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Biomedical subjects

E Bettinghausen

Publications and source records attributed to E Bettinghausen.

13 recordsLinked to original sources
PubMed2004

Detection of dysbaric osteonecrosis in military divers using magnetic resonance imaging.

This was a controlled cross-sectional study to investigate the prevalence of dysbaric osteonecrosis (DON) in military divers. MRI examinations of the large joints and adjacent bones were performed in a cross-sectional group of 32 highly experienced military divers and 28 non-divers matched for age and anthropometric data. Additional plain radiographs and follow-up controls were performed in all persons with signs certain or suspicious of DON. In two subject groups (one of divers and one of non-divers), lesions characteristic of DON were detected. From this controlled study, it may be concluded that MRI is a highly sensitive method to detect signs of osteonecrosis. It could be shown that the prevalence of bone lesions characteristic of osteonecrosis in highly experienced military divers is not higher than in non-diving subjects of comparable age. The outcome of this comparably small study group fits to the results of previous extensive studies performed with radiographs. The detected low incidence of DON in this collective may be due to the fact that military divers follow stricter selection criteria, decompression schemes and medical surveillance than commercial divers.

Adult↗
PubMed2001

Cardiac output changes during hyperbaric hyperoxia.

OBJECTIVES: Increased ambient pressure and oxygen partial pressure (pO2) influence cardiovascular regulation during diving and caisson work. We measured the cardiac output (Q) in subjects who practiced moderate work at a usual diving depth of 30 m. METHODS: In 23 healthy male Navy divers who performed steady state bicycle exercises (100 W workload) in a hyperbaric chamber Q was measured by a CO2-rebreathing technique at normal pressure (100 kPa) and at raised ambient pressure (400 kPa), in a random order. During the rebreathing maneuver the subjects were exposed to pO2 values which theoretically may have reached a maximum value of 87 kPa (normobaric) and 388 kPa (hyperbaric). During the experiments the ambient temperature ranged between 22 and 25 degrees C. RESULTS: There was a significant decrease of the directly measured Q, heart rate (HR) and the calculated stroke volume at depth when compared with normoxic and normobaric exercise. The decrease of Q amounted to 64% of the normobaric value (8.9 l min-1 versus 13.9 l min-1). The mean HR decreased from 104.7 min-1 (100 kPa) to 94.0 min-1 (400 kPa). The calculated mean stroke volume decreased from 133 ml (100 kPa) to 96 ml (400 kPa). CONCLUSIONS: During hyperoxic hyperbaria the peripheral vascular tonus increases due to the consecutively increased arterial oxygen content. The cardiac output may correlate to the peripheral vasoconstriction and is therefore indirectly influenced by elevation of inspiratory pO2 i.e. during the rebreathing maneuver.

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PubMed2000

Neurologic outcome of controlled compressed-air diving.

The authors compared the neurologic, neuropsychological, and neuroradiologic status of military compressed-air divers without a history of neurologic decompression illness and controls. No gross differences in the neuropsychometric test results or abnormal neurologic findings were found. There was no correlation between test results, diving experience, and number and size of cerebral MRI lesions. Prevalence of cerebral lesions was not increased in divers. These results suggest that there are no long-term CNS sequelae in military divers if diving is performed under controlled conditions.

Adult↗
PubMed1999

Blood lactate changes in men during graded workloads at normal atmospheric pressure (100 kPa) and under simulated caisson conditions (400 kPa).

OBJECTIVES: A hyperbaric environment may influence lactate metabolism due to hyperoxia affecting biochemical pathways. The purpose of our study was to determine the blood lactate levels occurring at high workloads in a sample of professional divers under simulated caisson conditions. The ambient air pressure was equivalent to a diving depth of 30 m of seawater (400 kPa). METHODS: A total of 23 healthy male subjects performed graded bicycle exercise in a dry hyperbaric chamber up to a maximum of 3.5 W kg(-1) body weight at normal (100 kPa) and elevated ambient air pressure (400 kPa). The blood lactate level and the heart rate were measured. RESULTS: In comparison with control conditions, the heart rate and the peripheral blood lactate level were significantly lower at depth for all workloads. CONCLUSIONS: The differences between the normobaric and hyperbaric lactate values may be explained by an overall improvement in lactate metabolism at elevated ambient pressure, especially in the working muscles and the organs responsible for the lactate reduction, i.e., the liver. The reduced heart rate may be an effect of the improved tissue oxygen supply at depth.

Adult↗
PubMed1999

Functional and high-resolution computed tomographic studies of divers' lungs.

