We present a study investigating the effect of non-medical face masks (FFP2 and surgical) on cerebral hemodynamics measured by transcranial hybrid diffuse optics, and on systemic physiology in 13 healthy adults (age: 23-33 years)

Delgado Mederos, R

Durduran, T

Fischer, JB

Kobayashi Frisk, L

Mayos Pèrez, M

Scholkmann, F

Tachtsidis, I

English

UCL Discovery

PROCEEDINGS OF SPIESPIEDigitalLibrary.org/conference-proceedings-of-spieDoes wearing a non-medical facemask cause changes in cerebralhemodynamics?Fischer, Jonas, Kobayashi Frisk, Lisa, Tachtsidis, Ilias,Delgado Mederos, Raquel, Mayos Pèrez, Mercedes, et al.Jonas B. Fischer, Lisa Kobayashi Frisk, Ilias Tachtsidis, Raquel DelgadoMederos, Mercedes Mayos Pèrez, Felix Scholkmann, Turgut Durduran, "Doeswearing a non-medical face mask cause changes in cerebralhemodynamics?," Proc. SPIE 11920, Diffuse Optical Spectroscopy andImaging VIII, 119200J (9 December 2021); doi: 10.1117/12.2615227Event: European Conferences on Biomedical Optics, 2021, Online OnlyDownloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 02 Feb 2022  Terms of Use: https://www.spiedigitallibrary.org/terms-of-useDoes wearing a non-medical face mask causechanges in cerebral hemodynamics?Jonas B. Fischer,1,* Lisa Kobayashi Frisk,1 Ilias Tachtsidis,2Raquel Delgado Mederos,3 Mercedes Mayos Pèrez,4,5 Felix Scholkmann,6 andTurgut Durduran1,71ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels(Barcelona), Spain; 2Department of Medical Physics and Biomedical Engineering, University College London,London, London, UK; 3Hospital de la Santa Creu i Sant Pau, Department of Neurology, Sant Pau BiomedicalResearch Institute, Barcelona, Spain; 4Hospital de la Santa Creu i Sant Pau, Department of RespiratoryMedicine, Sleep Unit, Barcelona, Spain; 5CIBER Enfermedades Respiratorias (CibeRes) (CB06/06), Madrid,Spain; 6University Hospital Zurich, University of Zurich, Department of Neonatology, Biomedical OpticsResearch Laboratory, Zurich, Switzerland; 7Institució Catalana de Recerca i Estudis Avançats (ICREA),Barcelona, Spain*jonas.fischer@icfo.euAbstract: We present a study investigating the effect of non-medical face masks (FFP2and surgical) on cerebral hemodynamics measured by transcranial hybrid diffuse optics,and on systemic physiology in 13 healthy adults (age: 23-33 years).IntroductionThe COVID-19 pandemic has led many countries to introduce regulations obliging or recommending the publicto wear facial masks [1] as a preventative method to minimize the spread of the disease.Discussions are ongoing about possible adverse effects of mask wearing (e.g. dizziness, headaches, exhaustion,fainting), especially in elderly people and those wearing the mask for longer times and during physical activity.Currently, research about those possible adverse effects is currently being carried out. For example, Chan et al. [2]found in a recent study in elderly (age: 76.4 ± 6.1 years) no statistically significant change in arterial oxygenation(SpO2) after wearing a mask for one hour. Recently, Law et al. [3] published the first result of a fMRI study(eight subject, age: 44 ± 15 years) showing that wearing a mask increased the BOLD signal by 30% on average,increases end-tidal carbon dioxide pressure (EtCO2), but does not alter significantly task-induced changes in theBOLD signal. Clearly more research is needed.To this end, we have studied the effect of wearing non-medical face masks (FFP2 and surgical) on cerebralhemodynamics, oxygenantion and metabolism as well as systemic physiology in a group of young healthy volun-teers using transcranical, hybrid, near-infrared diffuse optical spectroscopy. This is the first study that uses opticalneuroimaging to study possible effects of mask-wearing on cerebral hemodynamic and systemic physiologicalparameters.MethodsThe study protocol was approved by the ethical committee of Hospital Clinic Barcelona (Spain) and all participantssigned informed consent. Young adults between 20 and 35 years of age were recruited from the general populationof a research institute adhering to COVID-19 regulations. We have ruled out existing cardiovascular, neurologicalor respiratory conditions assessed by a questionnaire.A ten minute baseline data was acquired without the use of a mask while the subjects were asked to sit calmlyin front of a computer and read a scientific paper of interest. After the baseline the mask was put on and data wasacquired for another ten minutes. All subjects were measured on two separate days – FFP2 mask was utilized onday one, and a surgical mask was utilized on day two.Data was acquired bilaterally and continuously using optical probes placed over