American Board of Internal Medicine (ABIM) Certification Practice Exam

In cases of massive pulmonary embolism (PE), what systolic blood pressure reading is considered critical?

1. Lower than 100 mmHg

2. Exactly 90 mmHg

3. Greater than or equal to 90 mmHg

4. Between 90 mmHg and 100 mmHg

The correct answer is: Lower than 100 mmHg

In the context of massive pulmonary embolism, a systolic blood pressure reading lower than 100 mmHg is considered critical because it indicates the presence of significant hemodynamic instability. This threshold is important as it reflects the heart’s compromised ability to adequately pump blood due to the obstruction of blood flow in the pulmonary arteries. Massive pulmonary embolism often leads to right ventricular strain and failure due to increased pressure in the pulmonary circulation. When systolic blood pressure falls below 100 mmHg, it suggests that the body's compensatory mechanisms are failing, and the patient is at increased risk for shock and multi-organ failure. This low blood pressure reading necessitates immediate medical intervention and often indicates the need for urgent therapies such as thrombolysis or surgical embolectomy. In contrast, systolic blood pressure readings at or above 90 mmHg can indicate that the patient is maintaining enough perfusion and may not be in immediate existential danger, even though intervention may still be required based on clinical presentation. Thus, recognizing the threshold of less than 100 mmHg is critical for appropriate management of patients with massive PE.