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At least 235 records · Page 13Linked to original sources
PubMed1982

Operator performance in the one-atmosphere diving system JIM in water at 20 degrees C and 30 degrees C.

Performance and physiology of five operators of the one-atmosphere diving system JIM were assessed when diving JIM in mild (20 degrees C) and warm (30 degrees C) water. Each operator completed a minimum of 3 dives at each water temperature; during each dive 5 walks of 18 m and 3 step maneuvers were accomplished. At the conclusion of 40-min dives in water at 30 degrees C, operator heart rate averaged 151 beats/min, system interior temperature averaged 32.6 degrees C, and the mean respiration rate of operators was 28 breaths/min. Task completion times were faster in warm water. Thermal considerations in the deployment of the JIM system are discussed in relation to these data.

Adult↗
PubMedDate not supplied

[Adaptive reactions in humans during repeated exposure to deep-water saturation immersion].

Evaluation of changes in respiration circulation and respiratory gas transport has shown that long-term influence of hyperbaria gives rise to phase changes and promotes a shift to a new level of the functional state of aquanauts. It is established that the postdecompression syndrome is characterized by the lability of main parameters of breathing and circulation, depression of gas exchange, disorders of bronchial permeability, relaxation of the cardiac pump function, decrease of physical workability against the background of inhibition of the adrenal cortex and weakening of the non-specific immunoresistance. Examination of 145 deep divers has revealed regularities of readaptation dynamics and has permitted a conclusion on an increase of unfavourable tendencies in the ventilatory pulmonary function and cardiac pump function under repeated effect of saturated diving. The normative values of external respiration are worked out as applied to divers. Some new approaches to the technology of medical providing of deep divings and correction of non-specific professional pathology of acquanauts are physiologically substantiated proceeding from tendencies of shifts in the periods between divings and diving norms.

Adaptation, Physiological↗
PubMed2002

A review of asthma and scuba diving.

An increasing number of asthmatics participate in recreational scuba diving. This activity presents unique physical and physiological challenges to the respiratory system. This review addresses the susceptibility of divers with asthma to diving accidents, acute asthmatic attacks, and long-term exacerbation of their disease. Recommendations on fitness to dive with asthma and airway hyperresponsiveness are provided.

Asthma↗
PubMed1992

Reduced sensitivity of O2 transport to allosteric effectors and temperature in loggerhead sea turtle hemoglobin: functional and spectroscopic study.

The functional and spectroscopic (EPR and absorbance) properties of the adult loggerhead sea turtle (Caretta caretta) hemoglobin have been studied with special reference to the action of allosteric effectors and temperature. Present results indicate that turtle Hb displays a very low O2 affinity and a very small sensitivity to allosteric effectors and temperature. Furthermore, the amplitude of the Bohr effect for O2 binding is strongly reduced. In parallel, EPR and absorbance spectroscopic properties of the nitrosylated derivative of turtle Hb suggest that the hemoprotein is in a low-affinity conformation, even in the absence of allosteric effectors. These findings suggest the existence of unusual molecular mechanisms modulating the basic reaction of Hb with O2, which may be linked to specific physiological needs related to the diving behavior of the turtle.

Allosteric Regulation↗
PubMedDate not supplied

Development of cardiorespiratory patterns associated with terrestrial apneas in free-ranging southern elephant seals.

Elephant seals resting on land show an irregular breathing pattern that combines periods of eupnea and apnea. In this article we describe ontogenetic changes in the breathing pattern and in the associated cardiac response in resting pups and weanlings of the southern elephant seal, Mirounga leonina. Apnea duration and the percentage of time spent in apnea were positively correlated with age: mean apnea length was greater in weanlings than in pups, with weanlings holding their breath for up to 8.7 min. Apnea length was not correlated with the duration of preceding or subsequent eupneas. The heart rate of pups and weanlings on land followed the pattern of bradycardia during apnea and tachycardia during eupnea. Young weanlings had a significantly smaller decrease in heart rate during apnea than older weanlings (28% vs. 36%). The instantaneous heart rate response to breathing changed from a variable to a regular pattern. These results suggest that the control processes that modulate the physiological cardiorespiratory changes necessary for diving start to develop on land during the first 11 wk of life.

Age Factors↗
PubMed2004

Microgravity simulation: physical and psychological workload evaluation tests in an underwater environment.

As weightlessness is not completely reproducible on Earth, usability evaluation of space systems is often simulated through tests in an aquatic environment. A Neutral Buoyancy Facility test programme was organized in a special pool to simulate Extra-Vehicular Activities on the Columbus module of the future International Space Station with the aim of assessing various aspects of crew interface design. This study was designed to evaluate workload using visibility, accessibility and operability tests. Diving workload was determined through basic physiological measurements, such as pulmonary ventilation and heart rate during underwater operations. As anxiety can influence physiological processes, and consequently also the workload evaluation determined through these parameters, we developed an evaluation methodology to investigate the anxiety level based on a specific questionnaire submitted to all subjects before and after the dives. Heart rate increased in underwater work to a value approximately 50% larger than the value obtained in the resting condition while sitting outside the pool. This increase in heart rate was accompanied by an increase in pulmonary ventilation of 200% larger than the value recorded in the rest condition while sitting outside the water. The extent of these increases was notable in all the test subjects, who varied in age and stature. Recorded values of workload, heart rate and pulmonary ventilation were evaluated on the basis of Christensen's (Arbeitsphysiol. 14 (1950) 251) and Wells' (J. Appl. Physiol. 10 (1957) 51) classifications. Through this analysis it was possible to determine that the workload, indicated by performance on our neutral buoyancy tests, corresponds to moderate physiological work. For test subjects, anxiety related to underwater performance was light. Among the causes of anxiety all the subjects indicated the lack of confidence with neutral buoyancy tests and a feeling of lack of safety, typical of aquatic environments. We can conclude that context did not produce considerable psychological effects, and consequently that the psychological load did not influence heart rate and pulmonary ventilation values that can therefore be directly related to task workload.

Adult↗