Breathing Liquids: Reality Or Science Fiction

Charlotte and Louis Marley were just informed that if they would give permission to the physician to fill their 18-month-old baby with liquid similar to Teflon, their baby girl would have a chance of surviving the respiratory distress that she was now experiencing! Charlotte, having had trouble getting pregnant in the first place, was especially frantic about her only child.

At C.S. Mott Children's Hospital in Ann Arbor, Michigan, Dr. Ronald B. Hirschl, a pediatric surgeon, and a few other others were the first physicians to give this treatment called "liquid ventilation" to over 270 adults and children in small-scale experimental trials over the past 10 years. These patients were doomed to die of respiratory failure if treatment was not performed. The success rate of this procedure was between 25-50% without any harmful side effects.

What We Need to Know

What is respiratory distress? What is the process called ventilation?
Name the parts of the airway to the lung tissue.
How is gas exchanged in the airways?

Fluid in the lungs is normally associated with drowning--that is, when the fluid is water or normal body secretions. Delicate air sacs, called alveoli, are thin membranes where gases are exchanged. If there are body fluids accumulating in these alveoli, as in cases of pneumonia and other medical conditions, the air sacs collapse and cannot be filled with air. This causes respiratory distress to the patient. However, when air is replaced by this Teflon-like liquid called perfluorocarbon, a colorless, odorless biologically inert fluid, breathing can continue as usual; but instead of air going into and out of the lungs, it is a liquid! The liquid replaces the unwanted body fluid with a liquid that can carry a high amount of gas. Therefore, the alveoli become inflated again with a liquid instead of air. The idea is that the liquid, perfluorocarbon, is a gentler way to send valuable oxygen into the lungs and carbon dioxide out than forcing air into lungs of patients who are already having a hard time breathing.

What We Need to Know

How would water or fluids in the thin alveoli cause them to collapse and be unable to exchange air? Can you think of an analogy to something that you have observed in the physical world?
Respiratory distress causes breathing to be very difficult. Predict why this is true.
Why can the physicians use the perfluorocarbon instead of air? Why not water?
Why would the perfluorocarbon be easier to breathe than water or body fluids?

About 10 years ago pulmonologists devised a machine to add oxygen, remove carbon dioxide, warm, and perfuse the liquid to the lungs. Recently, doctors at 45 hospitals will test 450 gravely ill patients. It is reported that 35 to 40 of these patients will survive, who would not without the treatment. Charlotte and Louis have been offered the experimental trial for their hopelessly sick infant.

What We Need to Know

If you were the Marleys, what decision would you reach?
What are the chances of their child surviving when it would otherwise die?
Do you support research on terminally ill patients?

Assignment

Are you opposed to clinical trials such as this one just described? Why or why not? Write an essay to describe the ethical stand that you are taking on clinical trials.

Pretend that you are a representative of the drug company that is going to make the perfluorocarbon available for general use. Discuss the issues with the Marleys to persuade them to use the experimental product.

RESOURCES

Wayt, W. 1999. Breath of fresh liquid: saving the sick by flooding their lungs. Scientific American. February, pp. 40-41.

http://www.med.unipi.it/patchir/bloodl/bmr/artif.htm#s1