Biomedical subjects

Bryan Goldman

Publications and source records attributed to Bryan Goldman.

5 recordsLinked to original sources

PubMed2006

Modeling distortion product otoacoustic emission input/output functions using segmented regression.

Distortion product otoacoustic emissions (DPOAEs) are low-level acoustic signals, the detection of which involves extraction from a background of noise. Boege and Janssen [J. Acoust. Soc. Am. 111, 1810-1818 (2002)] described a method for modeling the presence and growth of these responses. While improving growth function parameter estimation, this technique excludes a significant fraction of the data (especially low-level responses), and relies on ad hoc model fit acceptance criteria. The statistical difficulties associated with these limitations are described, and a weighted segmented linear regression model that avoids them is proposed. A simple test is presented for the presence of DPOAE growth. This technique is compared to that of Boege and Janssen in a dataset of 9 556 input/output (I/O) functions collected over 4 years on 866 ears from 379 construction apprentices and 63 age-matched controls. Comparisons are made on the entire dataset and within audiometric hearing loss categories. Segmented regression avoids the statistical pitfalls of the previous method, allows estimation of the threshold and slope of auditory response on a far greater number of I/O functions, and improves estimation of these parameters in this dataset. The potential for this method to yield more sensitive metrics of hearing function and compromise is discussed.

Acoustic Impedance Tests↗

PubMed2005

Alternative metrics for noise exposure among construction workers.

Although the exposure-response relationships for noise-induced hearing loss are relatively well established, there is not complete agreement on which metrics of noise exposure best represent risk of hearing damage. In particular, while L(eq), based on a 3 dB exchange rate (ER) is used by most agencies, US OSHA's standard is based on the L(avg), which uses a 5 dB ER. In addition, peak levels of exposure, which are commonly found in some industries, including construction, are believed to increase risk above that predicted by the L(eq). This paper presents an analysis of a large database of noise exposures among construction workers, comparing several noise metrics, and their application to a cohort of construction workers. Metrics examined were the L(avg), L(eq) and L(max), expressing average levels of exposure across an exposure interval. Two novel metrics were derived from these monitored metrics, L(eq)/L(avg) and L(max)/L(eq), as measures of exposure variability and 'peakiness', respectively. A total of 730 workshifts, including data on 361 492 min of exposure to workers in nine trades were examined. Correlations between average metrics (L(eq), L(avg) and L(max)) are generally very high, while the variability metrics are poorly correlated with either average levels, or with each other, indicating that they characterize different aspects of exposure. Alternative models for estimating exposure for the cohort were considered and the use of a task-within-trade specific mean level was adopted. The task-specific estimates of exposure using the various metrics will be applied to the cohort's work history to explore the importance of these alternative metrics in estimating risk of noise-induced damage.

Hearing Loss, Noise-Induced↗

PubMed2005

Primary operative versus nonoperative therapy for pediatric empyema: a meta-analysis.

OBJECTIVE: The optimal treatment of children with empyema remains controversial. The purpose of this review was to compare reported results of nonoperative and primary operative therapy for the treatment of pediatric empyema. METHODS: A systematic comprehensive review of the scientific literature was conducted with the PubMed (National Library of Medicine) database for the period from 1981 to 2004. This reproducible search identified all publications dealing with treatment of empyema in the pediatric population (<18 years of age). A meta-analysis was performed with studies with adequate data summaries for > or =1 of the outcomes of interest for both treatment groups. RESULTS: Sixty-seven studies were reviewed. Data were aggregated from reports of children initially treated nonoperatively (3418 cases from 54 studies) and of children treated with a primary operative approach (363 cases from 25 studies). The populations were similar in age. Patients who underwent primary operative therapy had a lower aggregate in-hospital mortality rate (0% vs 3.3%), reintervention rate (2.5% vs 23.5%), length of stay (10.8 vs 20.0 days), duration of tube thoracostomy (4.4 vs 10.6 days), and duration of antibiotic therapy (12.8 vs 21.3 days), compared with patients who underwent nonoperative therapy. In 8 studies for which meta-analysis was possible, patients who received primary operative therapy were found to have a pooled relative risk of failure of 0.09, compared with those who did not. Meta-analysis could not be performed for any of the other outcome measures investigated in this review. Similar complication rates were observed for the 2 groups (5% vs 5.6%). CONCLUSIONS: These aggregate results suggest that primary operative therapy is associated with a lower in-hospital mortality rate, reintervention rate, length of stay, time with tube thoracostomy, and time of antibiotic therapy, compared with nonoperative treatment. The meta-analysis demonstrates a significantly reduced relative risk of failure among patients treated operatively.

