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FRIDAY, June 27, 2003 (HealthDayNews) -- A small, preliminary study has found that performing cardiopulmonary resuscitation (CPR) on a person who's lying on his stomach rather than on his back improves blood flow.
"This is very experimental, and we are not recommending anyone to start doing this," says Dr. Myron Weisfeldt, the lead author who did the study when he was chairman of medicine at Columbia Presbyterian Medical Center. But Weisfeldt, who is now chairman of the Johns Hopkins department of medicine, adds that the results are promising enough to conduct further research into the procedure.
The results of the study appear in the June issue of the journal Resuscitation.
Weisfeldt says that the study, which took four years to arrange because of the ethical considerations involved in trying a new technique on patients suffering from heart failure, is an effort to improve techniques for resuscitation.
"We know that the amount of blood flow in CPR is very modest, and for some years have been trying to develop new ways to improve blood flow using mechanical devices," he says.
"This is an effort to use the principles that we had been using for mechanical devices to instead devise something for people in the field to do with their hands," he adds.
The benefits of performing CPR on a person in the prone position seem to be clear: Because it is easier to apply pressure to the back than to the chest -- there's more room to maneuver and not worry about damaging the rib cage -- more force can be applied, which increases blood pressure.
The problem, Weisfeldt points out, is making sure a person can breathe when lying on his stomach. In the hospital study, the patients were given oxygen, though that wouldn't be true in a normal setting.
"We do not know how good or bad the ventilation would be on subjects [outside a hospital setting]," he says.
"This is a very small, early study on a very select population, but it shows a potential physiologic benefit in looking at blood pressure and blood flow, and gives some hope that in a certain population, prone CPR might increase blood flow," says Dr. Vinay Nadkarni, chairman of the emergency cardiovascular care committee of the American Heart Association and an associate professor of anesthesiology and critical care at the University of Pennyslyvania.
Another benefit, he says, could be the fact that in supine CPR, the tongue tends to fall back in the throat, blocking the airway, and in a prone position, the tongue might stick out, keeping the passage clearer.
Nadkarni adds that CPR originally was performed on patients in a prone position, when people were rescued from drowning and the aim was to push water out of their lungs.
"So this is sort of an exciting new look at an old technique," he says, "a first building block to look at CPR a little differently, but it isn't enough to make the American Heart Association change its recommendations."
These recommendations including performing CPR in the supine position, Nadkarni says.
For the study, CPR was tested on six critically ill patients already in Columbia Presbyterian's critical care unit because their hearts had stopped. They had failed to respond to standard CPR for at least a half-hour.
Toward the end of this period, an additional 15 minutes of standard CPR was performed on the patients while their blood pressure was monitored, and then the patients were turned over and given another 15 minutes of CPR while on their stomachs.
While prone, the doctors were able to increase the systolic blood pressure, which measures heartbeats, on the patients by an average of 34 millimeters of mercury, a statistically significant improvement. Also statistically improved was the average arterial blood flow pressure, by an average 14 mm.
The diastolic blood pressure, the resting rate of the heart, improved by an average of 10 mm, which was not statistically significant.
Each patient given reverse CPR in the study also had a 10-pound sandbag placed underneath his lower chest to stabilize his body while pressure was applied to his back. His head was turned to one side to allow him to breathe with oxygen supplied by a nurse.
None of the patients in the study survived, because of their condition before the reverse CPR was attempted.
But Weisfeldt says the statistical improvement in blood pressure and blood flow between the two CPR positions demonstrates the value of pursuing research into the optimal position for CPR.
More information
The National Heart, Lung and Blood Institute has an informative site on blood pressure. For an explanation of CPR, you can visit Amherst College.
