key: cord-0706894-0gdnbmyp
authors: Pasli, Sinan; Imamoglu, Melih; Beser, Muhammet Fatih; Sahin, Abdul Samet; Ilhan, Engin; Yadigaroglu, Metin
title: Examination of the Effects of 4-hour Nonvalved Filtering Facepiece Respirator Use on Blood Gas Values of Health Care Professionals: A Before and After Study
date: 2022-05-09
journal: Journal of emergency nursing
DOI: 10.1016/j.jen.2022.03.006
sha: 5d10b08f0e57fd1f995bcb198cf63d5a2375851d
doc_id: 706894
cord_uid: 0gdnbmyp

Introduction The use of personal protective equipment increased rapidly during the COVID-19 pandemic that began in 2019. The purpose of this study was to examine the effects of uninterrupted 4-hour use of internationally certified nonvalved filtering facepiece respirators on venous blood gas in health care workers during the COVID-19 pandemic. Methods A before-after design included venous blood gas analyses collected at the beginning of shifts before nonvalved filtering facepiece respirator had been put on and after 4-hour uninterrupted use of nonvalved filtering facepiece respirator. Results In this study, 33 volunteer health care workers took part. In terms of blood gas values, mean pCO2 values were 47.63 (SD = 5.16) before and 47.01 (SD = 5.07) after nonvalved filtering facepiece respirator use, mean HCO3 values were 23.68 (SD = 1.10) in first blood gas analysis and 24.06 (SD = 1.31) in second blood gas analysis, and no significant difference was observed between before and after the use of nonvalved filtering facepiece respirator (t = 0.67, P = .50, t = −2.0, P = .054, respectively). The only significant difference in parameters investigated between the groups was in pH levels, at pH = 7.35 (SD = 0.29) before and pH = 7.36 (SD = 0.20) after nonvalved filtering facepiece respirator use (t = −2.26, P = .03). Conclusion Continuous nonvalved filtering facepiece respirator use for 4 hours was not associated with clinician impairment in blood gas and peripheral SpO2 levels during nonexertional clinical ED work.

respectively). The only significant difference in parameters investigated between the groups was in pH levels, at pH ¼ 7.35 (SD ¼ 0.29) before and pH ¼ 7.36 (SD ¼ 0.20) after nonvalved filtering facepiece respirator use (t ¼ À2.26, P ¼ .03).

Diseases transmitted by respiration can cause epidemics and pandemics. Health care workers adopted a series of measures to protect themselves during the severe acute respiratory syndrome (SARS) epidemic caused by the SARS coronavirus originating in Hong Kong in 2002 and during the influenza A H1N1 swine flu epidemic originating in Mexico in 2009. The most important of these measures was the use of surgical masks and nonvalved filtering facepiece (N95/ FFP2) respirators. 1 The use of personal protective equipment (PPE) increased rapidly during the COVID-19 pandemic that began spreading across the world from the Chinese city of Wuhan in 2019. Studies have also emphasized the importance of PPE use. 2 Studies performed during the SARS outbreak have also revealed significant findings regarding the protective nature of PPE. 3 Health care professionals serving patients with probable and confirmed COVID-19 were advised to use respirators (N95, FFP2, or equivalent standard), especially for aerosol-generating procedures. 4 It may be reasonable to consider European FFP2 as "equivalent" to US NIOSH N95 respirators, for filtering at least 94% of non-oil-based particles such as virus bio-aerosols. 5 We hypothesized that the pCO 2 value in the blood gas might increase, and the pH and SpO 2 values may decrease after the continuous use of N95/FFP2 respirators. The purpose of this study was to examine the effects of uninterrupted 4-hour N95/FFP2 respirator use on venous blood gas in health care professionals.

We used a before-after design. The study population consisted of health care professionals (emergency nurses and physicians) working in the emergency department of a tertiary hospital between March 1, 2021, and April 1, 2021. Inclusion criteria were age 18 or over, voluntary participation with written consent, being clean-shaven, and receiving training in the use of PPE. Exclusion criteria were the presence of severe chronic pulmonary disease or mask use being medically contraindicated and participants who removed their N95/FFP2 respirator for any reason during the study period. No incentive was provided.

