A 25-year-old female is obviously upset as you walk into the office suite. She’s sitting in a chair, anxious and crying. Her coworkers explain she’s been getting over a breakup with her long-time boyfriend, who left her about a month ago. This afternoon she became anxious, stating she couldn’t breathe. Her coworkers attempted to calm her down, but called 9-1-1 after having no success.
Your assessment reveals the patient is healthy. She tells you she was sitting at her desk when she experienced a sudden onset of dyspnea. She is short of breath and her left chest hurts. Her skin is warm and dry to the touch. Her heart rate is 110, blood pressure is 112/80 and respirations are 20 with no noted accessory muscle use. Breath sounds are clear in all fields. Her capnogram reveals a normal waveform with an end tidal value of 30 mmHg and a pulse oximetry reading of 90%. Her chest discomfort is not reproducible with physical palpation, but is made worse with deep breaths.
The remainder of her physical exam is unremarkable and she denies any recent traumatic events. She denies recreational drug use but says she smokes cigarettes on occasion with a recent increase in frequency. When asked about medications, she says she takes Klonopin (clonazepam), a multivitamin, and, recently, a friend told her to try valerian root to help with the anxiety caused by her breakup.
Oxygen is administered via a non-rebreather mask that causes slight relief of the dyspnea but no notable change in pulse oximetry readings. Her respiratory rate decreased with no appreciable change in capnography. The patient tells you she feels better and thinks she just “freaked out” and will be fine. Concerned about her chest pain and the low pulse oximetry reading, you convince the patient to go to the hospital. During transport, you continue the administration of oxygen with no change in pulse oximetry and establish vascular access. Her vital signs don’t change. Follow-up with the ED revealed the patient had a pulmonary embolism (PE).
This case is interesting but not uncommon. Pulmonary embolisms can be a life-threatening condition but often present with subtle, nondescript signs and symptoms. A PE is typically a blood clot that travels from the systemic venous system into the pulmonary circulatory system. The majority of these clots come from deep vein thrombosis (DVT) that develops in the legs. Other origins include the veins of the pelvis, renal system, upper extremities or the heart. Risk factors for developing these clots are likely to occur during long-term immobility—from recent travel, recent surgery or trauma, and pregnancy—by taking oral contraceptives, drug abuse, recent cancer treatment, smoking and clotting disorders.
The clot, in part or in whole, breaks free and becomes an embolism. As the embolism leaves the systemic venous system, it moves to the right atrium, right ventricle and then into the pulmonary circulatory system where it moves through until it becomes lodged, too large to travel further. Large emboli may result in sudden death, and even if witnesses take action immediately, survival rate is low. Smaller emboli may result in minimal-to-no signs and symptoms. Young patients without lung disease may tolerate a pulmonary obstruction up to 30% with minimal symptoms.1
Common signs and symptoms associated with PE include shortness of breath unexplained by other causes, pleuritic chest pain and tachycardia. Other symptoms may be dizziness, syncope and seizures. Breath sounds are commonly clear because the obstruction is in the vascular system rather than the bronchial system. If the embolism results in pulmonary infarction, however, lung sounds can reveal localized rales. The lodged clot can redistribute blood flow in the lungs that increases blood flow through patent vessels but doesn’t allow for full oxygenation, resulting in decreased pulse oximetry readings. An increase in respirations (tachypnea) and decreased blood flow around the lungs can result in a decreased capnography reading.
It can be easy to attribute the signs and symptoms caused by a PE to other factors. In the case of the patient described here, the EMS providers could have accepted the patient’s evaluation of just “freaking out” and allowed her to remain on scene. In one study of patients who died from pulmonary embolisms, it was determined 40% had recently seen a physician for treatment of symptoms attributable to PE.2
Pulmonary embolisms are commonly missed by healthcare providers at all levels due to their sometimes subtle presentation. Another study identifies PE as the most-commonly missed or delayed diagnosis.3 A set of criteria known as the Wells Scoring System is sometimes used by emergency physicians to help identify the probability of PE. EMS can use components of the Wells Scoring System to help identify patients who are likely to have a PE. In order of significance, providers should consider PE if:
Treatment for patients with suspected PE should include oxygen administration and monitoring pulse oximetry and capnography. Vascular access should be obtained as allowed by protocol. Collect a complete history and conduct a thorough physical exam. Remember, patients with PE may deteriorate quickly if more clots are dislodged, so you should be prepared for cardiac arrest. Maintain a high level of suspicion with any unexplained shortness of breath and tachycardia and transport for evaluation.
The patient in this case had developed a thrombosis in her left leg. The exact cause was not determined but could be attributed to birth control pills, smoking and possible decrease in activity secondary to her being upset after her recent failed relationship. In some cases of PE the origin of the clot may not be determined.
Her treatment during transport was mostly supportive. One of the most important roles of the emergency provider is to recognize the possibility of PE. Oxygen should be administered as necessary based on patient complaint and pulse oximetry reading. Obtain vascular access and prepare for cardiac arrest. If a 12 lead ECG is obtained during the patient assessment, there may be changes indicative of PE. In some patients with PE there will be a large S wave in lead I, a Q wave in lead III and an inverted or flattened T wave. Lead VI may show a right bundle branch pattern with a narrow QRS. These changes should be considered in conjunction with other assessment findings as they aren’t guaranteed to exist nor do they confirm PE. Always consider your patient critical, then let them prove you wrong.
1, Marx J, Hockberger R, Walls R. Rosen’s Emergency Medicine Concepts and Clinical Practice, 6th edition, volume 2. Elsevier Health Sciences: Philadelphia, Pa., pp. 1371–1372, 2005.
2. Courtney DM, Kline JA. Identification of prearrest clinical factors associated with outpatient fatal pulmonary embolism. Acad Emerg Med. 2001;8(12):1136–1142.
3. Schiff GC, Hason O, Kim S, et al. Diagnostic error in medicine: analysis of 583 physician-reported errors. Arch Intern Med. 2009;169(20):1881–1887.