Mitigation of Respirable Aerosol Particles from Speech and Language Therapy Exercises.

INTRODUCTION: Phonation and speech are known sources of respirable aerosol in humans. Voice assessment and treatment manipulate all the subsystems of voice production, and previous work (Saccente-Kennedy et al., 2022) has demonstrated such activities can generate >10 times more aerosol than conversational speech and 30 times more aerosol than breathing. Aspects of voice therapy may therefore be considered aerosol generating procedures and pose a greater risk of potential airborne pathogen (eg, SARS-CoV-2) transmission than typical speech. Effective mitigation measures may be required to ensure safe service delivery for therapist and patient. OBJECTIVE: To assess the effectiveness of mitigation measures in reducing detectable respirable aerosol produced by voice assessment/therapy. METHODS: We recruited 15 healthy participants (8 cis-males, 7 cis-females), 9 of whom were voice-specialist speech-language pathologists. Optical Particle Sizers (OPS) (Model 3330, TSI) were used to measure the number concentration of respirable aerosol particles (0.3 µm-10 µm) generated during a selection of voice assessment/therapy tasks, both with and without mitigation measures in place. Measurements were performed in a laminar flow operating theatre, with near-zero background aerosol concentration, allowing us to quantify the number concentration of respiratory aerosol particles produced. Mitigation measures included the wearing of Type IIR fluid resistant surgical masks, wrapping the same masks around the end of straws, and the use of heat and moisture exchange microbiological filters (HMEFs) for a water resistance therapy (WRT) task. RESULTS: All unmitigated therapy tasks produced more aerosol than unmasked breathing or speaking. Mitigation strategies reduced detectable aerosol from all tasks to a level significantly below, or no different to, that of unmasked breathing. Pooled filtration efficiencies determined that Type IIR surgical masks reduced detectable aerosol by 90%. Surgical masks wrapped around straws reduced detectable aerosol by 96%. HMEF filters were 100% effective in mitigating the aerosol from WRT, the exercise that generated more aerosol than any other task in the unmitigated condition. CONCLUSIONS: Voice therapy and assessment causes the release of significant quantities of respirable aerosol. However, simple mitigation strategies can reduce emitted aerosol concentrations to levels comparable to unmasked breathing.

Quantification of Respirable Aerosol Particles from Speech and Language Therapy Exercises.

INTRODUCTION: Voice assessment and treatment involve the manipulation of all the subsystems of voice production, and may lead to production of respirable aerosol particles that pose a greater risk of potential viral transmission via inhalation of respirable pathogens (eg, SARS-CoV-2) than quiet breathing or conversational speech. OBJECTIVE: To characterise the production of respirable aerosol particles during a selection of voice assessment therapy tasks. METHODS: We recruited 23 healthy adult participants (12 males, 11 females), 11 of whom were speech-language pathologists specialising in voice disorders. We used an aerodynamic and an optical particle sizer to measure the number concentration and particle size distributions of respirable aerosols generated during a variety of voice assessment and therapy tasks. The measurements were carried out in a laminar flow operating theatre, with a near-zero background aerosol concentration, allowing us to quantify the number concentration and size distributions of respirable aerosol particles produced from assessment/therapy tasks studied. RESULTS: Aerosol number concentrations generated while performing assessment/therapy tasks were log-normally distributed among individuals with no significant differences between professionals (speech-language pathologists) and non-professionals or between males and females. Activities produced up to 32 times the aerosol number concentration of breathing and 24 times that of speech at 70-80 dBA. In terms of aerosol mass, activities produced up to 163 times the mass concentration of breathing and up to 36 times the mass concentration of speech. Voicing was a significant factor in aerosol production; aerosol number/mass concentrations generated during the voiced activities were 1.1-5 times higher than their unvoiced counterpart activities. Additionally, voiced activities produced bigger respirable aerosol particles than their unvoiced variants except the trills. Humming generated higher aerosol concentrations than sustained /a/, fricatives, speaking (70-80 dBA), and breathing. Oscillatory semi-occluded vocal tract exercises (SOVTEs) generated higher aerosol number/mass concentrations than the activities without oscillation. Water resistance therapy (WRT) generated the most aerosol of all activities, ∼10 times higher than speaking at 70-80 dBA and >30 times higher than breathing. CONCLUSIONS: All activities generated more aerosol than breathing, although a sizeable minority were no different to speaking. Larger number concentrations and larger particle sizes appear to be generated by activities with higher suspected airflows, with the greatest involving intraoral pressure oscillation and/or an oscillating oral articulation (WRT or trilling).

