PreClass Case Summary

Synopsis: Ms. Petrovich is a 37 year old female who presents to the ED with three days of progressive shortness of breath accompanied by cough, subjective fever, and fatigue. Her history is significant for being a smoker and using oral contraceptive pills. Her vital signs are notable for a temperature of 38.3C, HR of 112, RR of 24, and room air O2 saturation of 94%. Her lung exam is notable for rales at the right base with egophony. The team considers pneumonia to be the most likely diagnosis and VTE to be less likely. Her rapid SARS-CoV-2 PCR is negative and her CXR does NOT reveal a consolidation leading to discussion of thresholds and testing to rule out pulmonary embolism. There is a discussion about D-dimer and CTPA in relation to LRs and the resultant impact on the threshold to test and treat. The D-dimer returns positive and is followed by a CTPA which does not reveal a PE, but does show a small right-sided infiltrate consistent with pneumonia. The patient is started on antibiotics for likely bacterial pneumonia.

Diagnosis: Pneumonia

PreClass Case Question and Answer

1. What are the key elements of the history and physical that help sort out the cause of dyspnea?

As shown below, only a few historical findings are highly suggestive of a specific disease in a patient with dyspnea, but rather it is the combination of findings that leads to a diagnosis.

Key Clinical Reasoning Learning Points

1. Threshold to test: The probability of the disease below which no further testing is necessary. These thresholds are affected by the risk associated with undiagnosed disease, the risk/cost associated with the test, and the accuracy of the test.
For example, the threshold to test with a chest film for most diseases on the differential diagnosis for dyspnea is very low as it is a safe, accessible, and relatively low-cost test that provides at least moderate quality information on a significant number of diseases.  Similarly, the thresholds to test for ACS and COVID-19 are low given the ease and safety of testing (ECG and PCR, respectively) and the seriousness of these diagnoses.  The threshold to test for PE is also very low given the seriousness of the disease, but testing is a bit more involved and one often tests first with an ECG for ACS in a patient with chest pain and dyspnea (the result of which also indirectly affects the likelihood of PE).

2. Threshold to treat: The probability of a disease above which treatment is thought reasonable. These thresholds are affected by the risk associated with untreated disease and the risk/cost associated with the treatment. For example, the threshold to treat PE with anticoagulation is high given the risks of bleeding and even higher for thrombolytic therapy given the higher risks of bleeding. Patient-specific factors may also influence the threshold to treat (e.g., the individual patient’s risk of bleeding). Other threshold to treat examples include chemotherapy and cancer (very high and the basis for the axiom “tissue is the issue”) and statins and cardiovascular disease (low).

Key Clinical Learning Points

• It is often the combination of findings that helps sort out the cause of dyspnea in a particular patient (see above table).
• Always consider the four most common causes of dyspnea: pneumonia, congestive heart failure, obstructive lung disease (COPD and asthma), and venous thromboembolic disease.
• Always consider the diagnosis that require immediate treatment in addition to the above four which also require immediate treatment:
  • ACTASAP
    • Arrhythmia, Coronary syndrome, Tamponade, Airway obstruction, Stenosis (aortic), Anaphylaxis, Pneumothorax

Pattern Recognition Vignettes

A 24 year-old male with a history of tobacco use (1ppd x 6 years) presents to the ED complaining of acute dyspnea.  It started one hour ago and has been persistent without change. It was associated with a sharp, severe (9/10) pain in his left chest worsened by breathing.  Nothing has made it better.  Vital signs were 98.4, BP 90/60, HR 124, RR 32, pulse ox 88% on room air.  Physical exam reveals decreased breath sounds throughout the left posterior lung field with hyperresonance to percussion. He has not yet received her SARS-CoV-2 vaccine and PCR testing is negative. (Pneumothorax)

A 62 year-old female recently diagnosed with breast cancer presents to the ED with 3 days of progressively worsening shortness of breath.  She had met with the oncologist to discuss chemotherapy options and was traveling home and noticed difficulty walking to the bus.  Since that time, she has worsened to the point where she can only walk 10 feet without shortness of breath. It is associated with lightheadedness and new mild swelling in both feet over the last few days.  She has no cough or fevers.   Exertion makes it worse and rest makes it better.  Vital signs 97.6, BP 81/52, HR 112, RR 24, pulse ox 95% on room air.  Physical exam reveals a normal lung exam, quiet but normal heart sounds, a jugular venous pressure of 10 cm (elevated), and 1+ lower extremity edema of both feet. She has not yet received her SARS-CoV-2 vaccine and PCR testing is negative. (Pericardial tamponade)

An 80 year-old female with a history of DM, HTN presents to clinic with dyspnea, fever, cough productive of yellow sputum for the past two days.  It has been progressively getting worse.  She also notes myalgias and arthralgias diffusely along with headaches and diarrhea.  Vital signs 102.4, 93/54, HR 116, RR 24, pulse ox 86% on room air.  Exam revealed a normal JVP, lungs with crackles and egophony in patchy areas in both lung fields, normal cardiac exam. She does not believe in vaccines. (Pneumonia; likely COVID-19)

A 68 year-old male with a history of coronary artery disease presents to the ED with one night of shortness of breath.  He went to bed and awoke gasping for air.  He stood up and tried to get relief but the symptoms persisted.  He denied fever.  He did note that he was coughing up some whitish, frothy sputum.  He also notes some swelling in both feet over the last few days.  VS 98.3, BP 180/100, HR 118, RR 28, pulse ox 89% on room air.  Physical exam revealed elevated JVP of  12 cm, lung exam with crackles 2/3 of the way up, and heart exam that was notable for a third heart sound in mitral position. He is immunized against SARS-CoV-2 and PCR testing is negative. (Congestive heart failure)