Heart rate: Is it truly a vital sign?

Background: Tachycardia, often defined as heart rate >100 bpm, has been utilized as a physical sign of hypovolemic shock among the injured for decades without evidence to support its use as a predictor of injury or significant hypovolemia. We sought to determine whether admission heart rate is a valid predictor of hemodynamically significant injuries. Methods: Trauma registry data from 1998 to 2004 were analyzed with logistic regression to determine whether heart rate was associated with need for emergent intervention for bleeding (laparotomy, thoracotomy, or angiography), need for packed red blood cell (pRBC) transfusion in the first 24 hours, or severe injury (ISS >25) after blunt or penetrating trauma. Results: Records of 10,825 patients were analyzed. Overall, heart rate was neither sensitive nor specific in determining the need for emergent intervention, pRBCs in the first 24 hours or severe injury. This was not altered by the presence of hypotension (systolic blood pressure <90 mn Hg) or age in the blunt cohort. Conclusions: Heart rate alone is not sufficient to determine the need for emergent interventions for hemorrhage. Although tachycardia may still indicate need for emergent intervention in the trauma patient, its absence should not allay such concern.