When a hospital patient goes into cardiac arrest, doctors and nurses perform cardiopulmonary resuscitation, or CPR, which includes chest compressions that need to be deep enough to move blood out of the heart and toward the rest of the body.

But when the rescuer is short and the victim is on a hospital bed there's a problem: It's hard to get enough leverage to press down on the chest, and the rescuer has to rely on upper-body strength.

It would seem logical that giving rescuers a boost with a step stool could help.

But equipping every hospital crash cart with a step stool is an expense, noted Dr. Dana P. Edelson of the University of Chicago Medical Center, the lead researcher on the new study.

A stool like the one in your kitchen is not good enough: It has to be of the sturdy, industrial variety, Edelson told Reuters Health.

So hospitals will first want to know whether step stools actually improve CPR quality.

To find out, Edelson and her colleagues had 50 people at their hospital, all trained in CPR, perform chest compressions on a mannequin. Each did two two-minute rounds while standing on the floor, and two while on a nine-inch-high step stool.

The mannequin was outfitted with a sensor that recorded the depth of the chest compressions and other measures of CPR quality.

Overall, the step stool worked best if the rescuer was about 5 feet, 6 inches or shorter, Edelson's team reports in the journal Resuscitation.

On average, the depth of their chest compressions increased by about a centimeter -- which is significant, according to Edelson. It suggests that shorter rescuers "may get a big benefit" from using a step stool, she said.

On the other hand, taller rescuers increased their compression depth by only two-tenths of a centimeter. And that seemed to be offset by too much "leaning."

Between compressions, the rescuer has to let up enough to allow the chest to "recoil" so the heart can fill back up with blood, Edelson explained. And if a taller person stands on a step stool, it's harder to pull his or her weight back.

"We were a little surprised by the unintended consequence of leaning," Edelson noted.

The study was not large enough to set a hard-and-fast height cutoff for using a step stool, according to Edelson. But based on their results, the researchers write, it seems "reasonable" for rescuers who are about 5 feet, 6 inches or shorter to use a stool.

Regardless, Edelson said, shorter people should also always lower the hospital bed.

Since this study used mannequins, no one knows if step stools can help save lives.

But researchers do know that the depth of chest compressions matters.

In cardiac arrest, the heart stops pumping blood to the rest of the body, often because it goes into a chaotic quivering known as ventricular fibrillation. If that happens, CPR chest compressions can keep blood and oxygen flowing to the rest of the body; but the only way to get the heart pumping on its own again is with a defibrillator or with certain drugs.

Even with those efforts, though, cardiac arrest is often fatal. The survival rate for in-hospital cardiac arrest hovers around 17 percent.

In an earlier study, however, Edelson's team found that a half-centimeter increase in compression depth doubled the odds that an actual cardiac arrest victim's heart could then be successfully "shocked" back into a normal rhythm with a defibrillator.

SOURCE: bit.ly/HbJm9D Resuscitation, online March 16, 2012.

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