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PubMed1995

Variations in the presentation of altitude-induced chokes.

Altitude-induced decompression sickness (DCS) remains a potential risk for individuals involved in flying or altitude chamber activities. The pulmonary form of DCS, commonly referred to as chokes, although uncommon, represents the most serious manifestation of the disease. This study reports the Davis Hyperbaric Laboratory experience with altitude-induced chokes from 1 January 1966 to 31 July 1994. Age, gender, type and extent of altitude exposure, time of symptom development, type of initial symptoms, and response to treatment were reviewed for each chokes patient. There were 15 cases of chokes; all were treated with compression therapy with complete resolution. Only 2 of the 15 individuals presented with the classic triad of substernal chest pain, dyspnea, and cough. Substernal chest pain was universally present, and usually occurred very early in the course of the disease. The other classic triad symptoms were frequently absent. The etiology, pathophysiology, and treatment of chokes are discussed.

Adolescent↗
PubMed1998

Hyperbaric oxygen therapy in the pediatric patient: the experience of the Israel Naval Medical Institute.

UNLABELLED: The pediatric patient is to be found in hyperbaric facilities throughout the world, receiving hyperbaric oxygen (HBO) therapy for both life-threatening and chronic diseases. OBJECTIVE: To review the experience accumulated at the Israel Naval Medical Institute in the treatment of pediatric patients. DESIGN: A retrospective analysis and review of all records of patients younger than age 18 years. RESULTS: Between 1980 and 1997, 139 pediatric patients age 2 months to 18 years (mean, 7.7 years) received HBO treatment at the Israel Naval Medical Institute. Of the children, 111 (79%) suffered from acute carbon monoxide (CO) poisoning; 13 (9.2%) were treated after crush injury, traumatic ischemia, or compartment syndrome; 4 (2.8%) had clostridial myonecrosis; 1 (0.7%) had necrotizing fasciitis; 5 (3.6%) had refractory osteomyelitis; 2 (1.4%) had suffered massive air embolism; 2 (1.4%) had purpura fulminans; and 1 (0.7%) suffered from decompression sickness. Outcome, judged by neurologic sequelae, mortality, and extent of soft tissue loss and limb amputation, was favorable in 129 patients (93%). Two patients (1.4%) died, 1 as a result of CO poisoning and the other, gas gangrene; 2 of the patients in the CO group (1.4%) remained with neurologic sequelae, and 6 patients in the acute traumatic ischemia group (4.3%) underwent limb amputation. CONCLUSIONS: We had a favorable experience with 129 of a total 139 pediatric patients treated at our facility for the indications listed. A basic knowledge of HBO therapy is needed to refer the pediatric patient for treatment when indicated. The needs of the pediatric patient, especially the critically ill, require specific skills and equipment inside the hyperbaric chamber. Close collaboration between the pediatrician and the hyperbaric medicine physician is essential to ensure adequate care for infants and children.

Adolescent↗
PubMedDate not supplied

[Effect of decompression on the compliment system].

Decompression effects on the complement system were studied in healthy male volunteers who made 39 "ascents" to 7000-9000 m and 13 "descents" to 30 m. Hemolytic activity of the complement system components was determined in the blood serum taken from the cubital vein of the subjects immediately before and after decompression. The results of this study showed that in the absence symptoms of decompression sickness (DCS) and doppler-detected gas bubbles (GB) the subjects reduced activities of C1 and C4. In the event of altitude joint pains the activity of the complement system components was significantly unchanged. In subjects with circulating GB the complement status was more markedly altered following simulated descents rather than ascents pointing to an alternative activation of the system. Subject with the skin DCS had a two-fold reduction of the complement system activity by the alternative mechanism and a reduction of C5 activity whereas there were no changes in the activities of C1, C2, C3, C4, CH50. It is concluded that alternative activation of the complement system may be involved in the genesis of those DCS forms whose emergence relates to gaseous embolism of veins and pulmonary capillaries.

Adult↗
PubMed1986

Caisson disease of bone.

