Kronenberg R S, Drage C W
J Clin Invest. 1973 Aug;52(8):1812-9. doi: 10.1172/JCI107363.
The response of ventilation and of heart rate to hypoxia and hypercapnia was determined in eight young normal men age 22-30 yr and eight elderly men age 64-73. The elderly men were selected and carefully screened to eliminate the possibility of cardiopulmonary disease. All the subjects were born at low altitude and had no significant prior exposure to hypoxia. The ventilatory response to hypoxia was measured as the exponential slope constant. k, of regression lines relating the logarithm of incremental ventilation to PAo(2) during isocapnic progressive hypoxia. The heart rate response to hypoxia was measured as the percentage change in heart rate between PAo(2) = 100 and PAo(2) = 40 mm Hg. The ventilatory response to hypercapnia was measured as the slope of regression lines relating ventilation to PAco(2) during rebreathing with PAo(2) > 200 mm Hg. The heart rate response to hypercapnia was measured as the percentage change in heart rate between control values at the start of the rebreathing test and PACO(2) = 55 mm Hg. The ventilatory and heart rate responses to both hypoxia and hypercapnia were significantly decreased in the elderly men as compared to the young men. Hypoxic ventilatory drive was decreased by 51+/-6% (mean +/-SEM: P < 0.001) and hypercapnic drive by 41+/-7% (P < 0.025). The percentage change in heart rate produced by hypoxia was 34+/-5% (mean +/-SEM) in the young normals and 12+/-2% in the old normals (P < 0.005). Similar figures for heart rate in response to hypercapnia were 15+/-3% and -1+/-1% for the young and old normal groups (P < 0.001). We conclude that ventilatory and heart rate responses to hypoxia and hypercapnia diminish with age. These alterations in both ventilatory and circulatory controls could make older individuals more vulnerable to hypoxic disease states.
在8名年龄为22 - 30岁的年轻正常男性和8名年龄为64 - 73岁的老年男性中，测定了通气和心率对低氧和高碳酸血症的反应。老年男性经过挑选并仔细筛查，以排除心肺疾病的可能性。所有受试者均出生于低海拔地区，之前没有显著的低氧暴露经历。对低氧的通气反应通过等碳酸渐进性低氧期间，将递增通气量的对数与动脉血氧分压（PAo₂）相关的回归线的指数斜率常数k来衡量。对低氧的心率反应通过动脉血氧分压从100降至40 mmHg期间心率的百分比变化来衡量。对高碳酸血症的通气反应通过在动脉血氧分压>200 mmHg的重复呼吸期间，将通气量与动脉血二氧化碳分压（PAco₂）相关的回归线的斜率来衡量。对高碳酸血症的心率反应通过重复呼吸测试开始时的对照值与动脉血二氧化碳分压为55 mmHg时心率的百分比变化来衡量。与年轻男性相比，老年男性对低氧和高碳酸血症的通气及心率反应均显著降低。低氧通气驱动降低了51±6%（平均值±标准误：P < 0.001），高碳酸通气驱动降低了41±7%（P < 0.025）。年轻正常组中低氧引起的心率百分比变化为34±5%（平均值±标准误），老年正常组为12±2%（P < 0.005）。年轻和老年正常组对高碳酸血症的心率反应类似数据分别为15±3%和 -1±1%（P < 0.001）。我们得出结论，随着年龄增长，对低氧和高碳酸血症的通气及心率反应会减弱。通气和循环控制方面的这些改变可能使老年人更容易患低氧性疾病状态。
