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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thirteen healthy male divers were repeatedly studied during the exposure to a moderate hyperbaric environment of 4--6, 7 and 9 ATA, in a hyperbaric chamber. The maximal duration of the exposure was 35 min, and that of decompression 90 min. As compared to the dynamics of the changes found in 14 controls, under hyperbaric conditions a significant increase in the number of static tremor, an impairment of the sensory-motor performance in O'Connor's and in the rotation test were found and also of the muscular strength and resistance to fatigue (this latter only at 9 ATA).
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PMID:The influence of moderate hyperbaric environment on the sensory-neuro-motor processes in man. 82 30

Measures of spatial orientation, associative memory, general intelligence, arithmetic ability, reaction time, and personal/social perceptions were administered to five subjects during a 31-day saturation exercise. Performance decrements were noted during 17 days of exposure to hyperbaric Hi-O2 at 18.6 ATA. Significant losses in general intellectual ability were noted, as well as trends toward significant losses in other cognitive tests. Reaction time and arithmetic errors increased significantly during the early testing sessions. Performance during a 3-day cold period was equivocal; arithmetic errors increased, but other measures improved or remained constant. Environmental stressors such as fatigue, anxiety, health problems, personal and social adjustment, and aspects of perceptual deprivation were considered to be influential in reducing performance effectiveness.
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PMID:Hana kai ii: a 17-day dry saturation dive at 18.6 ATA. VI: Cognitive performance, reaction time, and personality changes. 91 Mar 19

Five divers were tested for alterations in auditory, visual, and gustatory functioning during a 17-day saturation exposure to He-O2 at 18.6 ATA. No evidence of permanent hearing loss was disclosed. Critical flicker fusion was not affected, but peripheral visual thresholds were significantly increased during the first two weeks at 18.6 ATA; this was interpreted to be evidence of severe psychological and physiological stress. Foveal vision was unaffected across testings. Magnitude estimation techniques disclosed changes in taste sensitivity, with sweet sensitivity increasing over time and sour sensitivity declining over the course of the dive. Subjects were more sensitive to bitter stimuli at maximum pressure than at sea level, and less sensitive to salt at maximum pressure. The results indicate that appreciable alterations in sensory functioning can occur during saturation exposures, although the sense modalities were differentially affected by such environmental stressors as pressure, psycho-social stress, fatigue, and perceptual deprivation.
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PMID:Hana Kai II: a 17-day dry saturation dive at 18.6 ATA. VII: Auditory, visual, and gustatory sensations. 91 Mar 20

Two divers spent over 50 hours at 610 msw in a helium-oxygen mixture (PO2:0.38-0.52 ATA). The dive duration was 27 days, including predive stages of confinement, compression, time at maximum pressure, and decompression. The divers were asked to answer 30 questions on their feelings of mental and physical fatigue and to indicate on a nine-point scale their estimation of a general feeling of fatigue. Subjective feelings of fatigue reported in this dive suggested that the divers were in good condition. Hyperbaric arthralgia and physical complaints were reported, especially during decompression, with some postdive persistence, but they should be considered as distinct signs of feelings of fatigue. The critical flicker frequency (CFF), measured throughout the dive for the two divers, showed systematic variations and a relationship between compression and pressure. These variations were grossly parallel to EEG modifications reported in other studies and probably reveal neurophysiological troubles that were not apparent from subjective reports.
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PMID:Critical flicker frequency (CFF) and subjective fatigue during an oxyhelium saturation dive at 62 ATA. 96 26

Associations between the psychological and pulmonary effects of breathing intermittent oxygen at 2 ATA were examined among four experienced divers. A fifth diver, who served as a control, breathed only normoxic nitrogen. Psychological tests included digit span, short-term memory for easy and difficult word associations, simple and complex psychomotor performance, and reported moods. The criterion of oxygen toxicity was the total hours of intermittent oxygen exposure tolerated before developing a 10% reduction in vital capacity. Short-term memory for difficult word associations and self-reported moods of Activity, Depression, Fatigue, and Happiness were found to be significantly correlated with this criterion of oxygen toxicity. Part of the impairment found on these measures, however, was probably related to the absence of adequate sleep and rest as evidenced by the worsened performance of the control diver over the 15-h testing period. The results replicated the findings of earlier research on the psychological effects of continuous oxygen breathing under hyperbaric conditions and at 1 ATA, and may indicate that oxygen intesifies the effects of other stressors such as fatigue. In addition, the results showed that reported moods may be important indicators of impending pulmonary toxicity during intermittent oxygen exposure.
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PMID:Associations between psychological factors and pulmonary toxicity during intermittent oxygen breathing at 2 ATA. 125 11

The rationale for the present study was to test the hypothesis that increased work of breathing during experimental deep diving may lead to respiratory muscle fatigue. For this purpose, electromyograms (EMGs) of respiratory and skeletal muscles, plus electrocardiogram and electroencephalogram (EEG) derivatives, were continuously recorded in conscious cats. In each muscle group, the ratio of power in a high (H) to that in a low (L) band of EMG frequencies was computed. Direct diaphragmatic stimulation in selected animals produced a mass action potential to obtain the muscle fiber conduction velocity (MFCV). The maximal pressure was 101 ATA (1,000 msw) with a maximal duration of 72 h. Four cats breathed an He-O2 mixture and five others a ternary mixture (10% N2 in He-O2). Inspired O2 partial pressure was 350 Torr. With the He-O2 mixture, all the animals died within 2-54 h during the study at maximal depth. EEG signs of high-pressure nervous syndrome (HPNS) were present in all cats, and low-frequency (11-14 Hz) hyperbaric tremor discontinuously contaminated all EMG tracings. The H/L ratio computed from diaphragmatic and intercostal muscle EMGs increased after 12 h at 101 ATA. With the He-N2-O2 mixture, the cats survived until the end of the sojourn at 101 ATA, during which no hyperbaric tremor was detected from EMG tracings, and EEG signs of HPNS were weak or absent. From 31 ATA, the H/L ratio decreased significantly in respiratory but not in skeletal muscles; this was associated with decreased MFCV in the diaphragm after several hours at maximal depth.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Changes in respiratory muscle activity in conscious cats during experimental dives at 101 ATA. 139 67