Caisson disease of bone, which may affect compressed air workers and divers, is characterized by regions of bone and marrow necrosis that may lead to secondary osteoarthrosis of the hip and shoulder joints. A review of the pathologic, radiologic, and clinical aspects demonstrated uncertainties in the exact etiology. Early diagnosis is often not possible because of the delayed appearance of radiologic abnormalities. Research into these two aspects of this condition was carried out by the Medical Research Council Decompression Sickness Research Team in Newcastle upon Tyne over a ten-year period (1972 to 1982). Because no suitable animal model exists for the study of this condition, bone and marrow necrosis was produced by embolism of bone blood vessels with glass microspheres. With this model, it was shown that the presence of bone and marrow necrosis could be detected by bone scintigraphy using 99mTc-MDP and by measuring changes in serum ferritin concentration at a much earlier stage than was possible by radiography. However, only the former method has proved useful in clinical practice. Investigations into the etiology of caisson disease of bone have shown evidence for an increase in marrow fat cell size resulting from hyperoxia. This phenomenon may play a role in the production and localization of gas bubble emboli, which are thought to be the cause of the bone and marrow necrosis.

Animals↗
PubMed1999

Open water scuba diving accidents at Leicester: five years' experience.

OBJECTIVES: The aim of this study was to determine the incidence, type, outcome, and possible risk factors of diving accidents in each year of a five year period presenting from one dive centre to a large teaching hospital accident and emergency (A&E) department. METHODS: All patients included in this study presented to the A&E department at a local teaching hospital in close proximity to the largest inland diving centre in the UK. Our main outcome measures were: presenting symptoms, administration of recompression treatment, mortality, and postmortem examination report where applicable. RESULTS: Overall, 25 patients experienced a serious open water diving accident at the centre between 1992 and 1996 inclusive. The percentage of survivors (n = 18) with symptoms of decompression sickness receiving recompression treatment was 52%. All surviving patients received medical treatment for at least 24 hours before discharge. The median depth of diving accidents was 24 metres (m) (range 7-36 m). During the study period, 1992-96, the number of accidents increased from one to 10 and the incidence of diving accidents increased from four per 100,000 to 15.4 per 100,000. Over the same time period the number of deaths increased threefold. CONCLUSIONS: The aetiology of the increase in the incidence of accidents is multifactorial. Important risk factors were thought to be: rapid ascent (in 48% of patients), cold water, poor visibility, the number of dives per diver, and the experience of the diver. It is concluded that there needs to be an increased awareness of the management of diving injuries in an A&E department in close proximity to an inland diving centre.

Accidents↗
PubMed1996

A voxel-by-voxel multivariate analysis of cerebral perfusion defects in divers with 'bends'.

Past analysis of dysbaric-induced cerebral perfusion defects, demonstrated by 99Tcm-hexamethylpropylene amine oxime (99Tcm-HMPAO) single photon emission tomography in divers using quantitative and/or univariate techniques, has resulted i considerable controversy regarding the significance of these lesions compared to those seen in control subjects, correlations with clinical findings and the role of 99Tcm-HMPAO as a prognostic indicator in decompression sickness. We tried to address these problems by using a multivariate approach to a voxel-by-voxel analysis, involving the use of principal components, to determine ranges of normality in 50 reference controls. In subsequent images, abnormality was defined as 10 spatially connected voxels at an appropriate significance level of three standard deviations. The images of 50 divers with clinically diagnosed 'bends' were compared with those of a further 40 normal population controls with no previous history of loss of consciousness, head injury or dysbarism. The results showed that 19 of 50 divers with 'bends' and 3 of 40 population controls had significant perfusion defects, representing a significant difference between divers with dysbarism and population controls at the level P < 0.002. It is concluded that dysbarism causes significant cerebral cortical perfusion defects in affected divers both in 'silent' and symptomatic (clinically correlated) areas.

Adolescent↗
PubMed1996

Medical aspects of sport diving.

Medical issues in sport diving include illnesses that are caused by diving, and medical disorders that compromise safety. Cerebral air embolism and decompression sickness of the brain and spinal cord can result from diving. Sport divers may manifest a spectrum of symptoms from air embolism, which can range from unconsciousness to minimal symptoms, which include fatigue, personality change, poor concentration, irritability, and changes in vision. The physician must search for these minor symptoms in divers who are suspected of pulmonary barotrauma. Medical disorders of concern in diving include diseases of the lungs, the heart, the brain, and the endocrine system, particularly diabetes. Other factors involved in diving safety are exercise capacity and training. Clinical practice standards usually prohibit diving by individuals who have a seizure disorder that requires continuous medication. In the United States, we will not approve diving for individuals who have insulin-dependent diabetes or severe asthma. Some divers can return to diving after myocardial infarction or bypass surgery if they demonstrate good exercise tolerance and no ischemia on a graded exercise test, which simulates the physical activity needed for safe diving.

