It’s a paradigm shift for a field that has a 200-year history with the stethoscope.Įxperimental models need to be designed to include measurement of injury, from cellular to whole organ level, along with measurement of sound. Since no one has ever viewed lung sounds as a cause of disease, they have not been investigating it. Grotberg: Well, this is completely new territory. How do you see this new understanding impacting diagnoses or treatments? The sequence is very damaging to the cells, and again they respond with inflammation and injury. The gurgling is a mixture of liquid and air with popping bubbles, just like a fluid-overloaded lung. The sound mechanism is very similar to drinking through a straw when you get down to the last sips at the bottom of the cup. Grotberg: Crackles are ruptures of liquid plugs in the smaller airway tubes that pop open during inspiration. Asthma already involves inflammation of the airway tubes in the lung, so wheezing likely just makes things worse.Īnd what’s going on when patients inhale and produce a crackling sound? Grotberg: Vibrating the lung cells makes them promote inflammation which damages the lung. The pitch you hear is the frequency of oscillation of the balloon material, which for a lung would be the airway tube made of cells. An asthmatic lung airway is similar because it is constricted to a small narrow passageway. Grotberg: Wheezing is very much like the sound from a deflating balloon when you make it squeal by stretching the outlet. What exactly is happening when a sick patient wheezes as they exhale?

That is a 180-degree thought reversal from interpreting them as only a “sign” of disease.īreak this down for us a bit more. We’ve seen evidence of this in our experiments. So wheezes and crackles actually “cause” disease. The cells respond with inflammation, which, itself, is a disease. They make the sound, and that mechanical event is also pounding away on the lung tissue. The physical mechanisms that cause wheezing and crackling, while smaller forces than a cough, are similar. Ouch!Īs an extreme example, the loudest sound a lung generates is a severe cough, which can cause, in rare instances, a pneumothorax (ruptured lung), i.e. If you clap hard enough, your hands will hurt. Grotberg: Well, for a sound to be created, a mechanical event must occur, like clapping your hands. You’ve found that sounds could represent more than just the presence of a disease. Pulmonary edema is a common example, often a byproduct of heart failure. Crackles, on the other hand, are only heard by a stethoscope and are a sign of too much fluid in the lung.

Patients who wheeze can be so loud you can hear it standing next to them. Grotberg: Typically, wheezing is found in asthma and emphysema. These wheezes and crackles are signs of what diseases? There are normal sounds of air movement, but also there can be abnormal sounds, like wheezes during expiration (breathing out) and crackles during inspiration (breathing in). For the lungs, typically the patient is asked to breathe in and out deeply. Grotberg: Two important organs being monitored are the heart and the lungs. When doctors pull out a stethoscope, what are they listening for? He answered some questions about the research. And they represent a paradigm shift for how doctors understand what they hear through a stethoscope. The findings could eventually change how lung diseases are treated, he says. Exploring this in humans is a research goal. His conclusion is based on evidence from experiments on microfluidic chips and on animal models. James Grotberg, professor of biomedical engineering at the College of Engineering and professor of surgery at the Medical School, recently published a study describing how the mechanics that produce those noises with every breath are likely a cause of injury and inflammation.

Pleurisy lung sounds