Study on noninvasive and continuaous monitoring of myocardial oxygen metabolism by NIRS

1994 Fiscal Year Final Research Report Summary

• Project/Area Number: 05557070
• Research Category: Grant-in-Aid for Developmental Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: Anesthesiology/Resuscitation studies
• Research Institution: Kagoshima University
• Principal Investigator: ODA Toshiyuki Kagoshima University School of Medicine Associate Professor, 医学部, 助教授 (90041342)
• Co-Investigator(Kenkyū-buntansha): TAMURA Tomomi Shimadzu Corporation Researcher, 科学計測機器研究所, 研究員 ; KAKIHANA Yasuyuki Kagoshima University School of Medicine Assistant Professor, 医学部・付属病院, 助手 (20264426)
• Project Period (FY): 1993 – 1994
• Keywords: Myocardial oxygen metabolism / Near-infrared spectrophotometry / Transesophageal analysis

Research Abstract

We examined the possiblity of the measurements of myocardial oxygen status by near-infrared spectrophotometry (NIRS) in beating heart in three series of experiments.
Experiment (1) : analysis of hemoglobin (Hb) , myoglobin (Mb) and cytochrome oxidase (Cyt.aa3) in the myocardium.
The experiments were performed in isolated perfused rat heart for in situ measurement of Hb, Mb and Cyt.aa3. As a result, we established the following equations.
[Hb] =5.12xA_<700>-13.99x_<730>+8.45x_<750>
[Mb] =-2.85x_<700>+9.94x_<730>-6.44x_<750>
[HbO2+MbO2] =-4.97x_<700>+7.99x_<730>-2.08x_<750>
[Cyt.aa3] =_<805>- (-2.69x_<700>+3.93x_<730>-0.08x_<750>)
Experiment (II) : in vivo measurements of Hb, Mb and Cyt.aa3 in the rat.
The measurements were performed in exposed heart and through the chest wall during normoxic and hypoxic conditions. Following reduction of inspired oxygen concentration, it was shown that propotinal deoxygenation of Hb with FIO2, that the reduction of Mb for FIO2 at 0.12, and that the reduction of cyt.aa3 at 0.08 indicating successful measurements of myocardial oxygen metabolism by our equations.
Experiment (III) : transesophageal measurements of myocardial Hb, Mb and Cyt, aa3 in the pig.
The measurements were performed through esophagus. The signals of myocardial Hb+Mb or Cyt.aa3 were able to detect showing the reduction of Hb, Mb and during hypoxic hypoxia, however, we so far could not completely eliminate the contaminated signals from esophageal muscle.
We conclude that we can measure the myocardial oxygen status by near-infrared spectrophotometry in beating heart, and that transesophageal measurement could be possible indicating wide applicability in clinical practice.