Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DECOMPRESSION SICKNESS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources
PubMed1993

Evidence for iC3 generation during cardiopulmonary bypass as the result of blood-gas interaction.

Earlier we have shown that iC3 is generated at the blood-gas interface in vitro and that the generation of this molecule is independent of complement activation and the composition of the gas. In order to investigate whether iC3 is also generated during cardiopulmonary bypass where blood comes into contact with oxygen bubbles, two bubble oxygenators were incubated at 37 degrees C with human heparinized blood. A continuous increase in the level of iC3 was shown in the oxygen-perfused bubble oxygenator (up to 100 nmol/l after 180 min) in contrast to the unbubbled control. Similarly, in plasma drawn from patients undergoing cardiopulmonary bypass using either bubble or membrane oxygenators, the levels of iC3 were shown to increase continuously during the operation. Furthermore, this form of C3 was found to be susceptible to cleavage by factor I. The formation of iC3 at the blood-gas interface in vivo could be a mechanism by which gas bubbles induce clinical manifestations associated with complement activation, e.g. during cardiopulmonary bypass, adult respiratory distress syndrome and decompression sickness.

Adult↗
PubMed1996

Detection of Embolism with Doppler Ultrasound: A Review.

Doppler detection of venous and arterial gas emboli has been recognized since 1968. The technology has been applied using 5-MHz ultrasound to study decompression sickness and monitor cardiopulmonary bypass and intracranial surgery. Since the advent of transcranial Doppler, which requires the use of lower ultrasonic carrier frequencies to penetrate the temporal bone, the detection of particulates moving in the bloodstream has been available. Using 2 MHz, microembolic signals have been detected in a variety of clinical situations, including cardiac conditions known to have high probabilities to produce embolic stroke. The basic features of a Doppler embolic signal have been clarified, and many investigators are applying the technology to determine the clinical significance of the detected emboli and their use in diagnosis and medical and surgical treatments. The basis for automatic sizing, counting, and characterizing the emboli is under development. The applications of Doppler detection of emboli will range from diagnosis and localization of embolic sources to improvement in surgical techniques and adjustments in medical treatments. (ECHOCARDIOGRAPHY, Volume 13, September 1996)

Journal Article↗
PubMed1989

Immediate neurological effects of diving to a depth of 360 metres.

Eighteen divers performed a simulated dive to a depth of 360 metres of seawater breathing a mixture of helium and oxygen. Clinical neurological examinations and neurophysiological tests were performed before and after the dives. Two divers had mild ataxic signs and changed electronystagmography after the dive, and one had impaired vibration sense in one lower extremity. Abnormal EEGs with slow waves and sharp potentials, seen primarily in the temporal regions, occurred in 2 divers. No changes were found in the magnetic resonance imaging brain scans. The divers with evidence of previous central nervous system injury, or a history of unconsciousness or previous decompression sickness seemed more likely to develop neurological signs after these deep dives. This study shows that deep diving may induce immediate neurological changes. We recommend that future deep divers have a neurological examination and 2 separate EEGs included in their medical examinations.

Adult↗
PubMed1992

Ocular fundus lesions in sports divers using safe diving practices.

Ocular fundus fluorescein angiography was performed on 26 divers, who had used safe diving practices for at least 10 years, and on seven controls. There was no significant difference in the incidence of macular abnormalities between these groups and those of a previous study. Adherence to safe diving practice confers some protection against the macular abnormalities known to occur in divers with a history of decompression sickness.

Adult↗
PubMed1992

Carbon monoxide poisoning in a diver.

Carbon monoxide poisoning is a well recognized, but uncommon hazard of sport and inshore diving, which occurs either as a result of a faulty air compressor or from air contamination by the exhaust of nearby petrol engines. The incidence of carbon monoxide poisoning may be under-reported as it may mimic decompression sickness, and respond to the same treatment i.e. hyperbaric oxygen.

Adult↗
PubMed1991

Neurological long term consequences of deep diving.