OBJECTIVES: Several cross-sectional studies have described a decrease in the expiratory flow rates of divers. The objective of this study was to determine whether the combined application of high-resolution computed tomography (HRCT) and lung function testing supports the reported development of small airway obstruction in divers. METHODS: Thirty-two navy divers, 27 commercial divers, and 48 referents matched for age and smoking history underwent pulmonary function testing and HRCT of the lungs supplemented by a limited number of expiratory scans. The commercial divers were older and dived longer than the navy divers. Multivariate regression analysis was used to assess the relevant correlations of age, height, pack-years of cigarette smoking, and indices of diving exposure with lung function parameters. RESULTS: The inspiratory vital capacity and forced vital capacity (FVC) were greater, while the FEV% [(100 x FEV10)FVC] and maximum expiratory flow (MEF) at 25% (MEF25) of the FVC were lower for the navy divers than for the referents. The lung volumes and expiratory airflow pattern did not differ between the commercial divers and the corresponding referents. The forced expiratory volume in 1 second (FEV10), FEV%, MEF75, and MEF25 correlated negatively with the years of diving experience. This association was independent of age, height, and pack-years of cigarette smoking. For the majority of the divers and referents the expiratory HRCT revealed minor lobular air trapping without any difference between the groups. The HRCT did not show relevant morphologic abnormalities of small or large airways. CONCLUSIONS: The data confirm that diving may affect pulmonary function. However, there is no radiologic evidence for the development of small airway disease in these 2 subgroups of divers.

Adult↗
PubMed1998

Respiratory responses to exercise in divers at 0.4 MPa ambient air pressure.

OBJECT: This study was carried out to evaluate changes in the breathing pattern of divers during exercise at an elevated ambient air pressure equivalent to a depth of 30 m of seawater. METHODS: A total of 22 healthy male subjects performed graded bicycle exercise in a dry hyperbaric chamber up to a maximum of 3.5 W kg(-1) body weight at normal (0.1 MPa) and at elevated ambient air pressure (0.4 MPa). The exercise ventilation (VE), tidal volume (VT), breathing frequency (BF), oxygen uptake (VO2), carbon dioxide elimination (VCO2), and heart rate (HR) were measured. Perceived dyspnea was assessed by Borg scale ratings. RESULTS: Comparison of respiratory indices between conditions (0.1 versus 0.4 MPa) revealed a significant reduction in VE, VT, BF, and HR during exercise at 0.4 MPa. VO2 and VCO2 did not differ significantly between conditions. Likewise, no significant difference between conditions emerged in perceived dyspnea. CONCLUSION: Ventilation is significantly impaired during heavy bicycle exercise at 0.4 MPa. This is obviously not apparent with regard to subjective perception of dyspnea.

Adult↗
PubMed1998

Memory deficits at 0.6 MPa ambient air pressure.

We investigated the effects of an elevated ambient air pressure of 0.6 MPa on verbal memory performance. Twenty-four experienced divers were compressed in a dry hyperbaric chamber to pressures equivalent to 0.5 meters of seawater (msw) (n = 12) and 50 msw (n = 12). Verbal memory was assessed by free recall and recognition of visually presented word lists. The testing procedure specified learning and testing at surface, learning at surface and testing at depth, learning and testing at depth, and learning at depth and testing at surface. Non-specific stress was assessed by measurement of salivary cortisol, heart rate, and subjective stress before, during, and after the dives. The 50-msw dive group showed a significant decrease of free recall performance when the material was learned at depth (P < 0.01). However, only postdive recall of material learned at depth remained significantly impaired (P < 0.05), whereas recognition performance was normal. For both groups no significant effects of depth on the investigated stress indices were obtained. These results are taken as evidence that inert gas narcosis may interfere with encoding and/or retrieval of verbal information, although the possibility that other stressors in the hyperbaric environment contributed to these deficits cannot be eliminated entirely.

Adult↗
PubMed1997

MR imaging of the central nervous system in diving-related decompression illness.

PURPOSE: This investigation was conducted to determine whether MR imaging showed cerebral or spinal damage in acute diving-related decompression illness, a term that includes decompression sickness (DCS) and arterial gas embolism (AGE). MATERIAL AND METHODS: A total of 16 divers with dysbaric injuries were examined after the initiation of therapeutic recompression. Their injuries comprised: neurological DCS II n = 8; AGE n = 7; combined cerebral-AGE/spinal-DCS n = 1. T1- and T2-weighted images of the brain were obtained in 2 planes. In addition, the spinal cord was imaged in 7 subjects. The imaging findings were correlated with the neurological symptoms. RESULTS: MR images of the head showed ischemic cerebrovascular lesions in 6/8 patients with AGE but showed focal hyperintensities in only 2/8 divers with DCS. Spinal cord involvement was detected in 1/7 examinations, which was the combined cerebral-AGE/spinal-DCS case. There was agreement between the locations of the documented lesions and the clinical manifestations. CONCLUSION: MR readily detects cerebral damage in AGE but yields low sensitivity in DCS. A negative MR investigation cannot rule out AGE or DCS. However, MR is useful in the examination of patients with decompression illness.

