Sinus arrhythmia refers to a changing sinus node rate with the respiratory cycle, on inspiration and expiration. This is quite common in young, healthy individuals and has no clinical significance.

Conversely, left heart filling decreases during inspiration, as the intrapericardial volume is fixed (if the right heart is full, the left heart is less full, and vice versa). During expiration ...

Intrathoracic obstruction is most severe during expiration and is relieved during inspiration. Extrathoracic obstruction is increased during inspiration because of the effect of atmospheric ...