the frontal lobes while avoid-ing the sinuses. The probes utilized transcranial diffuse correlation spectroscopy (DCS) and time-resolved near-infrared spectroscopy (TR-NIRS) to measure microvascular cerebral blood flow (CBF), cerebral blood oxygensaturation (StO2), and total hemoglobin concentration (THC) [4]. Various systemic physiological signals such asarterial blood pressure (ABP), heart rate (HR), SpO2 (all with Finapres, Finapres Medical Systems BV, Nether-lands), respiratory rate (RR), EtCO2 (all by Capnostream 20p, Medtronic, Minneapolis, USA) and transcutaneouscarbon dioxide partial pressure (TCO2) (SenTec Digital monitor, SenTec AG, Switzerland) were monitored werealso continuously acquired. Since, in the case of mask wearing, the nasal cannula used to measure EtCO2 mayDiffuse Optical Spectroscopy and Imaging VIII, edited by Davide Contini, Yoko Hoshi,Thomas D. O'Sullivan, Proc. of SPIE-OSA Vol. 11920, 119200J · © 2021 OSA-SPIECCC code: 1605-7422/21/$21 · doi: 10.1117/12.2615227Proc. of SPIE-OSA Vol. 11920  119200J-1Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 02 Feb 2022Terms of Use: https://www.spiedigitallibrary.org/terms-of-usebe influenced by the carbon dioxide (CO2) trapped between face and mask, its readings are not reliable in thisscenario, therefore, we opted for the TCO2 measurement.In order to test the effect of mask wearing, the data has been normalized to the last five minutes of the baselineperiod and compared to the last seven minutes while the mask was worn. All parameters were smoothed with therloess method using a 30 second window to reduce physiological noise. Changes in hemodynamic parametersof both hemispheres were averaged. Since the same subject was measured twice, linear mixed effect modelswere utilized for statistical analysis. We have tested whether each mask-type is statistically different from zeroand whether the difference between the mask-types is statistically different considering the “false discovery rate”(FDR) correction for the p-value and a significance level of 0.05.ResultsThirteen volunteers (median age 27.0 years [range, 23 to 33 years], 6 female [46%]) were recruited. Figure 1shows time traces for the population average of the changes in CBF (panel A), StO2 (panel B), HR (panel C) andTCO2 (panel D) for both mask-types.Fig. 1. Time traces of CBF (A), StO2 (B), HR (C) and TCO2 (D) shown as the population averagefor both mask types (FFP2 in red, surgical in blue). The shaded area indicates the standard deviation.Small but significant changes in CBF and StO2 were detected for both mask-types. CBF increased by 6.5 (95%confidence interval (CI): 2.6,10) % for the FFP2 mask and by 6.2 (95% CI: 2.4, 9.9) % for the surgical mask. StO2increased by 0.9 (95% CI: 0.2, 1.7) % for the FFP2 mask and by 0.9 (95% CI: 0.1, 1.6) % for the surgical mask.THC only increased significantly for the FFP2 mask by 0.9 (95% CI: 0.3, 1.5) μM. All hemodynamic parametersdid not differ between the two mask-types.As further observed, the systemic parameters such as TCO2 and SpO2 did not significantly change due to wear-ing a mask, while mean arterial blood pressure (MAP) and HR increased significantly for the surgical mask by 4.1(95% CI: 0.5, 7.6) mmHg and 2.0 (95% CI: 1.0, 3.1) beats per minute, respectively. RR decreased significantly forthe FFP2 mask by 3.2 (95% 5.4, 1.1) breaths per minute. In the systemic physiology only a significant differencebetween both mask-types was detected for HR, the difference was 1.2 (95% CI: 0.0, 2.4) beats per minute.A detailed overview of all results will be presented.DiscussionOur findings show that wearing a face mask leads to statistically significant changes in the cerebral hemodynamics(CBF and StO2). The changes are minimal and comparable to the values observed in typical neuroimaging studiesfor standard tasks such as basic cognitive, visual or motor tasks [5–7]. They are representative of the lower limitof changes observed in daily life. Here, we did not account for potential confounding effects due to discomfort ofProc. of SPIE-OSA Vol. 11920  119200J-2Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 02 Feb 2022Terms of Use: https://www.spiedigitallibrary.org/terms-of-useprobes, removal/ placement of masks and the order of studies, which may be a cause of increased MAP and HRin for the surgical mask. Generally, these stressors are part of daily life and the addition of mask use did not alterthe physiology at a level of potential concern.Compared to the results of Law et al. [3] we have also observed an increase in EtCO2 while wearing a mask,but we discarded the parameter after evaluation as being unreliable due to the re-breathing