Asthma↗
PubMed1989

[Principles of acute management of the severe diving accident].

The basics of the acute management of severe diving accidents are outlined by means of 25 patients (20 patients presented with decompression sickness, 5 suffered from a barotrauma of the lungs with consecutive air embolism) treated at our facilities. Contrary to widespread notion, disturbed vital functions have to be treated by intensive care measures, prior to the definite recompression therapy. These are: (1) Treatment of generalized or localized tissue hypoxia secondary to bubble-generation; (2) puncture of a (valvular-) pneumothorax after a pulmonary barotrauma; (3) haemodynamic stabilization when cardiac or spinal shock is present; (4) improvement of the rheological situation. When vital functions are unstable or endangered, these patients must not be transported in a monoplace chamber. This type of chamber does not leave any access to the patient in case of a deteriorating status. Since the severe diving accident mostly turns out to be a problem of intensive care medicine in close combination with the recompression therapy, the continuous integration of the recompression protocol with a comprehensive intensive care therapy is considered crucial.

Adult↗
PubMed2004

[Diving accidents. Emergency treatment of serious diving accidents].

Decompression injuries are potentially life-threatening incidents mainly due to a rapid decline in ambient pressure. Decompression illness (DCI) results from the presence of gas bubbles in the blood and tissue. DCI may be classified as decompression sickness (DCS) generated from the liberation of gas bubbles following an oversaturation of tissues with inert gas and arterial gas embolism (AGE) mainly due to pulmonary barotrauma. People working under hyperbaric pressure, e.g. in a caisson for general construction under water, and scuba divers are exposed to certain risks. Diving accidents can be fatal and are often characterized by organ dysfunction, especially neurological deficits. They have become comparatively rare among professional divers and workers. However, since recreational scuba diving is gaining more and more popularity there is an increasing likelihood of severe diving accidents. Thus, emergency staff working close to areas with a high scuba diving activity, e.g. lakes or rivers, may be called more frequently to a scuba diving accident. The correct and professional emergency treatment on site, especially the immediate and continuous administration of normobaric oxygen, is decisive for the outcome of the accident victim. The definitive treatment includes rapid recompression with hyperbaric oxygen. The value of adjunctive medication, however, remains controversial.

Barotrauma↗
PubMed2002

Physiological incidents during 39 years of hypobaric chamber training in Japan.

BACKGROUND: Hypobaric chamber training for military aircrew is very important for flight safety. Since we began hypobaric training in our laboratory in 1960, some trainees have suffered physiological incidents. This study will characterize the physiological incidents during hypobaric chamber training at the Japan Air Self-Defense Force (JASDF). METHODS: All available training records from 1960-1998 were reviewed and the frequency of physiological incidents counted and analyzed. RESULTS: There were 29,677 trainees and 58,454 exposures. Overall frequency of physiological incidents was 6.3%. Physiological incidents included ear pain, paranasal sinus pain, abdominal pain, hypoxia, hyperventilation, joint pain, and toothache. Decompression sickness (DCS-I, simple joint pain only) was rare. In cases of DCS-I, joint pain was easily relieved with controlled descent. During the last three decades, overall prevalence of physiological incidents has gradually increased from 5.3 to approximately 6.1% before 1991, to 6.8-9.9% after 1991. However, prevalence rate showed no change through out the period when ear pain was factored out. The increase in prevalence was entirely due to an increased frequency of ear pain: 3.6 to approximately 4.6% before 1991, and 5.4 to approximately 7.2% after 1991. CONCLUSIONS: DCS has not been a problem in the JASDF hypobaric chamber training experience. The majority of physiological incidents during hypobaric chamber training in JASDF have been ear pain, a minor but frequent obstacle to hypobaric training. The exact cause of the observed increase in frequency of Eustachian tube dysfunction currently remains unclear.

Adult↗
PubMed2003

[Central nervous system involvement in patients with decompression illness].

Dysbarism or decompression illness (DCI), a general term applied to all pathological changes secondary to altered environmental pressure, has two forms decompression sickness (DCS) and arterial gas embolism (AGE) after pulmonary barotrauma. Cerebral and spinal disorders have been symptomatically categorized as AGE and DCS, respectively. Magnetic resonance images (MRIs) of divers with DCI showed multiple cerebral infarction in the terminal and border zones of the brain arteries. In addition, there were no differences between MRI findings for compressed air and breath-hold divers. Although the pathogenesis of the brain is not well understood, we propose that arterialized bubbles passing through the lungs and heart involved the brain. From the mechanisms of bubble formation, however, this disorder has been classified as DCS. We propose that there is a difference between clinical and mechanical diagnoses in the criteria of brain DCI. In contrast to brain injury, the spinal cord is involved only in compressed air divers, and is caused by disturbed venous circulation due to bubbles in the epidural space. The best approach to prevent diving accidents is to make known the problems for professional and amateur divers.

