Lung Physiology Research Articles

Lung Mechanics: A Review of Solid Mechanical Elasticity in Lung Parenchyma.

The lung is the main organ of the respiratory system. Its purpose is to facilitate gas exchange (breathing). Mechanically, breathing may be described as the cyclic application of stresses acting upon the lung surface. These forces are offset by prominent stress-bearing components of lung tissue. These components result from the mechanical elastic properties of lung parenchyma. Various studies have been dedicated to understanding the macroscopic behaviour of parenchyma. This has been achieved through pressure-volume analysis, numerical methods, the development of constitutive equations or strain-energy functions, finite element methods, image processing and elastography. Constitutive equations can describe the elastic behaviour exhibited by lung parenchyma through the relationship between the macroscopic stress and strain. The research conducted within lung mechanics around the elastic and resistive properties of the lung has allowed scientists to develop new methods and equipment for evaluating and treating pulmonary pathogens. This paper establishes a review of mathematical studies conducted within lung mechanics, centering on the development and implementation of solid mechanics to the understanding of the mechanical properties of the lung. Under the classical theory of elasticity, the lung is said to behave as an isotropic elastic continuum undergoing small deformations. However, the lung has also been known to display heterogeneous anisotropic behaviour associated with large deformations. Therefore, focus is placed on the assumptions and development of the various models, their mechanical influence on lung physiology, and the development of constitutive equations through the classical and non-classical theory of elasticity. Lastly, we also look at lung blast mechanics. No explicit emphasis is placed on lung pathology.

PM2.5: Epigenetic Alteration in Lung Physiology and Lung Cancer Pathogenesis.

Particulate matter (PM) has a very negative impact on human health, specifically the respiratory system. PM comes in many forms, among these is PM2.5,which is a major risk factor for lung cancer and other cardiovascular diseases. PM is inherent in emissions from industrial production, manufacturing, vehicle exhaust, mining, and cigarette smoking. For this reason, the composition of PM differs from area to area although its primary constituents are heavy metals and petroleum elements. PM has a long and toxic impact on human health. After extended exposure to PM2.5 the mortality rate for lung cancer patients increases. Already, lung cancer is the leading cause of death globally with the highest mortality rate. PM2.5 creates epigenetic changes in miRNA, histone modification, and DNA methylation, causing tumorigenesis followed by lung cancer.

Angiotensin Converting Enzyme 1 Polymorphisms and Lipid Profile in Mexican Patients With COVID-19.

Renin-angiotensin system (RAS) is present in a diverse type of cells and plays an important role in lung physiology and pathophysiology. Angiotensin converting enzymes (ACE) are part of the RAS system. There are still controversies about the association of I/D polymorphisms of ACE1 with COVID-19 severity. The goal of the study was to determine whether there is an association of the I/D polymorphism with severity of COVID-19 in Mexican patients. The study included voluntary participants: 53 healthy individuals negative to RT-PCR COVID-19 (control), and 165 patients positive to COVID-19. Severity was defined by the need of hospitalization, invasive ventilation, shock, or multiple organ failure. The patient group consisted of 28 asymptomatic, 82 with mild, and 55 with severe COVID-19. I/D polymorphism was determined by PCR. Rutinary laboratory tests were performed in all the participants. DD polymorphism was significantly associated with severe COVID-19, independently of comorbidities, or any other variable. Receiver operator characteristic curves demonstrated association of low total cholesterol, low high-density lipoproteins, and high c-reactive protein with severity of COVID-19. The DD polymorphism was associated with the course of the infection and severity of COVID-19 in a sample of Mexican patients.

A Technique for Pulmonary Artery Reconstruction for Ductal Origin of the Right Pulmonary Artery

Ductal origin of the pulmonary artery is a rare cardiovascular anomaly; it is often mislabeled as absent pulmonary artery or pulmonary artery agenesis resulting in delayed interventions. We present a case of ductal origin of the right pulmonary artery highlighting the need for early detection and prompt intervention to reestablish perfusion to the lung. This approach allows for continued lung development and reduces the morbidity related to single lung physiology. The aim of this article is to describe a refinement in the operative technique used in the reconstruction of the ductal origin of the right pulmonary artery via creation of an interposition homograft roll for centralization. Ductal origin of the pulmonary artery is a rare cardiovascular anomaly; it is often mislabeled as absent pulmonary artery or pulmonary artery agenesis resulting in delayed interventions. We present a case of ductal origin of the right pulmonary artery highlighting the need for early detection and prompt intervention to reestablish perfusion to the lung. This approach allows for continued lung development and reduces the morbidity related to single lung physiology. The aim of this article is to describe a refinement in the operative technique used in the reconstruction of the ductal origin of the right pulmonary artery via creation of an interposition homograft roll for centralization.

