Chapter 27. Pulmonary Embolism
A 59-year-old man undergoes total knee replacement for severe degenerative joint disease. Two days after surgery, he develops acute onset of shortness of breath and right-sided pleuritic chest pain. He is now in moderate respiratory distress with a respiratory f = 28 breaths/min, HR = 120 beats/min (sinus rhythm), and systemic BP = 110/70 mm Hg. His SaO2 = 90% by pulse oximetry on room air. His lung exam is normal and his cardiac exam reveals sinus tachycardia but is otherwise unremarkable. The right lower extremity is postsurgical, healing well, with 2+ pitting edema, calf tenderness, erythema, and warmth; the left leg is normal. Laboratory work up reveals a serum creatinine of 1.6 mg/dL. What is the most appropriate next diagnostic step?
a. Ventilation/perfusion scan
b. CT angiogram of the chest
d. Duplex venous ultrasonography of the lower extremities with Doppler flow
e. No additional test, given high pretest probability of PE
The most correct answer is d, conduct a duplex venous ultrasonographic examination of the legs with Doppler flow studies.
Ventilation/perfusion scan (answer a) is a reasonable choice to diagnose pulmonary embolism, although this patient has leg swelling and a simpler test would give an answer. The CT angiogram (answer b) is not without risk for contrast-induced nephropathy especially with serum creatinine of 1.6 mg/dL as noted in this patient. A pulmonary angiogram (answer c) is the "gold standard" test for diagnosis especially in clinical situations where other diagnostic tests have been equivocal and pretest probability of disease is high. Even though the pretest probability of disease is high (answer e) it is prudent to conduct a diagnostic study as anticoagulation has its inherent risks. In the absence of an established diagnosis other possibilities should be considered.
A 52-year-old obese woman who is recovering from a viral illness presents with acute onset shortness of breath of 3 hours duration. She reports symptoms of cough and is very anxious as she noticed blood in her sputum, approximately 1-2 teaspoonfuls in quantity. At the time of presentation her initial BP = 90/50 mm Hg and then increases to 110/65 mm Hg after IV infusion of 1 liter NS. Her ECG reveals sinus rhythm with normal PR and QRS intervals, however the medical student points out the S1, QIII, and TIII pattern. A helical CT scan with a PE protocol is obtained with findings of bilateral filling defects in the interlobar pulmonary arteries. Which of the following is the most appropriate next treatment for this patient?