A22-year-old man sustains a gunshot wound to the left chest and is transported to a small community hospital at which surgical capabilities are not available. in the emergency department, a chest tube is inserted and 700 ml of blood is evacuated. the trauma center accepts the patient in transfer. just before the patient is placed in the ambulance for transfer, his blood pressure decreases to 80/68 mm hg and his heart rate increases to 136 beats per minute. the next step should be to