Title:  Promethazine as a Motion Sickness Treatment : Impact on Human Performance and Mood States
Authors:  P.S. Cowings, W.B. Toscano, C. DeRoshia, N.E. Miller
Reference:  Aviation, Space, and Environmental Medicine. 71(10):1013-32

Purpose:
Intramuscular (i.m.) injections of promethazine in 25 mg or 50 mg dosages are commonly used to treat space motion sickness in astronauts. The present study examined the effects of i.m. injections of promethazine on performance, mood states, and motion sickness in humans.

Methods:
Twelve men, mean age 36 ± 3.1, participated in one training day and three treatment conditions: a 25 mg injection of promethazine, a 50mg injection of promethazine, and a placebo injection of sterile saline. Each condition, scheduled at 7 day intervals, required an 8–10 hr day in which subjects were tested on 12 performance tasks, and were given a rotating chair motion sickness test. On the training day subjects were trained on each task to establish stability and proficiency. Treatment conditions were counterbalanced and a double-blind procedure was used to administer the medication or placebo.

Results:
Statistically significant decrements in performance were observed for both dosages of promethazine as compared to the placebo. Performance decrements were associated with mean blood alcohol dose equivalency levels of 0.085% for 25 mg and 0.137% for 50 mg doses. Mood scale results showed significant changes in individual subjective experiences with maximum deterioration in the arousal state and fatigue level. Only the 25 mg dosage significantly increased motion sickness tolerance when compared to the placebo.

Conclusions:
These data suggest that effective doses of promethazine currently used to counteract motion sickness in astronauts may significantly impair task components of their operational performance.



Title:  Cerebrovascular Responses During Lower Body Negative Pressure-Induced Presyncope
Authors:  Kana Kuriyama1, M.S., Toshiaki Ueno, M.D., Ph.D., Richard E Ballard, M.S., Patricia S Cowings, Ph.D., William B Toscano, Ph.D., Donald E Watenpaugh, Ph.D.
Reference:  Aviation, Space, and Environmental Medicine. 71(10):1033-1038 Manuscript #79027

Background:
Reduced orthostatic tolerance is commonly observed after space flight, occasionally causing presyncopal symptoms which may be due to low cerebral blood flow (CBF). It has been suggested that CBF decreases in early stages of exposure to orthostatic stress. The purpose of this study was to investigate cerebrovascular responses during presyncope induced by lower body negative pressure (LBNP).

Hypothesis:
Although CBF decreases during LBNP exposure, blood pressure (BP) or heart rate (HR) contributes more to induce presyncopal conditions.

Methods:
Eight healthy male volunteers were exposed to LBNP in steps of 10 mmHg every 3 min until presyncopal symptoms were detected. Electrocardiogram (ECG) was monitored continuously and arterial BP was measured by arterial tonometry. CBF velocity at the middle cerebral artery was measured by transcranial Doppler sonography (TCD). Cerebral tissue oxygenation was detected using near-infrared spectroscopy (NIRS). We focused our investigation on the data obtained during the final 2 min before the presyncopal endpoint.
Results:

BP gradually decreased from 2 min to 10 sec before the endpoint, and fell more rapidly during the final 10 sec. HR did not change significantly during presyncope. CBF velocity did not change significantly, while cerebral tissue oxygenation decreased prior to the presyncopal endpoint in concert with BP. Our results suggest that CBF is maintained in the middle cerebral artery during presyncope, while BP decreases rapidly.

Conclusions:
Cerebrovascular hemodynamics are relatively well maintained while arterial hypotension occurs just prior to syncope.



Title:  Motion Sickness in the Command and Control Vehicle (C2V): Space technology applied on Earth
Authors:  COWINGS, PS, TOSCANO, WB, DEROSHIA, C., TAUSON, R.

Background:
The purpose of this project was to assess motion sickness and performance of soldiers within an enclosed armored vehicle equipped with four computers, the U.S. Army’s Command and Control Vehicle (C2V), using technology developed by NASA.

Methods:
Sixteen men and eight women participated for 15 days. Performance subtests (DELTA), physiological data, mood and symptom scales were collected during classroom and field test conditions. Operational significance of performance degradation was graded by calculation of blood alcohol level equivalencies (BAL%). Three different vehicle seating configurations were tested: oblique, (3 seats at 20-degree angles from the direction of travel); perpendicular, (3 seats at 90 degree angles); and 4-forward, (all seats facing forward). Conditions for field tests were: an initial park; four moves )i.e., travel over a mixed terrian); and four short-halts following movement. All subjects rode in all seats of all vehicles.

