Science behind chest compressions
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The Science Behind Chest Compressions
Matthew Sholl, MD MPH, FACEP
Maine Medical Center/MaineHealth
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Curr Op Crit Care 2004;10:208-212
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Excellent Chest Compressions are the Foundation of Survival!
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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?
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What’s The Big Deal?Do Chest Compressions Really Work?
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• 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
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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
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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 compression2. 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
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Benbrow, B –6th Annual Symposium on Neurologic Emergencies and Neurocritical Care , June 2009, NYC, NY
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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…
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Three Phase Model of Resuscitation
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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
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The Message may Not Have Been Received….
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• 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….
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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
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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
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Questions?
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Thank You