April 23, 2008

The Ups and Downs of Mechanical Ventilation

Posted in Articles of Interest tagged , , , , , at 10:25 am by D. Borst

So mechanical ventilators are perhaps one of the most important advances in critical care medicine ever. Critically ill patients get too ill to manage their own breathing, and to make sure that their bodies get enough of an air supply, hooking them up to a machine for hours or days has saved countless lives. It has also enabled many invasive surgeries that require the use of drugs that suppress the respiratory drive along with consciousness.

But as with all medical advances, ventilators do come with a cost. When a ventilator is put in, the physician sticks a tube down the patients trachea to make sure that air is going into the patients lungs and not into her stomach. Having a tube stuck down one’s throat precludes much movement, and also slightly abrades the surfaces it comes in contact with. This is postulated to cause the increase in nosocomial, or hospital acquired, infections such as pneumonia.

On March 27, 2008, Sanford Levine and Joseph Shrager, et. al. published a paper in the New England Journal on yet another problem that faces use (especially extended use) of ventilators. The diaphragm is the muscle in the chest that drives the work of the lungs. As such, like the heart it is working 24 hours a day, until one is put on ventilation. Levine and Shrager et. al. showed that time spent on mechanical ventilation led to rapid atrophy of the diaphragm muscles.

This is particularly worrying, because it means that being on a ventilator makes it harder to get off one. It is thus particularly essential that physicians try to minimize the time that patients spend on the vent.

The study only went into patients who were on the ventilator for 72 hours, however it is not uncommon for folks to be on the ventilator for weeks in the ICU. We need ventilators, that is clear, but we must be aware of the problems they present as much as we are aware of the good they can do.

For those of you with access to the Journal: http://content.nejm.org/cgi/reprint/358/13/1327.pdf

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