Limitations
First, the data was only collected at two sites on a single study day
and a larger sample across more sites and over a longer period of time
would increase the external validity and generalisability of the study
results. Nonetheless, other investigators have reported that performance
is variably maintained up to 3 months after teaching[4, 8,13].
Second, the participants were sequentially allocated to the different
teaching methods and random allocation would have improved the internal
validity of the study. Third, the method of measuring applied pressure
relied on the study investigators reading the unblinded real-time values
on the measuring scales which may have contributed to bias in the study
results. Fourth, the airway model is not a true representation of a
patient and whilst the general anatomy and size are similar, the
different texture, resistance and lack of overlying soft tissue and
other attached structures (i.e. head and torso) limit real-life
applicability. Of note, some investigators have used cadavers instead of
airway models for assessing cricoid pressure[24]. Fifth, the height
of the table on which the cricoid model was placed may not be the same
as the height of an intubation table. Sixth, the varying experience of
the participants was not accounted for. Finally, study conditions, such
as the position of the participant when applying the force, were not
protocolised.
The results of our study confirm earlier reports that the biofeedback
method is easy to teach and is the most effective technique for teaching
the correct cricoid pressure[2,10,15–19]. Whilst we did not assess
performance over time, other investigators have reported that
performance is variably between one week and 3 months[4, 8,13]