The cardiopulmonary resuscitation, or CPR, delivered to Michael Jackson by his personal physician may not have been as effective as it could have been, heart experts told ABC News based on a transcript of the 9-1-1 call placed from Michael Jackson's Los Angeles mansion on the day of his death.
The transcript, which documents a call that Los Angeles emergency dispatchers received at 12:21 p.m. last Thursday, revealed that Jackson lay on a bed while receiving CPR from his personal physician Dr. Conrad Murray -- not on a floor or other hard surface as CPR experts suggest.
In was a point that the 9-1-1 dispatcher actually raised in his conversation with Jackson's security staff at the time of the emergency call.
"Do you have him on the floor? Where's he at right now?" the operator asked.
"He's on the bed sir," the caller responded. "He's on the bed. We need [paramedics]."
"Let's get him on the floor," the operator responded.
During his appearance on "Good Morning America" on Monday, Murray's attorney Ed Chernoff confirmed that Murray began administering CPR while Michael Jackson was lying on a bed.
"He did administer CPR on the bed," Chernoff said. "The bed is a very firm bed. He braced Michael Jackson's back with his hand under his back and compressed his chest with the other hand."
The American Heart Association recommends that cardiac arrest victims lie on a hard surface while receiving CPR -- usually either a backboard or the floor.
The reason for this, said Dr. Benjamin Abella of the University of Pennsylvania's Center for Resuscitation Science, is backed by research that suggests performing compressions while the patient is lying on a surface that is softer than the ground essentially robs the compressions of the power needed to keep blood flowing through the body until help arrives.
"When CPR is performed on a mattress, much of the 'depth' of compression is absorbed by the mattress, so that the chest does not move as much as it should," Abella said. "Chest compression depth is one of the most important characteristics of CPR, and several studies from our group and others have confirmed that better depth leads to better outcomes,"
Dr. Douglas Zipes, professor of cardiology at the Indiana University School of Medicine and past president of the American College of Cardiology, agreed. "[It's] very difficult to impossible to do CPR in bed; [there's] no leverage, no firm support, [and] no neck extension."
In certain cases, though, those performing CPR may be forced to resort to a less solid surface. Dr. Deepak Bhatt, director of the Integrated Interventional Cardiovascular Program at Brigham and Women's Hospital in Boston, said that depending on the circumstances, CPR on a softer surface can still be somewhat effective.
"Whether to move them if they are on an uneven or soft surface is not always clear," Bhatt said. "If moving the patient would delay instituting CPR -- if you were the only person in the area and could not easily lift them, for example -- it might make sense to start right away and scream out for help and then move the patient when a second responder arrives.
"It really is a matter of trying to use good judgment and weighing the risks of delaying potentially adequate CPR while aiming for perfect CPR," he said.