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Biomedical subjects

R Vaernes

Publications and source records attributed to R Vaernes.

14 recordsLinked to original sources
PubMed1996

Crew compatibility and interaction.

A crew of four (three males and one male) were isolated for 60 days in hyperbaric chambers at DLR, Cologne, Germany. The aim of the study was to investigate how group functioning, relations with ground control, and interaction between crew members would change during isolation. A broad array of methods was used, including analysis of communication, peer ratings, questionnaires, and a post-isolation interview. The main findings are: 1. Group functioning declined at three times, immediately before and after the start of isolation, and in weeks 2 and 5; 2. Conflicts were often focused on project management. 3. Crew members showed a marked tendency to deny team conflicts, making them vulnerable to "group think;" 4. Towards the end of isolation, social factors were given more importance than task-related factors; 5. Lasting antagonism between two of the male crew members were noted, which made one of them withdraw from interaction, while the other one--the most dominant crew member--developed an alliance with the Commander. Several findings in this study are consistent with our earlier results from the ISEMSI study. The existence of several interpersonal issues has been identified, which are also likely to occur during actual space missions. Many of the interpersonal problems could probably be prevented or reduced through behavioral and sensitivity training, composition of crews according to compatibility, and monitoring of group functioning during the flight. We suggest that future simulation studies should be directed towards gaining practical experience in how to influence interpersonal relations in a desirable way. The joint training of ground crew and chamber crew created good co-operation between the two crews, but the adjustment to management requires more experience and new training procedures. The lack of formalized rules caused serious frustrations and negative feelings in both crews towards project management. Data from management and principal investigators were not available, but we suggest that such information should be collected in future simulation studies.

Adult↗
PubMed1996

Psychological reactions during polar expeditions and isolation in hyperbaric chambers.

BACKGROUND: Psychological data from environments that are considered as analog to space was collected from 68 subjects; 18 in hyperbaric chambers, 16 in polar expeditions, and 34 on Arctic stations. The objective was to identify psychological reactions expected in different phases of spaceflights and examine personality variables associated with superior adaptation. METHOD: Helmreich Personality Characteristic Inventory was administered before the isolation. Adaptation to the environment was assessed through a questionnaire once a week. RESULTS: Crews in hyperbaric chambers indicated a steady increase in coping over the isolation. Polar expeditions members reported high aggressiveness and anxiety in the first quarter and an increase in homesickness over time. A personality characterized by strong expressiveness and instrumentality ("the right stuff") predicted superior adaptation in hyperbaric chambers. CONCLUSION: The data suggest that isolation in hyperbaric chambers and polar expeditions should be considered as models for different aspects of the space environment.

Adaptation, Psychological↗
PubMed1995

Interpersonal relations during simulated space missions.

The present article derives from two isolation studies performed for the European Space Agency (ESA) as simulations of space travels, lasting for 4 and 9 weeks. The aim was to study how interpersonal relations were affected by time, and how individual characteristics related to conflicts and tension among crewmembers. A broad battery of methods was used, including video-recording, peer-ratings and self-reports. In both studies, group-functioning declined in the middle of the isolation and towards the end of the stay. Dominance and task motivation seemed to be important characteristics for compatibility between crewmembers, and negative relations established early in the isolation remained stable over time. These findings have implications for composition, training, and support of crews for extended spaceflights.

Adult↗
PubMed1993

[Acute and chronic effects of deep diving on the nervous system].

Diving deeper than 180 metres of seawater (msw) will impose neurological symptoms in most divers. Atactic signs and abnormal EEGs were found in five of 18 divers immediately after deep diving. Neuropsychological testing before and after deep diving in 64 divers revealed a reduction in autonomic reactivity (48%), increased hand tremor (27%) and impairment of spatial memory and reduced finger coordination (8%) after the dives. These results had not improved one year later. A follow-up study of 40 divers one to seven years after their last deep dive revealed that the divers experienced more problems of concentration and paresthesia in feet and hands than the controls. Two had had seizures, one had suffered episodes of transitory cerebral ischemia and one had experienced transitory global amnesia after the deep dives. In the future, oil installations at depths below 180 msw should be installed and maintained with remote control and robot technology.

Acute Disease↗
PubMed1993

European isolation and confinement study. Water and salt turnover.

