5. DISCUSSION
This study demonstrated that intraoral mask has more easy ventilation
rate than classic face mask according to Han Scale (123(85.4), 84(58.3);
n(%); respectively; p=0.000). Also it has higher expiratory tidal
volume (481.92±173.99, 430.85±154.87 mL; respectively; p=0.000) and
decreased air leak volume (71.50±91.17, 159.38±146.31 mL; respectively;
p=0.000) than classic face mask.
There are very few studies in the scientific literature that discuss the
effectiveness of the intraoral mask 12-15,17,22. The
comparisons in terms of the effectiveness of masks in our study are
consistent with previous cadaver studies 13,15,17,22.
According to these results it can be assumed that intraoral mask may
have some advantages in difficult mask ventilation situations caused by
air leakage due to improper seal. Society of Airway Management
recommended using a well-sealed facemask with HEPA filter in suspected
COVID-19 patients for pre-oxygenation and ventilation4. It can be assumed that decreased air leakage may
result less aerosol formation and reduce the likelihood of virus
transmission in the COVID-19 era.
Secondly our study demonstrated that practitioners’ situational anxiety
level obtained from STAI FORM TX1 were similar between intraoral and
classic face mask. Despite of these results workload measurements of the
practitioners with the NASA task load index (NASA TLX) were higher for
intraoral mask than classic facemask. This can be attributed to the
users not being familiar with the intraoral mask and their routine use
of the classic mask.
There are conflicting results in the literature regarding users’
evaluation of intraoral and classic masks. In the study of Riggle et
al.12 conducted on the airway training manikin, the
average muscle pain perceived by the practitioners for both masks was
statistically insignificant and most of the practitioners preferred the
classical mask; stated that it is easier to grasp, less fatigue and
easier to use with the classical mask. The practitioners’ evaluations in
this study 12 are consistent with the results of our
study.
However, in terms of workload, the results of our study are contradicted
by the fact that McCroy et al.13 found the workload of
the intraoral mask higher in their study. The reason for this situation
may be that practitioners may evaluate the workload of a real mask
ventilation application on the patient higher than the workload of a
mask ventilation scenario on a cadaver. In addition, in our study, each
doctor was given the opportunity to try the mask on 4 different patients
instead of a single cadaver, and this situation may have changed the
workload assessment due to encountering different patient
characteristics.
The main difference of our study from others12,13,15,17,22 is that it was performed on real
patients under operating room conditions and both masks were used in a
large series of patients. Although there are many studies investigating
the risk factors for difficult mask ventilation in the literature3,8,9, to our knowledge our study is the first study
investigating these risk factors for intraoral mask together with the
classic mask in the same patient group. Since we have a large patient
series, we were able to secondarily investigate the predictors of
difficult mask ventilation for both of the masks. We comprehensively
investigated the risks of difficult mask ventilation, including the
STOP-BANG score, which evaluates the risk of obstructive sleep apnea
syndrome along with anthropometric features. The most significant factor
among the possible risks for difficult mask ventilation was the neck
circumference for the classical mask (other significant factors were
body weight, mallampati and stop-bang score). For NuMask the most
significant risk factor was BMI and the other was mallampati score. Our
results are compatible with a number of risk factors in studies
involving a larger number of patients for classic mask3,9 and additionally determines risk factors for
intraoral mask.
However, there are many limited aspects of our study. It is an important
deficiency that the risk factors for difficult mask ventilation are
calculated according to the Han scale for patients with> I
(II = Needs oral airway, III = requiring two care providers) and do not
include real difficult mask ventilation. According to Orbany23, the aspects in which Han scale is limited; not
validated, not sensitive enough for data comparisons and research
purposes, and it is not reproducible. Evaluation is also subjective and
observer dependent. Orbany 23 emphasized that there is
no standard definition of difficult mask ventilation based on precise
and objective criteria, therefore it is difficult to compare studies and
share clinical information. He points out that due to the subjective and
practitioner-dependent nature of success in mask ventilation, making
such a precise definition is also a difficult goal. However, the risk
factors found in our study when considered causally were rational and
this limitation is common in other studies 8.