The European guideline on management of major bleeding and coagulopathy following trauma: fifth edition

Table 3 American College of Surgeons Advanced Trauma Life Support (ATLS) classification of blood loss based on initial patient presentation. Signs and symptoms of haemorrhage by class. Table reprinted with permission from the American College of Surgeons [111]

Parameter	Class I	Class II (mild)	Class III (moderate)	Class IV (severe)
Approximate blood loss	< 15%	15–30%	31–40%	> 40%
Heart rate	↔	↔ / ↑	↑	↑ / ↑↑
Blood pressure	↔	↔	↔ / ↓	↓
Pulse pressure	↔	↓	↓	↓
Respiratory rate	↔	↔	↔ / ↑	↑
Urine output	↔	↔	↓	↓↓
Glasgow Coma Scale score	↔	↔	↓	↓
Base deficit*	0 to − 2 mEq/L	– 2 to −6 mEq/L	– 6 to −10 mEq/L	– 10 mEq/L or less
Need for blood products	Monitor	Possible	Yes	Massive transfusion protocol

*Base excess is the quantity of base (HCO₃⁻, in mEq/L) that is above or below the normal range in the body. A negative number is called a base deficit and indicates metabolic acidosis
Original data from Mutschler et al. [117]