Development of a Bioinspired, Self-Adhering, and Drug-Eluting Laryngotracheal Patch.

OBJECTIVES/HYPOTHESIS: Novel laryngotracheal wound coverage devices are limited by complex anatomy, smooth surfaces, and dynamic pressure changes and airflow during breathing. We hypothesize that a bioinspired mucoadhesive patch mimicking how geckos climb smooth surfaces will permit sutureless wound coverage and also allow drug delivery. STUDY DESIGN: ex-vivo. METHODS: Polycaprolactone (PCL) fibers were electrospun onto a substrate and polyethylene glycol (PEG) - acrylate flocks in varying densities were deposited to create a composite patch. Sample topography was assessed with laser profilometry, material stiffness with biaxial mechanical testing, and mucoadhesive testing determined cohesive material failure on porcine tracheal tissue. Degradation rate was measured over 21 days in vitro along with dexamethasone drug release profiles. Material handleability was evaluated via suture retention and in cadaveric larynges. RESULTS: Increased flocking density was inversely related to cohesive failure in mucoadhesive testing, with a flocking density of PCL-PEG-2XFLK increasing failure strength to 6880 ± 1810 Pa compared to 3028 ± 791 in PCL-PEG-4XFLK density and 1182 ± 262 in PCL-PEG-6XFLK density. The PCL-PEG-2XFLK specimens had a higher failure strength than PCL alone (1404 ± 545 Pa) or PCL-PEG (2732 ± 840). Flocking progressively reduced composite stiffness from 1347 ± 15 to 763 ± 21 N/m. Degradation increased from 12% at 7 days to 16% after 10 days and 20% after 21 days. Cumulative dexamethasone release at 0.4 mg/cm2 concentration was maintained over 21 days. Optimized PCL-PEG-2XFLK density flocked patches were easy to maneuver endoscopically in laryngeal evaluation. CONCLUSIONS: This novel, sutureless, patch is a mucoadhesive platform suitable to laryngeal and tracheal anatomy with drug delivery capability. LEVEL OF EVIDENCE: NA Laryngoscope, 131:1958-1966, 2021.

Adjustment of Vocal Tract Shape via Biofeedback: Influence on Vowels.

The study assessed 30 nonprofessional singers to evaluate the effects of vocal tract shape adjustment via increased resonance toward an externally applied sinusoidal frequency of 900 Hz without phonation. The amplification of the sound wave was used as biofeedback signal and the intensity and the formant position of the basic vowels /a/, /e/, /i/, /o/, and /u/ were compared before and after a vocal tract adjustment period. After the adjustment period, the intensities for all vowels increased and the measured changes correlated with the participants' self-perception.The diferences between the second formant position of the vowels and the applied frequency influences the changes in amplitude and in formant frequencies. The most significant changes in formant frequency occurred with vowels that did not include a formant frequency of 900 Hz, while the increase in amplitude was the strongest for vowels with a formant frequency of about 900 Hz.

Analysis of Measured and Simulated Supraglottal Acoustic Waves.

To date, although much attention has been paid to the estimation and modeling of the voice source (ie, the glottal airflow volume velocity), the measurement and characterization of the supraglottal pressure wave have been much less studied. Some previous results have unveiled that the supraglottal pressure wave has some spectral resonances similar to those of the voice pressure wave. This makes the supraglottal wave partially intelligible. Although the explanation for such effect seems to be clearly related to the reflected pressure wave traveling upstream along the vocal tract, the influence that nonlinear source-filter interaction has on it is not as clear. This article provides an insight into this issue by comparing the acoustic analyses of measured and simulated supraglottal and voice waves. Simulations have been performed using a high-dimensional discrete vocal fold model. Results of such comparative analysis indicate that spectral resonances in the supraglottal wave are mainly caused by the regressive pressure wave that travels upstream along the vocal tract and not by source-tract interaction. On the contrary and according to simulation results, source-tract interaction has a role in the loss of intelligibility that happens in the supraglottal wave with respect to the voice wave. This loss of intelligibility mainly corresponds to spectral differences for frequencies above 1500 Hz.

