Blood shift during cough in healthy subjects

Double Body Plethysmography (DBP), which combines total body plethysmography and opto-electronic Plethysmography, has been recently developed to measure the amount of blood displaced from the thorax to the extremities (Aliverti et al, PLoS One. 2009). By using DBP, we have recently shown that significant blood shifts (BS) occur during expulsive maneuvers and that abdominal pressure controls the outflow of blood from the splanchnic vasculature (Aliverti et al, J Appl Physiol, 2010). We hypothesized that also during cough a significant amount of blood can be displaced from the trunk to the extremities. We studied 7 healthy subjects (age: 28.6±2.5 yrs) during series of voluntary coughs at four different operating volumes: functional residual capacity (FRC), total lung capacity (TLC) and two intermediate volumes between FRC and TLC (namely, FRC+ and FRC++). BS from the thorax to the extremities were measured by DBP during quiet breathing and during cough at each operating lung volume. The results are shown in figure. ![Figure][1] BS during cough resulted significantly higher than during QB (p<0.001). BS increase with increasing operating volume, being maximal at total lung capacity (figure). These findings might help to better understand the cardiopulmonary interactions during cough and the mechanism by which coughing during asystolic cardiac arrest can maintain consciousness in human subjects. [1]: pending:yes