![]() ![]() Inclusion criteria for the study were: participants had to be at least 18 years old, and capable and willing to follow all study-related procedures. We evaluated the local concentration of CO2 under various PPE to determine its potential role as a causative factor in the symptomatology described with prolonged use Ī total of 11 volunteers were enrolled in the study. It is known that dead space (respirator volume) and hypoventilation related to breathing resistance in respirators can contribute to CO2 rebreathing, thereby increasing the CO2 to symptomatic levels. The National Institute for Occupational Safety and Health (NIOSH) has an 8-h threshold limit value - time-weighted average recommended exposure limit (TLV-REL) of 5000 ppm and a 15-min threshold limit value - short term exposure limit (TLV-STEL) of 30,000 ppm for CO2 in workplace ambient air. However, studies have shown that short-term exposure to CO2 levels above 1000 ppm start affecting cognitive function and at much higher levels, can be toxic to the human body. In normal room-air, CO2 levels are around 0.03–0.04%, equivalent to 300–400 ppm (ppm) and have no known toxic effect. ĬO2 is a colorless, odorless gas that is a natural by-product of respiration. Numerous side-effects such as dyspnea, dizziness, reduced cognition and headaches, have been reported with mask use, particularly with the tight-fitting N95 masks and valved respirators. These perceptions have been associated not only with mask fit but also with carbon dioxide (CO2) rebreathing from the mask. Although PPE use is necessary, the side-effects become more noticeable with their prolonged use. The personal protective equipment (PPE) include N95 respirators, valved-respirators and powered air purifying respirator (PAPR), in addition to face shields and goggles. Furthermore, some studies raised concerns related to the hypercapnoea and hypoxemia caused during donning the face masks. However, this recommendation became controversial and even politicized in some countries, because of concerns about the safety of masks. Public health officials have recommended face-masks since studies demonstrated that they reduce SARS-CoV-2 transmission. Wide-spread use of face-masks has been brought on by the current COVID-19 pandemic. However, whether PAPR should be advocated for healthcare workers requiring PPE for extended hours needs to evaluated in further studies. Use of PAPR prevents relative hypercapnoea. ![]() The clinical implications of elevated CO2 levels with long-term use of face masks needs further studies. Therefore, there should not be a concern in their regular day-to-day use for healthcare providers. ConclusionĪlthough, significant increase in CO2 concentrations are noted with routinely used face-masks, the levels still remain within the NIOSH limits for short-term use. However, whether increase in CO2 levels are clinically significant remains debatable. ![]() There was a statistically significant difference between all pairs ( p < 0.0001, except KN95 and valved-respirator ( p = 0.25). Importantly, these levels were considerably lower than the long-term (8-h) NIOSH limits during donning JustAir® PAPR. However, the increases in CO2 concentrations did not breach short-term (15-min) limits. Use of face masks (KN95 and valved-respirator) resulted in significant increases in CO2 concentrations, which exceeded the 8-h NIOSH exposure threshold limit value-weighted average (TLV-TWA). Percent mean (SD) changes in CO2 values for no mask, JustAir® PAPR, KN95 respirator and valve respirator were 0.26 (0.12), 0.59 (0.097), 2.6 (0.14) and 2.4 (0.59), respectively. The study included 11 healthy volunteers, median age 32 years (range 16–54) and 6 (55%) men. Serial CO2 measurements were taken with a nasal canula at a frequency of 1-Hz for 15-min for each PPE configuration to evaluate whether National Institute for Occupational Safety and Health (NIOSH) limits were breached. In a prospective observational study on healthy volunteers, CO2 levels were measured during regular breathing while donning 1) no mask, 2) JustAir® powered air purifying respirator (PAPR), 3) KN95 respirator, and 4) valved-respirator. ![]() We evaluated concentrations of CO2 under various PPE. Various symptoms attributed to the use of PPE are believed to be, at least in part, due to elevated carbon-dioxide (CO2) levels. COVID-19 pandemic led to wide-spread use of face-masks, respirators and other personal protective equipment (PPE) by healthcare workers. ![]()
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |