Which phenomenon is seen during cardiac tamponade, resulting in a larger than normal drop in systolic blood pressure during inspiration?

The phenomenon that occurs during cardiac tamponade, characterized by a larger than normal drop in systolic blood pressure during inspiration, is known as pulsus paradoxus. In this condition, the drop in blood pressure exceeds the usual variation that occurs with respiration and is indicative of impaired filling of the heart chambers due to external pressure.

During inspiration, negative intrathoracic pressure facilitates increased venous return to the heart. However, in cardiac tamponade, the fluid accumulation in the pericardial space restricts the heart's ability to expand, particularly affecting the right ventricle during diastole. This results in decreased stroke volume and consequentially a marked decrease in systolic blood pressure, which can be more than 10 mmHg.

As for the other options, pulsus alternans refers to alternating strong and weak heartbeats, pulsus bisferiens is characterized by a double pulse wave, and orthostatic hypotension is the drop in blood pressure upon standing. None of these specifically relate to the pronounced drop in systolic blood pressure during inspiration linked to cardiac tamponade.