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COLUMBIA-PRESBYTERIAN MEDICAL CENTER
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BREATHABLE LIQUID USED TO TREAT RESPIRATORY DISTRESS
NEW YORK, NY, MARCH 24, 1997 -- A breathable liquid for treating children in acute respiratory distress is undergoing clinical trials Columbia-Presbyterian Medical Center.
The liquid, called perflubron, is administered to the lungs with a conventional respirator, explains Charles Stolar, MD, Professor of Surgery and Pediatrics at Columbia-Presbyterian's Babies & Children's Hospital. To initiate the treatment, perflubron is slowly poured through the child's airway and into the lungs, filling the tiny air sacs, or alveoli, where gases are exchanged with the bloodstream. Each cycle of the respirator oxygenates the liquid, which in turn nourishes the alveoli.
"When a child is in respiratory distress, the alveoli tend to collapse and stiffen," says Dr. Stolar, explaining how this technique, known as partial liquid ventilation (PLV), works. "But if you get rid of the air in the lung and replace it with a liquid such as perflubron, it eases the surface tension of the lung. The lung then relaxes and opens up, allowing blood to enter the tissue and do what it is supposed to: pick up oxygen and get rid of CO2."
Studies show that perflubron is safe and well tolerated in humans. Only trivial amounts of this clear, colorless fluid are absorbed into the bloodstream. In preliminary clinical tests, PLV reduced the need for high ventilatory pressures, which can injure the lungs.
Dr. Stolar and his colleagues are now testing PLV to determine whether it improves patient survival and reduces length of stay in the intensive care unit. Thus far, more than 100 children with acute respiratory distress syndrome have been treated in the FDA-approved study at more than 40 different sites, including Babies & Children's Hospital. It is too early to draw any conclusions from the trials, but Dr. Stolar, one of the principal investigators, does call the initial results "promising."
PLV is administered in the intensive care unit. Since the fluid evaporates, it must be replenished every couple of hours. As with standard ventilator care, patients are sedated and fed intravenously during the treatment period, which can last up to five days in the current trials. In many cases, improvement is seen within 15 minutes.
According to Dr. Stolar, PLV is a potential treatment for all types of respiratory failure and for patients of all ages. Among the causes of respiratory failure are pneumonia, trauma, and aspiration of substances into the lungs. Respiratory failure also occurs in immunocompromised patients, such as those with cancer or AIDS. PLV may also serve as a treatment for severe asthma, Dr. Stolar speculates.
The idea for liquid ventilation has been around since WWI, when doctors searched in vain for a way to treat soldiers who inhaled mustard gas on the battlefield. Over the years, scientists experimented with a variety of liquids that can carry oxygen, including vegetable, mineral, and silicone oils. But each substance was plagued with a critical problem. "Once you get it into the lungs, you can't get it out," says Dr. Stolar.
A big breakthrough occurred during WWII, when scientists in the Manhattan Project developed a new class of chemicals for cooling atomic reactors. The chemicals, called perfluorocarbons (organic compounds in which the carbon atoms are replaced by fluorine atoms), turned out to be ideal for liquid ventilation: they can be saturated with oxygen, they are inert, and they evaporate. It also turns out that perfluorocarbons act like surfactant, which is usually lacking in injured lungs. (A naturally occurring pulmonary lubricant, surfactant helps to keep the alveoli inflated.) In addition, perfluorocarbons appear to lessen inflammation in injured lungs.
These observations led to clinical experiments with total liquid ventilation in the 1960s and 1970s. However, the results were disappointing, in part because of problems with the special ventilatKeywords: AMERICAN PSYCHIATRIC PSYCHIATRY MENTAL MEDICINE PSYCHOLOGY PSYCHIATRIST SCHIZ
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