Venous gas embolism after an open-water air dive and identical repetitive dive.

Decompression tables indicate that a repetitive dive to the same depth as a first dive should be shortened to obtain the same probability of occurrence of decompression sickness (pDCS). Repetition protocols are based on small numbers, a reason for re-examination. Since venous gas embolism (VGE) and pDCS are related, one would expect a higher bubble grade (BG) of VGE after the repetitive dive without reducing bottom time. BGs were determined in 28 divers after a first and an identical repetitive air dive of 40 minutes to 20 meters of sea water. Doppler BG scores were transformed to log number of bubbles/cm2 (logB) to allow numerical analysis. With a previously published model (Model2), pDCS was calculated for the first dive and for both dives together. From pDCS, theoretical logBs were estimated with a pDCS-to-logB model constructed from literature data. However, pDCS the second dive was provided using conditional probability. This was achieved in Model2 and indirectly via tissue saturations. The combination of both models shows a significant increase of logB after the second dive, whereas the measurements showed an unexpected lower logB. These differences between measurements and model expectations are significant (p-values < 0.01). A reason for this discrepancy is uncertain. The most likely speculation would be that the divers, who were relatively old, did not perform physical activity for some days before the first dive. Our data suggest that, wisely, the first dive after a period of no exercise should be performed conservatively, particularly for older divers.

The effectiveness of a health-surveillance program for caisson saturation divers in a tunnel-boring machine: a microbiological survey.

The purpose of this field study is to report and evaluate the implementation of a health surveillance program we developed to monitor the microbiological load for saturation divers, including preventive and therapeutic interventions. We extended the DMAC protocol for Saturation Diving Chamber Hygiene and added some components: ear inspections, swabs and environmental swabs every third day. The implementation was evaluated by analyzing the results of the activities. In a pre-saturation dive check we examined a total of 17 divers. Here we present the data from all seven saturation phases, collected over a period of 1.5 years. In every saturation phase we have found pathogenic bacteria or fungi in divers and in the environment, but more in some periods than in others. We did not observe any serious infection that required a diver to abort his stay in the living chamber. This health surveillance program has demonstrated the potential value of an early warning system to prevent problems. The bacterial load found in divers and in the environment was clearly visible. Prevention could be improved by more consistent implementation of the protocol. Fortunately, the infections had no serious consequences for the health of the workers or for the continuation of the work process.

Osteoradionecrosis of tympanic bone: reconstruction of outer ear canal with pedicled skin flap, combined with hyperbaric oxygen therapy, in five patients.

OBJECTIVE: To evaluate the results of one-stage surgical repair of the meatal skin defect in patients with long-lasting osteoradionecrosis of the outer ear canal, using a postauricular, inferiorly pedicled skin flap. All patients were also treated with hyperbaric oxygen both pre- and post-operatively. METHODS: A prospective study evaluating the results of a one-stage surgical procedure to repair the meatal skin defect in five patients with osteoradionecrosis of the outer ear canal. All patients were treated with hyperbaric oxygen both pre- and post-operatively. RESULTS: In four of the five patients, intact canal skin was achieved after surgery and hyperbaric oxygen therapy. One patient needed a second operation to cover a small remaining area of bare bone. In one patient, wound healing was unsatisfactory and an area of bare bone remained. CONCLUSION: In cases of osteoradionecrosis of the outer ear canal, the skin defect can be repaired with an inferiorly pedicled skin flap. Although not yet scientifically proven, the peri-operative application of hyperbaric oxygen may be of additional value to improve wound healing in areas of compromised tissue.

Evaluation of decompression tables by Doppler technique in caisson work in The Netherlands.

INTRODUCTION: Hyperbaric work was conducted for constructing an underground tramway in the Netherlands. A total of 11,647 exposures were conducted in 41,957 hours. For these working conditions specifically developed oxygen decompression tables were used. METHODS: Fifteen workers were submitted to Doppler monitoring after caisson work at a depth at 12 msw. Measurements were done according to the Canadian DCIEM protocol. For bubble grading the Kisman-Masurel 12-points ordinal scale (0-IV) was used. RESULTS: Bubbles were detected in 17 of the 38 examinations. The highest grade (III-) was found in four measurements. At rest the grading was never higher than I+. Two hours after decompression the grading was remarkably higher than after one hour. CONCLUSIONS: Bubble scores were relatively low, although the maximum grading probably is not reached within two hours after decompression. It may be concluded that the oxygen decompression tables used, were reliable under these heavy working conditions. At group level, decompression stress can be evaluated by Doppler monitoring. In order to reduce health hazard of employees, use of oxygen during decompression in caisson work should be embodied in the occupational standard.

