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Biomedical subjects

S Tønjum

Publications and source records attributed to S Tønjum.

11 recordsLinked to original sources
PubMed1987

Differential neuropsychological effects of diving to 350 meters.

Six divers were compressed on heliox to 350 m. Repeated neuropsychological and neurological tests were conducted during the dive. Averaged increased tremor during the compression was found. Two divers had major EEG changes, while two divers had a completely normal EEG. Memory was most impaired among the cognitive variables. At 350 m there was some normalization in the EEG, and the tremor levels returned to normal. Memory impairment, however, was sustained. Three months later nine divers performed an open sea dive to 300 m. Whereas minor fatigue effects were found for the experimental dive, examinations after the open sea dive indicated more specific cerebral after effects. An increased tremor, reduced hand grip strength and foot tapping speed, lowered autonomic reactivity, and memory problems were found. Some divers had unequivocal asymmetrical plantar responses and unilateral weak abdominal reflexes, accompanied by EEG changes with corresponding laterality. In three of the divers these signs were not present 1 month later.

Adult↗
PubMed1986

Gas bubbles in the circulation of divers after ascending excursions from 300 to 250 msw.

The occurrence of intravascular bubbles in arteries and veins has been studied using pulsed Doppler ultrasound in six subjects who performed two ascending excursions each from 300 to 250 meters of seawater (msw) during a heliox saturation dive. Following decompression, high-intensity reflections could be observed not only in the venous system but also in the arteries, most notably in the carotid artery. Intravascular bubbles were more numerous during the first ascent than during the second. The arterial bubbles most probably come from the venous side of the circulation, indicating that the pulmonary filter is not as effective as previously thought during saturation diving.

Adult↗
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↗
PubMed1984

Norwegian deep diving trials.

In 1983 NUTEC, together with two diving companies, completed two dives with 12 divers (6 in each dive) to pressures equivalent to 350 m s.w., one dive lasted for 17 d, and the other, 24 d. The purpose of the dives was to demonstrate that the diving companies were prepared for diving to 300 m depth in the North Sea. No major medical or physiological problems arose during the dives, although all divers had minor symptoms of high pressure nervous syndrome during compressions. During decompression three decompression sickness incidents occurred, which involved pain only, and all were successfully treated. All divers went through comprehensive medical physiological examinations before and after the dives. No significant changes from values measured before diving have been found in the six divers who have so far been examined after diving, except that five of them were considerably more sensitive to CO2 after the dive than before. Several problems arose in connection with the divers' breathing equipment, thermal protection and communication, which need to be improved.

Atmosphere Exposure Chambers↗
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

Heat loss and tolerance time during cold exposure in heliox atmosphere at 16 ATA.

Four different types of protective clothing and three different methods of heat conservation protection were evaluated during an exposure to 4 degrees C cold in a heliox atmosphere at 150 msw. The divers using protective systems with little insulation had to quit the test after 1-2 h due to uncontrollable shivering and an extreme feeling of cold, whereas the divers using the heavily insulated clothing were able to stay in the chamber for 8-10 h. However, even with adequate protection against convective heat loss from the skin, respiratory convective heat loss will be high unless inspired gas is heated. This can be adequately done by using a combined heat-exchanger and scrubber where the heat produced by CO2 absorption is used to warm the inspired gas.

Adult↗
PubMed1981

The effect of hyperbaric oxygenation on experimental Bacteroides fragilis infection in the rat liver.

An experimental intra-abdominal model for producing Bacteroides fragilis abscesses in the rat liver was used to evaluate the therapeutic effect of hyperbaric oxygenation (HO) at 3 ATA (atmospheres absolute). Two different experiments were performed. In the first experiment one half of the animals were inoculated with B. fragilis, and the other half were sham-operated. Whether the inoculated or sham-operated animals were given single or repeated HO treatment at 3 ATA for 90 min, the bacteriological pattern was about the same. In the second experiment all the animals were inoculated with B. fragilis; half of the animals were given HO at 3 ATA for 90 min as single or repeated treatments, and the other half acted as controls receiving no HO. Even if the HO treatment was given every day during 21 days, B. fragilis could be recovered in all inoculated animals 22 days after inoculation.

Animals↗
PubMed1979

Experimental Bacteroides fragilis abscess in the rat liver.

Liver abscess was induced in rats by injecting a culture of B. fragilis ss. fragilis (approx. 5X10(6) cells) into devascularized liver tissue. Mixed infection with B. fragilis and aerobes occurred in all animals subjected to repeated laparotomies for bacteriological sampling (4, 7, 14 and 28 days after inoculation). In animals sampled only at 8 or at 42 days after injection, B. fragilis was isolated in pure culture from the majority of animals. The size of abscesses containing B. fragilis in pure culture decreased markedly between 8 and 42 days after inoculation. In inoculated animals and in sham-operated animals with secondary infection histological examination revealed an abscess containing necrotic liver tissue and numerous granulocytes. In sham-operated animals with no bacterial growth the histological examination microscopy revealed a liver infarct with incipient organization and no accumulation of granulocytes.

Animals↗