Adult↗
PubMed1997

Computed tomography of the chest in diving-related pulmonary barotrauma.

Arterial gas embolism due to barotrauma of the lungs is a severe complication in compressed air diving. Precipitating factors are often missed on plain chest radiology. This study was conducted to detect occult lung disease predisposing to the development of pulmonary barotrauma in conditions associated with a change in ambient pressure. During the past 4 years, 11 patients who have suffered pulmonary barotrauma with or without subsequent development of cerebral or spinal arterial gas embolism underwent computed tomography of the chest several days post-injury. Examinations were conducted either using the conventional technique (n = 7) or, more recently, in the spiral mode (n = 4). Chest radiographs were available in all cases. In five patients CT revealed subpleural emphysematous blebs or cysts that were not detected by conventional radiography. Follow-up studies performed in two of these cases several months post-injury showed that the cystic lesions did not resolve. We assume that the lung cysts or blebs are preexisting conditions which caused pulmonary barotrauma. Computed tomography of the chest, preferably in the spiral mode, is recommended in any case of suspected pulmonary barotrauma in order to evaluate the possibility of pre-existing pathology and to predict future fitness to dive.

Adult↗
PubMed1997

Risk factors for pulmonary barotrauma in divers.

STUDY OBJECTIVES: Pulmonary barotrauma (PBT) of ascent is a feared complication in compressed air diving. Although certain respiratory conditions are thought to increase the risk of suffering PBT and thus should preclude diving, in most cases of PBT, risk factors are described as not being present. The purpose of our study was to evaluate factors that possibly cause PBT. DESIGN: We analyzed 15 consecutive cases of PBT with respect to dive factors, clinical and radiologic features, and lung function. They were compared with 15 cases of decompression sickness without PBT, which appeared in the same period. RESULTS: Clinical features of PBT were arterial gas embolism (n=13), mediastinal emphysema (n=1), and pneumothorax (n=1). CT of the chest (performed in 12 cases) revealed subpleural emphysematous blebs in 5 cases that were not detected in preinjury and postinjury chest radiographs. A comparison of predive lung function between groups showed significantly lower midexpiratory flow rates at 50% and 25% of vital capacity in PBT patients (p<0.05 and p<0.02, respectively). CONCLUSIONS: These results indicate that divers with preexisting small lung cysts and/or end-expiratory flow limitation may be at risk of PBT.

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PubMed1996

[Diving-associated pulmonary barotrauma as a rare differential diagnosis in internal medicine-pneumologic ambulatory care].

Arterial gas embolism due to pulmonary barotrauma (PBT) is a well known fatal complication in compressed air diving. Pulmonary damage is often missed in conventional diagnostic radiology. We present two cases of PBT in recreational divers, in which pre and post accidental chest x-rays were negative but chest-CT showed peripheral bullae in the lower lung lobes preferably responsible for PBT, Chest-CT is recommended in any case of suspected PBT to evaluate the possibility of preexisting pathology in order to predict further diving fitness.

Adult↗
PubMed1995

[Quantitative computed tomography of the lung in the early diagnosis of asbestosis: initial results in asbestos-exposed navy personnel].

AIM: To evaluate the diagnostic role of respiratory gated quantitative CT of the lung with regard to the early detection of asbestos-induced lung fibrosis. MATERIAL AND METHODS: 29 navy personnel with a mean asbestos exposure of 21.3 years and exclusively low profusion stages with regard to plain film X-ray (0/1 and 1/0, ILO 1980) were examined using high resolution CT and respiratory gated quantitative CT of the lung. RESULTS: A low but significant increase of the global lung density with -816 HU (range -844 to -749 HU) was found in comparison with the age-matched reference values of -829.8 HU (range -834 to -819 HU). In individual cases the histogram analysis demonstrated a shift of the density distribution towards higher density intervals without corresponding findings in HRCT. No alterations in lung function were observed. There was no correlation between the latency period or length of exposure and density values. CONCLUSION: The respiratory gated quantitative CT of the lung may potentially develop into an accessory parameter for monitoring dust exposed personnel.

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