DISCUSSION
Our study supports our assumption that wearing facial PPE reduces staff
understanding and conventional communication in simulated ITU and
theatre settings. Despite the small sample size, results suggest that
the louder background environments such as theatre produced the most
pronounced (statistically significant) effect on speech comprehension.
The excess noise generated in such environments can be attributed to
many factors (aptly summarised in the paper by Kam et al,
199419) that range from equipment and type of
surgical/anaesthetic activity to numbers of personnel and consequent
raised voice levels. We have demonstrated that wearing PPE will
complicate communication further. In this study, speech comprehension
wearing PPE within the theatre simulated environment (70dB) was
significantly worse than wearing no PPE. Raising of voice in a theatre
simulated environment when wearing PPE caused a significant improvement
of BKB scores to a level that was not significantly different from
scores when not wearing PPE.
Despite the observed variance in SNR, BKB scores were still generally
poorer with PPE which may indicate a difficulty in understanding
un-related to volume or SNR.
Background levels of noise in our simulation were derived from
environmental recordings that correlated with prior studies where noise
levels in the operating theatre exceed World Health Organisation
recommendations20. It has been suggested that noise
masking speech often results in surgeons having to repeat themselves and
consequently, it takes longer for other members of the team to respond
or assist20. Research exists on background noise and
its impact on adherence of staff to the WHO surgical safety checklist,
but outside of calls for quiet during the ‘Time Out’, perceptions of
barriers to communication during the rest of the procedure is less well
investigated21.
We have confirmed anecdotal reports that communication difficulties due
to PPE will impact on healthcare workers. Safety of healthcare staff is
paramount and the ongoing use of PPE as the initial coivd-19 pandemic
wanes is likely to continue. Therefore we anticipate that these
communication issues will be exacerbated, particularly in operating
theatres, where anaesthetists, operating department practionners, nurses
and surgeons will wear AGP PPE for prolonged durations once some longer
procedures and elective operating recommences. Interpretation of our
findings should be in light of the fact that we simulated background
noise and the study candidates were healthcare staff without hearing
impairment who regularly work together, which may mean our results would
not be reproduced “in the field”. Clinical situations regularly
involve a variety of shift-working healthcare providers and the
additional cognitive load of actually treating patients. Nonetheless,
our simulation used validated speech testing and we are unaware of any
other studies which have assessed communication difficulties with
Covid-19 PPE to this standard.
The importance of speech understanding for achieving success on shared
objectives has been extensively researched in military and industrial
occupational settings, with need to communicate with co-workers in noisy
backgrounds regularly resulting in the removal of protective
equipment22. There are obvious and immediate
implications in theatre e.g. safety compromised, wrong instrument being
selected or inadequate delivery of the WHO checklist.
Studies have suggested that as much as 12 dB SNR is required for speech
understanding in the presence of background noise levels up to 110 dB
SPL23 but thresholds for adults have also been
recorded with ratios close to 0 dB or <0
dB24.
One impact of PPE we have not discussed is the removal of visual cues to
communication. Various studies have demonstrated that visual features
strongly affect the perception of speech17. This
contribution is most pronounced in noisy environments where the
intelligibility of audio-only speech is quickly
degraded25.
We recommend that regular reminders to speak up and acknowledge
communication difficulties at key times during ITU ward rounds and
theatre pre-operative briefs may help staff to improve communication
whilst wearing PPE. Some specialty guidelines have recommended wearing
photographs of staff members over their PPE or writing their name and
roles on the apron26. Some centres have advocated
communicating with hand signals, transparent masks or
hoods17, white-boards or even two way
radio/walkie-talkies in cellophane bags where
possible27. Others have suggested possible wireless
microphone and speaker systems incorporated into PPE28(micrashell) or even already provided PPE designs with voice
amplification solutions29 that utilise mobile phone
technology. For modern multidisciplinary teams, this may not be a
suitable solution when there needs to be multidirectional conversation
and information exchange. Solutions like CARDMEDIC (a free to use
collection of communication flashcards) have been designed to help
healthcare workers speak to patients despite PPE, but we are unaware of
any similar device specific to communication between healthcare workers
i.e. in theatre (https://www.cardmedic.com/)30.
The drawbacks in this study were principally the small sample size that
did not allow us to measure an effect size. In addition the study was
performed in one hospital site only and representative environmental
noise levels could differ across different hospital sites. We welcome
the opportunity to work with other teams across the UK and further
afield in testing, trialling and simulation, as well as supporting
qualitative work for any PPE communication solutions for future working
practices.