The Science Behind Trauma Care Dr. Bryan E. Bledsoe Professor, Emergency Medicine The George Washington University Medical Center
Audience Interaction • Which of the following actresses is my favorite? • A. Sandra Bullock • B. Angelina Jolie • C. Salma Hayek • D. Nicole Kidman • E. George Michael
Science in Trauma Care Positive Evidence Negative Evidence No Evidence Or Equivocal Evidence
Levels of Evidence • Not all scientific evidence is the same.
Audience Interaction • My ambulance service practices evidence-based prehospital care? • A. Strongly agree • B. Agree • C. Neither agree nor disagree • D. Disagree • E. Strongly disagree.
Levels of Evidence • Center for Evidence-Based Medicine (Oxford) Ia. Meta-analysis of RCTs Ib. One RCT. IIa. Controlled trial without randomisation. IIb. One other type of quasi-experimental study. III. Descriptive studies, such as comparative studies, correlation studies, and case-control studies. IV. Expert committee reports or opinions, or clinical experience of respected authorities or both.
Levels of Evidence • American Heart Association 1. Positive randomized controlled trials. 2. Neutral randomized controlled trials. 3. Prospective, non-randomized controlled trials. 4. Retrospective, non-randomized controlled trials 5. Case series (no control group) 6. Animal studies 7. Extrapolations 8. Rational conjecture (common sense)
Levels of Evidence • The closer a study adheres to the scientific method, the more valid the study. • The more valid the study, the closer it is to the truth.
Ranking the Evidence • Class I: • Derived from the strongest studies of therapeutic interventions (RCTs) in humans. • Used to support treatment recommendations of the highest order called practice standards.
Ranking the Evidence • Class II: • Derived from the comparative studies with less strength (nonrandomized cohort studies, RCTs with significant design flaws, and case-control studies). • Used to support recommendations called guidelines.
Ranking the Evidence • Class III: • Derived from the other sources of information, including case series and expert opinion. • Used to support practice options.
Ranking the Evidence • Overall term for all of the recommendations is practice parameters.
EMS Practice Changes • EMS Practices refuted by empiric evidence: • Critical Incident Stress Management (CISM) • MAST/PASG • Trendelenburg Position • High-Volume Fluid Resuscitation
EMS Practice Changes • EMS Practices unsupported by empiric evidence: • Medical Priority Dispatch • System Status Management • High-Dose Epinephrine • High-Dose Steroids for Acute Spinal Cord Injury • Intraosseous Needles • CPR Compression Vest
EMS Practice Changes • EMS Practice changes based upon empiric evidence: • AED usage (first 6-8 minutes) • CPR • Field death pronouncement in blunt traumatic cardiac arrest.
EMS Practice Changes • EMS Practices at risk for change because of empiric evidence: • Pediatric Endotracheal Intubation • Rapid Sequence Intubation (RSI) in Traumatic Brain Injury (TBI) • Endotracheal Intubation in TBI
Guiding Prehospital Care • There should be a link between the available evidence and treatment recommendations. • Empirical evidence should take precedence over expert judgement in the development of guidelines.
Guiding Prehospital Care • “In science, there are no authorities.” Carl Sagan, PhD 1934-1996
Guiding Prehospital Care 3. The available research should be searched using appropriate and comprehensive search terminology. 4. A thorough review of the scientific literature should precede guideline development.
Guiding Prehospital Care 5. The evidence should be evaluated and weighted, depending upon the scientific validity of the method used to generate the evidence. 6. The strength of the evidence should be reflected in the strength of the recommendations reflecting scientific certainty (or the lack thereof).
Guiding Prehospital Care 7. Expert judgement should be used to evaluate the quality of the literature and to formulate guidelines when the evidence is weak or nonexistent. 8. Guideline development should be a multidisciplinary process, involving key groups affected by the recommendations.
Audience Interaction • In regard to the OPALS study: • A. I follow the OPALS study regularly. • B. I have read some of the OPALS study papers. • C. I have heard of the OPALS study but not seen any results. • D. What is the OPALS study? • E. None of the above applies.
Empiric Research in EMS Phase I: Determined baseline survival rate for each study community (36 months) prior to Phase II. Phase II: Assessed the survival for 12 months after the introduction of rapid defibrillation and demonstrated that relatively inexpensive community rapid defibrillation programs increase survival for cardiac arrest patients (n=5,000+ patients). Phase III: Assessed survival outcomes months after the introduction of full ALS programs for 36 months for cardiac arrest patients and major trauma patients, and for 6 months for respiratory distress patients.
