N95 Mask Wearing By Dentists: An Evaluation Of Cardiovascular Effects
Overview
Limited research exists on cardiovascular changes in dentists using N95 respirators or surgical mask-covered N95s during pediatric dental procedures. This crossover clinical trial involved 18 healthy dentists, exploring cardiovascular responses while treating pediatric patients with either an N95 respirator or a surgical mask-covered N95.
Throughout the trial, oxygen saturation (SpO2), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were monitored at baseline, intraoperation, and postoperation. The data underwent analysis using the generalized estimating equation.
Results revealed significant changes in mean SpO2, HR, SBP, DBP, and MAP from baseline to the end of procedures for both N95 respirators and surgical mask-covered N95s. The alterations after wearing an N95 were 3.1%, 19.3%, 11.5%, 17.7%, and 13.8%, respectively, and after wearing a surgical mask-covered N95, 3.0%, 20.2%, 5.3%, 13.9%, and 8.8%, respectively (p<.05). However, no noteworthy differences were observed between the two mask types (p>.05).
In conclusion, both N95 respirators and surgical mask-covered N95s significantly impacted the cardiovascular responses of dentists treating pediatric patients, with no discernible distinctions between the two mask varieties. These findings underscore the importance of understanding the physiological implications of mask use in dental settings, particularly when treating vulnerable patient populations.
Introduction
The global pandemic has significantly impacted healthcare, including dentistry. The virus spreads through droplets, aerosols, and contact with contaminated surfaces. Children typically experience mild symptoms or are asymptomatic, the emergence of variants like alpha, beta, gamma, delta, and omicron has altered the virus’s characteristics over time.
Dental procedures, particularly those involving aerosol generation, pose a risk of viral transmission. Occupational Safety and Health Administration (OSHA) classifies dental professionals as having a very high exposure risk to communicable disease. To mitigate this risk, the American Dental Association recommends the use of appropriate personal protective equipment (PPE), including N95 respirators, especially during aerosol-generating procedures.
Due to N95 respirator shortages, the Centers for Disease Control and Prevention suggests using an FDA-approved surgical mask over the respirator to extend its use while reducing contamination. The FDA defines surgical masks as loose-fitting barriers, while N95 respirators provide a close fit and efficient filtration.
A systematic review found no significant difference in respiratory infections between surgical masks and N95 respirators among healthcare workers, but surgical masks were reported to be less effective in filtering small particles and had more leakage. Some reports highlighted challenges associated with N95 respirator use, including communication difficulties, discomfort, shortness of breath, fatigue, dizziness, and headaches.
This study focuses on investigating and comparing cardiovascular responses among dentists treating pediatric patients while wearing either an N95 respirator or a surgical mask-covered N95. Pediatric dentists, facing unique challenges in behavioral guidance, aim to provide quality dental treatment to uncooperative children while adhering to recommended safety measures. The study addresses the critical concern of potential cardiovascular impacts associated with different masks/respirators during dental procedures.
Methods
The determination of the sample size for this study followed a formula derived from Kim et al., 2014, with a set significance level (α) of .05 and a test power (1−β) of .9, resulting in a sample size of 18 individuals per group. Ethical approval for this crossover study was obtained from the Institutional Review Board and Ethics Committee of the Faculty of Dentistry and Faculty of Pharmacy at Mahidol University (MU-DT/PY-IRB 2021/081.1509).
Conducted at the Department of Paediatric Dentistry, Mahidol University, the experiment employed NIOSH-certified 3M® surgical N95 respirators (model 1870) and FDA-approved Dura® ear loop surgical masks. Participants’ demographic data were collected post-protocol explanation, ensuring informed consent.
Participants were instructed to abstain from caffeine and alcohol for at least 2 hours before the test and maintain at least 6 hours of sleep the night prior, while wearing standardized attire and personal protective equipment (PPE).
Baseline physiological parameters, including oxygen saturation (SpO2), heart rate (HR), and blood pressure (BP) measurements (systolic blood pressure [SBP], diastolic blood pressure [DBP], and mean arterial pressure [MAP]), were recorded before mask application.
Randomization, achieved through coin toss methodology, determined the order of wearing N95 respirators or surgical mask-covered N95s during two trial sessions, separated by at least 24 hours. Positive- and negative-pressure seal checks were performed on the N95 respirators.
Monitoring, conducted using portable multiparameter patient monitors, recorded SpO2 and HR at various intervals during and after dental procedures. Blood pressure measurements were obtained at specified intervals using the Dash 4000 monitor.
Subjective symptoms related to mask use were assessed using a Likert scale, encompassing difficulty communicating, visual difficulties, palpitation, lightheadedness, dizziness, nausea, and shortness of breath.
Dental treatments were administered by the 18 participants to children requiring behavioral management, with participants allowed to communicate and behave in their customary manner during the procedures. The study design involved performing identical dental procedures with local anesthetic injections on two separate days.
Inclusion Criteria
This research involved the inclusion of eighteen healthy dentists aged 25 to 35 years old, classified as ASA Class I by the American Society of Anesthesiologists (ASA). These dentists were participants in the Pediatric Dentistry Program at the Department of Pediatric Dentistry, Mahidol University. Notably, they had no prior experience wearing N95 respirators until the onset of the pandemic. The selection of this specific demographic within the dental training program at Mahidol University emphasizes the focus on individuals with a common background and a shared lack of prior exposure to N95 respirator use before the pandemic.
