Biomedical subjects

Jack Jiang

Publications and source records attributed to Jack Jiang.

7 recordsLinked to original sources

PubMed2006

Estimating subglottal pressure using incomplete airflow interruption.

OBJECTIVE/HYPOTHESIS: Subglottal pressure (SGP) measurements are often used to assess laryngeal function; however, current methods to measure SGP are invasive or do not estimate SGP during phonation. The purpose of this study was to devise a noninvasive technique to estimate SGP without interrupting phonation. STUDY DESIGN: This was a methodologic study designed to calculate the SGP of a human subject. METHODS: A new technique to estimate SGP was developed in which subject airflow was partially interrupted by introducing two different impedances (pneumatic resistors) through a balloon valve controlled mouthpiece. The changes in airflow across varying impedances were used to estimate SGP in human subjects based on the predictable relationships between SGP, impedance, and airflow measurements. The technique was used to assess eight human subjects (age 19-30) phonating at intensities of 65, 72, and 80 dB. RESULTS: The estimated SGP from the human subjects fell within a range (5.52-8.91 cm H20) that was consistent with previous studies. As other studies have found, SGP estimations significantly increased as subjects phonated at greater intensities (P < .01). Intrasubject standard deviations compared favorably with those from previous studies of complete airflow interruption, suggesting satisfactory reliability. The technique was validated using a mechanical "pseudolung" device (r = 0.9982). CONCLUSIONS: Incomplete airflow interruption offers the potential for useful clinical application to assess the severity of vocal pathology by estimating SGP during continuous phonation.

Adult↗

PubMed2006

Clinical evaluation of Parkinson's-related dysphonia.

OBJECTIVES: Nearly one third of patients with idiopathic Parkinson's disease (IPD) cite dysphonia, characterized subjectively as causing a harsh and breathy voice, as their most debilitating deficit. Medical or behavioral treatments may lead to voice improvement. The purpose of this study was 1) to determine whether vocal fold injection of Cymetra (micronized form of collagen, elastin, proteoglycans; Lifecell Co.) is associated with changes in dysphonic voice characteristics in subjects with IPD, as judged perceptually using a standard instrument Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V), and (2) which acoustic and aerodynamic measurements of voice are most reflective of any observed perceptual changes in voice. STUDY DESIGN: Prospective clinical evaluation of patients with Parkinson's-related dysphonia (PRD). METHODS: Six patients with PRD were evaluated before treatment for the presence of dysphonia and glottal gap. All subjects underwent transoral vocal fold collagen injection using topical anesthesia in the otolaryngology clinic as part of their clinical care. At the initial clinic visit, and 10 to14 days after vocal fold collagen injection, patients were asked to complete the Voice Handicap Index (VHI), a questionnaire concerning voice-related quality of life, and perceptual analyses of voice quality were performed. In addition, patients underwent acoustic (pitch/loudness range, maximum phonation time [MPT], and aerodynamic phonation threshold pressure [PTP]) voice analysis. RESULTS: Five of six subjects had self-perceived improvements in voice after treatment, as determined by the VHI (range, +8 to -24). All five subjects who completed testing demonstrated decreased PTP (range, -1.3 to -2.7, P = .002). Five of six subjects demonstrated statistically significant improvements in MPT (range, -2-16 s, P = .05). Five of six subjects had improved pitch range (-26-343 Hz), whereas all subjects had increased intensity range (0.6-23 db) after injection. CONCLUSIONS: Transoral collagen injection in patients with PRD is safe, well tolerated, and is an effective temporary method of subjectively improving voice and speech in selected patients with IPD. Reduction of glottal gap with collagen improves MPT and subglottal PTP. The resulting gain of vocal efficiency may reduce vocal fatigue and provide a useful adjunct to voice therapy for PRD.

Auditory Perception↗

PubMed2005

Studying vocal fold vibrations in Parkinson's disease with a nonlinear model.

