A 70-year-old male presents to EMS complaining of shortness of breath for the past hour. He hasn’t been ill recently and has never smoked. His blood pressure is 240/118, respiratory rate is 24, pulse is 118 and irregular, temperature is 98.9_ F, and his O2 saturation on room air is 86%.
On exam, he has diffuse wheezing, JVD and 3+ pitting pretibial edema. His medications include Lasix and digoxin. His past medical history is significant for myocardial infarction (MI) with stent placement and congestive heart failure (CHF). He also admits non-compliance with his physician’s recommended low-salt diet.
When I was a paramedic, we would have instinctively treated this patient with albuterol. The teaching at the time was to treat wheezing with albuterol, and rales with Lasix. Although we’ve a come long way in differentiating CHF from chronic obstructive pulmonary disorder (COPD) in the field, it’s still a commonly confused differentiation that may require review.
The Sounds of CHF
Rales are the sounds we hear when the alveoli are partially filled with fluid. The sounds are similar to when a child (or an adult) blows through a straw into their drink. But why don’t we hear rales when a patient is in severe pulmonary edema? A better question is: Why do we hear wheezing in the patient we’re confident has severe pulmonary edema?
The answer is that when the alveoli are completely filled with fluid, there isn’t enough room for those bubbles to form, giving us the sounds we hear as rales. In severe pulmonary edema, that fluid has no other place to go and the bronchi become swollen and constricted, giving us the sounds of wheezing. This wheezing is called Ë™cardiac asthma,à“ which causes confusion because these patients don’t necessarily have asthma.
CHF patients will typically present with elevated blood pressures and pedal edema, with their history often indicating abrupt onset of symptoms and their medications consistent with preload reducers and diuretics.
In contrast, COPD patients typically wheeze because the bronchi are constricted from irreversible destruction of lung tissue. The resulting narrowed passages for air give us the sounds we hear as wheezing.
But remember the limitations of”žlung sounds. The patient with severe COPD may be severely constricted to the point that little air is moving through, and we may not hear anything. Not treating this patient with albuterol or another bronchodilator because we don’t hear wheezing could be a catastrophic error. Rather than treating the”žlung sounds, we must remember to treat the patient. It’s interesting to note that the COPD patient without discernible”žlung sounds may start to wheeze after they receive bronchodilator therapy; the bronchi may become dilated enough to allow sufficient air to pass, resulting in wheezing.”ž
The Big Difference
CHF and COPD are distinctly different processes. Typically, CHF is a disease of the heart, and COPD is a disease of the lung. Thus, typical medications, history and exam findings will provide clues about the underlying condition.
CHF patients are often prescribed diuretics (e.g., Lasix), preload reducers (e.g., nitrates or isosorbide) and digoxin to help promote cardiac function and to reduce fluid loads on the heart. CHF exacerbations are typically brought on by dietary indiscretion (e.g., high salt intake), infection or ischemia.
COPD patients are often prescribed oxygen, bronchodilators (e.g., albuterol or Xopenex) and steroids (e.g., prednisone). These patients will often have a slower onset of symptoms than CHF patients. COPD exacerbations may be brought on by infection and other stressors.
COPD and CHF patients often have different physical exam findings, so taking a good history can help maximize your interpretation skills even before you’ve listened to the patient’s lungs. CHF patients will often exhibit very high blood pressures as a result of the Ë™fight or flightà“ response. They’ll also often have pedal edema and be unwilling to lie flat. Your CHF patient may describe indiscretion with salt intake, the progressive need for more pillows at night or even sleeping in a chair.
Smoking history is always important to address with your patients. If you’re treating a patient who has never smoked, you’re probably not looking at a patient with COPD. More than 90% of COPD patients have a long history of smoking. Another helpful sign is the presence or absence of a fever. The febrile patient is much more likely to have an infection that’s causing their respiratory symptoms.
Lung sounds should be recognized for their value and limitations. You may not be able to hear them on a noisy scene or in very large patients with shallow breathing. Thus, the type of”žlung sounds we hear or don’t hear must be used with other equally important patient information.”žLung sounds must be emphasized in training and SOPs as simply another tool in our armamentarium to evaluate and treat patients.
Steven Katz, MD, FACEP, EMT-P, is the associate medical director of Palm Beach County (Fla.) Fire Rescue and medical director of Florida Professional Firefighters. He’s also president of the National Paramedic Institute and member of the Street Medicine Society.