A 70 kg man arrives in the emergency department after blunt trauma. He is anxious, heart rate 112/min, respiratory rate 24/min, blood pressure 116/88 mmHg with a narrowed pulse pressure. Estimated external blood loss is about 1000 mL. According to the ATLS classification, which class of hemorrhagic shock does he have?

• A Class I
• B Class IV
• C Class III
• D Class II ✓

Explanation

Class II hemorrhagic shock represents 15 to 30 percent blood loss (roughly 750 to 1500 mL in a 70 kg adult). The hallmark is tachycardia above 100 with a narrowed pulse pressure and a still normal systolic blood pressure due to catecholamine-mediated vasoconstriction. Class III begins at 30 to 40 percent loss and is defined by hypotension, which this patient does not have. Class I keeps the heart rate below 100, and Class IV shows marked tachycardia above 140 with unobtainable blood pressure.

Reference: ATLS Student Course Manual, American College of Surgeons, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.