Helmet fire
Although a head first loaded patient is safer rotary than in other forms of transport, the patient does much worse than if feet first. The reason is the attitude change occurs before the acceleration and the uncompensated G force raises intracranial pressure
When we fly ITU patients we have a pressure transducer inside an artery, often inside the head and increasingly now we are doing continuous ultrasound of the blood vessels. These are parameters HEMS do not routinely use so they do not pick up these problems.
Will send you the paper