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Dive into the research topics where Kevin Hofer is active.

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Featured researches published by Kevin Hofer.


Brain Research Bulletin | 2001

Coriolis-induced cutaneous blood flow increase in the forearm and calf

Bob Cheung; Kevin Hofer

Using venous occlusion plethysmography, Sunahara et al. reported that Coriolis-induced nausea was accompanied by an increase in forearm blood flow, suggesting a decrease in sympathetic activity to this vascular bed. No significant blood pressure and heart rate changes were observed. Vasodilation of the limbs theoretically impairs orthostatic tolerance, particularly if blood flow is shown to increase simultaneously in the lower limbs. This study examined the latter possibility. Seventeen subjects were exposed to the Coriolis cross-coupling effects induced by 20 RPM yaw rotation, and a simultaneous 45 degrees pitch forward head movement in the sagittal plane every 12 s. Forearm and calf skin blood flow were monitored in real-time using laser Doppler flowmetry (PeriFlux 4001). Our results indicated a significant (p < 0.001) simultaneous forearm and calf skin blood flow increase as a result of Coriolis cross-coupling across all 15 susceptible subjects. No significant changes in blood pressure and heart rate were observed. Coriolis-induced cardiovascular changes may confound previous reports on reduced G tolerance using ground-based centrifuges that invariably evoke cross-coupling effects.


Aviation, Space, and Environmental Medicine | 2011

Various anti-motion sickness drugs and core body temperature changes.

Bob Cheung; Ann Nakashima; Kevin Hofer

INTRODUCTION Blood flow changes and inactivity associated with motion sickness appear to exacerbate the rate of core temperature decrease during subsequent body cooling. We investigated the effects of various classes of anti-motion sickness drugs on core temperature changes. METHODS There were 12 healthy male and female subjects (20-35 yr old) who were given selected classes of anti-motion sickness drugs prior to vestibular Coriolis cross coupling induced by graded yaw rotation and periodic pitch-forward head movements in the sagittal plane. All subjects were then immersed in water at 18 degrees C for a maximum of 90 min or until their core temperature reached 35 degrees C. Double-blind randomized trials were administered, including a placebo, a non-immersion control with no drug, and six anti-motion sickness drugs: meclizine, dimenhydrinate, chlorpheniramine, promethazine + dexamphetamine, promethazine + caffeine, and scopolamine + dexamphetamine. A 7-d washout period was observed between trials. Core temperature and the severity of sickness were monitored throughout each trial. RESULTS A repeated measures design was performed on the severity of sickness and core temperature changes prior to motion provocation, immediately after the motion sickness end point, and throughout the period of cold-water immersion. The most effective anti-motion sickness drugs, promethazine + dexamphetamine (with a sickness score/duration of 0.65 +/- 0.17) and scopolamine + dexamphetamine (with a sickness score/duration of 0.79 +/- 0.17), significantly attenuated the decrease in core temperature. The effect of this attenuation was lower in less effective drugs. CONCLUSION Our results suggest that the two most effective anti-motion sickness drugs are also the most effective in attenuating the rate of core temperature decrease.


Journal of Vestibular Research-equilibrium & Orientation | 2002

Lack of gender difference in motion sickness induced by vestibular Coriolis cross-coupling

Bob Cheung; Kevin Hofer


Annals of Pharmacotherapy | 2003

Failure of Cetirizine and Fexofenadine to Prevent Motion Sickness

Bob Cheung; Raquel Heskin; Kevin Hofer


Journal of Vestibular Research-equilibrium & Orientation | 2001

The menstrual cycle and susceptibility to coriolis-induced sickness

Bob Cheung; Raquel Heskin; Kevin Hofer; Martin Gagnon


Aviation, Space, and Environmental Medicine | 2003

Eye tracking, point of gaze, and performance degradation during disorientation.

Bob Cheung; Kevin Hofer


Aviation, Space, and Environmental Medicine | 2005

Desensitization to strong vestibular stimuli improves tolerance to simulated aircraft motion

Bob Cheung; Kevin Hofer


Aviation, Space, and Environmental Medicine | 2000

Underwater disorientation as induced by two helicopter ditching devices

Bob Cheung; Kevin Hofer; Brooks Cj; Gibbs P


Aviation, Space, and Environmental Medicine | 2004

Physiological and behavioral responses to an exposure of pitch illusion in the simulator

Bob Cheung; Kevin Hofer; Raquel Heskin; Andrew Smith


Aviation, Space, and Environmental Medicine | 2003

Acceleration effects on pupil size with control of mental and environmental factors.

Bob Cheung; Kevin Hofer

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Bob Cheung

Defence Research and Development Canada

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Raquel Heskin

Defence Research and Development Canada

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Fethi Bouak

Defence Research and Development Canada

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Oshin Vartanian

Defence Research and Development Canada

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Ann Nakashima

Defence Research and Development Canada

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