高気圧酸素治療(HBO)の有効性の機序を検討することを目的とし,近赤外線法(near infrared spectroscopy: NIRS)を利用し,同時に全身的酸素動態の測定には経皮的ガス分圧モニターを利用した.著者らは新たにプローベを改造しHBO下のNIRSによる酸素動態の測定を可能とした.従って近赤外線法によるHBO下の酸素動態,代謝の検討は本研究が嚆矢となるものである.対象は20～67(平均40.7±15.4)歳,男性21例,女性2例で治療時間は2気圧で60分間である.治療開始前よりNIRSで右前腕部組織中の酸化ヘモグロビン(Oxy-Hb),還元型ヘモグロビン(Deoxy-Hb),総ヘモグロビン(Total-Hb),チトクロームaa3 (Cyt.Oxi.)を測定し,同時に経皮酸素分圧(PtcO_2),二酸化炭素分圧(PtcCO_2)も測定した.治療前後に左大腿動脈より血液を採取し酸素分圧(PaO_2),二酸化炭素分圧(PaCO_2),pH,重炭酸イオン(HCO_3^-),Base excess(BE)を検討した.治療開始前,治療中,治療後の各測定機器の測定値より酸素動態,代謝の変化を検討した.NIRSは開始前をa群,ピーク時をb群とし,経皮ガス分圧測定法はHBO開始前をc群,ピーク時をd群,減圧終了直後をe群とし,動脈血分析は開始直前をf群と減圧終了直後をg群とし検討した.結果,a群,b群間でOxy-Hb,Total-Hb,Cyt.Oxi.は有意に増加,Deoxy-Hbは有意に減少,PtcO_2はc群とd群,e群間で有意に増加,PtcCO_2はc群とd群,e群間で有意に減少,f群,g群間でPaO_2,pHは有意に増加,PaCO_2は有意に減少,BE,HCO_3^-は有意差を認めなかった.HBO下では酸化型チトクロームaa3の増加を認めた.これは,恒常状態で還元型チトクロームaa3が存在するという報告を支持するものであり同治療下ではOxy-Hb,Total-Hbも増加しており組織レベルで酸素代謝が亢進していると考えられた.また同治療中にPaO_2の著明な上昇とPaCO_2の低下を認めるが酸塩基平衡には影響の少ない治療法であった.To investigate the mechanism of the hyperbaric oxygenation (HBO) therapy efficacy, we assessed oxygen dynamics and metabolism during HBO therapy (60 hours at 2 ATA) by near infrared spectroscopy (NIRS) and percutaneous blood gas partial pressure monitoring in 21 men and 2 women aged 20～67 years (mean: 40.7±15.4). Oxyhemoglobin (Oxy-Hb), deoxyhemoglobin (Deoxy-Hb), total hemoglobin (Total-Hb), and cytochrome aa3 (Cyt.Oxi.) were recorded at intervals of 10 seconds from the rest period preceding HBO therapy until the measurements stabilized during rest after decompression. Percutaneous blood gas partial pressure (PtcO_2), carbon dioxide partial pressure (PtcCO_2), oxygen partial pressure (PaO_2), carbon dioxide partial pressure (PaCO_2), pH, bicarbonate ion concentration (HCO_3^-), and base excess (BE) were also determined. The Oxy-Hb, Total-Hb, and Cyt.Oxi. levels were significantly elevated and the Deoxy-Hb levels were significantly reduced during the stable period preceding HBO therapy and the peak stable time during therapy. PtcO_2 significantly increased and PtcCO_2 significantly decreased during the stable period before HBO therapy, the peak stable period during therapy, and immediately after the end of decompression. PaO_2 and pH were significantly elevated and PaCO_2 was significantly reduced immediately before the start of HBO therapy and immediately after the end of decompression. There were no significant differences in BE or HCO_3^- at any of the times measured. In conclusion, the oxidized Cyt.Oxi. levels increased during HBO, substantiating a report on the dominance of reduced Cyt.Oxi. under homeostatic conditions. The elevated Oxy-Hb and Total-Hb levels appear to reflect enhancement of oxygen metabolism at the tissue level. HBO therapy appears to have little effect on acid-base equibrium, although it markedly increased the PaO_2 levels and decreased the PaCO_2 levels
