Different reactions of human nasal and Eustachian tube mucosa after hyperbaric oxygen exposure: a pilot study.

Impairment of Eustachian tube function has been observed after hyperbaric oxygen treatment as well as after diving on oxygen used as breathing gas. The aim of the present study was to evaluate the influence of hyperbaric oxygen exposure on Eustachian tube ventilatory function and airflow characteristics of the nose. Six police task force divers performing two consecutive dives within a regular training schedule on oxygen were examined. Middle ear impedance, and nasal airflow velocities before and after diving as well as on the morning after the dive day were measured. Middle ear impedance decreased overnight in comparison to pre-dive values (P = 0.027) as well as compared to the value after the first dive (P = 0.032). Rhinoflowmetry did not reveal any changes of nasal airflow velocities related to the dives. Furthermore, no association between middle ear impedance and nasal airflow velocities was found. An impairment of Eustachian tube ventilatory function was obtained after hyperbaric oxygen exposure during dives employing oxygen as breathing gas. This impairment, however, was not associated with altered airflow characteristics of divers' noses. Thus, it seems unlikely that hyperbaric oxygen exerts an effect on the nasal mucosa similar to that on the Eustachian tube mucosa.

Contamination of tap water on an ocean-going vessel.

The crew of a container vessel detected an aromatic odor of the tap water that was produced on board. As the origin of the contamination was not obvious, water was taken at different sampling sites of the water supply of the vessel. Samples were analyzed for occurrence of chemical substances by GC-MS. Thereby xylene and ethylbenzene were detected in nearly each sample. The highest xylene concentration was found in the sample from the fresh water tank. As xylene was used as solvent in the tank coating, it could be concluded that it was released by the coating. Consequently, the crew was advised to ventilate and clean the fresh water tanks.

Lung function in military oxygen divers: a longitudinal study.

It is increasingly recognized that professional diving may elicit adverse long-term effects on the lungs, but conflicting results have been reported from distinct diving cohorts. This study reports the longitudinal change in lung function in professional divers who employ closed-circuit oxygen rebreathing apparatuses. All oxygen divers who attended the German Naval Medical Institute between 1994 and 1999 for regular medicals underwent spirometry and were entered if they had at least two follow-up examinations. Forced expiratory flows and volumes at baseline and at maximum follow up were compared. There were 39 divers who presented at least 3 times during a median period of 5.8 (2.7-8) yr. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) amounted to 4.86 +/- 0.62 L and 5.89 +/- 0.67 L at baseline, and 4.83 +/- 0.64 L and 5.87 +/- 0.69 L at maximum follow up, respectively. The change over time was statistically not significant. Substantial exposure to elevated oxygen partial pressure while diving is not associated with an accelerated decline in lung function. Factors other than hyperoxia (e.g., venous gas microemboli and altered breathing gas characteristics) may account for the long-term effects that have been found in professional divers.

Mechanical impedance of the respiratory tract in divers before and after simulated deep dives.

Previous studies have inconsistently shown changes in expiratory flows and volumes as well as diffusion capacity of the lungs after single dives and several diving related occupational conditions were considered as possible underlying factors. In this study mechanical impedance of the airways was measured before and after simulated dives to non-invasively determine whether there is evidence for lung function impairment due to hyperbaric exposure. Thirty-three healthy male divers employing air self-contained underwater breathing apparatus were randomly assigned to dry and wet chamber dives in a cross-over design to 600 kPa ambient pressure (total duration 43 min, bottom time 15 min, water temperature 24 degrees C). Immediately before and after diving, oscillometric parameters-e. g. resistance and reactance of the respiratory tract-were measured at defined frequencies (5, 20 Hz). Spirometry was carried out as well (FVC, FEV(1), MEF 25-75). No significant changes between post-exposure values and baseline values were detected by respiratory impedance and spirometry. Diving in accordance to diving regulations and without excessive workload is not a source for acute obstructive lung function changes as the obtained oscillometric data suggested. Moreover this study could not confirm changes in spirometry after simulated diving exposure.

Automated external defibrillators on board merchant vessels? Preliminary report article for discussion.

OBJECTIVES: Acute heart diseases are the most frequent causes for fatalities on merchant vessels. Presently there is no sufficient therapy available to treat ventricular fibrillation. The aim of this study was to test whether common automated external defibrillators [AED] may be appropriate for the use aboard merchant vessels. METHODS: In 2005, nine seafarers were introduced to four common models of AED (HeartStartFR2+, Lifepak500, AEDplus, FREDeasy) using standard video or DVD presentations. AED handling by the subjects was tested in standardized simulated emergency scenarios. After training, they subjectively rated each AED on 24 factors involved in the introduction and handling of the device. An actual ECG was then obtained with each AED at a site located beside the ship's main engine to test under maximum vibration. The ECG data were extracted and sent as an e-mail attachment via satellite to the German Telemedical Maritime Assistance Service [TMAS] in Cuxhaven. RESULTS AND CONCLUSIONS: All subjects handled the AED correctly. The AED received a total amount of points in the range between 2125 to 2241 (of 2400 possible). The subjects preferred AED with coloured as well as light marked buttons which gave a feedback (e.g. audible tones) when they were pressed. All AED were able to register an ECG in the vibrating ambient. Due to interface problems it was only possible to extract three ECG files, and only two files (data < 300 kB) could be sent as e-mail attachment via satellite to the German TMAS. In noisy areas the AED must guide the user, e.g. by screen massages and/or pictograms. Displays should provide additional data to help assess resuscitation effectiveness. A special procedure is necessary to ensure that ships and TMAS own the same software to read the transmitted ECG files, which are not allowed to exceed a size of 300 kB.

Leukotriene-B4 concentrations in exhaled breath condensate and lung function after thirty minutes of breathing technically dried compressed air.

In previous studies it had been shown that leukotriene-B4 [LTB4] concentrations in the exhaled breath mirror the inflammatory activity of the airways if the respiratory tract has been exposed to occupational hazards. In diving the respiratory tract is exposed to cold and dry air and the nasopharynx, as the site of breathing-gas warming and humidification, is bypassed. The aim of the present study was to obtain LTB4-concentrations in the exhaled breath and spirometric data of 17 healthy subjects before and after thirty minutes of technically dried air breathing at normobar ambient pressure. The exhaled breath was collected non-invasively, via a permanently cooled expiration tube. The condensate was measured by a standard enzyme immunoassay for LTB4. Lung function values (FVC, FEV1, MEF 25, MEF 50) were simultaneously obtained by spirometry. The measured pre- and post-exposure LTB4- concentrations as well as the lung function values were in the normal range. The present data gave no evidence for any inflammatory activity in the subjects' airways after thirty minutes breathing technically dried air.