Measurements of chest wall volume variation during tidal breathing in the supine and lateral positions in healthy subjects.

PURPOSE: To study the feasibility and the laterality of measurements of chest wall volume variation during tidal breathing in the lateral position in healthy subjects. METHODS: Eighteen normal subjects were studied. Chest wall volume changes were measured by optoelectronic plethysmography in the supine and right and left lateral positions during quiet breathing. The accuracy of measuring lung volume was also examined using hot wire spirometry in 10 of the subjects. RESULTS: The measurement errors between lung volume changes and chest wall volume changes were not significantly different in all positions. There was no significant difference between right and left compartmental volume changes in the supine position. However, chest wall volume changes were lower on the dependent side in the lateral position than on the non-dependent side because of the decrease in abdominal rib cage and abdomen volume changes. CONCLUSION: Chest wall volume measurements during quiet breathing in the lateral position have high measuring accuracy and show laterality.

Hypertensive patients with carotid artery plaque exhibit increased platelet aggregability.

BACKGROUND: Platelets play an important role in myocardial infarction and ischemic stroke events, but whether platelet aggregability is related to early stage arteriosclerosis remains unclear. METHODS: We used a novel platelet counting system which makes it possible to detect spontaneous platelet aggregation, to evaluate the relationship between platelet aggregability and carotid artery arteriosclerosis in 125 outpatients with primary hypertension (46-73 years old: 65 men, 60 women). All subjects underwent carotid artery ultrasonography to determine whether plaque was present and to estimate intima-media thickness. RESULTS: Patients with carotid artery plaques (Plaque(+), n=63) were older and had higher systolic blood pressures than patients without plaques (Plaque(-), n=62), but no significant differences in sex, body mass index, diastolic blood pressure, plasma concentrations of glucose, total cholesterol, triglyceride, lipoprotein cholesterol, fibrinogen or the platelet count in whole blood were observed between Plaque(+) and Plaque(-) groups. Plaque(+) subjects showed greater spontaneous platelet aggregability and platelet aggregation induced by 2 microM or 0.5 microM of ADP or 0.3 microM of epinephrine than the Plaque(-) group. When age and systolic blood pressure were matched (n=52 in both groups), the Plaque(+) subjects exhibited greater platelet aggregability than the Plaque(-) subjects. Platelet aggregation induced by 2 microM of ADP showed statistical significant positive correlation coefficients with age, HbA1c and diastolic blood pressure. CONCLUSION: Our results indicate that hypertensive patients with carotid artery plaque have increased platelet aggregability. A prospective study is recommended to clarify whether this increase in platelet aggregability promotes the progression of arteriosclerosis.