高地環境における低酸素、低気圧の健常者心血行動態に及ぼす影響 : 超音波心エコー・ドプラ法による検討 Influence of Hypoxia or Low Atmospheric Pressure in High Altitudes on the Cardiovascular Response of Normal Subjects at Rest and during Exercise : Assessment by Two-Dimensional and Doppler Echocardiography コウチ カンキョウ ニオケル テイサンソ, テイキアツ ノ ケンジョウシャ シンケッコウ ドウタイ ニ オヨボス エイキョウ : チョウオンパ シンエコー・ドプラホウ ニヨル ケントウ

博士論文

To clarify the influence of low oxygen pressure or low atmospheric pressure at an altitudo of 2，500m on the cardiovascular system，4 different environments (Env) were created in a hypobaric chamber [Env A: normal atmospheric pressure (AP) (760mmHg) and normal oxygen pressurc (OP) (160mmHg); Env B: low AP (560mmHg) and low OP (118mmHg); Env C: normal AP and low OP and Env D: low AP and normal OP]. Supine bicycle exercise echocardiography was performcd for 6 minutes in 17 normal subjccts. Heart rate， blood pressure，arterial oxygen saturation and two-dimensional echocardiographic diameters of thc left atrium and left ventricle were measured at rest and 1 minute before termination of the exercise. To assess the influence of an altitude， all indices were compared between Env A and Env B，to assess the influence of hypoxia，the indices were compared between Env A and Env C and between Env D and Env B，and to assess the influence of low atmospheric pressure，the indices were compared between Env A and Env D and between Env C and Env B. Heart rate at rest and during exercise were significantly increased in Env B (72±11 and 115±14 beats/min) compared to those in Env A (64±10 and 106±12 beats/min) and Env D (65±10 and 106±14 beats/min). Arterial oxygen saturation at rest and during exercise were significantly decreased in Env B (91±2 and 87±3 %) and Env C (92±2 and 89±2 %) compared to those in Env A (97±1 and 97±1 %) and were significantly decreased in Env B compared to those in Env D (97±1 and 96±2 %). Left atrial dimension at rest and during exercise were significantly decreased in Env B (31±2 and 32±3 mm) compared to those in Env A (33±3 and 34±3 mm)，and were significantly decreased in Env D (31±2 and 32±3 mm) and Env B compared to those in Env A and Env C (33±2 and 33±2 mm). Left ventricular diastolic dimension at rest was significantly decreased in Env B (45±4 mm) compared to that in Env A (48±3 mm)，and was significantly decreased in Env D (46±4 mm) and Env B compared to those in Env A and Env C (48±3 mm). Stroke volume and early diastolic left ventricular and right ventricular maximal inflow velocilies at rest in Env B (69±15 ml，89±12 cm/sec and 69±9 cm/sec) were significantly decreased compared to those in Env A(74±13 ml，94±15 cm/sec and 74±12 cm/sec) and Env C (75±10 ml，95±16 cm/sec and 77±13 cm/sec). At an altitude of 2，500 m，the increase in heart rate and decrease in arterial oxygen saturation at rest and during exercise seem to be influenced by hypoxia. Decrease in the left atrial dimension at rest and during exercise and decrease in the left ventricular diastolic dimension, stroke volume, and early diastolic left ventricular and right ventricular maximal inflow velocities at rest seem to be influenced by low atmospheric pressure.

医歯学総合研究科博士論文(医学) ; 学位取得日: 平成9年11月20日