With the organization of trauma systems, the development of trauma centers, the application of standardized methods of resuscitation, and improvements in modern blood banking techniques, the ability to aggressively resuscitate patients in extremis has evolved. The concept of the "golden hour" has translated into unprecedented speed and efficiency of trauma resuscitation with the ultimate goal of short injury-to-incision times. As the shift in care of patients in extremis has continued to move from the street to the emergency department and beyond, the focus of trauma resuscitation has shifted to the operating room and ultimately to the intensive care unit. The "new" golden hour may well be the time in the operating room before the patient reaches the physiologic limit, defined as the onset of the triad: hypothermia, acidosis and coagulopathy. Critical care nurses must understand this triad, because it forms the basis and underlying logic on which the damage control philosophy has been built. This article explores the pathogenesis and treatment of acidosis, hypothermia, and coagulopathy as it applies to the exsanguinating trauma patient.