Forty commercial saturation divers, mean age 34.9 (range 24-49) years, were examined one to seven years after their last deep dive (190-500 metres of seawater). Four had by then lost their divers' licence because of neurological problems. Twenty seven (68%) had been selected by neurological examination and electroencephalography before the deep dives. The control group consisted of 100 men, mean age 34.0 (range 22-48) years. The divers reported significantly more symptoms from the nervous system. Concentration difficulties and paraesthesia in feet and hands were common. They had more abnormal neurological findings by neurological examination compatible with dysfunction in the lumbar spinal cord or roots. They also had a larger proportion of abnormal electroencephalograms than the controls. The neurological symptoms and findings were highly significantly correlated with exposure to deep diving (depth included), but even more significantly correlated to air and saturation diving and prevalence of decompression sickness. Visual evoked potentials, brainstem auditory evoked potentials, and magnetic resonance imaging of the brain did not show more abnormal findings in the divers. Four (10%) divers had had episodes of cerebral dysfunction during or after the dives; two had had seizures, one had had transitory cerebral ischaemia and one had had transitory global amnesia. It is concluded that deep diving may have a long term effect on the nervous system of the divers.

Adult↗
PubMed1998

The physiological basis of diving to depth: birds and mammals.

There is wide diversity in the animals that dive to depth and in the distribution of their body oxygen stores. A hallmark of animals diving to depth is a substantial elevation of muscle myoglobin concentration. In deep divers, more than 80% of the oxygen store is in the blood and muscles. How these oxygen stores are managed, particularly within muscle, is unclear. The aerobic endurance of four species has now been measured. These measurements provide a standard for other species in which the limits cannot be measured. Diving to depth requires several adaptations to the effects of pressure. In mammals, one adaptation is lung collapse at shallow depths, which limits absorption of nitrogen. Blood N2 levels remain below the threshold for decompression sickness. No such adaptive model is known for birds. There appear to be two diving strategies used by animals that dive to depth. Seals, for example, seldom rely on anaerobic metabolism. Birds, on the other hand, frequently rely on anaerobic metabolism to exploit prey-rich depths otherwise unavailable to them.

Animals↗
PubMed1986

Nitrogen gas exchange in the human knee.

Human decompression sickness is presumed to result from excess inert gas in the body when ambient pressure is reduced. Although the most common symptom is pain in the skeletal joints, no direct study of nitrogen exchange in this region has been undertaken. For this study, nitrogen tagged with radioactive 13N was prepared in a linear accelerator. Nine human subjects rebreathed this gas from a closed circuit for 30 min, then completed a 40- to 100-min washout period breathing room air. The isotope 13N was monitored continuously in the subject's knee during the entire period using positron detectors. After correction for isotope decay (half-life = 9.96 min), the concentration in most knees continued to rise for at least 30 min into the washout period. Various causes of this unexpected result are discussed, the most likely of which is an extensive redistribution of gas within avascular knee tissues.

Half-Life↗
PubMed1993

Quantifying the effect of intravascular perfluorocarbon on xenon elimination from canine muscle.

Intravenous infusions of perfluorocarbon (PFC) may improve decompression sickness outcome in animals by accelerating inert gas elimination from tissue, but any such effect has not been quantified experimentally. In this study we used an animal model of tissue Xe kinetics to test this hypothesis and to quantify the effect of PFC. Eight dogs were ventilated with dilute 133Xe in air for 4 h of Xe uptake. Four dogs were then given an infusion (20 ml/kg iv) of a 40% (vol/vol) perfluorodecalin-glycerol emulsion, and four control dogs were given only isotonic glycerol. All were then switched to open-circuit air breathing for 4 h of Xe elimination. During this time Xe radioactivity-time curves were recorded from two intact hind leg muscles, and the Xe mean residence times during elimination were estimated using an analysis by moments and compared by group. Tissue blood flows were measured using microspheres once during Xe uptake and twice during Xe elimination, and cardiac outputs were measured by thermodilution at 30-min intervals. In the PFC group the measured circulating PFC fraction increased the calculated Xe solubility by an average factor of 1.77 and so was expected to increase the Xe elimination rate by 77%. The observed Xe mean residence times on elimination for the PFC group averaged 33.5 min [95% confidence interval (CI) 19.5-47.6] compared with the glycerol control average of 70.1 min (95% CI 56.1-84.2), representing an increase in the rate of Xe elimination by a factor of 2.09 or 109%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Effect of combined recompression and air, oxygen, or heliox breathing on air bubbles in rat tissues.

