventional detection of EEG defined wake or arousal. To automate recognition of sleep-wake transitions we then developed an artificial neural network (ANN) whose inputs were parameters derived exclusively from the airflow signal. This ANN was trained to identify the visually detected ventilatory irregularities. Finally, we prospectively determined the accuracy of the ANN detection of wake or arousal against EEG sleep/wake transitions. A visually identified irregular respiratory pattern (IrREG) was highly predictive of appearance of EEG wakefulness (Positive Predictive Value [PPV] = 0.89 to 0.98 across subjects). Furthermore, we were able to automate identification of this irregularity with an ANN which was highly predictive for wakefulness by EEG (PPV 0.66 to 0.86). CONCLUSIONS: Despite not detecting all wakefulness, the high positive predictive value suggests that analysis of the respiration signal alone may be a useful indicator of CNS state with potential utility in the control of CPAP in OSAHS. The present study demonstrates the feasibility of automating the detection of IrREG.

Potential mechanism for transition between acute hypercapnia during sleep to chronic hypercapnia during wakefulness in obstructive sleep apnea.

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-.

Measuring cultural awareness of nursing students: a first step toward cultural competency.

This pilot study was designed to measure nursing students' level of cultural awareness. It replicated phase II of Rew, Becker, Cookston, Khosropour, & Martinez's (2003) methodological study that developed and tested a Cultural Awareness Scale (CAS). Using a cross-sectional design, the CAS was distributed to nursing students in three nursing programs' (bachelor's, master's, doctoral) beginning and end courses. Cronbach's alpha for the CAS Total instrument was 0.869, with subscale scores ranging from 0.687 to 0.902, comparable to the findings of Rew et al. Given the limitations of this study, results must be viewed with a degree of caution. Recommendations include further educational research in the form of psychometric testing of the CAS among nursing students, including refinement of both the CAS instrument and the demographic tool. The authors also recommend that studies be conducted to determine the validity and reliability of the CAS with nurses in the health care arena.

Retention of teeth versus extraction and implant placement: treatment preferences of dental faculty and dental students.

The purpose of this study was to determine the treatment preferences amongst dental faculty and dental students for either retention of teeth by endodontic and restorative treatment or extraction and implant placement. A survey of 134 general dentistry faculty and 253 senior (fourth-year) dental students was conducted in a university college of dentistry. Participants completed a survey consisting of questions for which one of two choices could be selected. For questions describing specific clinical situations, dental faculty and dental students more frequently selected endodontic and restorative treatment over extraction and implant placement. However, dental students selected implants more frequently than dental faculty, and more recent graduates on the dental faculty selected implants more frequently than less recent graduates on the dental faculty. In addition, there was an increase in the selection of implants, for all participant groups, as the prosthetic and endodontic complexities of the clinical situations increased. Participants were more likely to select endodontics rather than implants for medically compromised patients, and an implant was overwhelmingly selected over a fixed bridge for the replacement of a single tooth unit. In conclusion, the findings of this study indicate that retention of teeth is preferred, but there may be an increased preference toward implants in the future.

Comparative mutational profiles of the environmental mammary carcinogen, 6-nitrochrysene and its metabolites in a lacI mammary epithelial cell line.

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.

Detection of flow limitation in obstructive sleep apnea with an artificial neural network.

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.

Effects of tones associated with drilling activities on bowhead whale calling rates.

During summer 2012 Shell performed exploratory drilling at Sivulliq, a lease holding located in the autumn migration corridor of bowhead whales (Balaena mysticetus), northwest of Camden Bay in the Beaufort Sea. The drilling operation involved a number of vessels performing various activities, such as towing the drill rig, anchor handling, and drilling. Acoustic data were collected with six arrays of directional recorders (DASARs) deployed on the seafloor over ~7 weeks in Aug-Oct. Whale calls produced within 2 km of each DASAR were identified and localized using triangulation. A "tone index" was defined to quantify the presence and amplitude of tonal sounds from industrial machinery. The presence of airgun pulses originating from distant seismic operations was also quantified. For each 10-min period at each of the 40 recorders, the number of whale calls localized was matched with the "dose" of industrial sound received, and the relationship between calling rates and industrial sound was modeled using negative binomial regression. The analysis showed that with increasing tone levels, bowhead whale calling rates initially increased, peaked, and then decreased. This dual behavioral response is similar to that described for bowhead whales and airgun pulses in earlier work. Increasing call repetition rates can be a viable strategy for combating decreased detectability of signals arising from moderate increases in background noise. Meanwhile, as noise increases, the benefits of calling may decrease because information transfer becomes increasingly error-prone, and at some point calling may no longer be worth the effort.

