Ryoko Maruyama

Differences in ventilatory responses to hypoxia and hypercapnia between normal and judo athletes with moderate obesity

SummaryHypercapnic and hypoxic ventilatory sensitivities were compared in twenty-one judoists and 24 control subjects with similar degrees of moderate obesity. Data from ten non-obese control subjects were also included as a reference. Mean body weight (BW) and % of ideal body weight in the judoists and the obese and non-obese controls were 100±14.8, 94.4±5.3 and 63.4±6.1 (mean±SD) kg, and 142.3±16.7, 142.2±12.9 and 98.4±10.7%, respectively. Mean body fat in the judoists was 16.2±13.9%, being 25.3±7.7% in the obese control group, the difference being significant (p<0.01).Hypercapnic sensitivities in terms of the CO2 ventilatory response slope (S) and its normalized value for 70 kg BW (SN) of the obese controls were higher than the judoists. These findings were also verified by the CO2-occlusion pressure responses. S and SN in the obese controls were significantly correlated with BW and % body fat. However, no positive correlation was found between BW and S or SN in the judoists as well as between lean body mass and S or SN in the obese control. Hypoxic sensitivity in terms of the

The Cardiac Sympathetic Nerve Activity in the Elderly Is Attenuated in the Right Lateral Decubitus Position

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Differential Sensitivity to Hypoxic Inhibition of Respiratory processes in the Anesthetized Rat

ventilation hyperbola slope (A) and its normalized value (AN) in the obese control was significantly higher than the non-obese control, but the difference from the judoists was not significant. A and AN were found to increase with increasing % body fat in both judoists and obese controls. We conclude that respiratory compensation to mechanical limitation due to fat accumulation may be one of the possible factors to enhance hypercapnic as well as hypoxic ventilatory chemosensitivities in moderate obesity.

Ventilation- and Carotid Chemoreceptor Discharge-Response to Hypoxia during Induced Hypothermia in Halothane Anesthetized Rat

The effects on the ventilatory response to acute hypoxia of increasing the Hb-O2 affinity by NaOCN administration were studied in the halothane anesthetized spontaneously breathing rat. Increases in ventilation during the progressive hypoxia test were significantly augmented, and ventilatory depression occurring in severe hypoxia was clearly inhibited in the NaOCN-treated rat. Beneficial effects of NaOCN treatment probably result from the protection of respiratory regulating mechanism from functional deterioration in severe hypoxia.

Dependence of biphasic heart rate response to sustained hypoxia on magnitude of ventilation in man

Objectives: The aim of this study was to evaluate the effect of the supine, left lateral decubitus, and right lateral decubitus positions on autonomic nervous activity in elderly adults by using spectral analysis of heart rate variability (HRV). Method: Forty-five adults aged 73.6 ± 5.7 years were enrolled. After lying in the supine position, all participants moved to the lateral decubitus positions in a random order and maintained the positions for 10 min, while electrocardiographic data were recorded to measure HRV. Results: The lowest heart rate continued for 10 min when participants were in the left lateral decubitus position compared with the other two positions (p < .001), while the HRV indexes remained unchanged. The low-frequency HRV to high-frequency HRV ratio (LF/HF) for the right lateral decubitus position was significantly lower than that for the other positions. Discussion: The right lateral decubitus position may attenuate sympathetic nerve activity in elderly adults.

Comparison of ventilatory response between dead space and CO2 breathing in humans

Some studies have reported that recumbent position may have advantages in patients with heart disease and in pregnancy. However, it remains controversial whether recumbent position affects autonomic nervous system activity and hemodynamics in healthy adults. The aim of this study was to evaluate alterations in heart rate variability (HRV) and hemodynamics in the supine, left recumbent and right recumbent positions in healthy young adults. A total of 80 participants aged 22.8 ± 3.1 years were enrolled in this observational study. Fifty-eight volunteers (29 men and 29 women) maintained the supine position followed by the left and right recumbent positions, while electrocardiographic data were recorded for spectral analysis of HRV to assess cardiac vagal nerve and sympathetic nerve activities. The heart rate (HR) was significantly lower in the left recumbent position than in the other positions. There were no statistically significant differences in HRV among the three positions. Considering the possibility that the echographic procedure affects autonomic nervous system (ANS) activity, the other 22 participants (11 men and 11 women) underwent an echographic evaluation of hemodynamics in the heart and inferior vena cava (IVC) across the three positions. Although a low HR was also observed, there were no statistically significant differences in the IVC or the heart blood volume between the supine and the left recumbent positions. A postural change to the left recumbent position does not affect the cardiac blood circulation or ANS activity, though it does decrease HR in healthy young adults. This finding indicates that the lower HR in the left recumbent position is not attributable to the ANS activity.