The fate of bubbles formed in tissues during the ascent from a real or simulated air dive and subjected to therapeutic recompression has only been indirectly inferred from theoretical modeling and clinical observations. We visually followed the resolution of micro air bubbles injected into adipose tissue, spinal white matter, muscle, and tendon of anesthetized rats recompressed to and held at 284 kPa while rats breathed air, oxygen, heliox 80:20, or heliox 50:50. The rats underwent a prolonged hyperbaric air exposure before bubble injection and recompression. In all tissues, bubbles disappeared faster during breathing of oxygen or heliox mixtures than during air breathing. In some of the experiments, oxygen breathing caused a transient growth of the bubbles. In spinal white matter, heliox 50:50 or oxygen breathing resulted in significantly faster bubble resolution than did heliox 80:20 breathing. In conclusion, air bubbles in lipid and aqueous tissues shrink and disappear faster during recompression during breathing of heliox mixtures or oxygen compared with air breathing. The clinical implication of these findings might be that heliox 50:50 is the mixture of choice for the treatment of decompression sickness.

Adipose Tissue↗
PubMed2001

Invited review: gender issues related to spaceflight: a NASA perspective.

This minireview provides an overview of known and potential gender differences in physiological responses to spaceflight. The paper covers cardiovascular and exercise physiology, barophysiology and decompression sickness, renal stone risk, immunology, neurovestibular and sensorimotor function, nutrition, pharmacotherapeutics, and reproduction. Potential health and functional impacts associated with the various physiological changes during spaceflight are discussed, and areas needing additional research are highlighted. Historically, studies of physiological responses to microgravity have not been aimed at examining gender-specific differences in the astronaut population. Insufficient data exist in most of the discipline areas at this time to draw valid conclusions about gender-specific differences in astronauts, in part due to the small ratio of women to men. The only astronaut health issue for which a large enough data set exists to allow valid conclusions to be drawn about gender differences is orthostatic intolerance following shuttle missions, in which women have a significantly higher incidence of presyncope during stand tests than do men. The most common observation across disciplines is that individual differences in physiological responses within genders are usually as large as, or larger than, differences between genders. Individual characteristics usually outweigh gender differences per se.

Exercise↗
PubMed1996

Spinal cord infarction: etiology and outcome.

We reviewed 44 cases of ischemia and infarction of the spinal cord at two university hospitals. Three patients experienced transient ischemic attacks. Etiologies of completed strokes were diverse and included rupture and surgical repair of aortic aneurysms, aortic dissection, aortic rupture and thrombosis, global ischemia, anterior spinal artery embolism, repair and thrombosis of spinal arteriovenous malformations, hematomyelia, epidural hematoma, cervical osteophytosis, celiac plexus block, systemic lupus erythematosus, coagulopathy, and decompression sickness. Motor function improved in 12 patients, was substantial in only one, and occurred largely within the first 2 to 4 weeks. Favorable ambulatory outcome correlated with improving neurologic examinations and relatively preserved strength in hip abductors and knee extensors. More extensive deficits without initial improvement portended a more severe prognosis. Autonomic dysfunction, pain, paresthesia, and depression were common and impeded recovery in some patients. The mean level of deficit was at T-8 and in cases of global ischemia was at T-9, which leads us to dispute the classical view of a midthoracic watershed zone of ischemic vulnerability near T-4.

Adolescent↗
PubMed2002

Buoyancy and maximal diving depth in penguins: do they control inhaling air volume?

Using a newly developed data logger to measure acceleration, we demonstrate that free-ranging king and Adélie penguins only beat their flippers substantially during the first part of descent or when they were presumed to be chasing prey at the bottom of dives. Flipper beating stopped during the latter part of ascent: at 29+/-9 % (mean +/- S.D.) of dive depth (mean dive depth=136.8+/-145.1 m, N=425 dives) in king penguins, and at 52+/-20 % of dive depth (mean dive depth=72.9+/-70.5 m, N=664 dives) in Adélie penguins. Propulsive swim speeds of both species were approximately 2 m s(-1) during dives; however, a marked increase in speed, up to approximately 2.9 m s(-1), sometimes occurred in king penguins during the passive ascending periods. During the prolonged ascending, oblique ascent angle and slowdown near the surface may represent one way to avoid the potential risk of decompression sickness. Biomechanical calculations for data from free-ranging king and Adélie penguins indicate that the air volume of the birds (respiratory system and plumage) can provide enough buoyancy for the passive ascent. When comparing the passive ascents for shallow and deep dives, there is a positive correlation between air volume and the depth of the dive. This suggests that penguins regulate their air volume to optimize the costs and benefits of buoyancy.

Air↗
PubMed1992

Hyperbaric oxygen therapy: effect on middle ear and eustachian tube function.

