Effectiveness of hyperbaric chamber ventilation.

INTRODUCTION: Hyperbaric chamber ventilation (HCV) refers to the intentional introduction of fresh gas, whether air, oxygen, or heliox, into a pressurised hyperbaric chamber in order to remove stale or otherwise compromised gas. The minimum required continuous HCV rate is usually determined by mathematical models derived from the contaminant mass balance within a well-stirred compartment. Non-uniform contaminant distribution patterns inside a hyperbaric chamber could emerge and invalidate the predictions of well-stirred models. METHODS: Contaminant distribution was investigated inside a clinical hyperbaric chamber with the aim of comparing well-stirred model predictions with the actual contaminant concentration measurements. RESULTS: Local ventilation effectiveness inside a clinical hyperbaric chamber may be compromised, leading to higher contaminant concentration values compared to the predictions of a mathematical model with a well-stirred assumption. CONCLUSIONS: A well-stirred assumption in mathematical models is a useful simplification that allows reasonably accurate estimates of HCV requirements. However, local ventilation effectiveness values in a particular hyperbaric chamber might vary, with the potential for hazardous contaminant accumulation in under-ventilated zones.

Hyperbaric oxygen therapy awareness within a doctor population.

Hyperbaric medicine is a relatively young specialty that remains in the blind spot of most doctors' awareness. This study endeavors to identify the level of awareness of the indications for hyperbaric oxygen (HBO2) therapy among a doctor population in a developed country and factors which may improve referral rates. An anonymized questionnaire was distributed to doctors licensed to practice in Malta. Questions included physician specialty, demographics and previous exposure to diving and/or hyperbaric medicine. Moreover, two scoring systems were used to score subjects on HBO2-related topics. Binomial logistic regression models and generalized linear models were used in the statistical analysis. A total of 152 full replies were obtained and analyzed. Respondents who had visited a hyperbaric unit (HBU) (p=0.002) or attended a lecture on HBO2 (p=0.006) scored better than their counterparts, indicating better awareness of HBO2 indications and local chamber location. A previous HBU visit (p=0.001), being a hospital-based doctor (p=0.027) and a history of scuba diving (p=0.03) were associated with willingness to refer patients for HBO2 in the future. Encouraging visits to an HBU has been shown to be associated with multiple factors, which are expected to result in improved referral rates. Targeted educational sessions to doctors and medical students are likely to be beneficial in improving correct referral of patients for HBO2. The findings from this study may prove useful in improving appropriate referral rates of patients who may benefit from this useful treatment modality.

Increasing prevalence of vestibulo-cochlear decompression illness in Malta - an analysis of hyperbaric treatment data from 1987-2017.

INTRODUCTION: Scuba diving is a big part of the tourism sector in Malta, and all the cases of decompression illness (DCI)are treated within the single hyperbaric referral centre in the country. METHODS: This retrospective analysis reviews all the medical records of divers with DCI in Malta within the 30-year period between 1987 to 2017 who required recompression therapy with hyperbaric oxygen. RESULTS: There were 437 discrete cases of DCI managed with recompression therapy. Amongst DCI subtypes, the prevalence of musculo-skeletal DCI is decreasing, whereas that of vestibulo-cochlear DCI is increasing. CONCLUSION: The increasing prevalence of vestibulo-cochlear DCI may be due to a change in diving practices in Malta.