Oropharyngeal airways are simple devices placed in the mouth that help to maintain an open
oral airway in anesthetized or otherwise unconscious or semi-conscious patients and also help
to facilitate assisted ventilation with a bag and mask. The current standard of care, the
Guedel airway, was originally designed by Dr. Arthur Guedel in 1933 and has remained
essentially unchanged since its inception. It is a narrow, curved plastic tube which slides
over the tongue to lie in the back of the throat. While this device has withstood the test of
time, proving to be largely safe and effective, it is known to have several drawbacks: 1) it
is not held securely in place in the mouth which allows it to become easily mal-positioned or
expelled, 2) it often triggers a gag reflex in even minimally conscious patients limiting its
utility in emergency and prehospital settings, 3) there are case reports of serious
complication and injury as a result of the poor fit and retention of the Guedel airway
including aspiration and injury to the tongue, posterior pharynx, and teeth, and 4) the
Guedel airway's narrow and rigid construction make it unsuitable for patients who may clench
their teeth, such as in patients who are seizing.
The purpose of this study is to obtain preliminary data to help determine the utility of the
ManMaxAirway (MMA) for ventilation and that will aid in future study designs for the device.
The MMA is a novel oral airway that is similar in size and shape to an athletic mouth guard,
and which fits between and is held in place by the teeth (or gums of the edentulous patient).
The external portion of the airway contains a flange in the front which remains anterior to
the teeth, allowing for ventilation in a similar fashion to the Guedel airway. It also has a
central lumen that divides posterior to the flange into two lateral passages, such that air
passes through the U-shaped device to the posterior-lateral aspect of the tongue behind the
back teeth. Unlike the Guedel device, it makes little contact with the tongue and does not
protrude into the posterior pharynx. Instead, the device will - in theory - force the
mandible to rest slightly anterior to the maxilla: this slight mandible-maxilla displacement
(similar to that achieved via the jaw thrust technique) will theoretically allow for a better
opening of the airway without requiring direct depression of the tongue. We hypothesize that
the ManMaxAirway will maintain a viable airway and allow for adequate ventilation of patients
while demonstrating the following advantages over the Guedel airway: 1) improved tolerability
and ease of insertion with decreased gag reflex stimulation in conscious patients 2) ability
to act as a bite block in patients actively seizing or likely to seize.
Our proposed study will include two major aims in assessing the utility of the MMA. Our first
aim will be to assess the mechanical effect of the device on the oropharyngeal anatomy. We
will obtain MRI images of several healthy volunteers, with and without the MMA in place, in
order to observe any displacement of the mandible relative to the maxilla, and any changes in
positioning of the tongue. We will also assess the physical performance characteristics of
the MMA vs. Guedel in terms of flow resistance in the simulation laboratory. Our second aim
will be to determine whether there is any difference in tolerability between the Man Max
Airway and the Guedel airway. To address the second aim we propose a crossover study using
conscious, healthy volunteers, in which subjects will be asked to place each device in their
mouth, one after the other. We will document the elapsed time and the number of breaths that
subjects are able to take with each device in place (up to one minute), and will obtain
ratings of device discomfort from each subject using a visual analog scale. We will also
measure resistance to forced oscillatory airflow in a subset of subjects, with and without
the airway in place, at a second visit.