Intake and output of water were studied in six male subjects from six European countries during 28 days of isolation and confinement in order to assess whether the observed reactions can be compared with those observed during space travel. On the average, the subjects drank 17.5 ml/kg/day fluids. An additional 25 ml/kg/day was recruited from food intake and metabolism. The lowest fluid intake of 11.3 and 12.1 ml/kg/day was shown by two subjects who concurrently lost 3 to 4% of body weight. Three subjects maintained body weight, and one subject gained. A linear correlation existed between the total water output and the fluid intake by drinking. The time series of fluid intake, urine output, and sodium excretion revealed a weekly pattern for these parameters, characterized by low values on Sundays and high values on Fridays. This pattern was most apparent for sodium excretion. Low water turnover rates were seen in the first week of isolation; in the last week the values were above average. In conclusion, it can be said that with respect to the water balance, strong individual differences and time dependent variations (day to day, week to week) of the respective parameters have to be taken into account for the data analysis during such long-term studies.

Adult↗
PubMed1991

Visual evoked and brain stem auditory evoked potentials in divers.

Visual evoked potentials (VEP) were examined in 14 divers during dives to 360 metres of seawater (msw). All latencies increased significantly with depth. VEP and brain stem auditory evoked potentials (BAEP) were similarly examined in 18 divers before and after these dives. N75 was significantly increased after compared to before the dive, while there was no significant difference in the P100 and N145 latencies. BAEP I-V latency was significantly decreased after the dives. VEP and BAEP were examined in 156 divers and 99 controls. There was no significant difference in VEP. BAEP I-III interpeak latency was significantly increased for the divers, but with no significant changes in I-V and III-V latencies. VEP and BAEP were examined in 26 divers after treatment for neurological decompression sickness. There was no significant difference compared to the control group. The conclusions are that VEP and BAEP change transitorily with influence of hyperbaric pressure, but do not measure major permanent disturbances in the divers' visual and auditory pathways.

Adult↗
PubMed1990

Analysis of neurologic symptoms in deep diving: implications for selection of divers.

Eighteen professional divers (age range 24-33 yr, mean 28.3) participated in one simulated dive to 360 meters of seawater (msw) in a helium-oxygen (heliox) atmosphere with equal compression and decompression profiles. All divers were given an extensive neurologic examination before diving. Clinical neurologic symptoms observed during the dives were equilibrium disorder, sleep disturbances, fatigue, nausea, loose stools, stomach pain, tremor, mental disturbances, reduced appetite, and headache. Symptoms were scored individually by each diver. The symptoms were analyzed statistically by factor analysis, which grouped them into four factors. These symptoms are presumably related to functional disturbances in the brain stem and the cerebellum. Factor 3 symptoms (tremor, mental disturbances, reduced appetite) correlated significantly to a history of predive decompression sickness (P = 0.006) and to cerebral concussion (P = 0.023). Three divers were periodically unable to work at bottom due to equilibrium disorder, diarrhea, or nausea. One diver with mild polyneuropathy and slight cerebral atrophy as seen by computerized tomography and another diver with abnormal electroencephalography were periodically unable to work due to equilibrium disorder and nausea, respectively. We advocate that divers with signs of central or peripheral nervous system dysfunction should not be selected for deep diving.

Adult↗
PubMed1989

Effects of underwater escape training--a psychophysiological study.

The effect of underwater escape training was analysed among 78 participants at the Norwegian Underwater Technological Center (NUTEC), Bergen, in a psychophysiological study. The training caused significant physiological activation. Perceived training effect was found to be inversely related to anxiety during training. Most of the participants developed a positive response outcome expectancy and increased confidence in flying. The learning aspects were versatile and partly dependent on personality factors. A more individualized approach to training is recommended.

Adaptation, Psychological↗
PubMed1985

Central nervous dysfunction associated with deep-sea diving.

A group of 23 professional divers was investigated before and after dives to 300 and 350 metres of sea water. 12 divers were also studied during the actual dive. All divers presented neurological symptoms and signs during compression. Intention tremor, ataxia, motor weakness, sensory symptoms, vertigo, nausea and reduced memory were the most prominent features of the High Pressure Nervous Syndrome (HPNS). There were considerable individual differences. Neuropsychological and neurophysiological investigations performed after one dive showed no significant changes in any of the divers, while there was a clear-cut impairment in a group of 6 divers who had performed 2 dives 3 months apart. These changes indicate that there may be pressure-induced brain dysfunction which persists for a transient post-dive period. Loss of short-term memory is a prominent part of this dysfunction. Transitory neurological signs indicating focal cerebral dysfunction were found immediately post-dive in 4 divers, presumably reflecting the unmasking of pre-existing subclinical minimal CNS lesions.

Adult↗
PubMed1985

CNS reactions at 51 ATA on trimix and heliox and during decompression.

