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Objective: To measure the natural prevalence of diaphragmatic (DB) and rib cage breathing (RCB) and their respective effects on venous return in human subjects.
Methods: Sixteen subjects (9 men, 4 women, and 3 boys, aged 10 to 83) were monitored for breathing patterns with stretch transducers on the upper chest, the mid chest, and the abdomen at the umbilicus. Monitoring for venous flow patterns was carried out with infrared transducers on the forehead, sampling superior vena cava (SVC) volume, and with leg electrodes, sampling leg blood volume (LBV) by electrical impedance. Recordings were made during 3 minute periods of sitting and standing after knee bending exercise.
Results: DB, indicated by inward movement of the mid chest with breathing, accounted for 0 - 46% of breathing activity in all positions (One subject had no DB) this breathing pattern correlated with an overflow of venous volume into the SVC. RCB, consisting of upper chest expansion, mid chest constriction, and inward abdominal movement at the umbilicus - accounted for 9 - 37% of breathing activity. This breathing pattern correlated with extraction of LBV, superimposed on an underlying sinusoidal fluctuation of LBV.
Conclusions: DB and RCB are normal, prevalent breathing patterns augmenting venous return to the heart. SVC backflow and rhythmic LBV were observed for the first time.