A comparison of respiratory particle emission rates at rest and while speaking or exercising.

Background: The coronavirus disease-19 (COVID-19) pandemic led to the prohibition of group-based exercise and the cancellation of sporting events. Evaluation of respiratory aerosol emissions is necessary to quantify exercise-related transmission risk and inform mitigation strategies. Methods: Aerosol mass emission rates are calculated from concurrent aerosol and ventilation data, enabling absolute comparison. An aerodynamic particle sizer (0.54-20 µm diameter) samples exhalate from within a cardiopulmonary exercise testing mask, at rest, while speaking and during cycle ergometer-based exercise. Exercise challenge testing is performed to replicate typical gym-based exercise and very vigorous exercise, as determined by a preceding maximally exhaustive exercise test. Results: We present data from 25 healthy participants (13 males, 12 females; 36.4 years). The size of aerosol particles generated at rest and during exercise is similar (unimodal ~0.57-0.71 µm), whereas vocalization also generated aerosol particles of larger size (i.e. was bimodal ~0.69 and ~1.74 µm). The aerosol mass emission rate during speaking (0.092 ng s-1; minute ventilation (VE) 15.1 L min-1) and vigorous exercise (0.207 ng s-1, p = 0.726; VE 62.6 L min-1) is similar, but lower than during very vigorous exercise (0.682 ng s-1, p < 0.001; VE 113.6 L min-1). Conclusions: Vocalisation drives greater aerosol mass emission rates, compared to breathing at rest. Aerosol mass emission rates in exercise rise with intensity. Aerosol mass emission rates during vigorous exercise are no different from speaking at a conversational level. Mitigation strategies for airborne pathogens for non-exercise-based social interactions incorporating vocalisation, may be suitable for the majority of exercise settings. However, the use of facemasks when exercising may be less effective, given the smaller size of particles produced.

Comparing aerosol number and mass exhalation rates from children and adults during breathing, speaking and singing.

Aerosol particles of respirable size are exhaled when individuals breathe, speak and sing and can transmit respiratory pathogens between infected and susceptible individuals. The COVID-19 pandemic has brought into focus the need to improve the quantification of the particle number and mass exhalation rates as one route to provide estimates of viral shedding and the potential risk of transmission of viruses. Most previous studies have reported the number and mass concentrations of aerosol particles in an exhaled plume. We provide a robust assessment of the absolute particle number and mass exhalation rates from measurements of minute ventilation using a non-invasive Vyntus Hans Rudolf mask kit with straps housing a rotating vane spirometer along with measurements of the exhaled particle number concentrations and size distributions. Specifically, we report comparisons of the number and mass exhalation rates for children (12-14 years old) and adults (19-72 years old) when breathing, speaking and singing, which indicate that child and adult cohorts generate similar amounts of aerosol when performing the same activity. Mass exhalation rates are typically 0.002-0.02 ng s-1 from breathing, 0.07-0.2 ng s-1 from speaking (at 70-80 dBA) and 0.1-0.7 ng s-1 from singing (at 70-80 dBA). The aerosol exhalation rate increases with increasing sound volume for both children and adults when both speaking and singing.

Effects of coronavirus disease-2019 on voice: our experience of laryngeal complications following mechanical ventilation in severe coronavirus disease-2019 pneumonitis and review of current literature.

