The Silent Alarm: Tachypnea in the Emergency Department.

Tachypnea is a sentinel sign of physiologic distress and a critical, early marker of illness in emergency department (ED) patients. Despite its clinical significance, it is often overlooked or inaccurately measured. Tachypnea frequently precedes dyspnea and may be the first clue to life-threatening conditions such as sepsis, pulmonary embolism, heart failure, diabetic ketoacidosis, or tamponade. This review provides emergency physicians with a practical framework to assess tachypnea at the bedside using physical examination, point-of-care ultrasound, capnography, and noninvasive ventilation. A systematic approach to this vital sign can improve diagnostic accuracy, guide management, and reduce missed diagnoses in the ED.