Berit Schneider-Stickler

Comparison of biofilm formation on new Phonax and Provox 2 voice prostheses—A pilot study

In voice rehabilitation for laryngectomized patients, voice prosthetic biofilm formation is still an unsolved problem. Design and materials of voice prostheses have been altered by manufacturers to improve function and extend the lifetime of devices. The goal of the study was to investigate biofilm formation on Provox 2 and Phonax, recently introduced voice prostheses made of thermoplastic polyurethane.

Inter-device reliability of DSI measurement

Abstract The Dysphonia Severity Index (DSI) is a measure that quantifies the overall vocal quality. The aim of the study is to evaluate the reliability of DSI measurements. The DSIs of 30 subjects were therefore measured using LingWAVES (WEVOSYS) and DiVAS (XION). To evaluate the inter-device reliability of DSI measurement, the devices’ results were compared for each subject. The DSI values of both devices showed great differences. The calculated DSI differences of 95% of the subjects were within the limits of +2.39 and –2.82, which makes a clinical interpretation of severity of voice disorder using different devices questionable. The technical and procedural aspects of measurement divergences are discussed, and the need to define hardware and software standards is shown.

Biofeedback on Voice Use in Call Center Agents in Order to Prevent Occupational Voice Disorders

BACKGROUND Call center agents (CCAs) are at high risk of voice disorders because of high-demanding vocal load and work-related stress factors. Goal of this prospective study was to examine the voice use at work and to introduce biofeedback software into real-life workplace situation to improve vocal performance. Individual fundamental frequency, sound pressure level (SPL) of speaking voice, and syllables per second should be optimized by visualization on-screen. Further, its impact on vocal attrition and vocal constitution should be investigated. METHODS Over a period of 6 months, 76 call center advisors voluntarily participated in this study (37 female, 39 male, mean age 29.3 years). At the beginning of the study, all the subjects received voice range profile (VRP) measurements and acoustic voice analyses at the beginning and at the end of shift. Additionally, several questionnaires have been completed. The subjects were classified into either the study group (group 1) or the control group (group 2). Group 1 had open access to results of the biofeedback software program at their workplace, and group 2 did not. The VRP measurements, questionnaires, and acoustic voice analyses were repeated 4 weeks later again at the beginning and at the end of shift. RESULTS All the subjects confirmed a rather high vocal load. In contrast, almost none of the subjects received any voice training before entering the floor. The percentage of voice-related hoarseness and regular throat clearing was rather high in both groups. The statistical analyses revealed a significant improvement of vocal performance in subjects with vocal fatigue in the study group when compared with the control group after a 4-week biofeedback intervention. All the subjects with vocal hypofunction defined as maximum SPLs lower than 90 dB in VRP measurements improved to normal voice constitution at the end of the study in contrast to the control group. CONCLUSION Biofeedback is a suitable method to improve vocal awareness and vocal performance of CCAs.

Anaerobic and microaerophilic pathogens in the biofilm formation on voice prostheses: A pilot study†

Voice rehabilitation with voice prostheses is a standard therapy in laryngectomized patients. Biofilm formation on the surface of the voice prostheses causes device failure and requires frequent replacements. Studies analyzing the biofilm of voice prostheses have mainly focused on aerobic bacteria. Anaerobic bacteria as an integral part of the biofilms on voice prostheses have not been investigated yet.

Growth kinetics of candida biofilm on medical polymers: A long‐term in vitro study

Recent in vitro models simulating biofilm formation on medical polymers are restricted to only short‐term observation periods of 2 hours to 12 days.

Pharyngolaryngectomy with free jejunal autograft reconstruction and tracheoesophageal voice restoration: Indications for replacements, microbial colonization, and indwelling times of the Provox 2 voice prostheses

The purpose of this prospective study was to investigate shunt‐related and device‐related complications and microbial colonization of voice prostheses in patients after pharyngolaryngectomy with jejunal autograft reconstruction in comparison to patients after standard laryngectomy.

Antibiofilm activity of carboxymethyl chitosan on the biofilms of non-Candida albicans Candida species

Although most cases of candidiasis have been attributed to Candida albicans, non-C. albicans Candida species have been isolated in increasing numbers in patients. In this study, we determined the inhibition of carboxymethyl chitosan (CM-chitosan) on single and mixed species biofilm of non-albicans Candida species, including Candida tropicalis, Candida parapsilosis, Candida krusei and Candida glabrata. Biofilm by all tested species in microtiter plates were inhibited nearly 70%. CM-chitosan inhibited mixed species biofilm in microtiter plates and also on medical materials surfaces. To investigate the mechanism, the effect of CM-chitosan on cell viability and biofilm growth was employed. CM-chitosan inhibited Candida planktonic growth as well as adhesion. Further biofilm formation was inhibited with CM-chitosan added at 90min, 12h or 24h after biofilm initiation. CM-chitosan was not only able to inhibit the metabolic activity of Candida cells, but was also active upon the establishment and the development of biofilms.

