If a casualty does not file a pulse at the wrist, what should be suspected?

When there is no detectable pulse at the wrist in a casualty, the situation can indicate a serious underlying problem with blood circulation. The most pressing concern in this scenario is tension pneumothorax, a condition where air becomes trapped in the pleural space, exerting pressure on the lung and leading to impaired circulation and respiratory function. As the condition progresses, it can drastically reduce blood return to the heart, leading to a lack of pulse and signs of shock.

Tension pneumothorax often presents with acute respiratory distress and may cause hypotension due to compromised venous return. The absence of a pulse at the wrist reflects this critical state, as the heart struggles to pump effectively when the thoracic cavity is compromised by excessive air pressure. Thus, the suspicion of tension pneumothorax is logical when a pulse is absent, warranting immediate intervention to relieve the pressure and restore circulatory function.

While cardiac arrest, severe blood loss, and hypothermia can also affect pulse presence, the specific context of acute respiratory compromise and the mechanics of how tension pneumothorax impacts circulation make it the most relevant suspicion in this scenario.