Formant characteristics of human laughter.

Although laughter is an important aspect of nonverbal vocalization, its acoustic properties are still not fully understood. Extreme articulation during laughter production, such as wide jaw opening, suggests that laughter can have very high first formant (F(1)) frequencies. We measured fundamental frequency and formant frequencies of the vowels produced in the vocalic segments of laughter. Vocalic segments showed higher average F(1) frequencies than those previously reported and individual values could be as high as 1100 Hz for male speakers and 1500 Hz for female speakers. To our knowledge, these are the highest F(1) frequencies reported to date for human vocalizations, exceeding even the F(1) frequencies reported for trained soprano singers. These exceptionally high F(1) values are likely to be based on the extreme positions adopted by the vocal tract during laughter in combination with physiological constraints accompanying the production of a "pressed" voice.

An automatic video instillator for intratracheal instillation in the rat.

Intratracheal instillation (ITI) of a test compound is an alternative method to inhalation methods that require complex aerosol generation, exposure chambers and airflow monitoring instruments for exposing the lungs of animals to a test compound. For ITI in the rat, a laryngoscope is generally used for endotracheal intubation, and the procedure is difficult to perform. Therefore, we designed and constructed an automatic video instillator (AVI) for the accurate delivery of a dose of a test compound into the trachea of rats. The device has a videocamera probe for image guidance, and a liquid-crystal display for image display. These two items are used to visualize the larynx and trachea for intratracheal insertion of the tubing, and for placing the tip of the instillation tubing beyond the vocal cords for ITI of the test compound. After a 2 h training session on the use of the AVI in an anaesthetized rat, we assessed the utility of the device by ITI of 0.25% (w/v) solution of Evans Blue dye into the lungs of 30 isoflurane-anaesthetized rats. Necropsy examinations were performed on 20 rats immediately after the completion of the procedure, and on 10 rats three days after the procedure. Based on the results of these examinations, we concluded that the device could be used for rapid, reproducible and successful ITI of a test compound into the lungs of a rat by one operator.

Transcutaneous injection laryngoplasty through the cricothyroid space in the sitting position: anatomical information and technique.

A variety of approaches have been introduced to perform injection laryngoplasty under local anesthesia. Among these reported methods, transcutaneous injection through the cricothyroid space offers many advantages, but it possesses some technical difficulties during access to the vocal fold. The aim of this study was to assess the anatomic references related to transcutaneous injection laryngoplasty through cricothyroid space using 3-dimensionally reconstructed computed tomography to provide guidelines and to achieve higher efficacy during the procedure. The study group consisted of 14 patients (7 male, 7 female) with unilateral vocal fold paralysis and who had undergone multi-detector array computed tomography (MDCT) between January 2004 and December 2005. Assumption was made that transcutaneous injection is approached from the surface at lower margin of the thyroid cartilage and 7 mm lateral to the midline through the cricothyroid membrane and spot at the posterior 1/3 of true vocal cord is the target for injection laryngoplasty. From the surface of the injection point to the target, a line was drawn. Its length and the angle formed between it and the approach direction of needle was measured. Based on these measurements, 15 patients (8 male, 7 female) with unilateral vocal fold paralysis received 15 trials of transcutaneous injection laryngoplasty through the cricothyroid space. The average length from the surface of the injection point (7 mm lateral to the midline) to the posterior 1/3 of the true vocal cord (target of the injection) was 15.75 mm in men and 13.91 mm in women. The average of the angle in medial direction at the surface needed to reach the target of the injection was 10.57 degrees in men and 12.71 degrees in women, and in superior direction was 47.57 degrees in men and 47.43 degrees in women. Injection laryngoplasty performed under acquired reference measurements were successful in 14 trials (93.3%) out of 15 trials in 15 patients. We suggest that knowledge of the anatomic references regarding the transcutaneous injection laryngoplasty through cricothyroid space will provide guidelines for beginners and improve the understanding of the procedure, eventually leading to easier and more precise access to the vocal cord.

