Circulation

Check the casualty’s pulse for rate, rhythm, ad character. If a radial pulse is present their systolic blood pressure is likely above 80 mmHg. If the radial pulse is not present but the carotid is, the systolic BP is likely above 60 mmHg. Additionally, check the capillary refill time (CRT) on the head or sternum by pressing for 5 seconds, a CRT of more then 2 seconds indicates poor perfusion (but consider cold effect).
Check for major internal or external haemorrhage using the mnemonic “one of the floor (external bleeding) and four more (internal bleeding).”

External Haemorrhage: Check around the casualty, under the casualty, and inside any waterproof clothing (“One on the floor”). If a major bleed is found, control the bleed with pressure, wound packing, or using a tourniquet. Review the catastrophic bleeding guidance (https://rescuevector.com/primary-survey-catastrophic-bleed/) for more details.

Internal Haemorrhage: Check the chest, abdominal cavity, pelvis, and long bones (“and four more”) for signs of bleeding. Consider the potential for major internal bleeding with any significant chest trauma, due to possibility for injuries such as haemothorax. Check the four quadrants of the abdomen for tenderness, distension, rigidity, or bruising. Check the pelvic ring for pain or instability, and check the legs for signs of shortening or abnormal rotation. Check the long bones (e.g. femurs) for fracture, signs of deformity, shortening, or swelling.