Predicting motion sickness during parabolic flight.
BACKGROUND
There are large individual differences in susceptibility to motion sickness. Attempts to predict who will become motion sick have had limited success. In the present study, we examined gender differences in resting levels of salivary amylase and total protein, cardiac interbeat intervals (R-R intervals), and a sympathovagal index and evaluated their potential to correctly classify individuals into two motion sickness severity groups.


METHODS
Sixteen subjects (10 men and 6 women) flew four sets of 10 parabolas aboard NASA's KC-135 aircraft. Saliva samples for amylase and total protein were collected preflight on the day of the flight and motion sickness symptoms were recorded during each parabola. Cardiovascular parameters were collected in the supine position 1-5 days before the flight.


RESULTS
There were no significant gender differences in sickness severity or any of the other variables mentioned above. Discriminant analysis using salivary amylase, R-R intervals and the sympathovagal index produced a significant Wilks' lambda coefficient of 0.36, p=0.006. The analysis correctly classified 87% of the subjects into the none-mild sickness or the moderate-severe sickness group.


CONCLUSIONS
The linear combination of resting levels of salivary amylase, high-frequency R-R interval levels, and a sympathovagal index may be useful in predicting motion sickness severity.
Neurosciences Laboratory, NASA Johnson Space Center, Houston, TX 77058, USA. dharm@ems.jsc.nasa.gov
Deborah L
DL
Harm
Todd T
TT
Schlegel
D000328:Adult; D000681:Amylases / Q000378:metabolism*; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009041:Motion Sickness / Q000175:diagnosis* / Q000201:enzymology / Q000503:physiopathology; D010275:Parasympathetic Nervous System / Q000503:physiopathology; D012016:Reference Values; D012463:Saliva / Q000201:enzymology*; D012471:Salivary Proteins and Peptides / Q000378:metabolism; D012720:Severity of Illness Index; D013026:Space Flight
D012471:Salivary Proteins and Peptides; D000681:Amylases