[Human skull development and voice disorders]. / De l'hominisation du crâne à la dysphonie fonctionnelle.

The hominisation of the skull comes with the bipedic posture, due to a network of muscular and aponevrotic forces applied to the cranio-facial skeleton. A brief sight of the morphogenetic origine and issues of these forces help to understand more clearly the postural statement of the larynx, his functions, and his many extrinsic biomechanical bounds; then further his most frequently dysfunctions. The larynx is surrounded by several effective systems of protection: active, activo-passive, passive. The architectural features of the components of the laryngeal system allows us to consider the laryngeal function as an auto-balanced system. All the forces engaged are auto-balanced in a continuum of tension. This lead us to the concept of tensegrity system, neologism coming from tensional integrity described by Buckminster Fuller. The laryngeal employement by extrinsic system is pathological in case of chronicity. Any osteopathic treatment, which aims to restore the losses of laryngeal mobility, has to release first the peripherical structures involved in the laryngeal defense, before normalising the larynx itself Finally, the larynx recovers his functions in a tensegrity system.

Red deer stags use formants as assessment cues during intrasexual agonistic interactions.

While vocal tract resonances or formants are key acoustic parameters that define differences between phonemes in human speech, little is known about their function in animal communication. Here, we used playback experiments to present red deer stags with re-synthesized vocalizations in which formant frequencies were systematically altered to simulate callers of different body sizes. In response to stimuli where lower formants indicated callers with longer vocal tracts, stags were more attentive, replied with more roars and extended their vocal tracts further in these replies. Our results indicate that mammals other than humans use formants in vital vocal exchanges and can adjust their own formant frequencies in relation to those that they hear.

[Basis of art phonetics in biomedical engineering].

Art phonetics' medicine, a new branch of traditional medicine, has not been developed perfectly, especially in the aspects of objective and scientific study. In this paper, the acoustical and anatiomical basis of art phonetics in viewpoint of biomedical engineering is explored, and then our work of quantitative measurement and analysis of art phonetic is introduced. The experiment data show further that quantitative measurement and analysis plays an important role in art phonetic medicine.

The laryngeal mask airway for awake diagnostic bronchoscopy. A retrospective study of 200 consecutive patients.

The laryngeal mask airway (LMA) provides a view of the larynx and moving vocal cords without loss of airway control and can be used in flexible fibreoptic bronchoscopy for both anaesthetized and awake patients. In this retrospective review of 200 consecutive patients over a 30 month period, bronchoscopy was successful via the LMA in all but one patient using a technique of topical anaesthesia and sedation. The LMA directs the fibrescope to the glottis, allows respiratory function to be monitored and oxygen to be given. Complication rates were similar to those reported for transnasal awake bronchoscopy. Insertion of the LMA in the awake fasted patient is safe and easily achieved.

Anatomical parameters of the voice.

Analysis of the anatomical parameters of the voice allows us to observe the relations--which exist not only within the cortical centres but also in the underlying centres--between structures governing phonation functions and those concerned with the functions of hearing and of language. Voice, articulation, speech, language and hearing are so many elements of one and the same function of communication.

The appendix of the ventricle of the larynx.

A review of 100 consecutive laryngograms showed visualization of the appendix of the laryngeal ventricle in 40% of cases. This high incidence of visulization is related to thorough anesthesia, repeated performance of phonation and the reverse "E" maneuver as well as awareness of the anatomical structure. The appendix of the laryngeal ventricle courses superiorly between the laryngeal vestibule and the thyroid cartilage which differentiates this normal structure from ulcerations and fistulous tracts of laryngeal tumors.