Big problems for small lungs  pg. 3

“When we breathe, our bodies use negative pressure to pull air in,” Rojas explains. “In artificial respiration, it’s very different. In these babies, it is just like blowing up a balloon. Positive air pressure creates sheer stress that damages the lung.”

Damage can occur in just the first few resuscitative breaths given to premature lungs through a ventilator. The longer a baby remains on a ventilator, the higher the risk of infection and a side effect called pneumothorax, in which the tiniest tubes leading to the deepest airways rupture.

Physicians and neonatal nurse practitioners must race to seal leaks in the lung -- like patching a tire on race day -- so that effective ventilation can resume. This collapsing and re-inflating, however, can tear up the sticky lung tissue.

Mario Rojas, M.D., examines a premature baby in the Neonatal Intensive Care Unit at the Monroe Carell Jr. Children’s Hospital at Vanderbilt.
Photo by Susan Urmy 

Studying the role of the ventilator in causing BPD is difficult to do in the United States, says Rojas, an associate professor of Pediatrics, “because we use ventilators so commonly here.”

But in Rojas’ native country Colombia, ventilators are in short supply. There, it is easier to study a less aggressive technique, called continuous positive airway pressure, or CPAP.

CPAP is frequently used in the United States to treat adults with sleep apnea, in which breathing is interrupted for long periods during sleep. The CPAP machine blows an oxygen mixture into the airways through the nose, and at a much lower pressure than do ventilators because the air can escape through the mouth if pressure gets too high.

Rojas and his colleagues in Colombia studied nearly 300 infants born at 27 to 32 weeks with signs of respiratory distress. “Our results showed that babies managed with nasal CPAP and very early surfactant, up to 74 percent of babies in this gestational age category with respiratory distress did well, and would not have required mechanical ventilation,” Rojas says.

Their study, published in the January 2009 journal Pediatrics, has helped fuel efforts to decrease ventilator use in premature infants.

“But even with the gentlest sorts of things we do, many times if the lungs are extremely premature, they simply don’t develop anatomically as they perhaps would if they had not been delivered so prematurely,” Stahlman says.

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