CPR (cardiopulmonary resuscitation) without mouth-to-mouth rescue breathing? It is called continuous chest compression CPR or compression only CPR and requires no rescue breaths. Several studies suggest that continuous chest compression CPR for adults that collapse suddenly presumably due to cardiac arrest is just as good as standard CPR or possibly even better. Okay, perhaps you are thinking... no way! What about 15:2 or the newer 30:2 compressions to breaths I learned in CPR class?
Researchers from Seattle, Tucson, and Japan have shown that bystander CPR is equally effective or better when performed with chest compressions alone compared to standard CPR with alternating compressions and rescue breaths. Why would this be? Isn't the point of CPR to breath for the person and to circulate their blood by compressing the chest? Right... but the blood is well oxygenated when somebody suddenly collapses from cardiac arrest (i.e., heart stops pumping). Thus, rescue breaths are not really necessary to get oxygen into the blood... rather chest compressions are most important to get needed blood flowing to the brain and heart's myocardium. In fact, delaying the compressions in order to perform breathing might actually reduce the effectiveness of CPR. The technical details are reviewed in Circulation by Dr. Gordon Ewy of the University of Arizona Sarver Heart Center. It seems the oxygenated blood in the body can support the heart and brain for several minutes as long as it is circulated adequately via chest compressions.
Some communities are already teaching continuous chest compression CPR... some have called this new CPR "Call and Pump" referring to the need to call 911 and then begin 100 chest compressions per minute until "the patient or paramedics tell you to stop" or until you can't continue. A very short and detailed tutorial on continuous chest compression CPR is published in Circulation. Go read it! This type of CPR is not recommended in children or when respiratory arrest is suspected such as drowning, drug/alcohol overdose, choking, severe asthma or carbon monoxide poisoning... in these cases CPR with mouth-to-mouth breathing is needed to help oxygenate the blood since the primary problem is not the heart but a lack of oxygen (i.e., suffocation) that eventually leads to cardiac arrest.
A study published in Nov. 2007 (Circulation) used a swine (pig) model of out-of-hospital cardiac arrest with bystander CPR to compare continuous chest compression (CCC) CPR with standard 30:2 compression to breaths CPR. Animals in cardiac arrest for varying amounts of time (3-6 minutes) due to ventricular fibrillation then underwent either CCC or Standard CPR. After 12 total minutes of fibrillation (cardiac arrest), defibrillation was performed using advanced cardiac life support standard guidelines. In essence, this study simulated a collapse, followed by some delay to the start of bystander CPR followed by later arrival of medics that initiated defibrillation. Then 24-hr after the resuscitation, survival and neurological state were evaluated. Neurologically normal survival at 24 hours after resuscitation was observed in 23 of 33 (70%) of the animals in the continuous chest compression group compared with only 13 of 31 (42%) in the standard 30:2 CPR group. Thus, CCC CPR improved survival with normal neurological function compared with standard CPR. Of course, this is an animal study and not humans. Nevertheless, the results are compelling and suggest that mouth-to-mouth might not be needed and could even be detrimental in the case of sudden cardiac arrest. Why? The idea is that the continuous compressions increase cerebral and coronary blood flow and thus improve survival. Interruptions in chest compressions required for rescue breathing reduce perfusion to the heart and brain which could explain the reduced survival and neurological outcomes with 30:2 CPR in this animal study.
The key potential benefit of compression only CPR is the idea that more bystanders would initiate and perform CPR if it is simple to remember and it does not require mouth-to-mouth contact.
This recent research might be changing the way you learn bystander CPR in the near future... well probably not until 2010 when the American Heart Association will review and revise CPR guidelines. But CPR can be easy and the key is to do it!
Finally, CPR helps save lives but ultimately defibrillation (shocking) of the heart is needed for the patient to recover from cardiac arrest. The faster this happens the better. Automated external defibrillators (AEDs) are becoming common place in gyms, malls, and airplanes. The faster bystanders or medics can shock the heart back into rhythm then the better the survival rate for the subject. Interestingly, after about 5 minutes of cardiac arrest, performing compressions immediately before and after the defibrillator shock appears to help survival rates. IN 1999 a study by the University of Washington and Seattle Fire Dept showed improved survival if medics performed 90 seconds of CPR immediately before automated external defibrillation was attempted (JAMA link). Basically, if the subject had been collapsed for 4-5 minutes or longer then CPR (with the goal of 150 compressions in 90 seconds) prior to any attempt to shock the heart actually improved survival. In a Norwegian study, 3 minutes of standard CPR was performed by arriving emergency personnel prior to attempts to shock the heart compared with immediate attempts to shock the heart (JAMA link). Overall, no difference in survival rates was observed until researchers examined the survival of subjects with ambulance arrival times greater than 5 minutes after collapse. In these subjects, 3 minutes of CPR prior to defibrillation significantly improved survival to hospital discharge (22% in the CPR first group versus 4% in the immediate defibrillation group). See figure below.