Estimating Subglottal Pressure using Incomplete Airflow Interruption

Jiang, Jack J.; Leder, Charles; Bichler, A.

doi:10.1097/01.mlg.0000184315.00648.2f

Cited by 17 publications

(10 citation statements)

References 14 publications

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“…Human subject testing yielded P s estimations that were well within the expected range as determined by invasive and noninvasive measurement techniques in previous studies (14,15 ). The observed difference in intrasubject standard deviations cannot be attributed to higher average values when using plateau analysis, as there was no significant difference between the mean P s for each method of analysis.…”

Section: Discussionsupporting

confidence: 77%

Reliable Time to Estimate Subglottal Pressure

2009

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Measuring subglottal pressure (SGP) with complete interruption can be problematic due to unsteady plateaus in supraglottal pressure data traces during balloon valve interruption. Subjectively determining when the graph plateaus neglects the effects of laryngeal, auditory, and other physical reflexes that may alter patient effort and glottal configuration. If the SGP estimation was made at a consistent time before the onset of reflexes, the recorded pressure would not be dependent on subjective analysis by a clinician, and intrasubject data would be more precise. Previously collected data using the airflow interruption system have shown consistency at approximately 150 milliseconds (ms) after balloon valve inflation. To evaluate the validity of estimating SGP at this point, a theoretical and a physical model were applied. A theoretical ideal gas model of capacitance calculated the time necessary for supraglottal pressure to equilibrate with SGP. Using a mechanical pseudolung which served as a constant pressure source, known subresistor pressures were compared to the pressure measured by the interruption device. Both models confirmed the validity of measuring SGP consistently at 150 ms into the 500 ms interruption. In human trials testing twenty-five subjects, mean intrasubject standard deviation using this optimal time constant was 0.66 ± 0.37 cmH 2 O, and 1.11 ± 0.48 cmH 2 O when performing plateau analysis (p < .0005). This novel modification to the clinically feasible interruption model for SGP estimation demonstrates a marked improvement in the reliability of balloon valve interruption while maintaining the validity demonstrated in previous studies.

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Section: Discussionsupporting

confidence: 77%

Reliable Time to Estimate Subglottal Pressure

2009

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“…Its measurement is integral to the calculation of both vocal efficiency (20) and glottal resistance (21). When this measurement is inconsistent, variations in vocal efficiency or glottal resistance could be attributed to measurement error rather than a change in laryngeal health.…”

Section: Discussionmentioning

confidence: 99%

Estimating Subglottal Pressure via Airflow Interruption with Auditory Masking

Hoffman

Jiang

2009

Journal of Voice

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Objective-Current noninvasive measurement of subglottal pressure using airflow interruption often produces inconsistent results due to the elicitation of audio-laryngeal reflexes. Auditory feedback could be considered as a means of ensuring measurement accuracy and precision. The purpose of this study was to determine if auditory masking could be used with the airflow interruption system to improve intrasubject consistency.Study Design-A prerecorded sample of subject phonation was played on a loop over headphones during the trials with auditory masking. This provided subjects with a target pitch and blocked out distracting ambient noise created by the airflow interrupter.Methods-Subglottal pressure was noninvasively measured using the airflow interruption system. Thirty subjects, divided into two equal groups, performed ten trials without auditory masking and ten trials with auditory masking. Group one performed the normal trials first, followed by the trials with auditory masking. Group two performed the auditory masking trials first, followed by the normal trials.Results-Intrasubject consistency was improved by adding auditory masking, resulting in a decrease in average intrasubject standard deviation from 0.93 ± 0.51 to 0.47 ± 0.22 cmH 2 O (p < . 001).Conclusions-Auditory masking can be used effectively to combat audio-laryngeal reflexes and aid subjects in maintaining constant glottal configuration and frequency, thereby increasing intrasubject consistency when measuring subglottal pressure. By considering auditory feedback, a more reliable method of measurement was developed. This method could be employed by clinicians, as reliable, immediately available values of subglottal pressure are useful in evaluating laryngeal health and monitoring treatment progress.

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“…Additionally, if nasal airflow exists during oral airflow occlusion this would be a source of error in PTP estimation (2). There have been several attempts to improve upon these less reliable techniques, using balloon valves to mechanically control both complete and incomplete interruptions, with promising results (10, 11). However, further development is necessary before these techniques become clinically viable.…”

Section: Introductionmentioning

confidence: 99%

Phonation Threshold Flow in Elongated Excised Larynges

Jiang¹,

Regner²,

Tao³

et al. 2008

Ann Otol Rhinol Laryngol

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Objectives-This study proposes the use of a new parameter of vocal aerodynamics, phonation threshold flow (PTF). The sensitivity of PTF and phonation threshold pressure (PTP) were quantitatively compared to the percent of vocal fold elongation from physiologic length.Methods-Ten excised canine larynges were mounted on a bench apparatus capable of controlling vocal fold elongation. Subglottal airflow was gradually increased until the onset of phonation. Elongation of the vocal folds was varied from +0% (physiologic length) to +15%, and PTF and PTP were measured. Results-MeanPTFs at physiologic vocal fold length ranged from 101 mL/s and 217 mL/s. No statistically significant relationship was found to exist between the size of the larynx and the measured PTF values (p=.404). The average percentage change of PTF compared to the magnitude of elongation was found to be statistically significant (p< 0.001). Data indicated that PTF was proportional to the percent of vocal fold elongation. Conclusion-PTF

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Estimating Subglottal Pressure using Incomplete Airflow Interruption

Abstract: Incomplete airflow interruption offers the potential for useful clinical application to assess the severity of vocal pathology by estimating SGP during continuous phonation.

Cited by 17 publications

References 14 publications

Reliable Time to Estimate Subglottal Pressure

Reliable Time to Estimate Subglottal Pressure

Estimating Subglottal Pressure via Airflow Interruption with Auditory Masking

Phonation Threshold Flow in Elongated Excised Larynges

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