Aerosols and human health – A multiscale problem

Chemical engineering is a scientific discipline that uses physicochemically based quantitative analysis of the momentum, energy, and mass transfer to design and optimize industrial processes. Technical issues are considered on different scales, starting from the molecular interactions, through the nano- and micrometric levels up to the design and control of the full-scale equipment and industrial installations. Such a multi-scale approach is needed to identify the critical factors of any process. In a similar way, chemical engineering can solve problems of physiology and medicine. This paper is focused on pulmonary drug delivery, which needs using a combination of the knowledge of lung physiology with the quantitative description of aerosol generation, multi-phase flow and interfacial phenomena in the respiratory system. The scientific evidence of the effectiveness of this approach has been referred to the extensive studies of the author's research team working in the field of chemical and process engineering.

A Randomized, Multicenter, Blinded Pilot Study Assessing the Effects of Gaseous Nitric Oxide in an Ex Vivo System of Human Lungs.

Normothermic ex vivo lung perfusion (EVLP) is used to evaluate and condition donor lungs for transplantation. The objective of this study was to determine whether administration of exogenous nitric oxide during EVLP contributes to improvement of lung health. A multicenter, blinded, two-arm, randomized pilot study evaluated the effect of gaseous nitric oxide (gNO) administered during EVLP on donor lungs rejected for transplantation. gNO introduced into the perfusate at 80 parts per million (ppm) was compared with perfusate alone (P). An open-label substudy assessed inhaled nitric oxide gas (iNO) delivered into the lungs at 20ppm via a ventilator. Primary endpoints were an aggregate score of lung physiology indicators and total duration of stable EVLP time. Secondary endpoints included assessments of lung weight and left atrium partial pressure of oxygen (LAPO2). Twenty bilateral donor lungs (blinded study, n = 16; open-label substudy, n = 4) from three centers were enrolled. Median (min, max) total EVLP times for the gNO, P, and iNO groups were 12.4 (8.6, 12.6), 10.6 (6.0, 12.4), and 12.4 (8.7, 13.0) hours, respectively. In the blinded study, median aggregate scores were higher in the gNO group compared to the P group at most time points, suggesting better lung health with gNO (median score range [min, max], 0-3.5 [0, 7]) vs. P (0-2.0 [0, 5] at end of study). In the substudy, median aggregate scores did not improve for lungs in the iNO group. However, both the gNO and iNO groups showed improvements in lung weight and LAPO2 compared to the P group. The data suggest that inclusion of gNO during EVLP may potentially prolong duration of organ stability and improve donor lung health, which warrants further investigation.

The establishment of COPD organoids to study host-pathogen interaction reveals enhanced viral fitness of SARS-CoV-2 in bronchi.

Chronic obstructive pulmonary disease (COPD) is characterised by airflow limitation and infective exacerbations, however, in-vitro model systems for the study of host-pathogen interaction at the individual level are lacking. Here, we describe the establishment of nasopharyngeal and bronchial organoids from healthy individuals and COPD that recapitulate disease at the individual level. In contrast to healthy organoids, goblet cell hyperplasia and reduced ciliary beat frequency were observed in COPD organoids, hallmark features of the disease. Single-cell transcriptomics uncovered evidence for altered cellular differentiation trajectories in COPD organoids. SARS-CoV-2 infection of COPD organoids revealed more productive replication in bronchi, the key site of infection in severe COVID-19. Viral and bacterial exposure of organoids induced greater pro-inflammatory responses in COPD organoids. In summary, we present an organoid model that recapitulates the in vivo physiological lung microenvironment at the individual level and is amenable to the study of host-pathogen interaction and emerging infectious disease.

Ozone impairs endogenous compensatory responses in allergic asthma

Asthma is a chronic inflammatory airway disease characterized by acute exacerbations triggered by inhaled allergens, respiratory infections, or air pollution. Ozone (O3), a major component of air pollution, can damage the lung epithelium in healthy individuals. Despite this association, little is known about the effects of O3 and its impact on chronic lung disease. Epidemiological data have demonstrated that elevations in ambient O3 are associated with increased asthma exacerbations. To identify mechanisms by which O3 exposure leads to asthma exacerbations, we developed a two-hit mouse model where mice were sensitized and challenged with three common allergens (dust mite, ragweed and Aspergillus fumigates, DRA) to induce allergic inflammation prior to exposure to O3 (DRAO3). Changes in lung physiology, inflammatory cells, and inflammation were measured. Exposure to O3 following DRA significantly increased airway hyperreactivity (AHR), which was independent of TLR4. DRA exposure resulted in increased BAL eosinophilia while O3 exposure resulted in neutrophilia. Additionally, O3 exposure following DRA blunted anti-inflammatory and antioxidant responses. Finally, there were significantly less monocytes and innate lymphoid type 2 cells (ILC2s) in the dual challenged DRA-O3 group suggesting that the lack of these immune cells may influence O3-induced AHR in the setting of allergic inflammation. In summary, we developed a mouse model that mirrors some aspects of the clinical course of asthma exacerbations due to air pollution and identified that O3 exposure in the asthmatic lung leads to impaired endogenous anti-inflammatory and antioxidant responses and alterations inflammatory cell populations.

Time Constant: What Do We Need to Know to Use It?

Mechanical ventilation is an important strategy to manage patients with respiratory ailments in the acute as well as chronic setups. To be able to do so, we need a good understanding of the physiology of the respiratory system and the disease pattern. Two major components of the lung physiology are compliance and resistance and these define time constants (TCs). Compliance is the measure of distensibility of lungs. It is the change in pressure by the change in volume. Resistance is the opposing force that is created when air flows in the airway. Compliance and resistance together produce an entity called TC. TC defines the amount of time taken in seconds for the lung unit to fill or empty. TCs normally vary within the lungs and do more so in the diseased lungs. This article gives an overview of TCs and its components for the better understanding of the reader.

Deep learning using multilayer perception improves the diagnostic acumen of spirometry: a single-centre Canadian study

RationaleSpirometry and plethysmography are the gold standard pulmonary function tests (PFT) for diagnosis and management of lung disease. Due to the inaccessibility of plethysmography, spirometry is often used alone but...

Bilateral Lung Transplantation With Donor Positive for COVID-19 Infection on Bronchoalveolar Lavage: A Case Report

Initial experience with lung transplant of COVID-19-positive donors was marked by disappointing results, including a reported case of mortality through donor to recipient transmission of infection. However, since that time a number of improvements in preventative and therapeutic measures against COVID-19 have been developed. We present the case of a 51-year-old woman with scleroderma-associated interstitial lung disease who was awaiting lung transplant. A potential donor with excellent lung physiology was located; however, initial testing on bronchoalveolar lavage (BAL) was positive for COVID-19. The donor had tested positive 2 weeks prior and had symptomatically recovered. Our patient had been fully vaccinated but not seroconverted. Given the history of a donor with recovering COVID infection and a fully immunized recipient, our multidisciplinary team elected to proceed with the transplant. The patient successfully underwent bilateral lung transplant with standard induction immunosuppression. Bebtelovimab was given post-transplant day 1 because the recipient remained seronegative to COVID-19. Serial bronchoalveolar lavages post transplant have been negative for COVID-19. The patient has done well after transplant. She was seen in the clinic 2 months post transplant and is ambulatory without supplemental oxygen requirements. To our knowledge, this represents the first reported successful case of lung transplant with a donor positive for COVID-19 on lower respiratory tract sampling.

Prophylactic surfactant nebulisation for the early aeration of the preterm lung: a randomised clinical trial

ObjectiveThe effect of prophylactic surfactant nebulisation (SN) is unclear. We aimed to determine whether prophylactic SN improves early lung aeration.DesignParallel, randomised clinical trial, conducted between March 2021 and January 2022.SettingDelivery...

The Potential Contribution of Hexavalent Chromium to the Carcinogenicity of Chrysotile Asbestos.

