Inspiratory Crackles: Is it Pneumonia or is it Congestive Heart Failure?
Short Summary:
Two most common root causes of inspiratory crackles are CHF and pneumonia. CHF is most likely to present as bilateral inspiratory crackles while pneumonia is most likely to present as unilateral inspiratory crackles. Ruling out one of the two ailments is simple and often only requires a history and physical exam.
Pneumonia and congestive heart failure (CHF): Both diagnoses can present with inspiratory crackles
An 85 year old male patient is complaining of shortness of breath with activity as well as lethargy for two weeks. Inspiratory crackles can be heard on auscultation over the posterior aspect of the left lower lobe.
Knowing nothing else about the patient, which diagnosis is more likely? Pneumonia.
Why do we hear inspiratory crackles? Pleural effusion, indirectly.
A common misconception is that the fluid involved in a pleural effusion is the direct cause of the inspiratory crackles. In reality, the crackles result from mucus in the alveolar space. In a pleural effusion, the affected lungs expansion is restricted. Therefore, normal mucus transport pathways are also restricted. Mucus then builds up in the alveolar space of the affected side and cause inspiratory crackles.
Why is this important to understand?
Congestive heart failure and pneumonia will both cause pleural effusions, but in different ways. There are two types of pleural effusions: transudative and and exudative.
- Transudative Pleural Effusion: This occurs when fluid is forced out of capillaries and into the pleural space due to increased capillary pressure. This scenario most commonly results from CHF. Because the capillary pressure tends to be virtually equal in both the right and left lungs, a transudative pleural effusion will most likely result in bilateral inspiratory crackles.
- Exudative Pleural Effusion: This occurs when there is an inflammatory process due to injury or infection of the pleura. Fluid is secreted into the affected area as part of the inflammatory process in an effort to repair the injury or neutralize the infection. This scenario most commonly results from pneumonia. In most cases, an exudative pleural effusion will present as unilateral inspiratory crackles.
- Transudative Pleural Effusion: In rare cases, this can present as unilateral inspiratory crackles. If it does, it almost always presents as right sided inspiratory crackles. This is because of the slight pressure difference between the right lung capillaries and the left lung capillaries. This is rare and may occur in early stages where a right sided pleural effusion forms shortly before a left sided pleural effusion is also formed.
- Exudative Pleural Effusion: In cases of severe bilaterally infiltrated pneumonia, the presentation may include bilateral inspiratory crackles due to bilateral pleural effusions.
My Patient Today:
85 year old male patient with cc of SOB and lethargy for two weeks. Inspiratory crackles over the left lower lung fields. Positive history of CHF but negative for ankle edema. Weights have been stable and he denies any urinary retention. I was now confident that this was acute bacterial lobar pneumonia. Today's research was prompted because I wondered, "What is the likelihood of this being a CHF exacerbation?"
Xray confirmation: significant bilateral infiltrates with left pleural effusion.
Xray confirmation: significant bilateral infiltrates with left pleural effusion.
Diagnosis: Pneumonia
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