Empiric Research in EMS • Phase I: Survival improved with: • Decreasing EMS response intervals • Bystander-CPR • First responder CPR by fire or police • Phase II: Survival improved with: • Rapid defibrillation (survival increased from 3.9% to 5.2%) resulted in 33% improvement in survival • An additional 21 lives saved each year • Increased survival was also associated with bystander and first responder CPR.
Empiric Research in EMS • Phase III: • Cardiac Arrest: • The addition of advanced-life-support interventions did not improve the rate of survival after out-of-hospital cardiac arrest in a previously optimized emergency-medical-services system of rapid defibrillation. • 8-minute response time too long.
Empiric Research in EMS • Phase III: • Cardiac Arrest: • Most cardiac arrests occur in private locations (84.7%) compared to public places (15.3%). Communities should review locations of their cardiac arrests when designing CPR training and public access defibrillation programs.
Empiric Research in EMS • Phase III: • Cardiac Arrest: • Among ALS interventions, intubation, atropine and epinephrine had a negative association and only lidocaine had a positive association with survival. • Pediatric cardiac arrests are most often due to respiratory arrests or trauma, SIDS, trauma and drowning. • Citizen-initiated CPR is strongly and independently associated with better quality of life.
Empiric Research in EMS • Phase III: • Chest Pain: • Clearly showed important benefit from ALS programs for mortality and other outcomes.
Empiric Research in EMS • Phase III: • Respiratory Distress: • After adjustment for demographic, clinical, and EMS factors, the only interventions associated with better survival were salbutamol and NTG. • Most children are not severely ill, most do not receive ALS interventions, there is a high rate of non-transport, and the vast majority are discharged home from the ED.
Empiric Research in EMS • Phase III: • Pediatric Care: • The majority of patients did not require immediate or urgent medical care and had good short-term outcomes.
Science in Trauma Care • Practices with strong positive evidence: • Access to trauma centers • Specialized care (pediatrics, burns, spinal cord injury)
Science in Trauma Care • Practices with positive evidence: • Permissive hypotension • Splinting • Pain management • Head injury management • Hemoglobin-Based Oxygen Carrying Solutions (HBOCs)
Science in Trauma Care • Practices with no evidence or equivocal evidence: • The “Golden Hour” • Medical helicopters • Trendelenburg position • Traction splints • Rapid sequence intubation (RSI) in traumatic brain injury (TBI)
Science in Trauma Care • Practices with negative evidence: • MAST/PASG • Steroids for acute SCI • High-volume fluid therapy • Prehospital intubation in traumatic brain injury • Pediatric endotracheal intubation
Audience Participation • In regard to current prehospital practice in my system, which of the following best describes trauma care? • A. We still used MAST/PASG and administer large volumes of fluid to restore normal BP. • B. We do not use the MAST/PASG but administer large volumes of fluid to restore BP. • C. We administer enough fluid to maintain a blood pressure >100 mm Hg. • D. We administer enough fluid to maintain a blood pressure > 90 mm Hg. • E. We administer enough fluid to maintain a blood pressure > 80 mm Hg.
Science in Trauma Care • Practices with strong negative evidence: • Scene stabilization
Changes in US Trauma Practice • IV Fluid Restriction • Permissive Hypotension • Hemoglobin-Based Oxygen Carrying Solutions (HBOCs) • Less Aggressive Airway Management • Helicopter Overutilization
IV Fluid Restriction • Should prehospital personnel administer large volumes of IV fluids rapidly to trauma victims or delay fluid resuscitation until hospital arrival?
IV Fluid Restriction • Traditional approach to trauma patient with hypotension was 2 large bore IVs and wide open crystalloid administration.
IV Fluid Restriction • Recommendation has been to replace lost blood with isotonic crystalloids at a 3:1 ratio (IVF:blood loss)
IV Fluid Restriction • High volume IV fluid administration was based on several animal studies from the 1950s and 1960s.
IV Fluid Restriction • High volume IV fluid treatment was used in Viet Nam and transferred to US and western civilian prehospital care practices.
IV Fluid Restriction • Several animal studies in the 1980s and 1990s found that treatment with IV fluids before hemorrhage was controlled increased the mortality rate, especially if the BP was elevated.
IV Fluid Restriction • Raising the BP and restoring perfusion to vital organs are clearly believed to be beneficial afterhemorrhage is controlled. • Growing evidence indicates that raising it before achieving adequate hemostasis may be detrimental.
IV Fluid Restriction • Administering large quantities of IV fluids without controlling the hemorrhage results in: • hemodilution with decreased hematocrit • decreased available hemoglobin (and oxygen- carrying capacity) • decreased clotting factors. • This effect is found regardless of the fluid used (blood, LR, NS, hypertonic saline).