The effect of hyperbaric oxygen therapy on quality of life in oral and oropharyngeal cancer patients treated with radiotherapy.

Radiotherapy is used in the setting of curative treatment for head and neck cancer. Xerostomia and related problems occur when major salivary glands are included in the irradiation fields. This reduces quality of life (QOL). Hyperbaric oxygen therapy (HBOT) is a well accepted treatment or prevention modality for osteoradionecrosis of the jawbones and soft-tissue necrosis. It is unknown if and to what extent HBOT influences xerostomia and xerostomia-related QOL. To address this, a prospective study was conducted. Twenty-one patients who underwent radiotherapy for an oral or oropharyngeal carcinoma completed a European Organization for Research and Treatment of Cancer QOL questionnaire before HBOT, as part of the treatment/prevention of osteoradionecrosis, and 1 and 2 years after HBOT. Swallowing-related problems significantly decreased in time, and there was a reported subjective increase in saliva quantity and an improvement in sense of taste. The results suggest that HBOT may positively influence these long-term radiotherapy sequelae.

Doppler ultrasound surveillance in deep tunneling compressed-air work with Trimix breathing: bounce dive technique compared to saturation-excursion technique.

The Western Scheldt Tunneling Project in The Netherlands provided a unique opportunity to evaluate two deep-diving techniques with Doppler ultrasound surveillance. Divers used the bounce diving techniques for repair and maintenance of the TBM. The tunnel boring machine jammed at its deepest depth. As a result the work time was not sufficient. The saturation diving technique was developed and permitted longer work time at great depth. Thirty-one divers were involved in this project. Twenty-three divers were examined using Doppler ultrasound. Data analysis addressed 52 exposures to Trimix at 4.6-4.8 bar gauge using the bounce technique and 354 exposures to Trimix at 4.0-6.9 bar gauge on saturation excursions. No decompression incidents occurred with either technique during the described phase of the project. Doppler ultrasound revealed that the bubble loads assessed in both techniques were generally low. We find out, that despite longer working hours, shorter decompression times and larger physical workloads, the saturation-excursion technique was associated with significant lower bubble grades than in the bounce technique using Doppler Ultrasound. We conclude that the saturation-excursion technique with Trimix is a good option for deep and long exposures in caisson work. The Doppler technique proved valuable, and it should be incorporated in future compressed-air work.

Health and efficiency in trimix versus air breathing in compressed air workers.

The Western Scheldt Tunneling Project in the Netherlands provided a unique opportunity to evaluate the effects of trimix usage on the health of compressed air workers and the efficiency of the project. Data analysis addressed 318 exposures to compressed air at 3.9-4.4 bar gauge and 52 exposures to trimix (25% oxygen, 25% helium, and 50% nitrogen) at 4.6-4.8 bar gauge. Results revealed three incidents of decompression sickness all of which involved the use of compressed air. During exposure to compressed air, the effects of nitrogen narcosis were manifested in operational errors and increased fatigue among the workers. When using trimix, less effort was required for breathing, and mandatory decompression times for stays of a specific duration and maximum depth were considerably shorter. We conclude that it might be rational--for both medical and operational reasons--to use breathing gases with lower nitrogen fractions (e.g., trimix) for deep-caisson work at pressures exceeding 3 bar gauge, although definitive studies are needed.

Modern methods improve hospital forecasting.

This study has shown that a sophisticated statistical technique can lead to better patient days forecasts and should lead to more accurate budgets for those hospitals using forecast budgets. Also, the modified time series decomposition method that adapts to sudden shifts in the environment can be used for not only changes in reimbursement mechanisms, but other changes, such as increased beds, as well.