The Science Journal of the American Association for Respiratory Care

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.

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