This study was conducted under the approval of the local ethics committee (approval number: 2021/12).

Venous blood gas measurements were performed at the beginning of shifts before the N95/FFP2 respirator had been put on and after 4-hour uninterrupted use of internationally certified N95/FFP2 (3M VFlex 9152E) respirators. Participants continued with their routine activities for 4 hours. They did not engage in high-effort interventions such as providing cardiopulmonary resuscitation and did not leave the emergency department for any reason. An average of 2 volunteers participated in the study each weekday, and the participants were observed by an author working in the same field.

Age, sex, smoking, and medical history were recorded on a research form for each participant (see Supplementary Appendix).

Major symptoms such as headache, nausea, palpitations, shortness of breath, or anxiety were questioned. At the end of 4-hour respirator use, participants were verbally asked whether they had any of these symptoms during the 4-hour period, and the results were recorded on a research form (see Supplementary Appendix).

Blood gas analyses were performed on a bench analyzer (Rapidlab 1265, Bayer Health Care LLC, Pittsburgh, PA). The device was calibrated at regular intervals (1-point calibration every 4 hours, 2-point calibration every 8 hours). The pH (reference range: 7.35-7.45), pCO 2 (reference range: 35-45 mmHg), and standard-HCO 3 (reference range: 21.2-27 mmol/L) levels were measured. The results were printed on a paper and stored.

The study data were recorded onto Microsoft Excel software (Microsoft Corporation, Redmond, WA) and analyzed using Statistical Package of Social Sciences version 24.0 (IBM Corp, Armonk, NY) and MedCalc software (MedCalc Software Ltd, Oostende, Belgium). Compatibility with normal distribution was evaluated using the Shapiro Wilk or Kolmogorov Smirnov tests. Normally distributed numerical variables were expressed as mean and standard deviation and 95% confidence interval. Non-normally distributed numerical variables were expressed as median (minimum-maximum) and 95% confidence interval. Categorical variables were defined as n (number) and %. The matched pairs t test was used to compare before and after values of normally distributed numerical variables. Wilcoxon's test was employed to compare non-normally distributed numerical variables. The independent samples t test was used to compare normally distributed numerical demographic variables between independent groups, and numerical data not exhibiting normal distribution were compared using the Mann-Whitney U test. P < .05 were regarded as statistically significant for all analyses. When the effect size was expected as d ¼ 0.5, alpha error ¼ 0.05, statistical power ¼ 0.85 for the t test in 2 dependent groups (matched pairs) using the GPower 3.1.9.7. program (Heinrich-Heine-University, Düsseldorf, Germany), we calculated that the sample size of the study should be at least 31.

Thirty-three volunteer health care professionals (emergency nurses and physicians) participated in the study. No participants were excluded from the study, and no data were missing. Men constituted n ¼ 17 (51.5%) of the participants and women n ¼ 16 (48.5%). Median ages were 28 years (24-47) among men and 27 years (24-29) among women. Nonsmokers (tobacco) were n ¼ 26 (78.8%) while n ¼ 7 (21.2%) smoked tobacco. Intermittent asthma was present in 2 participants (Table 1) . Median fingertip oxygen saturation values in room air were SpO 2 ¼ 98 (95-99) before N95/FFP2 use and SpO 2 ¼ 98 (92-100) after N95/FFP2 use, and the difference was not statistically significant (z ¼ À1.48, P ¼ .13). Mean pCO 2 values were 47.63 (SD ¼ 5.16) before N95/FFP2 use and 47.01 (SD ¼ 5.07) after N95/FFP2 use, and no significant difference was observed between these groups (t ¼ 0.67, P ¼ .50). The mean HCO3 levels were 23.68 (SD ¼ 1.10) and 24.06 (SD ¼ 1.3) before and after N95/FFP2 use, respectively, and no significant difference was observed (t ¼ À2.0, P ¼ .054). The only significant difference in parameters investigated between the groups was at pH levels. Mean pH levels were found at 7.35 (SD ¼ 0.29) before N95/FFP2 use and pH ¼ 7.36 (SD ¼ 0.20) after N95/FFP2 use (t ¼ À2.26, P ¼ .03) ( Table 2) . No major side effects (headache, nausea, palpitations, dyspnea, or anxiety) were reported by the participants. 

