During a situation with no vitals, what is a critical sign of improvement after an NCD?

The return of a radial pulse is a critical sign of improvement after an NCD (needle decompression) because it indicates that circulation has been restored to the extremities. In cases of tension pneumothorax, the collapse of the lung and subsequent build-up of air in the pleural space can lead to decreased venous return to the heart, and thus a compromised circulatory system.

Restoration of normal cardiac output can be signified by the presence of a palpated radial pulse, which reflects adequate perfusion. This means that blood is effectively being circulated, and the body is beginning to stabilize after experiencing a life-threatening condition. While skin color, blood pressure, and the ability to speak can provide valuable information about a casualty's status, the radial pulse specifically indicates that the heart is effectively pumping blood, making it a direct sign of improving vital signs crucial for survival in traumatic situations.