1. The Science Behind Chest
Compressions
Matthew Sholl, MD MPH, FACEP
Maine Medical Center/MaineHealth

2. Curr Op Crit Care 2004;10:208-212

4. Excellent Chest Compressions
are the Foundation of Survival!

5. 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?

8. What’s The Big Deal?
Do Chest Compressions Really Work?

13. • 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

15. 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

16. 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

17. Benbrow, B –6th Annual Symposium on Neurologic Emergencies and Neurocritical Care , June 2009, NYC, NY

18. 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…

20. Three Phase Model of
Resuscitation

21. 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

22. The Message may Not Have Been
Received….

24. • 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….

25. 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

26. 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

27. Questions?

28. Thank You