The new global threat SARS-CoV-2 is transmitted by droplets and aerosols. Health care workers were advised to use PPE to prevent transmission of the disease during the COVID-19 pandemic. 4 One recent meta-analysis showed that surgical masks provided a degree of protection comparable to that of N95/FFP2 respirators for aerosol-free procedures. 6 However, in aerosol-generating procedures, the use of N95, FFP2, or FFP3 respirators may be appropriate. 4 Although their findings vary, several studies have investigated the effects of N95/FFP2 and FFP3 respirators on metabolic and respiratory parameters. The present study examined the effect of 4-hour continuous N95/FFP2 respirator use on venous blood gas and peripheral oxygen saturation values. While a significant difference was observed in pH values, there was no significant difference between PCO 2 , HCO 3 , and peripheral SpO 2 values. Despite the significant difference in pH values, both groups remained within physiological limits. Although the reason could not be determined through measurements, this might be related to increased respiration rates. A study showed that the use of N95/FFP2 for 1 hour was associated with increases in respiratory rate (range, 1.4-2.4 breaths per minute). 7 Kao et al 8 performed a blood gas study on 39 patients receiving dialysis during the SARS epidemic. They reported that 4-hour use of an N95/FFP2 respirator significantly reduced PaO 2 in patients with end-stage kidney disease and increased respiratory side effects in those patients. These findings need to be confirmed in studies with a contemporaneous comparison or control group to address the unmeasured confounding of the work shift itself.

Ong et al 9 and Lim et al 10 both reported that N95/FFP2 caused a significant increase in headaches among health care workers. In a study performed during the COVID-19 pandemic, Ong et al 9 reported headaches associated with PPE use in 82% of health care workers. In another study carried out during the SARS epidemic, Lim et al 10 reported that 37.3% of participants had a headache after N95/FFP2 use. These authors interpreted that this headache finding might be related to increased inhaled CO 2 levels, but blood gas measurements were not performed in their study. There was no difference between pCO 2 levels before and after N95/FFP2 respirator use in our study, and the participants did not report any side effects. Coca et al 11 recommended establishment of appropriate working and rest periods to avoid undesirable side effects of PPE. When using respirators for extended periods of time during the COVID-19 pandemic, health care professionals may have developed physiological and behavioral adaptations or ignored side effects with extended PPE wear. Changes in nutrition, hydration, and resting habits, and adjustment of work tempo may be some of these adap-tation mechanisms. Further studies targeting pulmonary function tests or behavioral changes can be beneficial to clarify possible clinician adaptations.

Bharatendu et al 12 examined the effect of N95/FFP2 use on end-tidal CO 2 (ETCO 2 ), and no significant increase in ETCO 2 values was observed in participants using N95/ FFP2. A recent study found that the use of N95/FFP2 for 1 hour in 10 healthy emergency residents did not cause a significant difference in the pH and pCO 2 values measured at 20, 40, and 60 minutes. 13 A study conducted with 57 nurses and 47 paramedics working in the SARS coronavirus-2 intensive care unit showed that the use of FFP2 and FFP3 respirators did not cause deterioration in blood gas values in a median time of 240 minutes. 14 The results of these 2 studies are similar to our findings.

Yalciner et al 15 reported that using an FFP3 respirator for at least 4 hours caused no significant change in blood gas parameters in 15 health care workers. None of the participants removed the respirator for any reason during the study period, and this is interpreted as it being well tolerated by participants. 14 The methodology and results of our study are similar to those of Yalciner et al, 15 although we used N95/ FFP2 respirators in our research. In their study of 43 health care workers, Nafisah et al 16 reported that continuous N95/ FFP2 use significantly reduced pO 2 levels and increased pCO 2 . The results of our study are not consistent with this research, suggesting that respiratory parameters can be affected differently by the use of different brands of respirators. In a study with the participation of 154 health care professionals, the effect of using only the N95 and combined use of the N95þPowered Air Purifying Respirator (PAPR) on cerebral hemodynamics and blood gas parameters was examined. They found a significant increase in ETCO 2 values after using only the N95 respirator for 5 minutes. After the combination of N95þPAPR at 5 minutes, the ETCO 2 values measured at 10 minutes returned to their basal values. These N95þPAPR results are not corroborated by our study. The reasons for this difference may be that clinician adaptations to extended PPE wear had not yet developed in the early pandemic period, or it may be related to the measurement method (capnometer). In addition, it is not clear whether the ETCO 2 values returning to basal levels in that study is due to the combination of N95þPAPR or due to the adaptation that may occur over time. We did not perform a respirator fit test for the participants; therefore, air leaking from around the respirator may have affected the results and differences in our findings from those of other studies. 12 Currently, the evidence in the published literature does not provide consistent results, especially regarding changes in pCO 2 levels. 13, 16 Most studies have shown that respirator use does not lead to significant changes in pCO 2

