Module 14
Advanced Airway Techniques
Part 2 - New Generation Supraglottic Ventilatory Devices
Desirable Features and Optimal Methods for Testing
TESTING OF NEW GENERATION AIRWAY DEVICES - con't
The statutory requirements (of ‘safety and
quality’) do include a statement to the effect that the device
should function as intended by the manufacturer. However, in
practice the statutory assessments focus on production quality
control and manufacturing standards. A mixture of self- and
external assessment is made, depending on the risk that the
device is considered to pose to patients. These assessments
must be passed to allow continued marketing of a device. Airway
devices are considered to be of low / intermediate risk and are
primarily subject to manufacturers’ self-assessment. They may
be marketed before completion of external assessment.
Performance of the desired function, efficacy and cost
effectiveness are not a focus of these assessments. Passing
statutory requirements and obtaining a CE mark (a mark to
indicate this, which allows marketing of such a device,
throughout Europe) implies that the device is ‘fit for its
intended purpose’ but assessment of performance, efficacy and
cost effectiveness appears to be left to the manufacturers,
distributors and end users in the post-marketing phase.
Once marketed, clinical trials are not
required to demonstrate efficacy or quality of performance.
Manufacturers are legally bound to report ‘serious or
potentially serious’ adverse incidents.5
The statutory body requires reporting of incidences where
‘malfunction of or deterioration in the characteristics and
performance of a device’ leads to ‘actual or potential patient
harm’.5
There is also a mechanism for voluntary reporting of incidents
by users. Whether these mechanisms lead to reliable reporting
of such incidents and whether these schemes identify devices
that are simply poorly designed or under perform is not clear.
Formal assessment of performance may come from post-marketing
cohort or comparative studies. However, these are infrequent
and are published a long time after a device has been marketed.
This creates a further problem. New
devices are often redesigned after initial release to the
market, in the light of clinical experience and customer
feedback. These new ‘improved’ devices go through a similar
process before being marketed. Second (or even third and forth)
generation devices are then marketed, often under the same name
as the original. As an example, one supraglottic airway device
was modified three times (four versions, all named identically)
in the 18 mos after it was initially marketed. Publication
delay leads to considerable confusion, as the unsuspecting
reader of journals may not realize that a newly published paper
relates to a device that has subsequently been modified. The
performance of the old version may be very different to the
current version. There have been five published studies on the
device referred to above, but none evaluated the currently
available version. While this does not make trials of the
previous version of each device completely redundant, it does
make interpretation of the limited data even more difficult.
It would be better to determine the
desirable features of a new airway device and use these to
assess the design and function of a new device before and after
it is marketed.
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