II. Definition
- Normal Heart Rate despite impending cardiovascular collapse (e.g. Hemorrhagic Shock, Hypovolemic Shock, Septic Shock)
III. Precautions
- Tachycardia is typically an early marker of volume depletion or shock
- In some cases, Heart Rate may be unreliable in predicting catastrophic cardiovascular collapse
IV. Causes: Specific patient populations
- Pregnancy
- See Trauma in Pregnancy
- Increased reserve volume (Fetal Distress precedes maternal Tachycardia and Hypotension)
- Children
- See Trauma in Children
- Significant physiologic reserve until just before cardiovascular collapse leads to precipitous drop in systemic perfusion
- Elderly
- See Trauma in the Elderly
- Limited ability to mount tachycardic response and Blood Pressure correlates poorly with hemodynamic status
- Athletes
- Baseline Bradycardia and physiologic reserve until just before cardiovascular collapse leads to precipitous drop in systemic perfusion
V. Causes: Other
- See Sinus Bradycardia
- See Bradycardia due to Medications
-
Autonomic Dysfunction
- May limit compensatory Tachycardia reflex
- Abdominal Hemorrhage
- May cause vagal response (Bezold-Jarisch)