A non-saturated mixed-gas dive to 180 meters depth was carried out at JAMSTEC, using diving simulator (hyperbaric chamber) facilities. Compression started at 10:00 h with helium and oxygen and was carried out at a rate of 12 m/min. Decompression started at 11:15 h using the Comex Helox 180 Diving Manual. Decompression to 1 ATA required 49.2 h. A survey of subjective symptoms, sleep feelings and ball-bearing tests were performed. All night electrophysiological recording of subjects' sleep was performed and polygraphic analysis of nocturnal sleep was done with visual scoring. The results were as follows: Arriving at 180 meters, the complaint rate was 39.2% and fatigue was greater. The type of fatigue that was based on the composition + ratio of symptoms was that of mental fatigue. During the decompression it was recovery. The performance in the ball-bearing test decreased about 20% at a depth of 180 meters because of tremors and disturbance of attention as well as other factors showing symptoms of high-pressure nervous syndrome. The sleep feelings were different in experienced persons and non-experienced persons. The non-experienced persons had markedly decreased REM stages and slept badly all night. Based on these results, fatigue and the performance of divers were discussed.
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PMID:[Fatigue and performance of divers during a simulated, non-saturated oxygen-helium dive to 180 meters]. 221 91

Electromyographic (EMG) recordings of the 6th to 7th intercostal space (thoracic EMG) and abdominal muscles, ventilatory pattern, and the work of breathing were studied in 4 human subjects exposed for 12 days to 46 ATA of helium-oxygen (density = 8.7 g.liter-1) then of nitrogen-helium-oxygen gas mixture (ternary mixture) (density = 11.1 g.liter-1). We found that the respiratory muscle work necessary for eupneic ventilation was multiplied by 4 at 46 ATA. During quiet breathing as well as during forced inspiratory maneuvers, the power spectrum of thoracic EMG shifted to the left in three individuals during the sojourn at maximal pressure, whichever gas mixture was inhaled. This was corroborated by the decreased ratio of EMG power in a high to that in a low band of frequencies. These alterations disappeared at the end of the decompression period, suggesting the existence of inspiratory muscle fatigue at high pressure. Hyperbaric tremor was recorded on the thoracic EMG and was maximal with He-O2 inhalation. It disappeared at the end of the period at 46 ATA (He-N2-O2).
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PMID:Electromyographic study of respiratory muscles during human diving at 46 ATA. 232 17

Thirty-four healthy human subjects were exposed to shallow air saturation for 48 h [1.77 ATA (25.5 fsw) n = 19, 1.89 ATA (29.5 fsw) n = 15] and then decompressed to 1 ATA (0 fsw) in about 2 min. Symptoms included fatigue, limb and joint pain, headache, myalgias, and pruritus. No subject of 19 was diagnosed as having decompression sickness (DCS) after the shallower exposure, but 4 of 15 were diagnosed and treated for DCS subsequent to the deeper exposure. Almost all subjects in both groups had Doppler-detectable venous gas emboli (VGE) lasting up to 12 h postdecompression. Treated subjects had a recurrence of VGE several hours after the hyperbaric oxygen treatment. Only the duration of VGE, and not the VGE score, correlated with symptoms; and only the subjects body weight and age correlated with the VGE variables. This study indicates that hyperbaric air exposures of this magnitude are not as benign as previously thought.
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PMID:Direct ascent from shallow air saturation exposures. 353

Animal studies suggest that pulmonary oxygen toxicity proceeds more slowly in diluted oxygen breathing mixtures than in pure oxygen at the same inspired partial pressure. We exposed 12 healthy subjects to air at 5 ATA (PiO2 = 1.05 ATA) in a hyperbaric chamber for 48 h, and compared the rate of development of symptoms of O2 toxicity to rates seen in previous studies using 100% O2 at 1 ATA. Symptoms consisted of chest tightness, cough, substernal discomfort, exertional dyspnea, anorexia, nausea and vomiting, headache and digital paresthesias starting at about 12 h, and continuing several days into the recovery period. Pulmonary function changes consisted of significant decrements in vital capacity, flow rates, and DLCO. Initial recovery was in a 0.50 ATA oxygen atmosphere, with the majority of subjects showing definite recovery in both symptoms and pulmonary function. Subjects showed complete recovery in about 8 d, although symptoms of fatigue and exertional dyspnea continued for a month in some cases. In contrast, none of the above changes were noted in an additional 6 subjects exposed to a 5 ATA environment with 6% oxygen (PiO2 = 0.30 ATA). No change in resting gas exchange, as indicated by alveolar-arterial oxygen gradients, was detected in either group. Comparison of these data to that for pure oxygen studies reveals no significant difference in the progression or character of pulmonary oxygen toxicity.
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PMID:Progression of and recovery from pulmonary oxygen toxicity in humans exposed to 5 ATA air. 361 41


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