Inhibition of mixed fungal and bacterial biofilms on silicone by carboxymethyl chitosan

Mixed biofilms with fungi and bacteria are the leading cause for the failure of medical silicone devices, such as voice prostheses in laryngectomy. In this study, we determined the effect of carboxymethyl chitosan (CM-chitosan) on mixed biofilm formation of fungi and bacteria on silicone which is widely used for construction of medical devices. Mixed biofilm formations were inhibited 72.87% by CM-chitosan. Furthermore, CM-chitosan significantly decreased the metabolic activity of the biofilms using 2, 3-bis (2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5 carboxanilide (XTT) reduction assay. The examination using confocal laser scanning microscopy and scanning electron microscope confirmed that CM-chitosan inhibited the mixed biofilm and damaged the cells. Effects of CM-chitosan on different stages of biofilms were also evaluated. CM-chitosan inhibited the adhesion of fungi and bacteria with an efficiency of >90%. It prevented biofilm formation at efficiencies of 69.86%, 50.88% and 46.58% when CM-chitosan was added at 90min, 12h and 24h after biofilm initiation, respectively. Moreover, CM-chitosan inhibited Candida yeast-to-hyphal transition. CM-chitosan was not only able to inhibit the metabolic activity of biofilms, but also active upon the establishment and development of biofilm. Therefore, CM-chitosan may serve as a possible antibiofilm agent to limit biofilm formation on voice prostheses.

Towards Objective Voice Assessment: The Diplophonia Diagram.

OBJECTIVES Diplophonia is an often misinterpreted symptom of disordered voice, and needs objectification. An audio signal processing algorithm for the detection of diplophonia is proposed. Diplophonia is produced by two distinct oscillators, which yield a profound physiological interpretation. The algorithms performance is compared with the clinical standard parameter degree of subharmonics (DSH). STUDY DESIGN This is a prospective study. METHODS A total of 50 dysphonic subjects with (28 with diplophonia and 22 without diplophonia) and 30 subjects with euphonia were included in the study. From each subject, up to five sustained phonations were recorded during rigid telescopic high-speed video laryngoscopy. A total of 185 phonations were split up into 285 analysis segments of homogeneous voice qualities. In accordance to the clinical group allocation, the considered segmental voice qualities were (1) diplophonic, (2) dysphonic without diplophonia, and (3) euphonic. The Diplophonia Diagram is a scatter plot that relates the one-oscillator synthesis quality (SQ1) to the two-oscillator synthesis quality (SQ2). Multinomial logistic regression is used to distinguish between diplophonic and nondiplophonic segments. RESULTS Diplophonic segments can be well distinguished from nondiplophonic segments in the Diplophonia Diagram because two-oscillator synthesis is more appropriate for imitating diplophonic signals than one-oscillator synthesis. The detection of diplophonia using the Diplophonia Diagram clearly outperforms the DSH by means of positive likelihood ratios (56.8 versus 3.6). CONCLUSIONS The diagnostic accuracy of the newly proposed method for detecting diplophonia is superior to the DSH approach, which should be taken into account for future clinical and scientific work.

Influence of culture conditions for clinically isolated non-albicans Candida biofilm formation

Non-albicans Candida species have been isolated in increasing numbers in patients. Moreover, they are adept at forming biofilms. This study analyzed biofilm formation of clinically isolated non-albicans Candida, including Candida tropicalis, Candida krusei and Candida parapsilosis under the influence of different growth media (RPMI 1640, YPD and BHI) and several culture variables (inoculum concentration, incubation period and feeding conditions). The results showed that culture conditions strongly influenced non-albicans Candida species biofilm formation. YPD and BHI resulted in larger amount of biofilm formation with higher metabolic activity of biofilms. Furthermore, the growth media seems to have varying effects on adhesion and biofilm development. Growth conditions may also influence biofilm formation, which was enhanced when starting the culture with a larger inoculum, longer incubation period and using a fed-batch system. Therefore, the potential influences of external environmental factors should be considered when studying the non-albicans Candida biofilms in vitro.