Assessment of myocardial oxygen metabolism and its performance during progressive hypoxemia.

Research Project

Project/Area Number	08671756
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Anesthesiology/Resuscitation studies
Research Institution	Kagoshima University
Principal Investigator	ODA Toshiyuki Kagoshima University Faculty of medicine, Associate Professor, 医学部, 助教授 (90041342)
Co-Investigator(Kenkyū-buntansha)	KAKIHANA Yasuyuki Kagoshima University University Hospital, Reseach Associate, 医学部・附属病院, 助手 (20264426) TAKAYAMA Chihumi Kagoshima University University Hospital, Reseach Associate, 医学部・附属病院, 助手 (00265399)
Project Period (FY)	1996 – 1997
Project Status	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 / 体組織酸素代謝 / 左室左-容積関係 / 心筋収縮性 / 低酸素症
Research Abstract	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 … More 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. Less