Studies of masks in hospital settings.
While the focus on this site is the efficacy of masks in community settings, studies on hospitals settings have been posted in the past. Here are nine studies on masks in hospitals.
“None of the four studies found a difference in the number of post-operative infections whether you used a surgical mask or not. However, the limited numbers of studies make it unsafe to conclude whether or not surgical face masks reduce post-operative infections.”
“…In surgery, there are many aspects of current clinical practice that do not necessarily have an established evidence base. Indeed, it is permissible to bypass the evidence ladder when an intervention is so convincing that it is possible to discern its effect signal from noise by observation alone.24 In such circumstances, inter- ventions have a very clear mechanistic cause and effect relationship. Historically, it may have been thought that surgical masks fulfilled such criteria. This would explain why published literature examining surgical mask effectiveness has been lacking despite their ubi- quitous nature within the surgical profession.
What literature that is available on the subject tends to be dated with poorly explained methodology. There is also uncertainty over whether the results of such studies can be extrapolated to current surgical practice given the advent of new antiseptic techniques since they were completed. The evidence base investigating the effects of facemask usage on patient-based out- comes is, in general, more extensive than that of sur- geon-centred outcomes. Facemasks do have a clear role in maintaining the social cleanliness of surgical staff, but evidence is lacking to suggest that they confer protection from infection either to patients or to the surgeons that wear them.
Given that there is no evidence that they cause any harm either, proponents would rather err on the side of caution and encourage their continued use, stressing that there is no room for complacency when it comes to ensuring patient safety.25 This opinion is similarly echoed by the National Institute for Health and Care Excellence guidelines which assert that mask usage con- tributes towards ‘maintaining theatre discipline’.
Another unavoidable aspect of this debate is that of public perception. In the public psyche, facemasks have become so strongly associated with safe and proper surgical practice that their disposal could cause unnecessary patient distress. Indeed, the response on various medical forums following Mr Ahmed’s decision not to wear a mask during his broadcasted surgeries would reflect the prevalence of such a belief among the public.”
“…Surgical face masks worn by patients during regional anaesthesia, did not reduce the concentration of airborne bacteria over the operation field in our study. Thus they are dispensable. A higher airborne germ concentration has been detected in patients during general anaesthesia. The reasons for this finding are unknown, but it may be discussed as being a result of a higher activity and number of staff involved during general anaesthesia causing more air turbulence.”
“…A decision to eliminate masks would generate much discussion. The evidence for discontinuing the use of surgical face masks would appear to be stronger than the evidence available to support their continued use. In this climate of economic justifica- tion it would appear prudent to say that the use of surgical face masks by non-scrub operating theatre staff cannot be scientifically justified.
There is little evidence to suggest that the wearing of surgical face masks by staff in the operating theatre decreases postoperative wound infections. Published evidence indicates that postoperative wound infec- tion rates are not significantly different in unmasked versus masked theatre staff. However, there is evidence indicating a significant reduction in post- operative wound infection rates when theatre staff are unmasked.”
“…From the limited results it is unclear whether the wearing of surgical face masks by members of the surgical team has any impact on surgical wound infection rates for patients undergoing clean surgery.”
Surgical site infection rates did not increase when non‐scrubbed operating room personnel did not wear a face mask.
“…Our decision to no longer require routine surgical masks for personnel not scrubbed for surgery is a departure from common practice. But the evidence to support this practice does not exist, and studies to establish differences in infection rates with or without face masks will likely be difficult to design and implement given the small potential effect.”
“…The routine use of caps and masks does not seem to have that much beneficial impact on the occurrence of procedure-related inflammations or infections in the cardiac catheterisation laboratory.”
“…The wearing of a surgical face mask had no effect upon the overall operating room environmental contamination and probably work only to redirect the projectile effect of talking and breathing. People are the major source of environmental contamination in the operating room.”
“Although surgical mask media may be adequate to remove bacteria exhaled or expelled by health care workers, they may not be sufficient to remove the submicrometer-size aerosols containing pathogens “
“Face mask use in health care workers has not been demonstrated to provide benefit in terms of cold symptoms or getting colds. A larger study is needed to definitively establish noninferiority of no mask use.”
“Considering our findings, pulse rates of the surgeon's increase and SpO2decrease 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.”
“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.”
NLM:
“Healthcare providers may develop headaches following the use of the N95 face-mask. Shorter duration of face-mask wear may reduce the frequency and severity of these headaches.”
NLM (Cross-sectional study):
“Most healthcare workers develop de novo PPE-associated headaches or exacerbation of their pre-existing headache disorders.”
“….health care professionals and other individuals with occupational need for FFP masks should be aware of possible hazards that come with COVID-19 pandemic protection measures.”
“Following the commissioning of a new suite of operating rooms air movement studies showed a flow of air away from the operating table towards the periphery of the room. Oral microbial flora dispersed by unmasked male and female volunteers standing one metre from the table failed to contaminate exposed settle plates placed on the table. The wearing of face masks by non-scrubbed staff working in an operating room with forced ventilation seems to be unnecessary.”
“It would appear that minimum contamination can best be achieved by not wearing a mask at all but operating in silence. Whatever its relation to contamination, bacterial counts, or the dissemination of squames, there is no direct evidence that the wearing of masks reduces wound infection.”
CMAJ:
“Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.”
“…In such cases, single-use medical masks are preferable to cloth masks, for which there is no evidence of protection and which might facilitate transmission of pathogens when used repeatedly without adequate sterilization…We found no clear benefit of either medical masks or N95 respirators against pH1N1…Overall, the evidence to inform policies on mask use in HCWs is poor, with a small number of studies that is prone to reporting biases and lack of statistical power.”