II. Definition

  1. Normal Heart Rate despite impending cardiovascular collapse (e.g. Hemorrhagic Shock, hypovolemic shock, Septic Shock)

III. Precautions

  1. Tachycardia is typically an early marker of volume depletion or shock
  2. In some cases, Heart Rate may be unreliable in predicting catastrophic cardiovascular collapse

IV. Causes: Specific patient populations

  1. Pregnancy
    1. See Trauma in Pregnancy
    2. Increased reserve volume (Fetal Distress precedes maternal Tachycardia and Hypotension)
  2. Children
    1. See Trauma in Children
    2. Significant physiologic reserve until just before cardiovascular collapse leads to precipitous drop in systemic perfusion
  3. Elderly
    1. See Trauma in the Elderly
    2. Limited ability to mount tachycardic response and Blood Pressure correlates poorly with hemodynamic status
  4. Athletes
    1. Baseline Bradycardia and physiologic reserve until just before cardiovascular collapse leads to precipitous drop in systemic perfusion

V. Causes: Other

  1. See Sinus Bradycardia
  2. See Bradycardia due to Medications
  3. Autonomic Dysfunction
    1. May limit compensatory Tachycardia reflex
  4. Abdominal Hemorrhage
    1. May cause vagal response (Bezold-Jarisch)

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