Central Nervous System↗
PubMed1992

Menstrual history in altitude chamber trainees.

Previous studies have determined a higher rate of altitude-induced decompression sickness (DCS) in women than in men. Women are reportedly at higher risk for developing DCS during menses. A study of menstrual history in women completing altitude chamber training without developing DCS has never been accomplished. The purpose of this study was to collect and analyze menstrual history in these women. Thirteen U.S. Air Force Aerospace Physiology Units participated in a USAF-approved survey for 1 year. After completing altitude chamber flights, data on age, day of menstrual cycle (DMC), birth control pill use (BCP), and mean durations of menstrual cycle and menses were collected. There were 508 responses analyzed. There was no differences between mean duration of menstrual cycle and menses in the Yes (Y) and No (N) BCP groups. Y and N BCP groups were equally distributed across the menstrual cycle. Women completing altitude chamber training without developing DCS appear to be evenly distributed across their menstrual cycle, with use of BCPs not affecting their susceptibility to DCS.

Adolescent↗
PubMedDate not supplied

Direct ascent from air and N2-O2 saturation dives in humans: DCS risk and evidence of a threshold.

To estimate the risk of decompression sickness (DCS) for direct ascents from depth to the sea surface for personnel who are saturated with hyperbaric nitrogen, we analyzed 586 experimental air or nitrogen-based saturation dives. No DCS occurred on shallow saturation dives between 12.0 and 20.5 feet of seawater, gauge (fswg) but incidence of DCS rose abruptly when depth was deeper than 20.5 fswg, reaching 27% at 30 fswg. This is evidence of a threshold for clinical DCS. A model based on a Hill function that provides for a threshold predicts the observations better than a model having no threshold provision; the no-threshold model overestimates risk shallower than 20.5 fswg and underestimates risk between 20.5 and 30 fswg. For situations such as submarine rescues, we recommend our threshold model when the exposure pressure is 33 fswg or less. We also discuss deeper dives where there are no human data; extrapolations can be quite different for models that provide for a threshold than for models that do not.

Air↗
PubMed1991

Maximum likelihood analysis of air and HeO2 dives.

The method of maximum likelihood analysis was applied to data consisting of 1,949 man-dives, of which 1,041 were on air and 908 were on HeO2 mixtures. These dives represented a wide range of bottom time and depth combinations, and had an overall incidence of decompression sickness (DCS) of 4.64%. Several models, based on single exponential gas uptake in either one or two compartments, were tested for predicting the incidence of DCS. The criterion for defining the risk of DCS was based on the concept of potential gas volume (i.e., the volume of a bubble that could form and be in equilibrium with the remaining gas dissolved in solution). This criterion takes into account the solubilities of the gases in solution, but can be adjusted to account only for the partial pressures of the gases. The best model for the prediction of DCS was found for two compartments where the kinetics (time constants) and not the gas solubilities of nitrogen and helium were distinguished from each other. Results using the best prediction model with the present data suggests the following: 1) most of the risk of DCS occurs after surfacing; 2) most of the risk occurs in the "slow" compartment (approximately 420 min time constant); and 3) nitrogen contributes about twice as much as helium to the risk of DCS for HeO2 dives.

Air↗
PubMed1989

[Conception of a decompression table].

After a given time at bottom, different tissues become saturated to different extents with nitrogen. In diving back to the surface a hydrostatic decompression occurs first, followed by the desaturation process some time later. It is during this time interval that all important events are taking place, namely: either a monophasic desaturation, whereby inert nitrogen gas is given off at the alveolar capillary interface. or a biphasic desaturation takes place, giving rise to gas bubbles in the blood-stream as well as in the tissues. We may then encounter pathologies which are benign incidents or, worse, lead to decompression sickness grade II. Since Paul Bert dedicated his thoughts in 1878 to this problem, numerous authors tried to explain this time delay, for trying to suppress it would be entirely unrealistic. Unfortunately, mathematical reasoning has too often overshadowed physiological thinking in these matters. We also stuck to Haldane's concept of 1908, in incorporating Workman's improvements of 1965. This method is based on two main principles: 1. all calculations were done with several "tissues" in mind. Their anatomical boundaries are of no importance as, only their desaturation half-times are relevant. 2. a natural limit is given by the critical saturation-coefficient (CS). It expresses the ratio between the partial pressure of the dissolved gas and the reduction of hydrostatic pressure during ascent (given as pressure gradient). Through experience we were able to put up tables which were more and more safe, in examining foremost the CS ratio and the desaturation times of certain tissues. Several examples are given, the values of which are statistically highly significant, as they incorporate the results of more than 60,000 air dives.

