An impedance cardiographic study of the mechanism of blood pressure fall after moderate dietary sodium restriction.
Impedance cardiography was performed on 13 free-living subjects to determine the mechanism which ties modest sodium restriction to a reduction in blood pressure. During salt restriction intervention, significant decreases in systolic and diastolic blood pressure (6 and 7 mmHg) were observed associated with mild reduction in urinary sodium excretion from 176 to 85 mmol/day. The impedance cardiogram demonstrated a significant decrease in stroke volume (12 ml), which was related to a fall in diastolic pressure (r = 0.59, p less than 0.05). In the further analysis of individual parameters in Kubicek's formula calculating stroke volume, thoracic impedance (Zo/L) showed a significant increase during salt restriction and a change (delta) in ln L/Zo related significantly to delta ln diastolic pressure in linear multiple regression analysis. As thoracic impedance has been reported to reflect intrathoracic fluid content, a decrease in extracellular fluid volume was suggested as a possible mechanism of the fall in blood pressure even with modest sodium restriction.
D000328:Adult; D001794:Blood Pressure; D001835:Body Weight; D002302:Cardiac Output; D002307:Cardiography, Impedance; D004039:Diet, Sodium-Restricted; D004562:Electrocardiography; D005110:Extracellular Space / Q000502:physiology; D006347:Heart Sounds; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012964:Sodium / Q000652:urine; D013318:Stroke Volume
D012964:Sodium