飽和潜水用減圧表の研究 第1報:ラット･ウサギ･イヌの実証実験

Abstract

The validation study by applying the concept of universal decompression table to animals was conducted. The principal objectives were: (1) to shorten the decompression time systematically and safety; and (2) to produce animal models for the study of decompression sickness. A total of 25 decompression tables were formulated according to the UDT concept for decompression from 300 m H(sub e)-O2 (PO2 = 0.5 bar) saturation dives and tested on 82 rats (9 UDT300R tables), 52 rabbits (9 UDT300B tables), and 12 dogs (7 UDT300D tables). Some results were obtained. An interspecies relationship between body weight (W, in kg) tissue half-time (T1/2, in minute) for inert gas elimination as T1/2 = 26.36W(sup 0.59) (r = 0.994) was derived by using 5 Tau as the stage decompression time, of which 1 Tau was used to reduce pressure and 4 Tau for equilibration. To further reduce the decompression time, some UDT tables were tested by using the stage time of 3 Tau or 1 Tau. The shortest decompression time was achieved by varying the value of T1/2 and by using 1 Tau as the short decompression time In this case there were no pauses between stages and decompression rate falls progressively with each stage. It was found that linear decompression between stages was safer than the original UDT. Decompression time was successfully reduced by using linear decompression between stages. From these studies, the decompression sickness was able to be produced consistently. Rabbits and dogs are good models of experimental decompression sickness for the study of bends and central nervous system disorders.

Universal Decompression Tableを用いて(1)飽和潜水の減圧時間を安全に短縮するために動物実験で有効性を実証し、併せて(2)減圧症の研究のための動物モデルを作成するための減圧表としての有効性を検討した。実験動物には、ラット82匹(9実験)、ウサギ52羽(9実験)、イヌ14匹(7実験)を使用し合計25回の実験を実施した。飽和深度は、300m、He-O2、酸素分圧0.5barからの減圧で実施した。その結果を下記する。(1) 5 Tauでは体重と半飽和時間の関係式は、T1/2=26.36W{0.59}(r=0.994)が導かれた。5 Tauとは、SDT(減圧点間減圧時間および減圧点停留時間)の内1Tauを減圧点間の減圧時間に充て、残り4 Tauを減圧点での停留時間とする階段減圧である。(2) 3 Tau, 1 Tauの実験も行いTDT(総減圧時間)において最も短縮されたSDTは、1 Tauであった。1Tauとは、SDTの全ての時間を減圧点間の減圧時間に充てるもので半飽和時間の値が大きくなる直線減圧である。(3)階段減圧方法よりも直線減圧方法が、安全な減圧時間の短縮に有効性を示すことが示唆された。(4)UDTは、ウサギ、イヌのベンズから中枢神経系減圧症の動物モデル作成に十分有効性を示すことが確認された。