2012 Bill T. Teague Lectureship Summary - May 17, 2012
John Holcomb Addresses the 16th Annual Bill T. Teague lectureship: Damage Control Resuscitation
John B. Holcomb, MD, FACS, Professor and Vice Chair of Surgery, University of Texas Health Science Center, Houston, TX, was honored on May 17, 2012 with the prestigious Bill T. Teague Lectureship in Transfusion Medicine by Gulf Coast Regional Blood Center in Houston.
In his lecture Damage Control Resuscitation, Dr. Holcomb focused on: 1) data describing current transfusion practices in the ongoing war, 2) data supporting damage control resuscitation and how this concept may benefit the civilian population, and 3) limitations of these recommendations, based on currently available retrospective data and the need for well-designed prospective clinical trials.
Military conflict has always driven advances in medicine and surgery. New concepts in caring for the injured have been refined over time. Between 2003 and 2009, only 10% U.S. servicemen wounded in Iraq and Afghanistan died, compared with 24% in the first Gulf War and Vietnam War. The new approach of managing major trauma is known as damage control resuscitation (DCR), which is the resuscitation of the massively bleeding patient to restore physiology and hemostasis with the goal of increasing patient survival. Many of these advances are applied to trauma care in the civilian setting.
Dr. Holcomb next defined the lethal triad, which consists of hypothermia, acidosis, and coagulopathy. When the lethal triad is present in the most severely injured patients, death is imminent. DCR is actually an overall approach to treat the condition of severe hemorrhage and to avoid the concomitant deleterious effects on physiology. The concept of “permissive” hypotension is used to decrease the bleeding from uncontrolled bleeding points, warming the patient to avoid the coagulopathic effects of hypothermia, and the treatment of severe acidosis.
Among trauma patients, approximately 10% are severely injured, which also represent the majority of in-hospital trauma deaths. In current practices, the resuscitation fluid is crystalloids, which is the appropriate policy for the approximately 90% of trauma patients who are not in shock and are hypercoagulable after injury. However, for the approximately 10% most seriously injured, who are in shock and coagulopathic, liquid plasma is the optimal resuscitation fluid. Unwarmed crystalloids can simultaneously cause a dilutional coagulopathy and be a major cause for hypothermia, whereas an inadequately corrected shock state can result in acidosis. Lactated Ringer’s solution and normal saline are reported to cause increasing reperfusion injury and leukocyte adhesion, which may worsen the presenting acidosis and coagulopathy in severely injured trauma patients.
When replacing the blood lost after severe trauma, the logical ratio of blood components is 1:1:1 of plasma:red cells:platelets, which is the ratio found in whole blood. Retrospective analysis of data from combat and civilian trauma patients who received a massive transfusion (>10 units of blood in 24 hours) indicates a survival benefit for patients receiving a high ratio of plasma and platelets, for example, 3-5 liters of Ringer’s Lactate, 7 RBCs, 6 FFP, and 1 apheresis platelets.
The future of DCR is the use of dried/lyophilized components including lyophilized fibrinogen; frozen and freeze-dried platelets or lyophilized platelets; dried plasma; and stem-cell derived red blood cells and lyophilized red cells. For the military, it can be hard to find and store red cells for use on the battlefield. The Defense Advanced Research Project Agency (DARPA) “blood pharming” program was established with the aim of developing a system that can make red blood cells from progenitor cells on the battlefield.
Dr. Holcomb summarized DCR as follows: stop the bleeding; manage hypotensive resuscitation; minimize the use of crystalloid; and use more plasma and platelets to resuscitate patients, to reverse hypothermia, and to manage acidosis. Use blood products early and as a primary resuscitation fluid by placing blood products (RBCs, plasma, and platelets) in the emergency department and pre-hospital. Instead of transfusing blood components in a fixed, empiric ratio, there is a need to define the specific needs of the rapidly hemorrhaging patient and target blood components that are actually deficient in the intravascular space. Use new diagnostic tools. Thromboelastography is faster than conventional lab values and have documented improvement of coagulation with component therapy. Finally, predictive models are here but more preclinical and large prospective and randomized human studies with improved study design and analysis are needed.