A 74 year old woman, in otherwise good health, tripped and injured her right leg 2 days previously and has been bedridden since the accident. Two hours ago, she became delirious. On physical examination, her temperature is 99 F, blood pressure is 120/70 mmHg, hea rate is 110, and respiratory rate is 32. Pulse oximetry shows an oxygen saturation of 80%, and a chest x-ray film is normal. Which of the following is the most likely diagnosis?
Hip fracture and prolonged bed rest are classic risk factors for the development of pulmonary thromboemboli (PE). Common clinical manifestations of PE are hypoxia (due to ventilation/perfusion mismatch) despite a normal chest x-ray, tachycardia, and delirium in older patients. Cerebral hemorrhage might cause delirium but would not directly cause hypoxia unless the patient was hypoventilating (e.g., because of brainstem involvement). Cerebral infarction could produce delirium but would not directly cause hypoxia unless the patient was hypoventilating. Myocardial infarction could account for delirium and tachycardia, but not for hypoxia with a normal chest x-ray. Severe congestive hea failure after myocardial infarction could cause hypoxia due to pulmonary edema, but the chest x-ray would not be normal. Ref: Chesnutt M.S., Corona R., Prendergast T.J., Tavan E.T., Szklo M. (2013). Chapter 9. Pulmonary Disorders. In M.A. Papadakis, S.J. McPhee, M.W. Rabow, T.G. Berger (Eds), CURRENT Medical Diagnosis & Treatment 2014.
Acute cerebral hemorrhage
Acute cerebral infarction
Myocardial infarction
Pulmonary thromboembolism