Hypoxia symptoms in military aircrew: long-term recall vs. acute experience in training.

INTRODUCTION: It has been reported that many aircrew who experience hypoxia-related incidents are able to recognize hypoxia because of similarity to symptoms they experienced during hypoxia awareness training. This study aimed to explore the degree of similarity between symptoms reported after acute hypoxia and those remembered from previous hypoxia awareness training.
METHODS: An English-Arabic questionnaire listing 22 symptoms of hypoxia was distributed to aircrew during aviation physiology training at the beginning of the hypoxia lecture and again after hypoxia awareness training.
RESULTS: Cognitive and psychomotor impairment dominated the symptoms reported after acute hypoxia, as well as the symptoms remembered from previous hypoxia training. Aircrew reported a mean of 16 hypoxia symptoms on both surveys. During acute hypoxia, 65% of aircrew experienced the five symptoms they remembered to be dominant from previous training; 57% of aircrew remembered from previous training the symptoms that dominated their experience of acute hypoxia.
CONCLUSIONS: The level of agreement between the symptoms aircrew describe after acute hypoxia and the symptoms they remember several years later suggests that hypoxia awareness training is an effective method of allowing aircrew to recognize their personal manifestation of hypoxia (their 'hypoxia signature').