Respiratory consequences of N95-type Mask usage in pregnant healthcare workers—a controlled clinical study

Abstract

BackgroundOutbreaks of emerging infectious diseases have led to guidelines recommending the routine use of N95 respirators for healthcare workers, many of whom are women of childbearing age. The respiratory effects of prolonged respirator use on pregnant women are unclear although there has been no definite evidence of harm from past use.MethodsWe conducted a two-phase controlled clinical study on healthy pregnant women between 27 to 32 weeks gestation. In phase I, energy expenditure corresponding to the workload of routine nursing tasks was determined. In phase II, pulmonary function of 20 subjects was measured whilst at rest and exercising to the predetermined workload while breathing ambient air first, then breathing through N95-mask materials.ResultsExercising 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.ConclusionsBreathing 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.Trial RegistrationThe study was registered at clinicaltrials.gov, identifier NCT00265926.

Preventing Facial Pressure Injury for Health Care Providers Adhering to COVID-19 Personal Protective Equipment Requirements

“…19,20 It is possible that the protective dressing increases the mask's seal stability while mitigating pressure-related skin damage. Critically, extended periods of N95 mask wear may be related to mask-induced hypoxia in HCPs; 19,20 hypoxia is an established major risk factor for pressure-related skin breakdown. 3 Mitigation of this concern can be achieved by the split-shift approach previously described.…”

“…This is in line with extant studies on N95 mask use that confirms overall oxygen intake is diminished during wear, even with a perfectly fitting mask. 19,20 On the next day, the N95 mask was worn without any protection ( Table 2). Each participant positioned their own mask and it was again worn for 4 hours without any eating, drinking, or bathroom breaks.…”

N95 Filtering Facepiece Respirator Use during Pregnancy: A Systematic Review

“…14 It was theorized that the increase in CO 2 was due to rebreathing of higher CO 2 levels related to CO 2 retention in the dead space created by the mask; however, Tong disputes this argument given that the total CO 2 intake was decreased due to decreased minute ventilation. 16 Additionally, while studies are limited, the increase in CO 2 over short duration is not expected to pose an increased risk to the developing fetus unless the levels are at a high-enough concentration to lead to more significant physiologic changes or loss of consciousness in the pregnant woman. 18 While the slight increases in CO 2 found in these studies failed to have a significant physiologic impact on the pregnant participants, it is unclear if this would hold true with prolonged use of the N95 masks.…”

Procedural precautions and personal protective equipment during head and neck instrumentation in the COVID‐19 era

“…Moreover, headaches are common among health care workers wearing N95 masks, 8 a phenomenon postulated to be related to impaired gas exchange with retention of carbon dioxide, or mechanical factors associated with prolonged N95 mask usage. 9 3 | TESTING History and physical exam alone are often insufficient to guide PPE and procedural decision making, as up to 80% of patients may be mildly symptomatic or asymptomatic COVID-19 carriers. 10,11 Clear protocols to advise testing, with accommodations for limitations in resources, are therefore important to appropriately protect providers and patients against transmission.…”