Chrysotile asbestos is a carcinogenic mineral that has abundantly been used in industrial and consumer applications. The carcinogenicity of the fibers is partly governed by reactive Fe surface sites that catalyze the generation of highly toxic hydroxyl radicals (HO•) from extracellular hydrogen peroxide (H2O2). Chrysotile also contains Cr, typically in the low mass permille range. In this study, we examined the leaching of Cr from fibers at the physiological lung pH of 7.4 in the presence and absence of H2O2. Furthermore, we investigated the potential of cells from typical asbestos-burdened tissues and cancers to take up Cr leached from chrysotile in PCR expression, immunoblot, and cellular Cr uptake experiments. Finally, the contribution of Cr to fiber-mediated H2O2 decomposition and HO• generation was studied. Chromium readily dissolved from chrysotile fibers in its genotoxic and carcinogenic hexavalent redox state upon oxidation by H2O2. Lung epithelial, mesothelial, lung carcinoma, and mesothelioma cells expressed membrane-bound Cr(VI) transporters and accumulated Cr up to 10-fold relative to the Cr(VI) concentration in the spiked medium. Conversely, anion transporter inhibitors decreased cellular Cr(VI) uptake up to 45-fold. Finally, chromium associated with chrysotile neither decomposed H2O2 nor contributed to fiber-mediated HO• generation. Altogether, our results support the hypothesis that Cr may leach from inhaled chrysotile in its hexavalent state and subsequently accumulate in cells of typically asbestos-burdened tissues, which could contribute to the carcinogenicity of chrysotile fibers. However, unlike Fe, Cr did not significantly contribute to the adverse radical production of chrysotile.

Protective effects of Isodon Suzhouensis extract and glaucocalyxin A on chronic obstructive pulmonary disease through SOCS3–JAKs/STATs pathway

AbstractChronic obstructive pulmonary disease (COPD) is an irreversible disease with the leading causes of morbidity, mortality, and several physical limitations. Isodon Suzhouensis is a unique Chinese medicinal plant used for both medicine and food. It possesses strong anti‐inflammatory effects that may treat COPD. Considering the fact that the effects of Isodon Suzhouensis extract (WZZE) and its active ingredient glaucocalyxin A (GLA) on COPD have never been reported before, this study aimed to investigate the effects of WZZE and GLA against COPD and its underlying mechanistic pathway in COPD model rats or in CSE‐induced NR8383 cells. The variation in lung physiology was measured through spirometry while histopathological changes were studied via H&E staining of the COPD model rats lung samples. The levels of cytokine and other immunomodulatory proteins were determined by ELISA. Apoptosis of lung tissue cells was detected by TUNEL staining. Western blot and immunohistochemistry were used to detect the expression of related pathways and other proteins. The results show that WZZE improved the relevant lung function indicators, while restoring the activity of immunoglobulins (Ig A, IgG) and inhibiting the levels of TNF‐α and IL‐1β in serum and bronchoalveolar lavage fluid, thereby improving the body's immunity and inhibiting inflammation of the airways and lungs, slowing the progression of COPD. The results of H&E staining indicated that WZZE is capable of improving the pathological injury associated with COPD. In addition, the administration of WZZE reduced the expression of MUC5AC protein induced and the apoptosis rate of lung tissue cells in COPD model rats. The results also showed that WZZE significantly increased the expression of SOCS3 and inhibited the expression of JAKs/STATs pathway‐related proteins in COPD rats. In addition, GLA can also upregulate the expression of SOCS3 protein, inhibit JAKs/STATs pathway, inhibit the expression level of MUC5AC, upregulate the expression level of immunoglobulin, and downregulate the expression level of proinflammatory factors in NR8383 cells induced by CSE. Present study findings suggest that WZZE and GLA may ameliorate the progression of COPD via the SOCS3–JAKs/STATs pathway in COPD rats or in CSE‐induced NR8383.

Tumor-Derived Exosomes and Their Role in Breast Cancer Metastasis.

Breast cancer has been the most common cancer in women worldwide, and metastasis is the leading cause of death from breast cancer. Even though the study of breast cancer metastasis has been extensively carried out, the molecular mechanism is still not fully understood, and diagnosis and prognosis need to be improved. Breast cancer metastasis is a complicated process involving multiple physiological changes, and lung, brain, bone and liver are the main metastatic targets. Exosomes are membrane-bound extracellular vesicles that contain secreted cellular constitutes. The biogenesis and functions of exosomes in cancer have been intensively studied, and mounting studies have indicated that exosomes play a crucial role in cancer metastasis. In this review, we summarize recent findings on the role of breast cancer-derived exosomes in metastasis organotropism and discuss the potential promising clinical applications of targeting exosomes as novel strategies for breast cancer diagnosis and therapy.

