Potential Pitfalls of Lung Auscultation

Scenario

It’s 0200 and pouring down rain and the call notes read “HUSBAND TALKING TO DEAD PEOPLE x2 DAYS.” The patient is 76. You mentally go over the list of assessments you should perform first.

The wife is distressed but a good historian. Her husband is not aggressive, denies any illness or injury at all, but continually and sincerely speaks to an empty patch of carpet. You speak with his wife, who says that he has no history of dementia, Alzheimer’s, psychotic disorders or any similar behavior. He began having these one-sided conversations about two days ago, after an entirely normal day at their house. He’s usually healthy, running his own business, taking only Atorvastatin for his heart health.

The obvious steps lead nowhere. His blood pressure is 128/88, heart rate is 90 and blood sugar is 104. He has no facial droop, speaks clearly and moves all of his limbs with purpose. He has a mild fever at about 100.8. His pupils are PERRL. His skin is a normal color, warm, and dry. He speaks in complete sentences without obvious difficulty and shows no signs of accessory muscle use.

Despite this, your partner directs you to the clear culprit: his oxygen saturation is 86, with a good pleth wave that matches his heart rate precisely. His lung sounds are high-pitched whistles on expiration in every field.

Take Lung Sounds Habitually

Taking lung sounds on every patient you encounter is a good practice. There are a number of apps and lung sound libraries that are reasonably priced and even free put together by intelligent, resourceful and community-minded individuals. However, at the end of the day, recordings never sound precisely like noises patients produce.

Furthermore, while most of the time it is immediately apparent whether or not the respiratory system is playing a role in a patient’s condition, over a career you will catch enough patients who are unexpectedly in respiratory failure to warrant the habit.

However, like so many things done in medicine, clear lung sounds can and will never be a rule-out lung pathology. Even when correctly identified, they still may not direct you to the correct lung pathology.

You Can’t Always Hear the Swelling or Fluids

Auscultation is the art of listening to the sounds the lungs are making with a stethoscope and attempting to connect those noises with what is happening physiologically to the respiratory system.¹ Quiet sounds resembling a gentle breeze going through tall grass are normal. Sounds of whistling tend to indicate bronchoconstriction, often caused by disease process like asthma or anaphylaxis. Sounds that are gurgling or like crispy rice cereal that’s just had milk poured on it tend to indicate fluid in the lungs. These sounds can be heard in one or all fields as well as on inhalation, exhalation, or both. There are also many other lung sounds that indicate more subtle disease processes but being able to reliably identify clear wheezing and rales is sufficient for most prehospital providers. Obviously noting the total absence of lung sounds, particularly in trauma or unconscious patients, is also very important.

It’s also crucial to be humble and acknowledge the role of hearing loss in this particular assessment.² An estimated 40% of firefighters have reduced hearing, an inevitable result of spending so much time around sirens and loud machines. If you know you are among this number, either use a digital stethoscope where you can turn up the volume or have a trusted coworker with less damaged ears check the lungs for you.

However, even when you can clearly hear them, normal lung sounds do not rule out lung pathology.¹ Constriction, fluid buildup and many other pathologies can exist without ever changing the lung sounds. Lung sound changes have a high “specificity” in many pathologies. For example, one meta-study that combined and summarized 34 studies on the efficacy of lung sounds, found that the specificity of lung sounds changes for pneumonia is 0.9. Which means that if a patient has rales and a history consistent with pneumonia, there’s a 90% chance they have pneumonia. However, it’s only 0.33 sensitive. Which means that when a patient has pneumonia, the chance that the provider will hear rails is just about one in three. Lung sound changes in trauma, luckily, are much more reliable. The sensitivity of lung sound decreases in hemo- or pneumothorax is 0.7 and the specificity is 0.9.

To summarize: What this study teaches us is that lung sounds can be a rule-in but never a rule-out. Abnormal lung sounds can indicate an underlying respiratory disease but normal lung sounds can never rule it out.

Wheezing Can Conceal Fluid in Lungs

You’re presented with a patient who’s short of breath, with accessory muscle use and tripoding. Their oxygen saturation is low, and you can hear clear and obvious inspiratory and expiratory wheezing across all fields. This patient is clearly suffering from a bronchoconstriction and needs some sympathomimetics, right? Case closed?

Not so fast. There is another trick that lung sounds can play on you: Wheezing can actually be both a response to and means of concealing fluid.³ The lungs fill with fluid due to some heart failure or pneumonia, and they become irritated. They swell and constrict in response to this fluid. While you may only hear the wheezes, and the wheezes are objectively there, this patient’s underlying problem is entirely due to fluid buildup in the lungs.

There are a few ways to try and figure this out. If the patient has a fever and report of a productive cough with green and yellow sputum, consider pneumonia as the underlying issue. Albuterol can help reduce wheezing and shortness of breath in pneumonia and is therefore an appropriate initial treatment.⁴ However, albuterol is only a band-aid that will provide symptom relief without ever addressing the underlying issue. It’s still important to correctly identify the underlying pathology so the patient goes to the hospital and is provided medication to eradicate whatever organism is trying to live in their lungs.

Conversely, if this patient is very hypertensive, diaphoretic, and has a history of heart failure or current chest pain, consider a cardiac pulmonary edema.³ Any beta agonists, such as albuterol or epi, are contraindicated as they can worsen this patient’s condition by putting unnecessary strain on their heart.

Unfortunately, there is no perfect or even reliable way to avoid making this mistake. Be aware that this is a possibility and consider cardiac wheezing in situations where the patient’s shortness of breath persists after treatment for the wheezing or when the history is more consistent with a fluid buildup than bronchospasm. High flow oxygen is an appropriate and safe treatment for a hypoxic patient, even if the lung sounds clarify nothing at all.

Scenario Conclusion

The patient’s wife denies that he has any history of asthma, COPD, emphysema, or any lung pathology. Furthermore, he has no lip or tongue swelling, rash, or diarrhea that would indicate this is anaphylaxis.

His saturation and wheezing improve dramatically following a breathing treatment with beta agonists. Afterwards, you can hear what his fever already suggested to you: the sound of coarse bubbling in every lung field, loudest and most apparent in his right lower lobe. You make sure the patient continues to sit up and monitor for worsening hypoxia, further mental status changes or returning wheezes.

You hand off the patient to your favorite night shift nurse, who thanks you for taking the time to put in two lines.

He’s admitted but discharged a week later. He finishes his lengthy course of antibiotics and returns to his electrician business and marriage whole and unharmed.

Works Cited

1. Arts, L., Lim, E. H. T., van de Ven, P. M., Heunks, L., & Tuinman, P. R. (2020). The diagnostic accuracy of lung auscultation in adult patients with acute pulmonary pathologies: a meta-analysis. Scientific reports, 10(1), 7347. https://doi.org/10.1038/s41598-020-64405-6
2. DiGiovanna, S. (2024, August 19). Preventing hearing loss for firefighters. Lexipol. https://www.lexipol.com/resources/blog/can-you-hear-me-now-preventing-hearing-loss-for-firefighters/#:~:text=40%25%20of%20firefighters%20have%20noticeable,get%20the%20treatment%20we%20need.
3. American Heart Association. (2025) Heart failure signs and symptoms. Heart.org. https://www.heart.org/en/health-topics/heart-failure/warning-signs-of-heart-failure
4. Scheffler, M., Taggart, K., Kappes, J., Adrian, M., and Netfield, R. (2022). Albuterol and Levalbuterol utilization in pneumonia. Avera McKennon Hospital and University Health Center Conference.