of CO2, instead wetrusted the TCO2 reading, which did not show a change. Generally, the observed increase of 30% in the BOLDsignals compared to our detected increase in CBF and StO2 does indeed suggest that mask wearing has an effecton cerebral hemodynmics, although it may not necessarily be a CO2 effect, since, as already mentioned TCO2 didnot change.Our conclusion is that while the changes were measurable, they do not suggest any reason for concern for maskuse during daily life activities in healthy young adults at rest. Subjects with pre-existing respiratory problems,undergoing physical activity, affected by high altitudes or elderly may behave differently and further research isneeded to investigate possible adverse effects. Our technologies can be utilized for these kind of research questions.Another important conclusion is that neuroimaging studies using cerebral hemodynamics as a surrogate for neu-ronal function should carefully evaluate mask use as potential confounder. Our advice would be to take alternateprecautions to prevent risks between the subjects and operators. The Society of Neuroscience in Anesthesiologyand Critical Care has recently released their recommendations for neuroscience research during the COVID-19pandemic and stressed the use of personal protective equipment [8]. Our study provides additional data for suchrecommendations.Finally, since both DCS and TR-NIRS are suitable to use during realistic tasks, e.g. cognitive or motor, theycould be utilized to study whether the measured clinically insignificant changes could alter important aspects ofprofessional life such as attention, reaction times and more.Acknowledgments & disclosuresThis work leading to the results was funded by la Fundació La Marató de TV3 (201709.31, 201724.31);Fundació CELLEX Barcelona; Agencia Estatal de Investigación (PHOTOMETABO, PID2019-106481RB-C31/10.13039/501100011033, PRE2018-085082); the “Severo Ochoa” (CEX2019-000910-S); “laCaixa”(LlumMedBcn); Institució CERCA, AGAUR-Generalitat (2017 SGR 1380); RIS3CAT (CECH, 001-P-001682);LASERLAB-EUROPE V and EU Horizon 2020 (BitMap 675332, VASCOVID 101016087).We disclose the following: ICFO has equity ownership in the spin-off company HemoPhotonics S.L. Potentialfinancial conflicts of interest and objectivity of research have been monitored by ICFO’s Knowledge & TechnologyTransfer Department. No financial conflicts of interest were identified.References1. D. K. Chu, E. A. Akl, S. Duda, K. Solo, S. Yaacoub, H. J. Schünemann, A. El-harakeh, A. Bognanni,T. Lotfi, M. Loeb et al., “Physical distancing, face masks, and eye protection to prevent person-to-persontransmission of sars-cov-2 and covid-19: a systematic review and meta-analysis,” The Lancet (2020).2. N. C. Chan, K. Li, and J. Hirsh, “Peripheral oxygen saturation in older persons wearing nonmedical facemasks in community settings,” JAMA 324, 2323–2324 (2020).3. C. S. Law, P. S. Lan, and G. H. Glover, “Effect of wearing a face mask on fmri bold contrast,” NeuroImagep. 117752 (2021).4. T. Durduran, R. Choe, W. B. Baker, and A. G. Yodh, “Diffuse optics for tissue monitoring and tomography,”Rep Prog Phys 73, 076701 (2010).5. V. Quaresima, M. Ferrari, A. Torricelli, L. Spinelli, A. Pifferi, and R. Cubeddu, “Bilateral prefrontal cortexoxygenation responses to a verbal fluency task: a multichannel time-resolved near-infrared topographystudy,” J. biomedical optics 10, 011012 (2005).6. T. Durduran, G. Yu, M. G. Burnett, J. A. Detre, J. H. Greenberg, J. Wang, C. Zhou, and A. G. Yodh,“Diffuse optical measurement of blood flow, blood oxygenation, and metabolism in a human brain duringsensorimotor cortex activation,” Opt. letters 29, 1766–1768 (2004).7. K. Uludağ, D. J. Dubowitz, E. J. Yoder, K. Restom, T. T. Liu, and R. B. Buxton, “Coupling of cerebralblood flow and oxygen consumption during physiological activation and deactivation measured with fmri,”Neuroimage 23, 148–155 (2004).8. P. E. Vlisides, K. M. Vogt, D. Pal, E. Schnell, W. M. Armstead, A. M. Brambrink, P. Kuo, P. Nelson,S. Vacas, N. Goettel et al., “Roadmap for conducting neuroscience research in the covid-19 era and beyond:Recommendations from the snacc research committee,” J. Neurosurg. Anesthesiol. (2021).Proc. of SPIE-OSA Vol. 11920  119200J-3Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 02 Feb 2022Terms of Use: https://www.spiedigitallibrary.org/terms-of-use

Does wearing a non-medical face mask cause changes in cerebral hemodynamics?

https://discovery.ucl.ac.uk/10142835/1/119200J.pdf

Does wearing a non-medical face mask cause changes in cerebral hemodynamics?

Abstract

Similar works

Full text

Available Versions

UCL Discovery