PANCE Board Practice Exam

An acute pulmonary embolism triggers a rapid sympathetic response and sudden V/Q mismatch, so the heart rate tends to rise quickly to maintain cardiac output and oxygen delivery. Tachycardia is the most common early sign because the body aggressively compensates for the abrupt pulmonary vascular obstruction and resulting hypoxemia. While tachypnea commonly accompanies PE due to increased ventilatory drive, and pleuritic chest pain can occur, those signs are not as consistently early. ECG changes showing right heart strain can appear with larger emboli, but they are neither sensitive nor reliably immediate. Thus, tachycardia stands out as the earliest and most frequent finding among these options.