According to ATLS classification, Class III hemorrhagic shock corresponds to blood loss of approximately what percentage of total blood volume?
A. 50% or greater
B. 30–40%
C. 40–50%
D. 15–30%
Explanation
ATLS Classification of Hemorrhagic Shock
Key Point
The American College of Surgeons ATLS protocol stratifies hemorrhagic shock into four classes based on the percentage of circulating blood volume lost and the corresponding physiologic response.
Class III Hemorrhagic Shock
Class III hemorrhagic shock is defined by blood loss of 30–40% of total blood volume. At this stage, the patient exhibits significant physiologic derangement:
Systolic BP: Decreased (hypotensive)
Heart rate: >120 bpm (severe tachycardia)
Respiratory rate: 30–40 bpm (marked tachypnea)
Urine output: 5–15 mL/hr (oliguria)
Mental status: Confused, anxious, restless
Skin perfusion: Cool, pale, clammy
ATLS Hemorrhagic Shock Classification Table
Table
Class
Blood Loss (%)
HR (bpm)
SBP
RR (bpm)
Urine Output (mL/hr)
Mental Status
I
Up to 15%
<100
Normal
14–20
>30
Alert
II
15–30%
100–120
Normal
20–30
20–30
Anxious
III
30–40%
>120
Decreased
30–40
5–15
Confused
IV
>40%
>140
Decreased
>35
Minimal/absent
Lethargic/unresponsive
High-YieldNEET PG
Class III shock requires immediate aggressive resuscitation with blood products (PRBC and FFP in 1:1 ratio) and definitive hemorrhage control. This is the threshold at which crystalloid alone is typically insufficient.
Clinical Pearl
The progression from Class II to Class III represents the transition from compensated shock (normal BP maintained by sympathetic drive) to decompensated shock (BP begins to fall despite maximal compensation). Class III is the first class in which blood pressure typically drops.
Mnemonic
Think of the four classes as roughly 15%, 15–30%, 30–40%, and >40% — each step escalating in severity. Class III = 30–40% loss with overt hypotension and confusion.
Reference: ATLS Student Course Manual, 10th Edition, American College of Surgeons.
Practice similar questions
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.
