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INTRODUCTION

Key Clinical Questions

  • image What are the underlying physiologic mechanisms that result in dyspnea?

  • image How can a physician elicit a patient’s personal description of shortness of breath in order to gain insight into the underlying diagnosis?

  • image What physical exam findings are concerning for impending respiratory failure?

  • image What are the key diagnostic studies a physician should order to further elucidate the cause of a patient’s dyspnea?

  • image How can the disease states associated with dyspnea be organized into a clinical framework?

CASE 85-1 INPATIENT ADMISSION

A 63-year-old woman describes shortness of breath on postoperative day 3 after a hip replacement. At 3 am, the patient starts complaining that she “can’t catch her breath” and feels as though she is suffocating. Sitting upright, she appears in acute distress with rapid, shallow breathing and expiratory grunting. Her blood pressure is 210/95 mm Hg with a heart rate of 120 beats per minute and an oxygen saturation of 92% while using supplemental oxygen at 6 L/min by nasal cannula. On physical examination, auscultation of the lungs reveals rales over the lower one-third of the lung fields with dullness at the bases, as well as significant peripheral pitting edema. A chest radiograph (CXR) demonstrates increased interstitial markings and blunting of the costophrenic angles bilaterally. Of note, the patient has been receiving intravenous normal saline at 100 cc/h since the surgery. The clinical picture is most consistent with acute pulmonary edema. Increased interstitial edema activates a variety of receptors that stimulate the respiratory controller and cause air hunger, while pleural effusions cause an increase in work of breathing by affecting the body’s ventilatory pump. Note that while hypoxemia with low O2 saturation can lead to dyspnea via stimulation of chemoreceptors, this patient was experiencing breathing discomfort despite an acceptable saturation with the use of supplemental oxygen.

The history, exam findings and CXR help to confirm the diagnosis of volume overload. Other potential causes of dyspnea in an older patient who has undergone major surgery include myocardial ischemia, aspiration, and pulmonary embolism. In addition to treating congestive heart failure (CHF), it is important to seek out any underlying error that may have caused the condition and effect a system change that can improve quality of care for future patients. In the above case, indiscriminant use of maintenance fluids was the culprit; focused provider education and adjustment of existing order sets may be needed.

PRACTICE POINT

  • Indiscriminant use of maintenance fluids is a common and preventable cause of pulmonary edema in inpatients.

Dyspnea, or “shortness of breath,” is a common problem affecting up to half of patients in acute care hospitals and one quarter of ambulatory outpatients. This sensation of breathlessness can be associated with anxiety, fear, or depression and, thereby, cause substantial disability. The American Thoracic Society consensus statement on dyspnea describes it as “an uncomfortable sensation of breathing,” which encompasses several qualitatively distinct sensations that reflect the subjective nature ...

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