[Hokkaido igaku zasshi] The Hokkaido journal of medical science
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Hokkaido Igaku Zasshi · Nov 1997
Clinical Trial[Mechanism of ventilatory and heart-rate responses during sustained hypoxia in humans--role of endogenous adenosine].
To investigate whether lung stretch reflex modulates heart rate (HR) responses during hypoxia in humans, we measured ventilatory and HR responses to isocapnic progressive hypoxia and subsequent sustained hypoxia (arterial O2 saturation (SaO2); 80%, 20 min) in 22 healthy young adults. Moreover, to examine the role of endogenous adenosine in hypoxic ventilatory and HR responses in 9 of 22 subjects, a hypoxic challenge with or without dipyridamole pretreatment, an adenosine uptake blocker, was performed in a double-blind crossover fashion. Heart rate showed a biphasic change during the hypoxic challenge similar to that of ventilation. ⋯ As well as ventilatory decline during sustained hypoxia, which was completed earlier with dipyridamole than with control, HR decline was significantly affected with dipyridamole. There were no changes in blood pressure during hypoxic exposure except for a slight decrease in diastolic pressure at the end of sustained hypoxia in the control study. Accordingly we concluded that there was little effect of pulmonary stretch reflex on heart rate modulation during mild hypoxia in humans and that endogenous adenosine plays a modulating role more in ventilatory change during not only acute but also sustained hypoxia than in HR change.
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Hokkaido Igaku Zasshi · Nov 1997
Clinical TrialHaemodynamic correlation with lung biopsy findings in isolated ventricular septal defect with or without pulmonary hypertension.
Pulmonary hypertensive patients have been found to have greater morbidity and mortality from isolated ventricular septal defect closure than those pulmonary non-hypertensive patients. In this study, the author evaluated the relation between pulmonary artery muscularity and pulmonary artery pressure and resistance and compared the haemodynamic effects between normal and raised pulmonary artery pressure groups in isolated ventricular septal defect. The patients were divided into two groups, group-I (n = 14): pulmonary artery pressure of 50 mmHg or less than 50 mmHg, and group-II (n = 6): pulmonary artery pressure more than 50 mmHg. ⋯ Lung biopsy (n = 9) showed grade I Heath-Edward change in 6 cases (66.6%), grade II change in 1 case (11.1%), and grade III in 2 cases (22.2%). From these findings, when pulmonary vascular resistance is 8 units/m2 or more, operative indication should be determined on the basis of lung biopsy. Not only the gradings of pulmonary vascular changes, but the extent of vascular involvement and the duration of the lung exposure to the shunt anomally also need to be considered before surgery.