Lack of tachycardic response to hypotension in penetrating abdominal injuries

Vital signs upon arrival to the emergency department were studied retrospectively in 59 consecutive patients with isolated penetrating abdominal injuries to determine their chronotropic response to hypotension. Forty-three patients with documented intraperitoneal injury were included in the study and separated into hypotensive and normotensive groups using a systolic blood pressure of 90 or 100 mm Hg. The difference in mean pulse rates between normotensive and hypotensive groups was not statistically significant (P greater than 0.05) although a wide range of pulse rates was noted in both groups. Nearly half of all hypotensive patients were not tachycardic, defined as a pulse rate less than 100. Similar findings were observed when the 117 sets of vital signs recorded both in the field and in the emergency department were analyzed as independent pieces of data. Several mechanisms are proposed for the lack of tachycardia in the presence of hypotension. This data suggest that tachycardia may not be a reliable sign of hypovolemic shock when defined by blood pressure criteria in these patients.