Month 2022 VOLUME -ISSUE -WWW.JENONLINE.ORG levels. [12] [13] [14] The fact that pCO 2 levels were not impaired in our current study corroborates evidence in the published literature. However, our study contradicts other evidence in the published literature regarding side effects related to mask use. 9,10 Headache associated with respirator use has been reported frequently in the published literature, but in our study, the participants did not report any side effects.

Respirator type, duration of use, age groups, sample size, or different working conditions may be the reason for different results. We recommend that determining the duration of PPE use, respirator change frequency, and respirator reuse be aligned with current World Health Organization recommendations, health care administrator recommendations, and manufacturer recommendations. 4

The relatively low number of participants may be regarded as a limitation of this study, and the average age of study participants was young, which may not be generalizable to the typical health care setting. In addition, the results were based on venous blood gas tests, and arterial blood gas samples might have yielded more accurate results. Another limitation may be that we were unable to show the effects of respirator use in participants with chronic disease or with exertion during the clinical shift. A history of intermittent asthma was present in only 2 members of the study population, and no statistical comparison was possible. As another limitation the pre-4hour and post-4-hour measurements reflect values only at that immediate time and do not give an indication of shortterm excursions that may have occurred during the 4-hour period. We did not perform a respirator fit test for the participants before the study; therefore, we cannot comment on whether there was air leakage around the mask that affected our results. The N95/FFP2 respirator was fixed to the dorsum of the nose with a tape to support a mask seal to the face.

In light of evidence from the previously published literature with the findings of our study, using N95 respirators continuously for 4 hours by nurses and physicians working in nonexertional tasks in the emergency department who do not have pulmonary disease and have no contraindications for mask use is not associated with major side effects or blood gas deterioration. Our findings should be interpreted with caution and may not apply to older workers or those with characteristics markedly different from our study participants. We also think that it would be appropriate for other health care personnel working under similar conditions to use respirators for the same period of time.

Since the COVID 19 pandemic began, the use of PPE has been of the most significant importance for health care professionals' self-protection. The importance of using proper PPE cannot be underestimated. It is important to consult with the respirator manufacturer regarding the maximum number of uses they recommend for the N95/ FFP2 respirator. If no manufacturer guidance is available, data suggest limiting the number of reuses to no more than 5 total uses per device to ensure an adequate respirator performance. 17 In a survey of 27 countries overall, 17 countries (63%) provide no information on their websites about the long-term use or reuse of N95/FFP2 respirators. Some countries have proposed specific methods for decontamination of N95/FFP2 respirators, and some countries have left the decision to health care administrators. The maximum extended use time ranged from 4 hours to 40 hours. 18 World Health Organization recommends that wearing a respirator longer than 4 hours can cause discomfort and should be avoided. 4

Contrary to our initial concerns, continuous N95/FFP2 respirator use for 4 hours was not associated with any impairment in blood gas and peripheral SpO2 levels. At the same time, a statistically significant increase was observed in pH values, although these remained within physiological limits and may not be clinically significant. In light of the evidence in the published literature and the results of our study, we conclude that N95/FFP2 respirators can be used safely for 4 hours without interruption for nonexertional clinical tasks in the emergency department. More research is needed on the impact of extended PPE wear during exertional activities, such as chest compressions in cardiopulmonary resuscitation.

Patient consent statement: written consent of the participants was obtained.

Conflicts of interest: none to report.

Supplementary data related to this article can be found at https://doi.org/10.1016/j.jen.2022.03.006.

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