Exclusion Criteria
Participants for the study were subject to exclusion based on specific criteria. The criteria for exclusion encompassed pregnancy, smoking habits, and the presence of any pre-existing medical conditions. These criteria were established to ensure that the research cohort remained homogeneous and that potential confounding factors related to pregnancy, smoking, or existing medical conditions were minimized. This meticulous approach in participant selection aims to enhance the study’s internal validity by isolating and controlling for these particular variables.
Statistical Analysis
The data collected in this study were subjected to analysis using the IBM SPSS Statistics Grad Pack 27.0 Premium. Mean values, along with standard deviations (±SD), for oxygen saturation (SpO2), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were calculated at 15-minute intervals for each paired group. The analysis employed the generalized estimating equation to assess significant differences within each group compared to baseline and between the two groups. A p-value below .05 was considered statistically significant, guiding the determination of noteworthy findings in the observed physiological parameters. This rigorous statistical approach enhances the reliability and robustness of the study’s conclusions.
Results
A cohort of eighteen healthy participants was randomly assigned to wear both types of masks while administering pediatric dental treatment.
Findings from the study depict the responses of oxygen saturation (SpO2), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) at baseline, intraoperation, and postoperation for both an N95 respirator and a surgical mask-covered N95. The study illustrates the percentage change of each physiological parameter compared to baseline.
Significant alterations in mean SpO2 and HR were observed immediately after mask application and persisted throughout the 75-minute dental procedure (p<.05). Conversely, mean SBP, DBP, and MAP began to significantly change 15 minutes into the procedure until its conclusion (p<.05). These changes correlated with the duration of N95 respirator wear. Upon removal postoperation, parameters started to recover, albeit with significant differences compared to baseline (p<.05). By 15 minutes postoperation, mean SpO2, HR, SBP, DBP, and MAP had returned to baseline with no significant differences (p>.05).
No significant differences were found in mean SpO2, HR, SBP, DBP, or MAP changes between operators wearing an N95 or surgical mask-covered N95 (p>.05). Additionally, no significant changes in subjective symptoms were noted between the two groups (p>.05). Participants reported minimal discomfort, with dizziness and nausea rated as “not at all,” and other symptoms such as lightheadedness, palpitation, difficulty communicating, and visual difficulties described as “slightly.” Only shortness of breath was categorized as “moderate.” These findings contribute valuable insights into the physiological and subjective experiences of dental operators wearing different masks during pediatric dental procedures.
Conclusion
The objective of this study was to investigate the impact of different masks on the cardiovascular responses of paediatric dentists during treatment. Results indicated that both N95 respirators and surgical mask-covered N95s significantly influenced dentists’ cardiovascular reactions compared to baseline measures. Similar findings were reported by Gaikwad et al., demonstrating reduced oxygen saturation (SpO2) with N95 use. Scarano et al. also observed decreased SpO2 and increased heart rate (HR) during oral surgery with a surgical mask-covered N95, accompanied by subjective symptoms such as shortness of breath and lightheadedness.
In contrast, Rebmann et al. found no significant changes in SpO2, HR, or blood pressure (BP) compared to baseline in both mask types. Despite the observed negative effects on cardiovascular responses, these changes were not significantly associated with clinical parameters impacted by these reactions.
The study found no observable differences between the cardiovascular effects of N95 and surgical mask-covered N95 among dentists treating young patients, consistent with Rebmann et al.’s findings. Definitions provided by the World Health Organization highlighted the purpose of respirators in reducing inhalation risks, emphasizing the necessity of a tight fit for effective filtration. N95 respirators, meeting FDA and NIOSH regulations, require individual fit testing due to their design’s dependence on a close nasal-facial seal. This tight fit may lead to increased dead space ventilation, reducing SpO2, followed by elevated HR and BP to compensate for diminished oxygen levels in the blood.
On the other hand, surgical masks, as defined by the FDA, are disposable, loose-fitting, and lack the tight fit requirement of N95s. Wearing a surgical mask over an N95 for extended use does not necessitate a tight fit, mitigating the magnification of cardiovascular responses compared to N95 wearers.
Postoperative recovery of cardiovascular parameters occurred 15 minutes after N95 removal, suggesting the clinical benefit of incorporating 15-minute breaks before each case to allow dentists’ cardiovascular responses to return to baseline and mitigate prolonged adverse effects.
While the study identified reversible cardiovascular effects in young and healthy participants, caution was advised for older individuals or those with underlying cardiovascular conditions who might be more severely impacted by masking. The study’s limitations included the absence of a control group without N95 use, reflective of the COVID-19 pandemic context, and the focus on young and healthy participants. Further research on diverse age groups and body mass index (BMI) categories, along with extended chair times, was recommended to enhance understanding of these variables’ relationships. Overall, the study concluded that both N95 respirators and surgical mask-covered N95s significantly affect paediatric dentists’ cardiovascular reactions, with no discernible differences between the two types of masks.
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