Adolescent↗

PubMed2004

Contributions of non-occupational activities to total noise exposure of construction workers.

This paper describes how exposures received during routine and episodic non-occupational activities contribute to total noise exposure in a group of occupationally exposed workers. Two-hundred and sixty-six construction apprentices enrolled in a longitudinal hearing loss study and completed questionnaires at 1 yr of follow-up to determine their episodic activities (e.g. concert attendance, power tool use, firearms exposure). Noise exposure levels for these episodic exposures were determined from the published literature. Routine activities were assessed using activity cards filled out over 530 subject-days, along with noise dosimetry measurements made over 124 subject-days of measurement. Equivalent Leq exposure levels were then calculated for specific activities. These activity-specific Leq values were combined into estimated individual annual Leq exposure levels for the 6760 nominal annual non-occupational hours in a year (LAeq6760h), which were then transformed into equivalent levels for a 2000 h exposure period (LA2000hn) for comparison with occupational noise exposure risk criteria. The mean non-occupational LAeq6760h exposure values for the cohort ranged from 56 to 87 dBA (equivalent LA2000hn 62-93 dBA). At the mid range of the routine and episodic activity exposure level distribution, the mean LAeq6760h was 73 dBA (LA2000hn 78 dBA). Nineteen percent of the LA2000hn non-occupational exposures exceeded 85 dBA, the generally recommended occupational limit for a 2000 h workyear, at the mid-range of exposure levels. Due to a lack of available data, firearms use could not be incorporated into the total noise exposure estimates. However, firearms users reported more exposure to other noisy non-occupational activities and had statistically significantly higher estimated exposure levels even without including their firearms exposure than did non-shooters. When compared with the high levels of occupational noise found in construction, non-occupational noise exposures generally present little additional exposure for most workers. However, they may contribute significantly to overall exposure in the subset of workers who frequently participate in selected noisy activities.

Adult↗

PubMed2004

Nonoccupational noise: exposures associated with routine activities.

Efforts to characterize nonoccupational noise exposures have focused primarily on infrequent, episodic events. Few studies have assessed noise levels resulting from routine daily activities. In the current study, 112 construction workers wore datalogging noise dosimeters and simultaneously completed activity logs during two phases of data collection. The 81 subjects monitored in phase 1 received logs listing numerous preselected occupational and nonoccupational activities, while the 31 subjects monitored in phase 2 used free-field logs and reported nonoccupational activities in greater detail. Nearly all of the 221,439 1-min intervals of nonoccupational L(eq) level and activity reporting were below 70 dBA; only a small percentage exceeded 80 dBA. The primary contributor to nonoccupational noise exposure was traveling in a car or bus, while time at home contributed the least. One hundred seventy 24-h L(eq) levels were computed from the 1-min noise level data. The percentage of phase 2 workday L(eq(24)) levels which exceeded 80 dBA was higher than that of the nonworkday levels. The mean L(eq(24)) level of phase 2 workdays was higher than that of nonworkdays, and the difference was statistically significant. Routine nonoccupational noise exposures contributed much less to total noise dose than occupational exposures in the subjects evaluated.

Adult↗