PubMed · 13397392
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R FINOCHIETTO. 1956-11-22. [Decompression intradermal method Noeske].. https://pubmed.ncbi.nlm.nih.gov/13397392/
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BACKGROUND: Many occupational diving groups have substantially different diving patterns to those for which decompression schedules are validated. AIMS: To evaluate tuna farm occupational diving practice against existing decompression models and describe a method for collecting and modelling self reported field decompression data. METHODS: Machine readable objective depth/time profiles were obtained from depth/time recorders worn by tuna farm occupational divers. Divers' health status was measured at the end of each working day using a self administered health survey that produces an interval diver health score (DHS) with possible values ranging from 0 to 30. Depth/time profiles were analysed according to existing decompression models. The contribution of diving exposure and between diver variability to DHS was evaluated using linear regression. RESULTS: The mean risk of decompression sickness was calculated as 0.005 (SD 0.003, n = 383). The mean DHS following diving was 3 (SD 2, n = 383) and following non-diving activities was 1 (SD 1, n = 41). After accounting for between diver variability in intercept, DHS was found to increase one unit for every 1% increase in the risk of decompression sickness. CONCLUSIONS: A method has been established for the collection and analysis of self reported objective decompression data from occupational diving groups that can potentially be used as the basis for development of purpose designed occupational diving decompression schedules.
Both the longest tissue half-time (T1/2max) and the maximum allowable pressure gradient (deltaP) define the safe rate of decompression (DR) after saturation expositions. The mathematical relation between them (DR = -k x deltaP, where: k = ln(2)/(T1/2max)) suggests that experimentally established decompression rate can be hypothetically described by the infinite number of T1/2max and deltaP combinations. The observed number of decompression sickness after saturation decompressions forced to change those parameters subsequently and finally led to values far outside physiological range. Therefore the aim of this study was to compare values of the longest tissue half-time of nitrogen desaturation from diver's body published since 1908 in order to present the evolution of opinions concerning desaturation process. Non-physiological values of T1/2max (from 75 to 1280 minutes) have been published during historical evolution of decompression tables and systems. The currently accepted values of T1/2max (in the range of 320-480 minutes) for saturation and non-saturation air and nitrox divings and hypobaric decompressions, still need to be precised. The discrepancy between T1/2max values obtained using isobaric decompression method and decompressions after diving indicates different physiological phenomena during nitrogen elimination in both methods.
The basic problem in decompression is the limit of maximum tolerable change of pressure after diving. Due to the number of parameters involved in decompression models (bottom time, ambient pressure, exposition profile, content of breathing mixtures, properties of inert gases) the number of possible solutions is theoretically unlimited. Since the beginning of modern decompression models the starting point has been direct saturation decompression using air. The generally accepted form of solution is the linear relation between tolerable pressure P2 after saturation exposition to pressure P1 described by the equation in the form P1 = P2 x A + B, where A and B are parameters obtained by experiments. Since the introduction of this equation values of parameters have been changing in order to decrease the rate of decompression illness. The aim of this study was to analyse and interpret the trend of those changes. Sixteen published models, including the one developed in our center, were compared and gradual change of parameters was identified. This trend should result in safer decompression systems.