What device provides a firm surface under the patient's torso during CPR?

A CPR board is specifically designed to provide a firm and stable surface beneath a patient's torso during cardiopulmonary resuscitation (CPR). This firm surface is crucial because it allows for effective compression of the chest, which is necessary for proper blood circulation during cardiac arrest. The use of a CPR board helps to ensure that compressions are delivered consistently and at the correct depth, maximizing the chances of survival for the patient.

In contrast, while other options like a backboard or spine board provide support for patients, they may not have the specific design features that facilitate optimal CPR. A stretcher, commonly used for transporting patients, does not offer the rigidity needed during CPR, as it is often cushioned and designed for comfort over rigid support. Therefore, the CPR board is the most appropriate choice for supporting a patient’s torso during resuscitation efforts, ensuring effective and efficient delivery of lifesaving compressions.