Sleep continuity measured by survival curve analysis.

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.

Transition from acute to chronic hypercapnia in patients with periodic breathing: predictions from a computer model.

Acute hypercapnia may develop during periodic breathing from an imbalance between abnormal ventilatory patterns during apnea and/or hypopnea and compensatory ventilatory response in the interevent periods. However, transition of this acute hypercapnia into chronic sustained hypercapnia during wakefulness remains unexplained. We hypothesized that respiratory-renal interactions would play a critical role in this transition. Because this transition cannot be readily addressed clinically, we modified a previously published model of whole-body CO2 kinetics by adding respiratory control and renal bicarbonate kinetics. We enforced a pattern of 8 h of periodic breathing (sleep) and 16 h of regular ventilation (wakefulness) repeated for 20 days. Interventions included varying the initial awake respiratory CO2 response and varying the rate of renal bicarbonate excretion within the physiological range. The results showed that acute hypercapnia during periodic breathing could transition into chronic sustained hypercapnia during wakefulness. Although acute hypercapnia could be attributed to periodic breathing alone, transition from acute to chronic hypercapnia required either slowing of renal bicarbonate kinetics, reduction of ventilatory CO2 responsiveness, or both. Thus the model showed that the interaction between the time constant for bicarbonate excretion and respiratory control results in both failure of bicarbonate concentration to fully normalize before the next period of sleep and persistence of hypercapnia through blunting of ventilatory drive. These respiratory-renal interactions create a cumulative effect over subsequent periods of sleep that eventually results in a self-perpetuating state of chronic hypercapnia.

Membrane diffusion in diseases of the pulmonary vasculature.

INTRODUCTION: We examined pulmonary diffusing capacity (D(LCO)) and its partition in pulmonary vascular diseases without evident parenchymal disease to assess the pattern and proportionality of change in membrane diffusion (D(m)) and capillary blood volume (V(c)). Disproportionate reduction in D(m) relative to V(c) (low D(m)/V(c)) in these diseases has been attributed to associated alveolar membrane/parenchymal disease, thus providing a potentially important diagnostic tool. METHODS: Diseases included: idiopathic pulmonary arterial hypertension (n=6), chronic thromboembolic disease (n=5), and intravenous drug use (n=14), providing a spectrum of pulmonary vascular diseases. V(c) and D(m) were determined as described by Roughton and Forster. RESULTS: All diseases showed a reduced V(c) (59+/-10, 69+/-14, 71+/-21 % predicted, respectively) and D(m) (76+/-22, 53+/-19, 63+/-16 % predicted, respectively) with no differences between groups (p>0.05). Disproportionate reduction of D(m) (D(m)/V(c) % predicted <1) was seen in all diseases (range 0.36-1.89). A mathematical analysis is presented to illustrate that changes in vascular geometry may additionally influence the proportionality of changes in D(m) and V(c). The mathematical analysis suggests that when reduction in patency of some vessels co-exits with compensatory dilatation of the remaining vasculature, a disproportionate reduction in D(m) relative to V(c) may result. CONCLUSIONS: The balance between vascular curtailment and compensatory dilatation may contribute to the variability of the D(m)/V(c) relationship seen in pulmonary vascular disease. Disproportionate reduction in D(m) relative to V(c) may result from this imbalance and need not imply subclinical alveolar membrane and/or parenchymal disease.

Nursing home involuntary relocation: clinical outcomes and perceptions of residents and families.

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.

Choice of oximeter affects apnea-hypopnea index.

