From the Guidelines
Yes, pulmonary embolism (PE) can present with tachycardia and a normal oxygen saturation. Tachycardia (heart rate >100 beats per minute) is one of the most common findings in PE, occurring in about 40% of cases as the body attempts to compensate for decreased cardiac output 1. Normal pulse oximetry readings (≥95% on room air) can be seen in up to 40% of patients with confirmed PE, especially in those with smaller clots or good cardiopulmonary reserve. This normal oxygenation occurs because the body can compensate through increased ventilation or because the clot affects a relatively small portion of the lung. When evaluating a patient with unexplained tachycardia, PE should remain in the differential diagnosis even with normal oxygen levels. Other common PE symptoms include:
- Dyspnea
- Chest pain
- Cough
- Less frequently, hemoptysis or syncope Risk assessment tools like the Wells score or PERC rule can help determine the need for further testing such as D-dimer, CT pulmonary angiography, or ventilation-perfusion scanning 1. The combination of unexplained tachycardia with risk factors for venous thromboembolism should raise clinical suspicion for PE regardless of oxygen saturation. According to the most recent guidelines, anticoagulation should be initiated without delay in patients with high or intermediate clinical probability of PE while diagnostic workup is still ongoing 1.
From the Research
Presentation of Pulmonary Embolism
- Pulmonary embolism (PE) can present with various symptoms, including acute chest pain, shortness of breath, or syncope 2.
- Tachycardia can be a sign of PE, particularly in patients with submassive PEs and sustained tachycardia in the setting of normal blood pressures 3.
- Patients with PE may also have normal pulse oximetry readings, as hypoxia is not always present in the setting of PE 4.
Diagnosis of Pulmonary Embolism
- The diagnosis of PE is determined by chest imaging, and clinical probability of PE can be assessed using a structured score or clinical gestalt 2.
- A clinical decision rule can determine the pre-test probability of PE, and if PE is "unlikely", a D-dimer test can be used to exclude PE 5.
- Imaging with computed tomography pulmonary angiogram is accurate and preferred for diagnosing PE, but may detect asymptomatic PE of uncertain clinical significance 5.
Clinical Characteristics of Pulmonary Embolism
- Patients with a probability of PE that is less than 15% and have certain clinical characteristics (such as age <50 years, heart rate <100/min, and oxygen saturation level of >94%) are at very low risk of PE and may not require further testing 2.
- Tachycardia can be an ominous sign of right ventricular dysfunction and impending hemodynamic collapse, and should lead to aggressive therapy with vascular intervention 3.
- The clinical presentation of PE can vary considerably, and treatment is guided by the presence or absence of shock and ranges from therapeutic anticoagulation to pharmacologic versus mechanical thrombectomy 4.