patents whose respiratory muscles were paralyzed. Iron lungs worked by negative pressure generated with a big bellows. "There was this horrible racket. It was like a vacuum cleaner running all the time," recalls David Glass, M.D., chair of anesthesiology at Dartmouth and director of the ICU from 1977 to 1987. As a patient lay inside an iron lung, its negative pressure caused the chest to expand so air could enter the lungs. Then the chest collapsed, forcing air out of the lungs.

But there weren't always enough iron lungs to go around. Physicians found that they could manually deliver air to a patient by squeezing an inflatable bag attached to a tracheostomy tube. "Actually, medical students were the primary ventilators through the big polio epidemics of Europe in the early part of the '50s," says Glass. "They would take shifts, studying and so forth, . . . just ventilating patients" around the clock—sometimes 70 patients at a time. The concept of volumecontrolled ventilation evolved from this practice. The first such device, developed in 1963, was driven by a piston and delivered a fixed amount of air with each breath.

The next advance was portable ventilators that didn't require electricity. These were a great boon during the Vietnam War. "It was all done on pressurized gas and magnets," explains Glass. While everbetter respirators and ventilators were great at helping patients breathe, they could create problems, too. First "it became apparent that if you started to ventilate people, . . . and didn't provide humidity, that mucus would get really thick and they'd plug up and have complications," Glass says. A further complication arose in the late '50s and early '60s as sicker people—with stiffer lungs—were ventilated. Pressurized air alone couldn't force its way into stiff lungs, so ventilators had to be developed that would push the air in.

Boston-based entrepreneur John Emerson, who had improved on the iron lung design, invented an early volume-controlled ventilator. It looked like a green washing machine and used a system of valves and an old airplane piston to

Photos by Jon Gilbert Fox

The equipment in today's ICU would amaze those who staffed the 1955 unit—but the idea of concentrating well-trained and attentive staff has remained a part of the concept, too.

deliver precise volumes of air. "He added a humidifier, a little pressure cooker that put humidity in," says Glass, who knew Emerson personally. "The whole thing was built out of a hardware store, literally."

Early on, Glass arranged for DHMC to get a prototype of an Emerson high-frequency ventilator, which delivered air at many times the rate of other ventilators and was particularly beneficial for babies in the intensive-care nursery. Emerson also designed a timing device that allowed two ventilators to deliver air separately to the lungs of the same patient. Though some people considered Emerson "a little bubble off plumb," recalls Glass, "he was a great innovator . . . a very bright and interesting guy."

But even these improved ventilators could cause trouble. True, they saved lives, but sometimes survivors' lungs would become permanently injured. "We'd have people survive their illness and then be pulmonary cripples basically—because their lung had healed, but it had healed in such scar tissue that they were debilitated for the rest of their life," says Glass. "So that led to more research and different kinds of ventilators. Now they're all electronic flow generators. . . . [We] keep the pressures down and humidify much more fancily. So we're still able to keep people alive much longer, but we don't have nearly the ventilator-induced trauma that was the product of the '70s and '80s when we were sort of learning."

Mosenthal even introduced a few innovations back in the 1950s that seemed high-tech for the times. One was a mattress that would gently turn a patient. "It was a plastic mattress with two long, sausage-shaped compartments in it," Mosenthal said in the 1988 interview. "There was a motor that was an old vacuum cleaner motor. There was an outlet for each of these tubes, and they'd blow up. . . . There was a timer on the motor and an automatic reversal. And you get some old patient who was a sitting duck for . . . postoperative pneumonia and death. In the old days, you used to get them up and make them turn over, bang 'em." He clapped his hands for effect. But with the special mattress, as the "sausages" alternately inflated and deflated, the patient would be gently tilted back and forth. "I thought this was the greatest device known to man," recalled Mosenthal.

He also recognized early on the importance of bed scales. "I remember when this ICU was being formed, there was no way to weigh a patient who was in bed," Mosenthal said. He knew that maintaining fluid balance depends on many factors, including a patient's weight, so he wanted to order an expensive forklift-like bed scale. "You put [the patient] in there," he explained, "lifted him up, weighed him, and dropped him back."

Early on, Glass arranged for DHMC to get a prototype of an Emerson high-frequency ventilator, which delivered air at many times the rate of other ventilators. Emerson also designed a timing device that allowed two ventilators to deliver air separately to the lungs of the same patient.

So Mosenthal went to Dr. Bowler, then president of the Clinic. "I said, 'Bowler, we've got this special care unit set up here, which will not be effective until we can weigh patients who are in bed. Weigh them any time we want.' I told him about these bed scales, costing about $1,500... maybe more than that—the price of a car maybe—to be able to do this. He