Science behind chest compressions

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Science behind chest compressions

  1. 1. The Science Behind Chest Compressions Matthew Sholl, MD MPH, FACEP Maine Medical Center/MaineHealth
  2. 2. Curr Op Crit Care 2004;10:208-212
  3. 3. Excellent Chest Compressions are the Foundation of Survival!
  4. 4. Recent Changes in ACLS? • Most recent AHA changes (2005/2010)attempted to highlight the importance of uninterrupted chest compressions and limited the positive pressure ventilation rate to 8 – 12 breaths per minute Why focus on minimally interrupted chest compressions and limiting positive pressure ventilation?
  5. 5. What’s The Big Deal? Do Chest Compressions Really Work?
  6. 6. • While in early phases of OHCA (< 5 min), no benefit to bystander CPR existed • As time to shock increased, see increasing survival benefit of bystander CPR • No survivors seen if collapse to shock interval > 15 minutes
  7. 7. The Most Important Treatment You Offer… • … is effective chest compressions • Effective means: – Right rate (at least 100) – Right depth (2.5 inches or 5 cm) – Relax – allow for recoil – NO interruptions – Avoid excessive ventilations • Despite our best ALS capabilities, our BLS skills are what appears to be most important
  8. 8. Cardio-cerebral Resuscitation (CCR) • Based on the Three Phase Model of resuscitation • Generated in AZ –the AZ Sarver Heart Center Goals: 1. Minimize interruptions of chest compression 2. Provide immediate post-shock chest compressions for prolonged VF – Why is that important? 3. Delay or eliminate endotracheal intubation 4. Minimize all positive pressure ventilation 5. Decrease the time interval to IV Epinephrine
  9. 9. Benbrow, B –6th Annual Symposium on Neurologic Emergencies and Neurocritical Care , June 2009, NYC, NY
  10. 10. A New Horizon for OHCA… • Two new thoughts on OHCA: 1.Primary and Secondary Injury – Primary injury – cardiac arrest – Secondary injury – brain injury • Even if we can obtain ROSC – still see large numbers of deaths • These deaths predominantly due to hypoxic brain injury – Target of therapeutic hypothermia 2.Three Phase Model for Resuscitation…
  11. 11. Three Phase Model of Resuscitation
  12. 12. Minimizing Positive Pressure Ventilation • Old Paradigm: – ABC’s – M2M/BVM/ETT to deliver high flow O2 • New Concepts: – Positive pressure ventilation increases intrathoracic pressure – Increased intrathoracic pressure decreases venous return – Resultant decrease in coronary and cerebral blood flow • SO… AHA has recommended RR of 8 – 12 breaths/minute
  13. 13. The Message may Not Have Been Received….
  14. 14. • Observational study of EMS practitioners performing CPR • Measured ventilation rate • Average rate = 37 +/- 3 per minute – Range 15-49 – Recall: BLS/ACLS recommends 8-12 • Second part of the study….
  15. 15. Disadvantages to Ventilations During CPR • Delays/Interrupts chest compressions • Complicated • Stops bystanders from doing CPR • Gastric inflation – aspiration • Increases intrathoracic pressure – Reducing coronary/cerebral perfusion • Animal models show worse outocme
  16. 16. What Have We Learned So Far? • OHCA happens to a lot of people!! – One of the top causes of death • There remain opportunities to save lives – Especially through engaging laypersons and both PAD programs as well as by-stander CPR • New ACLS/BLS protocols attempted to improve well preformed, continuous chest compressions with minimal interruptions • Despite these recommendations, still see many interruptions and too aggressive ventilation
  17. 17. Questions?
  18. 18. Thank You

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