Two groups of divers (Group A and B) were compressed to 500 msw with trimix (n = 3) and heliox (n = 3). After 4 d at saturation depth Group A had a gas change to heliox. Both groups were followed with repeated neuropsychological and neurological tests during compression, at stable intermediate depths and at saturation depth. There were marked high pressure nervous syndrome effects during compression for both groups. Only tremor was inhibited by the nitrogen. In addition Group A was impaired due to nitrogen narcosis. During trimix and heliox saturation there was only some recovery in the EEG. Group B had a sustained high tremor during the saturation. On visuomotor and cognitive functions Group B performed up to predive level on the 3rd d at saturation while Group A was heavily impaired during the whole trimix saturation period. Although dizziness and tremor were the main symptoms in Group B, Group A reported concentration trouble, euphoria, and upset stomach during the saturation phase. Minor changes occurred in the EEG during the gas change. There was, however, a marked increase in postural tremor and recovery on cognitive tests relating to the elimination of the nitrogen. Up to the completion of the gas change no severe symptoms were reported. Six hours after the gas change, severe symptoms occurred with visual and auditory hallucinations and myoclonic jerks as the dominant characteristics. Some symptoms lasted for 12 h. During decompression there was a steady normalization in both groups.

Adult↗
PubMed1983

Central nervous system reactions during heliox and trimix dives to 51 ATA, DEEP EX 81.

UNLABELLED: Two groups of divers were compressed to 500 msw with heliox (n = 3) and trimix (n = 3). They were followed with repeated neuropsychological and neurological tests during compression, at stable intermediate depths, and at 500 msw. For the heliox group there was a marked increase in tremor and EEG slow waves and reduction in handgrip strength. For the trimix group the tremor increase did not occur, but the EEG changes were the same as in the heliox group. On motor tests only the trimix group showed impaired finger dexterity and manual dexterity. The same occurred for fine visuomotor coordination, but both groups had increased intentional tremor. On cognitive tests the same difference occurred. The trimix group was markedly impaired in reasoning and long-term memory, while only a mild impairment was found in the heliox group. Dizziness and other symptoms of high pressure nervous syndrome (HPNS) occurred in both groups. CONCLUSION: There were marked HPNS effects during compression for both groups. Only tremor was inhibited by the nitrogen. In addition, the trimix group was impaired because of nitrogen narcosis. These data indicated that 10% nitrogen did not inhibit HPNS effects during compression to 500 msw, but the considerable differences between subjects shows that susceptibility to compression must be an important area for future research.

Adult↗
PubMed1982

Endocrine response patterns and psychological correlates.

A group of young men volunteering for military service in the United States Navy were studied during an acute stress situation. The subjects (S's)(N = 62) were non-swimmers, and they all had to jump from a 5-foot platform into the deep end of a swimming pool. Before and after the exposure, blood and urine samples were taken for endocrine analysis. The Defense Mechanism Test (DMT), the Coping Operations Preference Enquiry (COPE), Joffe and Nanitch Scales for Defenses (J&N), and a Mood Questionnaire (MQ) were administered. For the endocrine reactions, postsamples, 3 factors emerged: a Cortisol factor, a Testosterone factor, and a Catecholamine factor. There was a significant correlation between the Cortisol factor and defense mechanisms, evaluated both by the DMT and the paper-and-pencil tests. Furthermore, there was a significant relationship between high anxiety, and defense mechanisms on the one hand, and physiological responses on the other.

Adaptation, Psychological↗
PubMed1982

Central nervous system reactions during heliox and trimix dives to 31 ATA.

UNLABELLED: Two groups of divers were compressed to 300 msw (984 fsw) with heliox (n = 3) and trimix (n = 3). Neuropsychological/neurological testing was performed repeatedly during the compression and on reaching 250 (820 fsw) and 300 msw. On the second day the trimix group was tested before and after a gas change to heliox. For the heliox group there was a marked increase in tremor and EEG slow waves, and reduction of alpha band and in hand-grip strength. For the trimix group visuomotor coordination was impaired. In the cognitive performance tests the heliox group was most impaired at 250 msw, whereas the trimix group was most impaired at 300 msw. Before the gas change to heliox the trimix group showed impaired performance in some tests. After the gas change, performance returned to predive levels, except for perceptual speed. There was an increase in tremor immediately after the gas change. CONCLUSION: There was a marked HPNS effect during compression on heliox. This effect was not observed in the trimix group, but this group was mildly intoxicated on reaching saturation depth. The tests indicated slight narcotic effects also after 26 h, but this disappeared after the change in heliox.

Adult↗