2004 OPEN FORUM Abstracts
Development and Implementation of the Mayo Hypoxia Awareness Training System (MHATS) for Aircrew Training
Thomas
Belda RRT, Steven Holets RRT, Curtis Buck RRT, Randy Stroetz RRT,
and Jan Stepanek MD, Mayo Clinic College of Medicine, Rochester
Minnesota
Background:
High altitude hypoxia and its effects on aircrew performance has been
a long standing concern for the aviation community. Hypoxia awareness
training involving the use of hypobaric chambers has been the gold
standard for training military aviators for decades. Following the
Payne Stewart accident in 1999, which was attributed to
incapacitation of the pilots due to hypoxia, civilian aviation began
to reinvigorate an interest in hypoxia awareness and flight
physiology training. During hypobaric chamber training pilots are
exposed to sub atmospheric pressures equivalent to what they would
encounter in the event their aircraft were to lose cabin pressure.
Common symptoms of high altitude hypoxia include dizziness, tingling
of the skin or extremities, blurred vision, decreased mental acuity,
color vision changes, and apathy. The rapid pressure changes
experienced during chamber training pose additional risks including
decompression sickness and dysbarism (pain in the ears, teeth, and
sinuses). Following chamber training pilots are restricted from
flying for 24 hours due to the hypothetically increased risk of
decompression sickness. These complications along with recent
accidents attributed to chamber training have led to increased
scrutiny of hypobaric training methods and a search for training
alternatives. In response to the safety concerns associated with
chamber based training we developed a Mayo Hypoxia Awareness Training
System (MHATS).
Methods: MHATS provides simulated high
altitude conditions by manipulating oxygen concentrations rather than
atmospheric pressure, a technique first used at our institution in
1936 by Drs Boothby and Lovelace. Pilots first undergo didactic
training in flight physiology and hypoxia. Then the pilots
experience a flight simulation during which they are exposed to a
simulated altitude of 22,500 feet (6,818 meters). Pilot exposure to
this simulated altitude is limited to 5-6 minutes to avoid complete
hypoxic incapacitation. Safety mechanisms within the simulator
prevent exposures exceeding 6.5 minutes total duration. Monitoring
of the pilots status is done by a trained operator. Sp02 and pulse
rates are measured and recorded. The pilot may cease the training if
discomfort is noted, resulting in a rapid return to normoxia. Every
simulation ends by administration of 100% oxygen. MHATS (patent
pending) incorporates integrated computer controlled components using
touch screen technology. During the simulation pilots are tasked to
perform psychomotor and problem-solving tasks while breathing hypoxic
gas mixtures. Additional components of MHATS capture and record the
pilot’s experience and physiological responses while under
simulated high altitude conditions. A detailed digital recording of
the pilots’ simulation experience allows the pilot to later
review and reinforce the recognition of his or her individual signs
and symptoms of hypoxia, hopefully resulting in better recall.
Results: Two independent aerospace safety experts have
provided evaluations of MHATS. Conclusions of these experts who are
familiar with chamber technologies and traditional methods of
training have hailed the merits of MHATS as being comparable to that
of the chamber experience, but without the associated risks inherent
to hypobaric exposure. Feedback from the first 100 civilian pilots
trained with this technology has been positive. Pilots who have had
previous chamber training favorably compare the MHATS experience to
their chamber experience. The MHATS allows the pilot to experience
and recall the subtle onset of hypoxic signs and symptoms in ways
that are not possible in the group environment of standard chamber
training.
Conclusion: The MHATS is a technologically advanced
hypoxia awareness training system providing a safe, effective,
alternative and a complementary enhancement to hypobaric chamber
training for civilian and military pilots.