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
A recent small survey of
supraglottic airway device manufacturers33
showed that for several recently introduced devices, the number
of patients in whom the device had been used before marketing
was less than 150 in all cases but one. The number of trials
published in peer-reviewed journals at the time of launching the
product has varied from 0-12. One device launched in 2001
remained without published data 18 mos later. Only two of seven
devices underwent comparison with the cLMA in randomised
controlled trials before marketing, and the largest of these
involved only 60 patients.
How does an anesthesiologist
start to use a new airway device? Typically, a company
representative may provide a few anesthesiologists with samples
of the new device and provide education in its use. These
anesthesiologists trial the device on a few patients and form an
opinion. Many hundreds of anesthesiologists may go through this
process, exposing perhaps thousands of patients to relatively
untested devices, before a consensus is slowly reached. The
quality of each evaluation will vary with the individual’s
practice and experience. Companies may use informal comments
from one user to encourage other users. Individual uptake may
therefore be swayed considerably by limited personal experiences
and new devices can be introduced without adequate evaluation of
clinical efficacy or safety, or conversely, the devices may be
rejected without due cause. In contrast, some companies
restrict the distribution of new devices to a few hospitals, or
to experts in the field. Some attempt to collect an assessment
of the device’s performance each time it is used. Some perform
extensive laboratory, model and clinical evaluations before
marketing. However, these practices are far from universal.
Is it still acceptable to
evaluate new devices in such an ad hoc manner?
Contrast this process with the introduction of a new drug, which
must go through laboratory and preclinical studies even before
clinical trials are considered. Three phases of clinical trials
are reviewed before release to the market. Post-marketing
surveillance is mandatory and extensive.
What regulations govern the introduction
of new medical devices, particularly airway devices? In
the UK, the use of medical devices is controlled by three
European Directives, as part of European law.36
Within these there are specific directives applicable to airway
devices. Adherence to these directives is overseen by a
statutory (regulatory) body. This statutory body has
responsibility for ensuring that medical devices do not threaten
patients’ health and safety. Statutory requirements are largely
harmonized throughout Europe, so compliance with one country’s
requirements allows distribution and marketing of a device
throughout the European Union. In addition to the statutory
body, there are other agencies that might have an interest in
monitoring the release of new anesthetic equipment. In the UK,
NICE (National Institute for Clinical Excellence) and CHAI
(Commission for Health Assessment and Improvement) might be
expected to be interested in this area. However, their specific
remits are for the evaluation of new devices, which are used as
part of a new procedure. Thus, the new supraglottic airways
fall outside this remit.
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