In order to turn an unconscious patient face-up in shallow water, you should use ________.

The head-splint technique is advantageous in this scenario because it allows for maintaining spinal alignment while turning an unconscious patient face-up, which is crucial for minimizing the risk of further injury, especially in water where the victim may have sustained a spinal injury.

In shallow water, using the head-splint technique involves stabilizing the head and neck of the patient while rolling the body, thus preserving the integrity of the spinal column. This technique is specifically designed to keep the airway clear and facilitate breathing while ensuring that the patient's head does not move excessively, which is critical in a setting where spinal injuries are a concern.

While other techniques have their applications, the head-splint method is particularly suited for situations involving potential spinal injuries, making it the best choice for turning an unconscious patient in shallow water safely and effectively.