PURPOSE OF REVIEW: Dysphonia has been described as a major symptom of coronavirus disease-2019 (COVID-19). A literature review examining this topic was undertaken and is presented here, combined with insights from our experience in managing patients with laryngeal complications following mechanical ventilation for severe COVID-19 pneumonitis. RECENT FINDINGS: Naunheim et al. reported that patients who are most at risk of needing intubation with COVID-19 disease are those with patient-specific risk factors and these are at an increased risk for subsequent laryngotracheal injury following intubation (1). In our cohort of 105 patients referred with laryngological symptoms postintubation for COVID-19 pneumonitis, 40% presented as urgent reviews, of which almost half had severe postintubation complications requiring surgery. Perceptual voice ratings and patient-reported voice ratings varied widely, but there was no significant change in voice scores postoperatively. The reflux symptom index (RSI) scores did improve significantly (p = 0.0266). The need for surgery was associated with the presence of comorbidities for instance hypertension, diabetes and obesity in our cohort. This is in support of reported association of comorbidity as a risk factor for intubation and subsequent development of postintubation airway complications. SUMMARY: Dysphonia following COVID-19 infection may have multiple causes. Literature reports demonstrate intubation injury, sensory neuropathy, and postviral neuropathy are associated with voice changes. Our personal experience has confirmed postintubation injury markedly affects glottic function with resultant dysphonia attributable to scar formation, posterior glottic stenosis, granulation and subglottic stenosis. Frequent surgical intervention is required for airway patency and may have short-term further deleterious effects on phonation, although in our cohort this is not statistically significant analysing Grade, Roughness, Breathiness, Asthenia, Strain, Voice Handicap Index-10 or Airway, Voice, Swallow scores. Maximal antireflux medications and advice statistically improved RSI scores postoperatively.

Ultrasound Study to Validate the Anterior Cervical Approach to the Longus Colli Muscle Using Electromyography Control Alone.

Background: One of the main difficulties in the treatment of dystonic anterocollis is the injection of the deep flexor muscles of the neck such as Longus Colli (LCo). The injection of the LCo has been regarded as difficult and potentially dangerous; since we published our anterior median approach, a number of questions about the precision and the safety of our technique have been raised by colleagues. Methods: 7 patients with anterocollis were injected, using our injection technique and when the needle was deemed to be in place, we used the ultrasound probe to determine what the needle had passed through, the depth of the tip of the needle and if the identified muscle was indeed LCo. Results: On the ultrasound section the LCo muscle is between 24 and 28 mm deep in the patients examined in this study. The location of the needle was confirmed by ultrasound and in most cases the needle was placed in the right axis but sometimes not deep enough. The EMG control made it possible to correct the depth in all cases. In most of the injections the needle traversed the thyroid. No acute incident occurred by this route of injection. Injections were performed between 22 and 28 mm deep. Discussion: From this study and based on a review of complications over 9 years experience with injecting LCo under EMG control using an anterior approach, we conclude that this technique is precise, safe and well tolerated. Summary Highlights: The injection of the Longus Coli muscle for anterocollis has been regarded as difficult and potentially dangerous. This study showed, using ultrasound to determine the needle trajectory, that the anterior approach using EMG control is a precise, safe and well tolerated technique.

A comparison of the voice handicap index-10 scores between medical and musical theater students.

OBJECTIVE: Elite professional voice users experience a high vocal load and if voice quality deteriorates, their livelihoods are affected. Our aim was to assess how an elite professional voice user group, musical theater students (n=49), perceive their voices in comparison with medical students (n=43). STUDY DESIGN: Cross-sectional study. METHODS: Participants completed a confidential questionnaire including demographics and the Voice Handicap Index-10 (VHI-10) in September 2010. RESULTS: Response rate was 100% (92/92). The mean age of the medical students was 25 years and of musical theater students was 20 years. The mean overall VHI-10 score was higher in musical theater students compared with that of medical students (mean score, 5.56 and standard deviation [SD], 4.13 vs mean score, 3.79 and SD, 3.02, P=0.02), particularly in three VHI-10 items: voice strain, lack of clarity, and being upset from voice problem (mean score, 0.82 and SD, 0.86 vs mean score, 0.44 and SD, 0.67, P=0.02; mean score, 0.92 and SD, 0.89 vs mean score, 0.53 and SD, 0.70, P=0.02; and mean score, 0.49 and SD, 0.79 vs mean score, 0.07 and SD, 0.26, P=0.001, respectively). Furthermore, musical theater students report higher possible voice problems in the past (6/43 [14%], 21/49 [43%], P=0.002). CONCLUSIONS: In this small group, musical theater students report more handicap compared with medical students. It is possible that this difference may be because of the musical theater students experiencing greater voice use over time or better recognition of potential voice problems. This may mean that we need to do more to protect student's voices by optimizing vocal care during their training, without neglecting the vocal needs of other students.