The first thing to remember about CPR is that if it is necessary the person is dead to begin with, so you can't do any further harm. Everything else is statistics.
That said, my department has just completed their part in a multi-year, multi-city North American study. At variation with the generally accepted AHA standards, our department (4th largest in North America) concentrated on early defib taking priority over all else. As I understand it, the study was designed to answer the "chicken and an egg" question: is it more important to circulate oxygenated blood or to re-establish a normal heart ryhthm?
I have not seen a formal report or analysis of the data as yet. But when we received our new protocols a few weeks ago, the defib has been dramatically de-emphasized in favour of early and efficient CPR compressions -- even ahead of establishing an airway. I leave you to draw your own conclusions as to the study's findings.
Personally, I have brought back several people with CPR alone. In two cases we captured the event on the monitor. The first was under the old AHA standard of 1 minute of CPR followed by de-fib. One rescuer was doing compressions, another airway (BVM over OPA) and the third was connecting electrodes. The strip showed compressions modulated by v-fib, then a couple of irregular QRS complexes and a cessation of CPR (more on that in a moment) and a gradual steadying into normal sinus rhythm. Respirations returned very shortly thereafter.
In the second case, Px was reported as choking. I connected the SAED, Px was asystole, and we proceeded to CPR. We could not establish an airway and I proceeded to abdominal thrusts alternating with attempted CPR. Thrusts would not clear the airway but brought a piece of meat up just far enough to be grasped with forceps and extracted. Shortly after O2 was introduced by BVM (but prior to intubation and drug therapy), we detected a spontaneous return of pulse during compressions. After a few minutes of bagging only, (and epinephrine etc.) respirations returned.
In both these cases, the return of pulse was detected early. Why? Because I was taught to monitor carotid pulse periodically during compressions to verify effectiveness. I felt the return of pulse. Femoral pulse is great and all, but we are really concerned with oxygenating the brain -- not the legs. It is a simple matter for a rescuer performing an inverse jaw thrust to reach down with one finger and verify a pulse. Not only does a natural pulse feel different, it's really obvious when it occurs between compressions.
I do not present these cases as typical, but as documented proof of the fallacy that early defib is the only effective treatment. Early defib is merely one tool in the bag.
Finally, I would like to address the issue of performing compressions in the water. There is no doubt that attempting compressions on any patient that is not supine on a flat surface is difficult. I always prefer to slide the px out of bed and onto the floor. But in some cases it is necessary to slide a backboard underneath the victim (or between the victim and the seat back) and work with what you have for the moment. The advantage in SCUBA is that the patient is already wearing a backboard. It would be very awkward, tiring and difficult, but if I was in the water with a VSA diver, I would attempt compressions for at least one minute (or until surface support arrived, whichever occured first) with one hand -- the other would be under the diver's backplate/BCD stabilizing us to each other.
Just my 2¢.
