Table 8-1. In-flight Medical events for U.S. Astronauts during the Space Shuttle Program (STS-1 through STS-89, April 1981 to January 1998) Medical Event or System by ICD9* Category Number Percent of Total Space adaptation syndrome 788 42.2 Nervous system and sense organs 318 17.0 Digestive system 163 8.7 Skin and subcutaneous tissue 151 8.1 Injuries or trauma 141 7.6 Musculoskeletal system and connective tissue 132 7.1 Respiratory system 83 4.4 Behavioral signs and symptoms 34 1.8 Infectious diseases 26 1.4 Genitourinary system 23 1.2 Circulatory system 6 0.3 Endocrine, nutritional, metabolic, and immunity disorders 2 0.1 *International Classification of Diseases, 9th Ed.