Alteration of Lung Physiology with the Administration of Convalescent Plasma in ARDS Patients Intubated with COVID-19 Pneumonia

Background: It remains unknown to what degree lung physiology is altered by administration of convalescent plasma in patients intubated with ARDS due to COVID-19 pneumonia. Although no longer clinically used as treatment for COVID-19, convalescent plasma therapy could be deployed again should new virus threats emerge in the future. Aim: To evaluate changes in ventilator physiologic variables in response to convalescent plasma transfusion using a retrospective, observational, case control study of intubated patients with COVID-19 pneumonia. Methods: Patients who were receiving mechanical ventilation due to COVID-19 at the time of administration of convalescent plasma therapy (CPT) were matched to control patients who did not receive convalescent plasma. Ventilatory data such as compliance, positive end-expiratory pressure (PEEP), FiO2 administered, PaO2/FiO2 ratio, and tidal volume were collected pre and post administration. Panel-level random-effects linear regression models were used to assess the mean difference and interactions between CPT and cases vs controls over time. Results: 12 patients received CPT while intubated and were matched to 35 intubated control patients who did not receive CPT. In total, 857 separate measurements of static compliance were obtained over time. No significant difference in static compliance was seen after CPT. In cases, adjusted mean static compliance was 30.8 (95% CI (23.3, 38.4))mL/cm H2O before CPT and 28.2 (95% CI (20.7,35.6)) mL/cm H2O afterwards. Controls adjusted mean static compliance was 33.9 (95% CI (29.5, 38.4)) mL/cm H2O before versus 32.2 (95% CI (27.9, 36.5)) mL/cm H2O afterwards. Variables that had small but statistically significant differences pre vs post CPT among cases and controls were systolic and diastolic blood pressure, FiO2, heart rate, applied PEEP, and respiratory rate. Conclusion: While some statistically significant physiologic effects were seen with CPT in mechanically ventilated patients, these were deemed to be small and clinically insignificant. This is consistent with prior research on less acutely ill COVID-19 patients.

The Lognormal Lung: A new approach to quantifying lung inhomogeneity in COPD.

Early diagnosis and disease phenotyping in COPD are currently limited by the use of spirometry, which may remain normal despite significant small-airways disease and which may not fully capture a patient's underlying pathophysiology. In this study we explored the use of a new non-invasive technique that assesses gas-exchange inhomogeneity in patients with COPD of varying disease severity (according to GOLD Stage), compared with age-matched healthy controls. The technique, which combines highly accurate measurement of respiratory gas exchange using a bespoke molecular flow sensor and a mechanistic mathematical model of the lung, provides new indices of lung function: the parameters σCL, σCd, and σVD represent the standard deviations of distributions for alveolar compliance, anatomical deadspace and vascular conductance relative to lung volume, respectively. It also provides parameter estimates for total anatomical deadspace and functional residual capacity (FRC). We demonstrate that these parameters are robust and sensitive, and that they can distinguish between healthy individuals and those with mild-moderate COPD (stage 1-2), as well as distinguish between mild-moderate COPD (stage 1-2) and more severe (stage 3-4) COPD. In particular, σCL, a measure of unevenness in lung inflation/deflation, could represent a more sensitive non-invasive marker of early or mild COPD. In addition, by providing a multi-dimensional assessment of lung physiology, this technique may also give insight into the underlying pathophysiological phenotype for individual patients. These preliminary results warrant further investigation in larger clinical research studies, including interventional trials.

Respiratory Physiology of COVID-19 and Influenza Associated Acute Respiratory Distress Syndrome.

