What should be suspected in a patient with hypotension and distended neck veins?

The combination of hypotension and distended neck veins is highly indicative of cardiac tamponade, which is a condition where fluid accumulates in the pericardial space, exerting pressure on the heart. This pressure prevents the heart from filling properly during diastole, leading to decreased cardiac output and resultant hypotension. The distended neck veins occur because the increased pressure in the pericardial sac interferes with the ability of blood to return to the heart, causing back pressure in the venous system.

In contrast, pneumothorax typically presents with respiratory distress and possibly shifts in tracheal position, but does not generally cause distended neck veins. Hypovolemic shock, caused by significant blood loss or fluid loss, usually leads to hypotension but is characterized by low or normal neck vein fullness, not distension. Spinal shock results in hypotension and can cause bradycardia, but again, does not typically lead to distended neck veins, which are more specific to conditions that impede venous return to the heart, such as cardiac tamponade.