Tuesday, February 9, 2010

A 75-Year-Old Man With Worsening Dyspnea Following Pneumothorax Treatment

A 75-year-old man presents to the emergency department with a dry cough and dyspnea on exertion. The cough began 2 weeks ago and has been progressively worsening. The patient began experiencing dyspnea approximately 1 week ago. He notes that there has also been left-sided chest pain. The patient has a history of coronary artery disease with a recent coronary bypass surgery, recurrent episodes of bilateral spontaneous pneumothoraces, and chronic obstructive pulmonary disease (COPD). He has smoked an average of 15 cigarettes daily for 40 years. His symptoms have drastically worsened by the time of presentation to the ED.

On physical examination, heart rate of 142 bpm (sinus rhythm), a respiratory rate of 41 breaths/min, a blood pressure of 170/100 mm Hg, and a pulse oximetry reading showing an oxygen saturation of 60% while breathing room air. He appears agitated, uncomfortable, and in respiratory distress. His airway is patent and he speaks single words at a time. His breathing is labored and peripheral cyanosis is appreciated. He has no breath sounds in the left hemithorax, but normal air movement is noted in the right hemithorax. Additionally, no murmurs or friction rubs are appreciated. The left hemithorax is tympanic to percussion and there is no tenderness to palpation. No tracheal deviation is noted.

The patient is immediately placed on supplemental oxygen, and he maintains an PO2 of approximately 90%. While a stat portable chest radiograph is performed, preparations are made for emergency tube thoracostomy placement. The radiograph (see 1st x-ray) reveals a left-sided tension pneumothorax. An emergency left-sided tube thoracostomy is inserted under local anaesthesia in the left fourth intercostal space at the midaxillary line. A large rush of air is appreciated. After draining the pneumothorax, the clinical picture rapidly improves. At this point the patient becomes much less dyspneic, with a respiratory rate of 22 breaths/min, a blood pressure of 124/63 mm Hg, a heart rate of 90 bpm (normal sinus rhythm), and 92% SPO2 via face mask.

10 minutes later, the patient experiences dramatic worsening of his condition,as shortness of breath. The respiratory rate rises to 32 breaths/min and the SPO2 drops to 80% despite the administration of oxygen via a nonrebreather mask. The blood pressure is maintained at 120/74 mm Hg, with a heart rate of 118 bpm (sinus rhythm). Crackles are now heard over the left lung, most prominently at the base. A blood gas analysis reveals a pH of 7.30, a PCO2 of 35.4 mm Hg, a PO2 of 52.8 mm Hg, and a bicarbonate level of 17.2 mEq/L (17.2 mmol/L), with a base excess of -7.9 mEq/L. As the patient is prepared for a new chest radiograph (2nd x-ray), empiric treatment is initiated with medications.

What is the most likely etiology of the patient’s deterioration?
Pulmonary embolus
Recurrent pneumothorax
Reexpansion pulmonary edema

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