A doctor with intimate knowledge of the medical response to the 2013 Boston Marathon bombing told Lehigh Valley EMS responders about lessons learned from the event and told his audience preparedness, drills and professionalism helped save lives after two bombs detonated last year near the finish line of the iconic race.

Leon Sanchez M.D., vice chair for emergency medicine at Beth Israel Deaconess Medical Center, one of five Level 1 trauma centers located within two miles of the marathon finish line near Copley Square, used a video of the bombing and aftermath, prepared by the Boston Globe, to describe the medical response to the bombing.

The video was overlaid by the real-time radio transmissions of medical responders to demonstrate how quickly medical professionals assessed the incident as a mass casualty event and organized 27 area hospitals to prepare to receive casualties.

The seminar for area EMS crews and other first responders was organized by the Lehigh Valley Health Network as part of the network's annual observation of national Emergency Services Week. The event was held in the Kasych Family Pavilion at the network's Lehigh Valley Hospital Cedar Crest Campus in Salisbury Township.

Since the annual marathon event in Boston draws such a wide-spread following of runners and spectators, the Boston medical community has a long history of extensive medical treatment for runners at the end of the race.

Medical practitioners, from volunteers to nurses, doctors and ambulance and other EMS personnel, were available at the finish line and at a large temporary medical facility set up in a tent nearby. The medical personnel are staged to treat runners suffering from any number of ailments at the end of the long race.

When the first of two bombs was detonated near the finish line, it took only moments, Sanchez said, for supervising medical personnel to turn the response from runner comfort to a multiple trauma response.

Three persons were killed instantly in the bombing and an estimated 264 were injured, some 40 of the victims were seriously injured, Sanchez said.

Within seconds, National Guardsmen were dismantling the barricade fences separating the runners on Boylston Street from spectators, allowing clinicians to get to the victims in less than a minute.

Approximately 100 wheelchairs on the scene, staged to transport collapsing runners to the medical tent, served to get the injured to the tent for triage and transport.

One of the first orders over the medical radio system was for all ambulance personnel to report to their units and stay there for subsequent transport. The ambulances were lined up at the rear of the medical tent to receive and transport the most critical patients first.

"Usually that happens in the reverse order," Sanchez said. "Hospitals usually see the least injured first, with the more severely wounded following after EMS units are dispatched and arrive at the scene. But, because of the large number of clinical people near the site, the immediate set-up of an operations center and effective triage available, we got people to our trauma centers in the right order."

There are five Level 1 hospital trauma centers in the city of Boston, all within two miles of the bombing site, Sanchez said.

Because the pressure cooker bombs used in the incident were left in backpacks among spectators at the race, there were a large number of lower extremity injuries, Sanchez said. Several victims lost one or more limbs as a result of the explosions.

"The availability of a large number of (military-style) tourniquets was a critical factor in stemming blood loss from victims and undoubtedly a number of lives were saved by the quick application of tourniquets to injured limbs," Sanchez said.

Sanchez said transport of 41 percent of patients with critical injuries was made within 30 minutes of the bombing; 75 percent were transported within 45 minutes and all transports were made within the first hour. Ambulance crews made 118 hospital transports of victims.

Prompt assessment of the incident and mass radio notification of all area hospitals within minutes gave hospital personnel eight-to-nine-minutes of heads-up time to organize and prepare for mass casualties, Sanchez said.

The medical response did not end on the day of the Monday bombing, Sanchez said. On Friday of that week the cities of Boston, Cambridge, Watertown and other nearby areas were on lockdown during the manhunt for the second identified bomber.

Sanchez said a great deal of creative medical personnel scheduling, housing and feeding was necessary to comply with the "stay home" order issued by law enforcement authorities. The large number of investigating officers within hospital facilities also required a great deal of "on the fly" accommodation, he said.

The most critical factor in responding to unthinkable events such as the bombing, Sanchez said, was the preparation, the brainstorming of possible scenarios, and the medical staff and EMS drills which made a bad situation manageable.

"The fact that no victims died after the initial blast was a testament to all the preparation and professionalism of the medical and EMS communities," Sanchez said.