Results:
Motion sickness symptoms were reported by all subjects, the most frequent being drowsiness (60-70% of subjects), which was unrelated to sleep quality or quantity. There were no significant differences found between vehicles or seats during field tests, however, all metrics were negatively affected when vehicles moving (p<0.003). Eight subjects showed a BAL% of >0.08 (the legal limit), and 19 subjects showed a BAL% of >0.025. Physiological data paralleled performance and were directly related to individual differences in motion sickness susceptibility.

Conclusions:
Seating configuration or vehicle was not a factor in any parameter measured. Movement in an enclosed vehicle while attending to visual displays was the principal cause of poor performance, mood, and health, a condition that was not mitigated by intermittent short-halts. The use of converging indicators provides more definitive information about the environmental impact on human functional state than any one indicator.



Title:  Control of Autonomic Responses During Long-Duration Spaceflight: Two case studies.
Authors:  COWINGS, PS, TOSCANO, WB, TAYLOR B, KORNILOVA, LP, KOSLOVSKAYA, IB, SAGALOVICH, SV, PONOMARENKO, AV, DEROSHIA C, MILLER, NE

Background:
The objective of this research was to study individual characteristics of adaptation to long duration spaceflight and possibilities of their correction using autonomic conditioning. Research on Autogenic- Feedback training Exercise (AFTE), a physiological conditioning method, has shown that it is an effective treatment for motion sickness, hypotension and improving pilot performance.

Methods:
Two male cosmonauts with previous flight experience participated in this study. Each subject was taught to alternating increase and decrease their physiological response levels during 6 hours of preflight AFTE. Skill at autonomic control was graded by the mean differences in responses between arousal and relaxation trials. Flight data, recorded on 8 mission days included: 8- hours of physiological monitoring, three 15- min AFTE practice sessions, diagnostic and mood scales and performance tests. Treatment effectiveness for post-flight orthostatic tolerance was evaluated 7-days after landing.

Results:
Preflight date of subject A during his final training session were: heart rate (18 bpm), mean arterial pressure (25 mmHg), and cardiac output (8.5 liters/min). His control of autonomic responses during the flight maintained. Following 208 –days in space this subject exhibited improved post-flight orthostatic intolerance compared to his previous 125 day flight, with heart rate 22% higher, a %0% increase in arterial tone and a 13% increase in blood pressure compared to preflight baseline tests. Preflight AFTE results of subject B were: heart rate (10bpm), mean arterial pressure (16 mmHg), cardiac output (3.5 liters/min). This subject participated for 6 days during flight and demonstrated less control than subject A. During the post-flight orthostatic tolerance test this subject was presyncopal within 14 minutes; similar to the post-flight results of his previous 75-day mission.

Conclusions:
AFTE may be a valuable countermeasure for multiple spaceflight related biomedical and performance problems. Additional data from space and ground-based operational tests are needed to validate its effectiveness.



Title:  Effects of US Army Command and Control Vehicle (C2V) Operational Environment Upon Human Performance
Authors:  C.W. DeRoshia*, P.S. Cowings*, and W.B. Toscano*.

Purpose:
This study was designed to assess cognitive and neuromotor performance in personnel during field exercises in the in the U.S. Army Command and Control Vehicle (C2V). This vehicle contains four computer workstations where crew members are expected to perform command decisions in the field during combat conditions.

Methods:
Eight active duty U.S. Army male soldiers participated in this at the Yuma Proving Ground, Arizona (YPG). Performance was assessed using seven subtests in the DELTA performance battery. After subjects were given eight training batteries in a classroom, performance in the field was conducted before and after exposure to four different field course conditions (paved road, gravel, hills and level cross-country (LXC). Motion sickness susceptibility was assessed using the Pensacola Diagnostic Rating Scale.

Results:
Composite performance (mean of subtest z-scores) was degraded between baseline and post-gravel and post-road (-4.0 to -14.1%, P<0.05) but not cross country courses. Pattern comparison performance deteriorated between baseline and road and LXC courses (-13.0 to -14.1%, P<0.02). Four subjects reported 4- 7 or more motion sickness symptoms while the other four reported 0-1 symptoms; however, no significant relationship was found between symptom levels and field performance. Subjects averaged 5.5 hours sleep prior to the field exercises.

Conclusions:
The C2V vehicle environment simulates a space analog environment in that crew members are subjected to confinement, vibration, noise, heavy workloads, and induction of motion sickness symptoms. While performance deterioration during vehicle movement can result from impairment in visual perception and manual control skills induced by vehicle vibration and movement, performance deterioration during the stationary phases of the field exercises likely resulted from the persistent effects of exposure to vehicle vibration, noise, and drowsiness induced by sopite syndrome, along with the cumulative effects of prior night sleep loss and workload fatigue during the field exercises.

This research was funded by an Interagency Agreement between the Bradley Fighting Vehicle System Program Manager and NASA Ames Research Center, Space Life Sciences Division.