Assessment of myocardial oxygen metabolism and its performance during progressive hypoxemia.
Grant-in-Aid for Scientific Research (C)
|Research Institution||Kagoshima University|
ODA Toshiyuki Kagoshima University Faculty of medicine, Associate Professor, 医学部, 助教授 (90041342)
TAKAYAMA Chihumi Kagoshima University University Hospital, Reseach Associate, 医学部・附属病院, 助手 (00265399)
KAKIHANA Yasuyuki Kagoshima University University Hospital, Reseach Associate, 医学部・附属病院, 助手 (20264426)
|Project Fiscal Year
1996 – 1997
Completed(Fiscal Year 1997)
|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1997 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1996 : ¥1,200,000 (Direct Cost : ¥1,200,000)
|Keywords||Systemic oxygen metabolism / Myocardial oxygen metabolism / Myocardial contractility / Left ventricular pressure-volume relations (LVPVR) / End-systomic pressure-volume relations (ESPVR) / End-systolic elastance / 体酸素代謝 / 心筋酸素代謝 / 心収縮力 / 左室圧-容積関係(LVPVR) / 収縮期末圧-容積関係(ESPVR) / 収縮期末エラスタンス(Ees) / 体組織酸素代謝 / 左室左-容積関係 / 心筋収縮性 / 低酸素症|
The relationships between cardiac function and both systemic and myocardial oxygen metabolism were investigated during progressive hypoxemia.
Sutudy 1 : relationship between cardiac function and systemic oxygen metabolism
Nine pigs were subjected to progressive hypoxemia by sequential reduction of inspired oxygen concentration (F_<IO2>) from 0.21 to 0.10. The reduction of an oxygen content of arterial blood (Cao_2) followed a significant increase in cardiac output (CO) at an F_<IO2> of 0.13. The increase in CO showed a peak value at an F_<IO2> of 0.11. Left ventricular end-systolic elastance (Ees), a measure of myocardial contractility, showed the peak value at an F_<IO2> of 0.13, then it turned to decline. The ventriculoarterial coupling, determined by the ratio of arterial elastance to Ees (Ea/Ees), was well-balanced at an F_<IO2> of 0.13. These observations suggest that the myocardial contractility may reduce even if CO reveals compensatory increase against the reduction of oxygen del
ivery (D_<o2>) during progressive hypoxemia.
Study 2 : Relationship between cardiac function and myocardial oxygen metabolism
The relationship between cardiac function and myocardial oxygen metabolism were investigated in three pigs subjected to progressive hypoxemia by sequential reduction of F_<IO2> from 0.21 to 0.10. The coronary blood flow. showed a maximum value at an F_<IO2> of 0.11, then decrased. The myocardial D_<o2> MD_<02> reached to maximum at an F_<IO2> of 0.13, then decreased below control (F_<IO2> 0.21) level at an F_<IO2> of 0.11. The changes in Ees shown in study 1 was coincided with the changes in MD_<o2> suggesting that the myocardial contratility may be changing dependent to MD_<o2>.
In summary, during progressive hypoxemia it is suggested that myocardial contractility reduces when the cardiac output is still increasing to compensate the reduction of Do_2, and that the myocardial contractility is changing dependent to MDo_2. Accordingly, in the treatment of hypoxemia, it will be necessary to adjust systemic oxygenation with myocardial oxygen metabolism assessing the myocardial contractility itself, e.g.Ees.
Research Output (3results)