A nonlinear model is applied to study pathologic vocal vibratory characteristics and voice treatments of Parkinson's disease. We find that a number of pathologic vocal characteristics commonly observed in Parkinson's disease, including reduced vibratory intensity, incomplete vocal closure, increased phonation threshold pressure, glottal tremor, subharmonics, and chaotic vocal fold vibrations, can be studied with this nonlinear model. We also find that two kinds of clinical voice treatments for Parkinson's disease, including respiratory effort treatment and Lee Silverman voice treatment can be studied with this computer model. Results suggest that respiratory effort treatment, in which subglottal pressure is increased, might aid in enhancing vibratory intensity, improving glottal closure, and avoiding vibratory irregularity. However, the Lee Silverman voice treatment, in which both subglottal pressure and vocal fold adduction are increased, might be better than respiratory effort treatment. Increasing vocal fold thickness would be further helpful to improve these pathologic characteristics. The model studies show consistencies with clinical observations. Computer models may be of value in understanding the dynamic mechanism of disordered voices and studying voice treatment effects in Parkinson's disease.

Computer Simulation↗

PubMed2004

Vocal efficiency measurements in subjects with vocal polyps and nodules: a preliminary report.

Vocal efficiency is a quantitative measure of the ability of the larynx to convert subglottal power to acoustic power. On the basis of the scant previous literature and clinical intuition, we tested the hypothesis that vocal efficiency, as an indicator of the functional status of the larynx, is abnormally reduced in persons with vocal nodules and polyps. Because the most difficult aspect of obtaining measures of vocal efficiency has been the determination of subglottal pressure, we applied a noninvasive airflow interruption technique for this purpose. Subjects with normal voices (n = 22), vocal polyps (n = 14), and vocal nodules (n = 16) phonated at different intensities into a mask connected by way of piping to a flow meter, a pressure transducer, and an acoustic microphone. Inflation of a balloon-type valve located within the piping provided interruption of phonation. The intraoral pressure plateau occurring during flow interruption was used to estimate subglottal pressure. Subglottal power and acoustic power were determined, and their quotient provided a measure of vocal efficiency. The vocal efficiency in the normal subjects averaged 1.15 x 10(-5) at 70 dB, 3.17 x 10(-5) at 75 dB, 7.52 x 10(-5) at 80 dB, and 1.41 x 10(-4) at 85 dB. The vocal efficiency in the patients with vocal polyps averaged 3.62 x 10(-6) at 70 dB, 8.34 x 10(-6) at 75 dB, 2.10 x 10(-5) at 80 dB, and 4.26 x 10(-5) at 85 dB. The vocal efficiency in the patients with vocal nodules averaged 4.32 x 10(-6) at 70 dB, 1.57 x 10(-5) at 75 dB, 4.26 x 10(-5) at 80 dB, and 8.34 x 10(-5) at 85 dB. As compared to the normal subjects, the patients with laryngeal polyps or vocal nodules had significantly reduced vocal efficiency. These results provide quantitative verification of the clinical impression of inefficient phonation in patients with mass lesions of the vocal folds.

Adult↗

PubMed2004

Receiver operating characteristic analysis of aerodynamic parameters obtained by airflow interruption: a preliminary report.

Aerodynamic parameters provide objective and quantitative measures of laryngeal functional status. Jiang et al previously introduced an airflow interruption technique that can determine mean phonatory airflow, subglottic pressure, and phonation threshold pressure simultaneously and noninvasively. In this study, we performed receiver operating characteristic (ROC) analysis to evaluate this airflow interruption apparatus for voice profile analysis in subjects with laryngeal polyps or nodules or with Parkinson's disease. Patients with polyps (n = 14), nodules (n = 9), and Parkinson's disease (n = 12) were evaluated with the airflow interruption apparatus. Normal subjects served as controls. Mean airflow, subglottic pressure, and phonation threshold pressure were determined. Discriminant analysis was used to create linear equations combining all three parameters in order to obtain a new combined parameter. Solutions to the linear equations yielded values for the combined parameter that took into account mean airflow, subglottic pressure, and phonation threshold pressure. Combined parameter values were used as data to generate ROC curves. Laryngeal polyps were distinguished from the normal larynx with a sensitivity of 0.929 and a specificity of 0.933 at the point of maximal efficiency. The area under the ROC curve was 0.977 (Az). Patients with Parkinson's disease were distinguished from normal subjects with a sensitivity of 0.667 and a specificity of 0.909 at the point of maximal efficiency. The area under the ROC curve was 0.7958 (Az). Nodules were able to be distinguished from normal with a sensitivity of 0.889 and a specificity of 1.00. The area under the ROC curve was 0.9565 (Az). Our conclusions are twofold. First, aerodynamic parameters may be combined for simultaneous consideration by the construction of linear equations by means of discriminant analysis. Second, the airflow interruption apparatus, when used for voice function evaluation, has high sensitivity and specificity.

