(USA TODAY) -- Blast injuries, caused by the sort of explosions that occurred in Boston Monday, can be some of the most difficult and complex injuries to treat.
The "blast wave" from the explosion acts like "an invisible wall of energy." Its tremendous energy can inflict massive internal injuries, says Mark Morocco, associate professor of emergency medicine, Ronald Reagan UCLA Medical Center.
"Blast injury is one of the most challenging constellation of injuries," says John Chovanes, trauma surgeon at Cooper University Hospital in Camden, N.J., and an Army reservist who has done three combat tours in Iraq and Afghanistan. He has treated dozens of blast victims.
In one explosive event, Chovanes says, a victim can suffer the blunt trauma of a high-speed auto accident from the high-pressure blast wave, the penetrating destruction of multiple bullet wounds from the shrapnel and potentially a swath of disfiguring burns.
The rapid pressure wave can instantly inflate the stomach with air, then immediately suck it out. Such pressure is many times worse than the sudden pressure changes that people feel in their ears when a plane changes altitude. The force can rupture intestines, collapse lungs and knock the brain around inside the skull, he says.
"You can have disruption of brain function without any physical finding," Morocco says. "You can have internal injuries even without any obvious bleeding."
Boston hospitals reported that many patients had injuries to their lower legs.
That's consistent with a bomb placed at ground level, such as in a backpack, Morocco says.
"Bits of leg can be blown away from the pressure wave, which is like a big wind," Morocco says. "It knocks you down."
In addition to creating a massive shock wave, an explosion can also cause shrapnel or other bits of metal to slice through flesh like a knife, Morocco says.
While no city is ever completely prepared for the kind of horror that beset Boston Monday, the city's emergency management system is about as good as it gets, says Richard Zane, chair of emergency medicine at the University of Colorado School of Medicine in Aurora.
"Boston has one of the most robust mass casualty plans of any city in the United States," says Zane, who previously worked in Boston's Brigham and Women's Hospital for 14 years. "I'm certain this response was so well orchestrated because they have planned for this before, they have drilled for this before."
Boston is home to some of the best regarded hospitals in the world.
Beyond the skill of its surgeons and staff, however, the city also has an integrated emergency response system - including police, fire and others - to coordinate and direct care in an emergency. That ensures that patients are portioned out to hospitals evenly, so that individual facilities aren't overwhelmed.
Coordinating care at the scene of a disaster can save lives, Morocco says, through making hard choices about which patients need to be taken first to a hospital, which can wait and which are too injured to even try.
Even patients with extensive injuries are likely to survive if treated within "the golden hour," Morocco says. Patients who languish more than an hour without treatment often don't make it.
That's a lesson doctors learned in World War II, Morocco says. Battlefield medicine in subsequent wars, including the wars in Iraq and Afghanistan, have taught civilian doctors better ways to save lives and treat serious injuries, he says.
"Everybody who's been deployed is really chilled by what we saw (in Boston) because it's such a familiar sight," says John Holcomb, a retired Army colonel who provided medical care to troops during several combat tours.
Current and former military doctors say the lessons learned from the carnage of roadside bomb explosions in Iraq and Afghanistan that left more than 1,700 American troops missing limbs after more than a decade of war, are being communicated to trauma systems nationwide and hopefully played a role in saving lives in Boston.
"The only silver lining of any war is really the advances in medical trauma care that comes out of it. A world-class expertise resides in the military with exactly these types of injuries," Holcomb says. "The surgical principles have been honed in Iraq and Afghanistan."
Andre Campbell, a trauma surgeon at San Francisco General Hospital, says, "The trauma surgeons and medics in Boston are going through what our military doctors go through."
Advances in the use of tourniquets, blood-clotting battle gauze, blood transfusion and surgery have led to about a 95% survival rate for the wounded of the wars in Iraq and Afghanistan, the greatest number of them blast injuries, doctors say.
Battlefield doctors also have learned to give blood transfusions earlier, instead of relying on saline, Campbell says. Special silver-containing dressings also can help burns heal, he says.
Many patients, and even physicians, have died to provide this information, Campbell says. "We learned a lot from their sacrifices," Campbell says.
The Iraq and Afghan wars also have brought about dramatic improvements in rehabilitation techniques and computerized prosthetics that provide significant improvements in long-term quality of life.
"When (victims) get to the point of being able to get up and around, we will certainly return the survivors to a pretty high functioning level sooner than I think would have happened previously," Holcomb says.
As for how this affects Americans psychologically, they once again will be hit with the feeling that "it could happen anywhere, close to us," said Laurie Richer, medical director of the Trauma Recovery Center at the University of California-San Francisco.
People will be on hyper alert all over the country. People might start to question whether they want to attend something that has a large crowd. Some events might be canceled."
Parents should ask their children what they've heard, and ideally keep them away from television and other visual images of the attack, Richer said. "Some of those images are going to be very difficult and you don't want to expose children to that, it can have long and lasting effects."
Mostly parents need to reassure children that they will be safe and that their families, their teachers and the police are there to keep them safe.
The good news is that in general people are very resilient. "I happen to see the 5 to 15% of people who don't recover easily from trauma," said Richer, a psychiatrist who specializes in treating those who've been in conflict zones and exposed to violence. "But close to 85% of the people who experience trauma will recover fully and there won't be any lingering symptoms. We need to remember how resilient human beings are."