Decompression↗
PubMed1981

[A Lance-Adams syndrome of a diver (author's transl)].

A 39 years old man with severe action myoclonus and epileptic seizure was reported. He had been in good health and worked as an occupational diver until August 16, 1966, when he had to dive into the sea bottom about 35 m deep without diving equipment. After finishing his work, he fell into unconsciousness and drowned. Sometime later, he was rescued and treated as decompression sickness. When he became alert, severe action myoclonus and epileptic seizure appeared. 8 years later, he was admitted to our hospital for rehabilitation. The danger of diving without equipment was indicated, because in sea bottom alveolar oxygen pressure (Pao2) is about 450 mmHg and alveolar air pressure 4.5 atmospheric pressure. In this condition patient could hold his breath longer time than in sea surface. When he finished his work and floated with muscle relaxing, however, his blood supply to the brain decreased. It was thought, therefore, that he fell into unconsciousness and drowned. In somatosensory evoked potentials (SEP) by median nerve stimulation, giat patterns were recognized but there were differences between SEP of myoclonus epilepsy and that of this patient. P50 and N70-80 were giant in him, suggesting that he had a brain stem disturbance. Since the inhibition system of fast conducted fiber did not work well in this state, the component of slow conducted fiber was magnified. Action myoclonus may be due to the disturbance of inhibition system in the brain stem.

Adult↗
PubMed2001

Acute psychosis associated with diving.

There are only a few reported cases of psychiatric disorders presenting a s decompression sickness (DCS). Previous reports indicate that DCS can result in personality change, depression, Munchausen's syndrome, and pseudo stroke. We report two cases of acute psychoses that occurred following diving as suspected DCS and were treated with hyperbaric oxygen, which did not improve the psychotic features. One patient had symptoms of DCS including myalgias, weakness, and fatigue; however the symptoms were inconsistent. The symptom onset and nitrogen loading from his dive profiles made the diagnosis of DCS unlikely. The second patient exhibited mild joint pain, fatigue, and psychosis that was temporally associated with diving but no other symptoms of DCS. Following a detailed medical evaluation we determined that these two patients did not have DCS or arterial gas embolism (AGE). Although it is highly unlikely that a pure psychotic episode will arise as a result of DCS, physicians caring for divers with symptoms of DCS or AGE and acute psychosis may consider a trial of recompression therapy while completing the medical evaluation. Divers with acute psychosis without signs and symptoms and benign dive profiles are unlikely to have DCS or AGE.

Acute Disease↗
PubMed1996

Relationship of the time course of venous gas bubbles to altitude decompression illness.

The correlation is low between the occurrence of gas bubbles in the pulmonary artery, called venous gas emboli (VGE), and subsequent decompression illness (DCI). The correlation improves when a "grade" of VGE is considered; a zero to four categorical classification based on the intensity and duration of the VGE signal from a Doppler bubble detector. Additional insight about DCI might come from an analysis of the time course of the occurrence of VGE. Using the NASA Hypobaric Decompression Sickness Databank, we compared the time course of the VGE outcome between 322 subjects who exercised and 133 Doppler technicians who did not exercise to evaluate the role of physical activity on the VGE outcome and incidence of DCI. We also compared 61 subjects with VGE and DCI with 110 subjects with VGE but without DCI to identify unique characteristics about the time course of the VGE outcome to try to discriminate between DCI and no-DCI cases. The VGE outcome as a function of time showed a characteristic short lag, rapid response, and gradual recovery phase that was related to physical activity at altitude and the presence or absence of DCI. The average time for DCI symptoms in a limb occurred just before the time of the highest fraction of VGE in the pulmonary artery. It is likely, but not certain, that an individual will report a DCI symptom if VGE are detected early in the altitude exposure, the intensity or grade of VGE rapidly increases from a limb region, and the intensity or grade of VGE remains high.

Adult↗