Shortness of Breath
Shortness of breath, or dyspnea, is a very common complaint, not only in respiratory disease, but also heart disease and states of anxiety. Everyone will get SOB with sufficient exercise.
Differential Diagnosis
Think of the differential before investigating, as this will guide your history and physical exam.
Respiratory |
CardiacHematologic |
MetabolicOther
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Approach to Shortness of Breath
rule out critical diagnoses as soon as possible
- history
- physical exam
- lab investigations
- diagonostic imaging
History
Onset and Duration
Timing and acuity of onset is of critical importance.
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abrupt, over a few seconds:
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short time |
chronic (can be insidious; as specific questions about functional status)
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Episodic dyspnea associated with exertion suggests parenchymal
lung disease or cardiac dysfunction.
Triggers such as environmental exposure or seasons can be asthma or hypersensitivity pneumonitis.
Orthopnea, paroxysmal nocturnal dyspnea - CHF
Constant or episodic, progression
Provoking or relieving factors
Associated Symptoms
diaphoresis
positional
pain
Severity
Medical Research Council dysnpea scale
- SOB with excess exertion (normal)
- SOB with usual exertion
- SOB with ADL's
- SOB at rest
Past Medical History
Cardiovascular, respiratory conditions and diseases
- COPD (last PFT, # of AE-COPD, admissison)
chest/abdominal trauma
Medications
Physical Exam
vitals: stable or unstable?
assess for respiratory distress: accessory muscle use, costal indrawing, tripoding, pursed lip breathing
peripheral or central cyanosis
smoker
cutaneous emphysema
CVS: JVP, jugular distension
Homan's sign: calf pain on dorsiflexion
pitting edema
Diagnostic Imaging
- pulmonary function tests
- CT (spiral if PE suspected)
- V/Q scan
- soft tissue neck
Orthopnea is defined as SOB when lying flat. This can be caused by congestive heart failure and fluid collection in the lungs. It can also result from decreased vital capacity as abdominal contents push against the diaphragm. Respiratory-induced orthopnea is usually relieved faster than cardiovascular-induced symptoms upon standing.
Paroxysmal Nocturnal Dyspnea occurs within 1-10 hours after lying down. It is primarily associated with CHF, as increased venous return collects in the pulmonary interstitium and causes symptoms. PND can also be caused by asthma, thought to be due to decreased vital capacity, decreased body temperature, decreased endogenous vasodilators (what?) and increased exposure to bed allergens.
Ankle edema
The oxygen dissociation curve predicts a gradual decrease in %sat to 90%, but the slope drops off more steeply after that.
PaO2 should ~equal the FiO2 x 6.