G Uidelines for W Ithholding or T Ermination of R Esuscitation in P Rehospital T Raumatic C Ardiopulmonary a Rrest : A J Oint P Osition P Aper From the N Ational a Ssociation of Ems P Hysicians S Tandards and C Linical P Ractice C Ommittee and the a Merican C Ollege of S Urgeons C Ommittee on T Rauma