Table 1.

Advanced Trauma Life Support (ATLS) Classification of Hypovolemic Shock²⁸

	Class I	Class II	Class III	Class IV
Estimated blood loss	<15%	15–30%	30–40%	>40%
Heart rate (bpm)	<100	100–120	120–140	>140
Blood pressure	Normal	Normal	Decreased	Greatly decreased
Pulse pressure	Normal or increased	Decreased	Decreased	Decreased
Respiratory rate (breaths/sec)	14–20	20–30	30–40	>35
Mental status	Slightly anxious	Mildly anxious	Anxious, confused	Confused, lethargic
Urine output (mL/hr)	>30	20–30	5–15	Minimal

Note: Data from American College of Surgeons Trauma Committee, Advanced Trauma Life Support (2008).²⁸