You encounter someone collapsed on the sidewalk and quickly dial 911. 

Whether or not the operator instructs you on how to deliver cardiopulmonary resuscitation (CPR) could mean life or death, especially if the victim is female, new research shows.

In a study involving nearly 2,400 emergency calls for cardiac arrest in North Carolina, rates for bystander CPR rose dramatically when the 911 operator helped guide the caller.  

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Without such assistance CPR was performed just 11% of the time for male victims and 9% for female victims, but those rates climbed to 40% and 44%, respectively, when 911 callers got help from operators. 

“Prompt delivery of CPR doubles a patient's chance of survival from out of hospital cardiac arrest,” said study lead author Audrey Blewer, assistant professor of family medicine at Duke University School of Medicine in Durham, N.C.

“What encourages me from a research standpoint is that there are so many opportunities to increase that number, and that’s really a matter of everybody working together and working towards the chain of survival from cardiac arrest,” Blewer said in a Duke news release.

The new findings were presented Monday at the American Heart Association’s Resuscitation Science Symposium in Chicago.

Blewer and colleagues looked at data from a seven-year study of responses by bystanders and others to cardiac arrest. The effort is a collaboration between Duke Clinical Research Institute and other hospitals and emergency medical agencies across North Carolina, and is funded by the National Institutes of Health.

Brewer said the hesitancy of some to perform CPR on women has been noted before.

“We know, based off of prior qualitative studies, some of the reasons why people are hesitant to do CPR on women center around the fear of being perceived as touching them inappropriately,” she said. “There's also that aspect of frailty. Some women are smaller. There are concerns, especially when the person in need of CPR is elderly, that whoever is performing CPR on them may be breaking the ribs, hurting them, harming them.”

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Overall, the new data showed that CPR was performed in 52% of cases, with 911 operator assistance a big factor in whether bystanders performed the procedure.

How might things improve, especially for female victims of cardiac arrest?

According to Brewer, the standard mannikin used to train folks for CPR hasn't changed much in the past three decades. Something as simple as creating CPR mannikins with breasts could help some people get past some of their hesitancy in performing the procedure on women.

Because these findings were presented at a medical meeting, they should be considered preliminary until published in a peer-reviewed journal.