Background: There is ongoing debate whether lung physiology of COVID-19-associated acute respiratory distress syndrome (ARDS) differs from ARDS of other origin. Objective: The aim of this study was to analyze and compare how critically ill patients with COVID-19 and Influenza A or B were ventilated in our tertiary care center with or without extracorporeal membrane oxygenation (ECMO). We ask if acute lung failure due to COVID-19 requires different intensive care management compared to conventional ARDS. Methods: 25 patients with COVID-19-associated ARDS were matched to a cohort of 25 Influenza patients treated in our center from 2011 to 2021. Subgroup analysis addressed whether patients on ECMO received different mechanical ventilation than patients without extracorporeal support. Results: Compared to Influenza-associated ARDS, COVID-19 patients had higher ventilatory system compliance (40.7 mL/mbar [31.8-46.7 mL/mbar] vs. 31.4 mL/mbar [13.7-42.8 mL/mbar], p = 0.198), higher ventilatory ratio (1.57 [1.31-1.84] vs. 0.91 [0.44-1.38], p = 0.006) and higher minute ventilation at the time of intubation (mean minute ventilation 10.7 L/min [7.2-12.2 L/min] for COVID-19 vs. 6.0 L/min [2.5-10.1 L/min] for Influenza, p = 0.013). There were no measurable differences in P/F ratio, positive end-expiratory pressure (PEEP) and driving pressures (ΔP). Respiratory system compliance deteriorated considerably in COVID-19 patients on ECMO during 2 weeks of mechanical ventilation (Crs, mean decrease over 2 weeks -23.87 mL/mbar ± 32.94 mL/mbar, p = 0.037) but not in ventilated Influenza patients on ECMO and less so in ventilated COVID-19 patients without ECMO. For COVID-19 patients, low driving pressures on ECMO were strongly correlated to a decline in compliance after 2 weeks (Pearson's R 0.80, p = 0.058). Overall mortality was insignificantly lower for COVID-19 patients compared to Influenza patients (40% vs. 48%, p = 0.31). Outcome was insignificantly worse for patients requiring veno-venous ECMO in both groups (50% mortality for COVID-19 on ECMO vs. 27% without ECMO, p = 0.30/56% vs. 34% mortality for Influenza A/B with and without ECMO, p = 0.31). Conclusion: The pathophysiology of early COVID-19-associated ARDS differs from Influenza-associated acute lung failure by sustained respiratory mechanics during the early phase of ventilation. We question whether intubated COVID-19 patients on ECMO benefit from extremely low driving pressures, as this appears to accelerate derecruitment and consecutive loss of ventilatory system compliance.

Protective Effect of Nebulized Heparin in the Animal Models of Smoke Inhalation Injury: A Meta-analysis and Systematic Review of Experimental Studies.

The pathophysiological mechanism of abnormal coagulation can result from smoke inhalation injury (SII). Heparin nebulization is a common treatment for lung disorders. This study aimed to use meta-analysis in animal models to examine the effectiveness of atomized heparin on SII. For our online searches, we used the Cochrane Central Register of Controlled Trials, PubMed, Web of Science, Chinese National Knowledge Infrastructure, Chinese BioMedical Literature Database, and Wanfang Database up to January 2022. Data for SII were retrieved and compared to control animals. The studies' findings were determined by combining standardized mean difference (SMD) analysis with 95% confidence intervals (CIs). The findings showed that as compared to the control group, the heparin-treated group had a lower death rate (relative risk 0.42; 95% CI 0.22, 0.80; p < .05). The meta-analysis demonstrated favorable changes in lung physiology, including PaO2/FiO2 (SMD 1.04; 95% CI 0.65, 1.44; p < .001), lung wet-to-dry weight ratio (SMD -1.83; 95% CI -2.47, -1.18; p < .001), and pulmonary shunt Qs/Qt (SMD -0.69; 95% CI -1.29, -0.08; p < .05) after heparin nebulization for lung injury. The present data indicated that pulmonary artery mean pressure in the heparin therapy group was significantly lowered after 24 and 48 hours of therapy, suggesting that the cardiovascular system could recover following heparin treatment. As a result, heparin nebulization appeared to be more effective against SII and improved cardiopulmonary function compared to the control group. Graphical Abstract.

Effects of face masks on oxygen saturation at graded exercise intensities.

Mask wearing to mitigate the spread of COVID-19 and other viral infections may raise concerns on the effects of face masks on breathing and cardiopulmonary health. Non-evidence-based apprehensions may limit the use of masks in public. We will assess the parameters related to heart and lung physiology between healthy male and female adults exposed to wearing face masks (or not) under conditions of rest and graded exercise. We performed a cross-sectional study including 20 male and 20 female adults who met our inclusion criteria. Adults with underlying respiratory and cardiac conditions were excluded. Physiologic parameters were measured while the participants underwent three activity levels (10min each) in a randomly assigned order: rest, walking, and stair climbing. Each activity level was conducted under three mask conditions: no mask, surgical mask, and N95 respirator. Heart rate (HR) and blood oxygen saturation (SpO2) were recorded via pulse oximeter after each activity. Perceived exertion was recorded utilizing a Borg 15-point scale. A mixed-effects analysis of variance (ANOVA) was utilized to interpret the results. A significant increase in perceived exertion was reported for N95 users (p<0.0001). There was also a significant increase in mean HR for N95 users in comparison to no-mask users (p=0.0031). The mean SpO2 in females was higher than males under rest and walking conditions (p=0.0055). There was no change in SpO2 between mask type overall, nor between mask type vs. exercise intensity, nor between mask type and sex. Our findings provide evidence that surgical masks and N95 respirators do not influence SpO2 at rest or during exercise.