Pulmonary Embolism: Learn About A Non Invasive Technique With A Great Deal Of Diagnostic Promise
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I included this subject because it is often missed in a diagnosis.
Shortness of Breath With Chest Pressure in A 55-Year Old Man CME/CE
Colleen McManaman, DO; Joseph J. Kaplan, MS, MD, FACEP
A 55-year-old man presents to the emergency department (ED) with a 1-month history of worsening shortness of breath and chest pressure. He was discharged from the hospital 3 weeks ago after a negative cardiac work-up and a stress test for these symptoms. He was followed up by his primary care provider (PCP) for worsening symptoms and a productive cough. At that time, he was diagnosed with asthma after undergoing pulmonary function testing, and he was started on fluticasone/salmeterol, prednisone, and albuterol. He then returned to the ED with worsening symptoms, including exertional dyspnea, cough with trace hemoptysis, chest pressure and exertional fatigue. Repeat cardiac enzyme tests and chest radio-graphs were all negative. An electrocardiogram (ECG) was also normal. Non contrast computed tomography (CT) scanning of the chest was read as negative, and a consult was ordered for pulmonary evaluation. He returned to the PCP 1 week later complaining of worsening symptoms over a 3-4 day period and was referred to the ED today. The symptoms did not resolve despite treatment with an albuterol nebulizer. The patient denies having any fever, chills, nausea, vomiting, swelling in the lower extremities, rapid breathing, chest pain, or pain radiating down his left arm. The patient's only travel history was over 2 months ago, when he drove 8 hours to New York and back. His past medical history includes hypertension, hypothyroidism, benign prostatic hyperplasia, obesity, sinusitis, obstructive sleep apnea, and gout. His past surgical history is significant for thyroidectomy, right ankle reconstruction, and a lumpectomy for removal of a benign right breast mass. The patient's current medications include cetirizine hydrochloride, fluticasone/salmeterol, celecoxib, metoprolol, doxazosin mesylate, allopurinol, benazepril, levothyroxine, and fluticasone propionate. He has no known drug allergies and does not use illicit drugs. He does occasionally drink alcohol and, although he quit 10 years ago, he has a past history of tobacco use (approximately 1-2 packs per day for 15 years).
On a physical exam, the patient's oral temperature is 95.5°F (35.3°C), pulse is 78 bpm, blood pressure is 96/86 mm Hg, respiratory rate is 18 breaths/min, and oxygen saturation is 90% while breathing room air. The examination of his head and neck is normal. He has decreased breath sounds in the right anterior lower lung fields, with no rales, wheezing, rhonchi, or rubs. His heart has a regular rate and rhythm, with no gallops, rubs, or murmurs. His S1 and S2 heart sounds are normal. His abdomen is soft and nontender, with normal bowel sounds and no organomegaly. The peripheral arterial pulses in all extremities are equal and palpable bilaterally. He has no edema, tenderness, or erythema in his extremities.
The laboratory analysis, including a complete blood cell count (CBC), basic metabolic panel, cardiac enzymes, and coagulation studies are normal, with the only exception being his bicarbonate reading, which is 20 mEq/L (20 mmol/L; normal range, 21-30 mEq/L). An ECG is performed, which shows a normal sinus rhythm with an incomplete right bundle branch block and T-wave abnormalities consistent with anterolateral ischemia. An echocardiogram is obtained that reveals pulmonary hypertension, tricuspid regurgitation, right atrial and ventricular enlargement, and a pulmonary artery pressure of 80 mm Hg (his previous echocardiogram, which was obtained a month earlier, was read as normal). A high-resolution, contrast-enhanced CT angiogram of the chest is ordered (see Figure 1)
Pulmonary Embolism Detection Without Invasive Procedures
Pulmonary Embolism and Spiral CT
The development of a new noninvasive, readily available technique, computed tomographic (CT) angiography, that could see the clot in pulmonary arteries was clearly exciting but not so widely embraced. Initial reports of the CT diagnosis of pulmonary embolism were viewed as interesting but not convincing enough to be clinically useful.[10-12] Now, helical or spiral CT, with its ability to image the entire lung during a single breath-hold and the attendant decrease in image misregistration, has led to increasing enthusiasm for its use. This article concentrates on the technique, risks, accuracy, and benefits of spiral CT scanning for the diagnosis of pulmonary thromboembolic disease.
For purposes of diagnosis, I believe that spiral CT should be treated in the same fashion as pulmonary angiography. A clear demonstration of the actual embolus should be made before calling a test positive. Thus, a vascular filling defect or cutoff vessel is necessary in order to diagnose pulmonary embolism (Fig. 1). Focal oligemia or decreased areas of pulmonary parenchymal attenuation and the possibility of pulmonary infarction suggested by a wedge-shaped opacity in the periphery of the lung are not, by themselves, sufficient for diagnosis. Filling defects in the main, right, and left pulmonary arteries are clear even to the casual observer. In fact, segmental branch filling defects or cutoff vessels are also easily identified. In some instances subsegmental and even smaller pulmonary emboli are well delineated, but in these smaller vessels the diagnosis may not always be as reliable. A large number of articles have addressed the accuracy and value of spiral CT, and this is the topic of the next section.
Reprint request Dr. Philip Goodman, Dept. of Radiology, 1515A Hospital North, Box 3808, Duke University, Durham, NC 27710. E-mail goodm008@mc.duke.edu
From Mike:
This is a non-invasive technique with a great deal of diagnostic promise. From the looks of this article, some day this technique might add another key factor in measuring optimal lung function or at least, lung function that is at risk; before serious illness presents itself. An ounce of prevention is worth a pound of cure. I ask them to raise their insights and standards as to what optimal breathing function looks, feels and sounds like.
