The response time for Boston’s emergency medical personnel to arrive at the scene of heart attacks, shootings, and other serious incidents has slowed in recent years, largely because of a little-understood surge in calls for help, city officials said.
The median response time for the most serious, or Priority 1, cases has trended upward since 2009, when it was 5.5 minutes. During 2014, it climbed to 6.4 minutes, above the agency’s own goal of 6 minutes, according to data provided to the Globe by Boston Emergency Medical Services.
This year, through the end of October, the median response time was 6.8 minutes for Priority 1 cases.
“Obviously, I worry that the times have gone up,” Boston EMS chief James Hooley said. “We really have to pay close attention to it.”
However, he said, “We haven’t seen that there has been any negative impact on our patients and their outcomes, and that’s the ultimate thing we have to look for.”
Boston EMS said it has seen a 26 percent rise in calls over the past decade, and said that the increase has driven a rise in response times.
The slower response times in Boston are similar to those in other cities, including San Jose, Calif., and Washington.
Boston EMS said it has seen a 26 percent rise in calls over the past decade, from about 95,500 in 2005 to about 120,000 in 2014. The agency said the increase in calls has driven the rise in response times.
“The call volume is way up. It’s a very, very busy system,” said James Orsino, union president of the EMS division of the Boston Police Patrolmen’s Association.
Priority 1 calls include heart attacks, uncontrollable arterial bleeding, and unconsciousness. Similar increases in response times have been seen in recent years for less-serious Priority 2 and Priority 3 calls.
Boston EMS officials said they have taken a number of steps in recent years to speed up response times.
The agency, which has 350 full-time staff, expanded its uniformed personnel by about 14 percent and added ambulances between 2008 and 2010. It also has staff work overtime hours when needed.
The agency opened a new EMS station, the 16th in the city, in downtown Boston several years ago. The agency is also working with city officials to find a home for a new EMS station in the burgeoning Innovation District.
And the agency just opened a new, larger EMS garage in Mattapan that it expects will improve response times in the surrounding neighborhood.
Agency officials also noted that they must balance speed against the risks that come with having ambulances career through busy streets.
While emphasizing the steps they have taken to address response-time issues, EMS officials also point to research in recent years suggesting that faster response times aren’t necessarily linked to better outcomes for patients.
The research found that only certain types of emergencies, such as heart attacks, serious blood loss, and airway obstructions, are time-sensitive.
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