STUDY OBJECTIVES: Current Medicare guidelines include an apnea-hypopnea index (AHI) > or = 15 events per hour, in which all hypopneas must be associated with 4% desaturation, to qualify for reimbursement for therapy with continuous positive airway pressure (CPAP). The present data demonstrate the effect of pulse oximeter differences on AHI. DESIGN: Prospective study, blinded analysis. SETTING: Academic sleep disorder center. PATIENTS: One hundred thirteen consecutive patients (84 men and 29 women) undergoing diagnostic sleep studies and being evaluated for CPAP based on the Medicare indications for reimbursement. INTERVENTIONS: Patients had two of four commonly used oximeters with signal averaging times of 4 to 6 s placed on different digits of the same hand during nocturnal polysomnography. MEASUREMENTS AND RESULTS: Apneas and candidate hypopneas (amplitude reduction, > 30%) were scored from the nasal cannula airflow signal without reference to oximetry. Candidate hypopneas then were reclassified as hypopneas by each oximeter if they were associated with a 4% desaturation. Although the use of three oximeters resulted in a similar AHI (bias, < 1 event per hour), the fourth oximeter showed an overall increase in AHI of 3.7 events per hour. This caused 7 of 113 patients to have an AHI of > or = 15 events per hour (meeting the Medicare criteria for treatment) by one oximeter but not when a different oximeter was used. More importantly, when our analysis was limited to those patients whose number of candidate hypopneas made them susceptible to the threshold value of 15 events per hour, 7 of 35 patients who did not meet the Medicare AHI standard for treatment by one oximeter were reclassified when a different oximeter was used. CONCLUSION: In the present study, oximeter choice affected whether the AHI reached the critical cutoff of 15 events per hour, particularly in those with disease severity that was neither very mild nor very severe. As oximetry is not a technique that produces a generic result, there are significant limitations to basing the definition of hypopnea on a fixed percentage of desaturation in determining the eligibility for CPAP therapy.

Immediate consequences of respiratory events in sleep disordered breathing.

BACKGROUND: In obstructive sleep apnea/hypopnea syndrome, immediate physiological consequences of events have a dual role: censoring artifacts and gauging physiological significance. Newer airflow monitors may have changed the relative importance of these functions. The purpose of this study was to determine the frequency and hierarchy of occurrence of oxygen desaturation, EEG arousal and heart rate changes as immediate consequences of respiratory events. METHODS: Thirty-nine sleep apnea patients underwent polysomnography with airflow detection by nasal cannula. Eighty events/subject were randomly selected and evaluated for 4% oxygen desaturation, EEG arousal and heart rate increase. RESULTS: Of apneas, 78% caused desaturation, 63% arousal, and 73% heart rate increase. Of hypopneas, 54% caused desaturation, 47% arousal, and 55% heart rate increase. Of events with mildest amplitude reduction 25% caused desaturation, 42% arousal, and 42% heart rate increase. Consequences overlapped but did not occur hierarchically: each occurred alone and in all combinations. CONCLUSION: No single consequence occurred after every event; thus none can be used to corroborate airflow reduction as non-artifactual without missing events corroborated by other consequences. As different consequences validate non-hierarchical sets of respiratory events, we propose there is need to capture all changes in breathing in obstructive sleep apnea/hypopnea syndrome before examining their role in clinical outcome.

Evolution of phonemic word fluency performance in post-stroke aphasia.

UNLABELLED: In this longitudinal study, quantitative and qualitative changes in responses of people with aphasia were examined on a phonemic fluency task. Eighteen patients were tested at 3-month intervals on the letters F-A-S while they received comprehensive, intensive treatment from 3 to 12 months post-stroke. They returned for a follow-up evaluation at an average of 10 months post-intervention. Mean group scores improved significantly from beginning to end of treatment, but declined post-intervention. Patients produced a significantly greater number and proportion of modifiers (adjectives and adverbs) between the beginning and end of treatment, with no decline afterwards, implying that they had access to a wider range of grammatical categories over time. Moreover, patients used significantly more phonemic clusters in generating word lists by the end of treatment. These gains may be attributed to the combined effects of time since onset and the linguistic and cognitive stimulation that patients received in therapy. LEARNING OUTCOMES: Readers of this paper should (1) gain a better understanding of verbal fluency performance in the assessment of aphasia, (2) recognize the importance of analyzing qualitative aspects of single word production in aphasia, and (3) contribute to their clinical judgment of long term improvement in aphasia.