What can impede venous return during chest compressions?

Leaning on the patient's chest can impede venous return during chest compressions because it may create excessive pressure on the chest wall, interfering with the heart's ability to fill effectively between compressions. When compressions are performed, the chest must recoil fully to allow the heart to expand and fill with blood before the next compression. If the rescuer leans on the chest instead of allowing it to fully return to its resting position, it reduces the negative pressure necessary for venous blood to return to the heart. This can ultimately reduce the effectiveness of the compressions and compromise circulation during cardiopulmonary resuscitation (CPR).

The other options, while they may have their own implications for the quality of compressions, do not directly affect the venous return in the same way. For instance, rapid arm movements might disrupt compression depth and rate but aren't specifically linked to venous return. Similarly, pushing too slowly would decrease the overall efficacy of compressions but does not produce the same mechanical obstruction to venous blood flow that leaning on the chest does. Finally, using too much force may cause injury or diminish the effectiveness of the compressions but wouldn't have the same immediate impact on the heart's ability to receive blood as leaning on the chest