Journal of Yeungnam Medical Science
- Volume 15 Issue 1
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- Pages.97-113
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- 1998
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- 2799-8010(eISSN)
Changes of Blood Gases, Plasma Catecholamine Concentrations and Hemodynamic Data in Anesthetized Dogs during Graded Hypoxia Induced by Nitrous Oxide
아산화질소에 의한 점진적 저산소가스 흡입이 혈중 가스치와 Catecholamine치 및 혈역학에 미치는 영향
- Kim, Sae-Yeon (Department of Anesthesiology College of Medicine, Yeungnam University) ;
- Song, Sun-Ok (Department of Anesthesiology College of Medicine, Yeungnam University) ;
- Bae, Jung-In (Department of Anesthesiology, College of Medicine, Keimyung University) ;
- Cheun, Jae-Kyu (Department of Anesthesiology, College of Medicine, Keimyung University) ;
- Bae, Jae-Hoon (Department of Physiology, College of Medicine, Keimyung University)
- 김세연 (영남대학교 의과대학 마취과학교실) ;
- 송선옥 (영남대학교 의과대학 마취과학교실) ;
- 배정인 (계명대학교 의과대학 마취과학교실) ;
- 전재규 (계명대학교 의과대학 마취과학교실) ;
- 배재훈 (계명대학교 의과대학 생리학교실)
- Published : 1998.06.30
Abstract
The sympathoadrenal system plays an important role in homeostasis in widely varing external environments. Conflicting findings, however, have been reported on its response to hypoxia. We investigated the effect of hypoxia on the sympathoadrenal system in dogs under halothane anesthesia by measuring levels of circulating catecholamines in response to graded hypoxia. Ten healthy mongreal dogs were mechanically ventilated with different hypoxic gas mixtures. Graded hypoxia and reoxygenation were induced by progressively decreasing the oxygen fraction in the inhalation gas mixture from 21%(control) to 15%, 10% and 5% at every 5 minutes, and then reoxygenated with 60% oxygen. Mean arterial pressure, central venous pressure and mean pulmonary arterial pressure were measured directly using pressure transducers. Cardiac output was measured by the thermodilutional method. For analysis of blood gas, saturation and content, arterial and mixed venous blood were sampled via the femoral and pulmonary artery at the end of each hypoxic condition. The concentration of plasma catecholamines was determined by radioenzymatic assay. According to the exposure of graded hypoxia, not only did arterial and mixed venous oxygen tension decreased markedly at 10% and 5% oxygen, but also arterial and mixed venous oxygen saturation decreased significantly. An increased trend of the oxygen extraction ratio was seen during graded hypoxia. Cardiac output, mean arterial pressure and systemic vascular resistance were unchanged or increased slightly. Pulmonary arterial pressure(PAP) and pulmonary vascular resistance(PVR) were increased by 55%, 76% in 10% oxygen and by 82%, 95% in 5% oxygen, respectively(p<0.01). The concentrations of plasma norepinephrine, epinephrine and dopamine increased by 75%, 29%, 24% in 15% oxygen and by 382%, 350%, 49% in 5% oxygen. These data suggest that the sympathetic nervous system was activated to maintain homeostasis by modifying blood flow distribution to improve oxygen delivery to tissues by hypoxia, but hemodynamic changes might be blunted by high concentration of nitrous oxide except PAP and PVR. It would be suggested that hemodynamic changes might not be sensitive index during hypoxia induced by high concentration of nitrous oxide exposure.
교감신경계는 광범위한 각종 기능의 항상성 조절에 결정적인 역할을 하고 있으며, 저산소증, 출혈, 통증 등에 따른 스트레스 반응에 의해 자극되어 심박출량의 증가 및 조직으로 산소공급 향상을 위한 혈류 조절 반응이 나타나게 되나 주어진 환경에 따라 반응 정도는 다양하게 보고되고 있다. 고농도의