Differential diagnosis:

1.     Pulmonary:

  • Pneumonia - cough, fever, sputum.
  • Pneumothorax - acute onset, pleuritic CP. Consider in any intubated patient.
  • PE - often difficult to rule in or out by history/exam. Consider this early.
  • Aspiration - common problem in patients with decreased consciousness or AMS.
  • Bronchospasm - can occur in CHF, pneumonia as well as asthma/COPD.
  • Upper airway obstruction - often acute onset, stridor/focal wheezing.
  • ARDS - usually in pts hospitalized with another diagnosis (e.g. sepsis).

2.     Cardiac:

  • MI/ischemia - dyspnea can be an anginal equivalent.
  • CHF - common in elderly pts on IVF, or due to ischemia.
  • Arrhythmia - can cause SOB even without CHF/ischemia.
  • Tamponade - consider when pt has signs of isolated right heart failure.

3.     Metabolic:

  • Sepsis - dyspnea can be an early, non-specific sign of systemic infection.
  • Acidosis - patients become tachypneic to blow off CO2 in compensation.

4.     Hematologic:

  • Anemia - easy to miss this by history/general exam.
  • Methemoglobinemia - rare; consider in patients taking dapsone or certain other meds with cyanosis/low sat, normal PO2.

5.     Psychiatric:

  • Anxiety - common, but a diagnosis of exclusion!


Evaluation of the patient:

1.     History:

  • Acuity of onset of dyspnea.
  • Associated symptoms (cough, chest pain, palpitations, fever).
  • New events or medications given (including IV fluids!) around the time of onset.
  • Relevant PMH and admitting diagnosis.

2.     Physical exam:

  • Vital signs: You should ask for these (including an O2 sat) as soon as you hear that the patient is complaining of shortness of breath.  This will help you decide how quickly you need to respond.
  • Lungs: wheezes, rales, stridor, symmetry of breath sounds.  Remember that adventitial lung sounds may be absent in someone with severe airflow limitation.
  • Cardiac: JVP, carotids, rate/rhythm, and murmurs or rubs.
  • Extremities for edema (unilateral vs. bilateral) and perfusion (cool vs. warm, capillary refill, cyanosis).
  • Mental status: important because it gives you an idea of cerebral oxygen delivery; also, if the patient is mentating poorly, intubation for airway protection should be considered.

3.     Labs/studies:

  • CXR, ECG, and ABG.  CBC if clinically indicated.
  • These basic studies will give you a great deal of information, and help you sort out what might be going on with your patient if it's not clear from the above.
  • Certainly, in any patient you don't know well, you should almost always get all of these.


Initial management:

1.     Oxygen:

  • Initial intervention for any patient who is dyspneic.
  • Even CO2 retainers need oxygen and it takes longer than the few minutes you need to evaluate them for significant respiratory depression to develop.
  • Your goal is a PO2 > 60, or O2 sat > 92%. If nasal cannula isn't doing the trick (max FiO2 is ~40%), try a simple mask (up to 50%), non-rebreather (70%), or high-humidity mask (90%).
  • Remember that the RT is your friend; call early if you?re having any trouble, and they will help with nebulizers, suction, masks, ABGs, oral/nasal airways.

2.     Beta agonists:

  • Patients with wheezing from any etiology can benefit from bronchodilators.
  • Remember that wheezing can occur in many conditions other than asthma (e.g., CHF, pneumonia).

3.     Diuretics:

  • Consider furosemide in any patient with history or exam consistent with CHF; other processes associated with increased lung fluid (pneumonia, ARDS) may also improve temporarily with diuresis, and a single dose of furosemide is unlikely to do any irreversible damage.

4.     Assess potential need for intubation (see Critical Care: Mechanical Ventilation).  BiPAP trial may be helpful method of temporizing while making this decision.

5.     Once you have the patient stabilized and the results of your initial studies, you can initiate therapy directed at the specific etiology of the patient's dyspnea.