1956: The A-B-Cs of CPR are born

In 1949,  Dr. James Elam, an anesthesiologist, investigated old records of how mouth to mouth breathing was used on newborn infants.  While trying to save the life of a boy, he used this method and it worked.  This was the beginning of the re-birth of mouth to mouth resuscitation.  (1)

I say re-birth because when the Royal Humane Society was established in 1773, mouth to mouth resuscitation was recommended as one of many options for reanimating victims of near drownings. It as later removed from the list due to complaints that it was gross and unhygienic. The Sylvester and Shaefer methods of reanimation were added in its place.

Dr. Elam and Dr. Peter Safar would prove that neither the Sylvester nor Shaefer method provided enough tidal volume, although mouth to mouth breathing did. So this brought back the method once thought to be gross and unhygienic.

Also recommended by the Humane Society back in 1773 were chest compressions and abdominal thrusts, and these were ultimately phased out.

By the 1890s chloroform was a common anaesthetic during operations. Occasionally a patient would go into what was then referred to as "chloroform syncopy." This was a term used to describe patient's who stopped breathing and ceased to have a heartbeat, or who were in cardiac arrest. Physicians had no treatment for this, and so it was almost always fatal. (3, page 6)

However, in his 1891 book, "General Surgery," Dr. Franz Koenig of Germany described using "external cardiac massage" to treat such a patient at the University of Goettingen. He recommended compression of the chest over the heart at a rate the person would spontaneously breathe. He later settled on a rate of 30-40 per minute, and recommended chest compressions during "chloroform sycopy" instead of one of the other methods of resuscitation.  (3, page 6) (4, page 2968)

A search was ongoing to determine the optimal rate to perform chest compressions. The first official recommendation was to perform 60 compressions per minute. (3, page 6) (4, page 2968)

A year later, a resident at the University of Goettingen, Dr. Fredrick Maass, and a student to Dr. Koenig, published a paper in the Berlin Clinical Weekly called "Resuscitation technique following cardiac death after inhalation of chloroform." Here he described the first successful use of external cardiac massage. He observed a clinical response from the patient at a compression rate of 120 per minute.  (3, page 6) (4, page 2968)

Ever since then the rate of chest compressions has been the subject of much debate and many studies. The recommendation as of March 28, 2010, by the American Heart Association is 100 per minute. The main reason for choosing this number is seems to be effective and easy to remember.

Studies during the 1940s showed that chest compressions stimulated blood to circulate through the body, and this was essential during artificial resuscitation.  This revolutionary idea transformed artificial respiration to cardiopulmonary resuscitation, otherwise known as CPR.

In 1956, while having a conversation with Dr. Elam, Dr. Peter Safar came up with the following anagram for artificial resuscitation: (1)

• A (Airway)
• B (Breathing)

Although the anagram was later changed to:

• A (Airway)
• B (Breathing)
• C (Circulation)

Thus was the beginning of the modern A-B-C's of artificial resuscitation, now more commonly referred to as cardiopulmonary resuscitation, or CPR). It was taught to all the citizens of the world who aspired, or were required by their employers, to save lives.

The American Heart Association officially endorsed CPR in 1963, and in 1966 adapted their first guidelines for performing CPR. These guidelines are reviewed every five years and updated.

A most significant change came on October 8, 2010. Here the decision was made to change A-B-C to C-A-B. The reason for the change was noted in the "2010 Guidelines for CPR and ECC: "

There are many reasons for this change. First, this change allows rescuers to begin chest compressions right away. As we know, most victims of sudden cardiac arrest (SCA) receive no bystander CPR. One of the reasons for this may be that the A-B-C CPR sequence began with opening the airway, the most difficult and daunting task for the rescuer. This change attempts to decrease the barriers to performing CPR by allowing the rescuer to start with chest compressions. Also, the vast majority of SCAs occur in adults who suffer a witnessed arrest and ventricular fibrillation or pulseless ventricular tachycardia. In these victims, critical elements of resuscitation are chest compressions and early defibrillation, which can begin earlier if there is no delay to open the airway and provide breaths. The process of opening the airway (which may involve getting a barrier device or setting up ventilation equipment) takes time and delays the start of CPR. Using the C-A-B sequence lessens this delay. 

For those not familiar with the terms "ventricular fibrillation" or "pulseless ventricular tachycardia," these are names for life threatening cardiac arrhythmias, or ineffective heart rhythms. This change included adults, children and infants, but not newborn infants. The ABC algorithm should be used for newborns, because "newborn cardiac arrest is most often respiratory."

The American Heart Association made one other change to increase the chances that CPR would be performed by bystanders: it removed the recommendation to perform mouth to mouth breathing. Once coming upon a witnessed or non-witnessed cardiac arrest, and once confirming that the person is non-responsive, the recommendation is now to perform effective chest compressions until emergency responders are on the scene. 

Modern studies also proved the following: 

• Mouth to mouth breathing provided enough positive pressure, coupled with the natural recoil of the chest after a compression, to allow for enough ventilation to occur. 
• That circulation was far more important than breathing (It may also be underestood that chest compressions causes pressure changes within the chest to allow for ventilation to occur, thus eliminating the need for mouth to mouth breathing.) 
• That bystanders were more likely to do CPR when all they had to do was chest compressions

That's all I'm going to write about CPR. 

References: 

1. Donahue, Mary, "History of Lifesaving," DeAnza Collegge, http://faculty.deanza.edu/donahuemary/Historyoflifesaving, accessed 8/10/13
2. "2010 AHA Guidelines for CPR & ECC," American Heart Association, 2010, http://cpr.heart.org/idc/groups/heart-public/@wcm/@ecc/documents/downloadable/ucm_317319.pdf, accessed March 28, 2010
3. Figl, Marcus,  et al., "Resuscitation Great: Franz Koenig and Friedrich Maass," Resuscitation, July, 2006, 70, pages 6-9
4. Nolan, Jerry P., et al, "Editorials: Chest Compression Rate: Where Is The Sweet Spot?" Circulation, 2012, 125, pages 2968-2970)