S99 The impact of wearing face masks on neural respiratory drive and breathlessness in healthy subjects

• Published in: Thorax Vol. 77; no. Suppl 1; pp. A62 - A63
• Main Authors: Bilby, J, Jolley, C, Patel, D, Taylor, S, Rafferty, GF, Samara, Z
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and British Thoracic Society 11.11.2022; BMJ Publishing Group LTD
• Subjects: Dyspnea; Electromyography; Severe acute respiratory syndrome coronavirus 2; ‘Gone with the Wind’ – Measuring breathlessness and airway obstruction
• DOI: 10.1136/thorax-2022-BTSabstracts.105
• ISSN: 0040-6376

Introduction and ObjectivesSurgical face masks (SM) and FFP3 respirator masks have been mandated in clinical settings to mitigate against transmission of SARS-CoV-2 during the COVID-19 pandemic. Wearing face masks can provoke respiratory discomfort in some individuals. Neural respiratory drive (NRD) is closely related to breathlessness and can be quantified using second intercostal space electromyography to measure the surface parasternal intercostal muscle electromyogram (sEMGpara). Our objective was to investigate the impact of wearing SM and FFP3 respirators on NRD and breathlessness in healthy subjects. We hypothesised that sEMGpara and breathlessness would be highest wearing an FFP3 than wearing a SM or no mask (NM).MethodsA cross-over study was conducted in 9 healthy participants (median (IQR) age 22 (21 – 22.5) years, 6 female). Participants were studied during 10 minutes of seated resting breathing under three conditions in random order: no mask (NM), wearing a Type IIR surgical face mask (SM) and wearing an FFP3 respirator mask (FFP3). SpO2% and sEMGpara were recorded continuously. sEMGpara signals were converted to root mean square and expressed as a proportion of volitional maximum (sEMGpara%max). Respiratory pattern (ti/ttot) and respiratory rate were derived from thoracic expansion measured using a respiratory belt. Breathlessness and respiratory discomfort were assessed using the Multidimensional Dyspnea Profile (MDP). Within-subject differences between mask conditions were analysed using Friedman’s ANOVA.ResultsMDP breathing discomfort, immediate perception and total score were higher during FFP3 compared to NM (Table 1). MDP Emotional Response scores were similar under all three conditions. sEMGpara%max was significantly higher during SM and FFP3 compared to NM, but the absolute difference in sEMGpara%max was small (table 1).Abstract S99 Table 1SpO2%, sEMGpara%max, respiratory pattern, respiratory rate and Multidimensional Dyspnea Profile scores wearing no mask, a Type IIR surgical face mask and an FFP3 respirator mask. Data are presented as median (interquartile range). * indicates p<0.05 vs ‘no mask’ Abbreviations: ti/ttot = the ratio of inspiratory time to total breathing cycle time. sEMGpara%max = neutral respiratory drive quantified using second intercostal space electromyography to measure the surface parasternal intercostal muscle electromyogram, normalised to volitional maximum. MDP = Multidimensional Dyspnea Profile. MDP A1 Breathing Discomfort is measured on a 0 – 10 Scale. MDP Immediate Perception Subdomain Score is the sum of the A1 score and five SQ intensities (SQ1 muscle work/effort, SQ2 air hunger, SQ3 chest tightness, SQ4 mental effort, SQ5 breathing a lot). MDP Emotional Response Subdomain Score is the sum of the five A2 (0–10) emotional response scores (E1 depressed, E2 anxious, E3 frustrated, E4 angry, E5 afraid). MDP Total Score is the sum of A1 Breathing Discomfort and intensities for the five SQs and five emotional responsesConclusionsWearing a SM or FFP3 respirator was associated with small increases in NRD, and an increase in respiratory discomfort when wearing a FFP3 compared to the ‘no mask’ condition. SM and FFP3 respirators did not provoke significant emotional distress, suggesting that the increase in NRD reflects an increase in respiratory effort rather than anxiety or fear.