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Preliminary report on surgical mask induced deoxygenation during major surgery – PubMed (2008)

Abstract
Objectives: This study was undertaken to evaluate whether the surgeons’ oxygen saturation of hemoglobin was affected by the surgical mask or not during major operations.

Methods: Repeated measures, longitudinal and prospective observational study was performed on 53 surgeons using a pulse oximeter pre and postoperatively.

Results: Our study revealed a decrease in the oxygen saturation of arterial pulsations (SpO2) and a slight increase in pulse rates compared to preoperative values in all surgeon groups. The decrease was more prominent in the surgeons aged over 35.

Conclusions: Considering our findings, pulse rates of the surgeon’s increase and SpO2 decrease after the first hour. This early change in SpO2 may be either due to the facial mask or the operational stress. Since a very small decrease in saturation at this level, reflects a large decrease in PaO2, our findings may have a clinical value for the health workers and the surgeons.

https://pubmed.ncbi.nlm.nih.gov/18500410/

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“Exercise with facemask; Are we handling a devil’s sword?” – A physiological hypothesis – NCBI

Straying away from a sedentary lifestyle is essential, especially in these troubled times of a global pandemic to reverse the ill effects associated with the health risks as mentioned earlier. In the view of anticipated effects on immune system and prevention against influenza and Covid-19, globally moderate to vigorous exercises are advocated wearing protective equipment such as facemasks. Though WHO supports facemasks only for Covid-19 patients, healthy “social exercisers” too exercise strenuously with customized facemasks or N95 which hypothesized to pose more significant health risks and tax various physiological systems especially pulmonary, circulatory and immune systems. Exercising with facemasks may reduce available Oxygen and increase air trapping preventing substantial carbon dioxide exchange. The hypercapnic hypoxia may potentially increase acidic environment, cardiac overload, anaerobic metabolism and renal overload, which may substantially aggravate the underlying pathology of established chronic diseases. Further contrary to the earlier thought, no evidence exists to claim the facemasks during exercise offer additional protection from the droplet transfer of the virus. Hence, we recommend social distancing is better than facemasks during exercise and optimal utilization rather than exploitation of facemasks during exercise.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7306735/

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Respiratory consequences of N95-type Mask usage in pregnant healthcare workers—a controlled clinical study – Antimicrobial Resistance and Infection Control (2015)

Results
Exercising at 3 MET while breathing through N95-mask materials reduced mean tidal volume (TV) by 23.0 % (95 % CI −33.5 % to −10.5 %, p < 0.001) and lowered minute ventilation (VE) by 25.8 % (95 % CI −34.2 % to −15.8 %, p < 0.001), with no significant change in breathing frequency compared to breathing ambient air. Volumes of oxygen consumption (VO2) and carbon dioxide expired (VCO2) were also significantly reduced; VO2 by 13.8 % (95 % CI −24.2 % to −3 %, p = 0.013) and VCO2 by 17.7 %, (95 % CI −28.1 % to −8.6 %, p = 0.001). Although no changes in the inspired oxygen and carbon dioxide concentrations were demonstrated, breathing through N95-mask materials during low intensity work (3 MET) reduced expired oxygen concentration by 3.2 % (95 % CI: −4.1 % to −2.2 %, p < 0.001), and increased expired carbon dioxide by 8.9 % (95 % CI: 6.9 % to 13.1 %; p <0.001) suggesting an increase in metabolism. There were however no changes in the maternal and fetal heart rates, finger-tip capillary lactate levels and oxygen saturation and rating of perceived exertion at the work intensity investigated.

Conclusions
Breathing through N95 mask materials have been shown to impede gaseous exchange and impose an additional workload on the metabolic system of pregnant healthcare workers, and this needs to be taken into consideration in guidelines for respirator use. The benefits of using N95 mask to prevent serious emerging infectious diseases should be weighed against potential respiratory consequences associated with extended N95 respirator usage.

https://aricjournal.biomedcentral.com/articles/10.1186/s13756-015-0086-z

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The physiological impact of wearing an N95 mask during hemodialysis as a precaution against SARS in patients with end-stage renal disease – PubMed (2004)

Results: Thirty nine patients (23 men; mean age, 57.2 years) were recruited for participation in the study. Seventy percent of the patients showed a reduction in partial pressure of oxygen (PaO2), and 19% developed various degrees of hypoxemia. Wearing an N95 mask significantly reduced the PaO2 level (101.7 +/- 12.6 to 92.7 +/- 15.8 mm Hg, p = 0.006), increased the respiratory rate (16.8 +/- 2.8 to 18.8 +/- 2.7/min, p < 0.001), and increased the occurrence of chest discomfort (3 to 11 patients, p = 0.014) and respiratory distress (1 to 17 patients, p < 0.001). Baseline PaO2 level was the only significant predictor of the magnitude of PaO2 reduction (p < 0.001).

Conclusion: Wearing an N95 mask for 4 hours during HD significantly reduced PaO2 and increased respiratory adverse effects in ESRD patients.