運動負荷の気管支喘息患者肺機能に及ぼす影響
1969 年 6 巻 7-8 号 p. 487-496
詳細
1969 年 6 巻 7-8 号 p. 487-496
The effects of exercise on the blood gas and ventilatory mechanics were studied in patients with brochial asthma in remission.
The initial study, involving 7 asthmatic children, used moderate exercise on a bicycle ergometer for 5 minutes. Expired gas and arterial blood were collected simultaneousely before and during the last 2 minutes of the exercise. At rest there were marked hypoxemia and high (A-a) O2 difference. The latter was slightly larger than the high (a-A) N2 difference observd, indicating that the decrease in arterial PO2 was mainly due to the lesions of the lung which were underventilated and overperfused. There was no apparent correlation between the magnitude of airway obstruction, as measured by the FEV0.75 and MMF, and the (a-A)N2 difference on 6 cases examined. During exercise it was shown that arterial PO2 increased with a concomittant decrease in (A-a) O2 as well as a drop in (a-A) N2. In two cases blood pH and base excess decreased slightly indicating development of mild metabolic acidosis during exercise. Their blood lactate concentration and L/P ratio increased slightly.
The response was further studied in an additional 2 children and 8 adults with asthma using a controlled step exercise for 4.5 to 6 minutes. Pre- and postexercise measurements were made with bodyplethysmography and spirometry. A consistent, marked, transient increase in airway resistance immediately after exercise with gradual return to pre-examined levels was seen in 9 cases. The average of the maximum decrease in airway conductance /thoracic gas volume was 54.9% of the control values. In 2 cases the airway obstruction following exercise lasted more than 30 minutes. There was a rough correlation between the severity of the disease and the magnitude of the bronchial response to exercise but none between the response to sulfur dioxide and to exercise.
The possible contributing factors to the observed increase in arterial PO2 during exercise and the decrease in airway conductance following exercise are discussed.