Glottis↗

PubMed2002

Clinical evaluation of 70 degrees and 90 degrees laryngeal telescopes.

OBJECTIVES: Rigid telescopy is widely used in otorhinolaryngology for endolaryngeal visualization. Laryngeal telescopes are made with several angles, including 70 degrees and 90 degrees. In this study, the performances of 70 degrees and 90 degrees telescopes are compared and evaluated on the basis of ability to visualize specific regions of the larynx. METHODS: Each subject (N = 121) received evaluation with both 70 degrees and 90 degrees telescopes. The investigator used the telescopes to attempt to visualize 4 key regions: (1) the subglottic area, (2) the pyriform fossae, (3) the anterior commissure, and (4) the laryngeal surface of the epiglottis. The telescopes were connected to a video camera and videotape recordings were made. The percentage of attempted visualizations that were successful was calculated for both the 70 degrees and the 90 degrees telescopes. RESULTS: The 70 degrees telescope provided successful visualization of the subglottic area in 111 patients (91.7%), of the pyriform fossae in 115 (95.0%), of the anterior commissure in 112 (92.6%), and of the laryngeal surface of the epiglottis in 114 (94.2%). The 90 degrees telescope provided successful visualization of the subglottic area in 103 patients (85.1%), of the pyriform fossae in 112 (92.6%), of the anterior commissure in 100 (82.6%), and of the laryngeal surface of the epiglottis in 102 (84.3%). Differences in rates of visualization were significant for the posterior surface of the epiglottis, the anterior commissure, and the subglottic area. CONCLUSIONS: The 70 degrees telescope provided a significantly higher rate of successful visualization for 3 of the 4 regions studied. This result contributes information that may help the clinical examiner select an instrument of choice.

Adult↗

PubMed2002

Biological mechanisms underlying voice changes due to dehydration.

Four vocally untrained healthy adults, 2 men and 2 women, completed the study. A double-blind placebo-controlled approach was used to administer three treatments to each participant on separate days. Drugs treatments involved a single 60-mg dose of a diuretic, Lasix (LA), on one day, and a single 50-mg dose of an oral antihistamine, diphenhydramine hydrochloride (DH), on another day. A third day involved the administration of a placebo, sugar pills (SP). Critical posttreatment measures were weight (kg), which estimated systemic dehydration, saliva viscosity (centipoise), which estimated secretion dehydration, and phonation threshold pressure (PTP, in cm H2O), at high pitches, which indicated pulmonary drive for phonation. The central experimental question was: Does systemic dehydration, or secretory dehydration, or both, mediate increases in PTP that are known to occur following dehydration treatments? The results showed that LA induced systemic dehydration, as shown by a decrease in total body mass of about 1%. Weight losses were seen during a 1- to 4-hour block following drug administration and persisted for at least 8 hours thereafter. PTPs also increased in that condition, about 23% relative to baseline, but only several hours after whole-body dehydration was initially seen (5-12 hours after drug administration). In contrast, no evidence was seen that DH accomplished either secretory dehydration or PTP shifts. The results indicate that systemic dehydration can mediate PTP increases. The influence of secretory dehydration on PTP is unclear.

Adult↗