Hyperbaric oxygen therapy (HBO) involves intermittent inhalation of 100% oxygen under a pressure greater than 1 atm. It is an important mode of adjuvant therapy for disease processes such as decompression sickness, osteomyelitis, carbon monoxide poisoning, and poorly healing wounds. Patients undergoing this therapy often complain of ear pain and/or fullness which can be transient or long standing. This prospective study objectively measured the changes in eustachian tube function before and after HBO treatment in 33 adult patients by the 9-step inflation-deflation test described by Bluestone. The results show 15 of the 33 patients (45%) had evidence of eustachian tube dysfunction after treatment was initiated. Of these, 15 (100%) developed the sensation of fullness, 13 (87%) developed serous otitis media, and 7 (47%) required tympanostomy tubes. The overall incidence of middle ear problems was 27 patients (82%) experiencing a sensation of fullness, 17 (52%) developing serous otitis media, and 8 (24%) requiring tympanostomy tubes. The middle ear complications reported in this study are much higher than those in previous reports in the literature. Twelve of 33 patients presented with a subjective history of eustachian tube dysfunction, and all 12 (100%) developed fullness in their ears and serous otitis media during the course of the treatment. The findings reveal that patients manifesting eustachian tube dysfunction after their first HBO treatment were at significantly greater risk toward developing symptoms of fullness and serous otitis media, often requiring tympanostomy tube placement. In addition, a history of eustachian tube dysfunction accurately predicted the development of fullness and serous otitis media.

Acoustic Impedance Tests↗
PubMed2005

A mystery featuring right-to-left shunting despite normal intracardiac pressure.

The cause of right-to-left atrial shunting despite normal intracardiac pressures and normal or near-normal pulmonary function through a patent foramen ovale has still not been completely clarified. It is probably responsible for several linked diseases, such as paradoxical embolism, platypnea-orthodeoxia syndrome, migraine with aura, transient global amnesia, and decompression sickness in sport divers. Despite modern diagnostic methods, the underlying anatomophysiologic and pathogenic mechanisms of right-to-left atrial shunting without abnormal intracardiac pressures remain a matter of debate and controversy. Holistically speaking, a return to a direct study of embryology, gross anatomy, and physiology may help us elucidate the real mechanism of this paradoxical shunting.

Heart Atria↗
PubMed2005

Microbubbles: pathophysiology and clinical implications.

Gas embolism is a known complication of various invasive procedures, and its management is well established. The consequence of gas microemboli, microbubbles, is underrecognized and usually overlooked in daily practice. We present the current data regarding the pathophysiology of microemboli and their clinical consequences. Microbubbles originate mainly in extracorporeal lines and devices, such as cardiopulmonary bypass and dialysis machines, but may be endogenous in cases of decompression sickness or mechanical heart valves. Circulating in the blood stream, microbubbles lodge in the capillary bed of various organs, mainly the lungs. The microbubble obstructs blood flow in the capillary, thus causing tissue ischemia, followed by inflammatory response and complement activation. Aggregation of platelets and clot formation occurs as well, leading to further obstruction of microcirculation and tissue damage. In this review, we present evidence of the biological and clinical detrimental effects of microbubbles as demonstrated by studies in animal models and humans, and discuss management of the microbubble problem with regard to detection, prevention, and treatment.

Blood Coagulation↗
PubMed1987

[Medical aspects of the environmental sanitation of workplaces in compressed air work in Japan].

Actual follow-up investigations were made for a period of 5 yr and 10 months since February 1980 on 55 places of caisson and shield work. The maximum bottom pressure in caisson work was 3.6 kg/cm2 (4.6 ATA) and that of shield work was 1.6 kg/cm2. The number of exposures of workers was 23,737 in caisson work and 75,244 in shield work. The items of geomedical measurements were temperature (degrees C), humidity, dust, illumination, noise, oxygen, carbonic acid gas and others. In compressed air work, it is most important to prevent decompression sickness (bends) from the view of occupational health. The incidence of bends has decreased in recent years because of strict control by regulations. Environmental hygiene, however, has seldom been discussed in this field and little geomedical control has been made on compressed air work. In view of this situation, we have, therefore, studied, observed, and measured the hygienic factors of this work during the past five years. This investigation is without doubt the first of its kind in Japan and the areas covered most of the regions where compressed air works have been made in the past. From these results, it can be concluded as follows: The working temperature was controlled, but humidity was too high (nearly 90%). Illumination was insufficient. Dust was a problem, but high humidity played an important role in decreasing the volume. The environment was noisy. It is therefore natural that environmental studies should be continued and hygienic consideration be further emphasized in compressed air work.

Atmospheric Pressure↗