CAISS External and Thermal 4 — Questions and Answers
Question 1: A chemical burn from concentrated hydrofluoric acid to 5% TBSA is particularly dangerous because it also causes:
- Superficial thermal damage only
- Systemic hypercalcemia
- Systemic hypocalcemia and cardiac arrhythmia (Correct answer)
- Methemoglobinemia exclusively
Correct answer: Systemic hypocalcemia and cardiac arrhythmia
Hydrofluoric acid binds calcium, causing systemic hypocalcemia which can trigger life-threatening cardiac arrhythmias even from small TBSA exposure.
Question 2: In the AIS framework, an avulsion injury is best described as:
- Skin tearing with full separation of tissue from underlying structures (Correct answer)
- A puncture wound through the dermis
- A bruise without skin disruption
- A friction-based abrasion
Correct answer: Skin tearing with full separation of tissue from underlying structures
An avulsion involves full tearing away of skin (and possibly deeper tissue) from the underlying structures, distinct from a laceration or abrasion.
Question 3: Which burn patient characteristic increases the estimated mortality risk the most when using the Revised Baux Score?
- Female sex
- Inhalation injury (Correct answer)
- Pre-existing diabetes
- Burn location on the torso
Correct answer: Inhalation injury
The Revised Baux Score adds 17 points for the presence of inhalation injury, significantly increasing predicted mortality.
Question 4: An AIS code of 751020.3 indicates which severity level for a thermal injury?
- AIS 1 — minor
- AIS 2 — moderate
- AIS 3 — serious (Correct answer)
- AIS 4 — severe
Correct answer: AIS 3 — serious
The final digit of an AIS code represents the severity; '.3' indicates AIS 3 (serious).
Question 5: Radiation burns (e.g., from ionizing radiation) in the AIS system are coded under which chapter?
- External (mechanical)
- Thermal (Correct answer)
- Unspecified
- Head
Correct answer: Thermal
AIS codes radiation burns within the Thermal chapter, grouping them with other energy-transfer injuries to the skin.
Question 6: A patient has extensive road-rash abrasions covering both anterior thighs after a motorcycle crash. The primary infection risk is due to:
- Loss of the stratum corneum barrier (Correct answer)
- Disruption of subcutaneous fat only
- Deep muscle contamination
- Periosteal exposure
Correct answer: Loss of the stratum corneum barrier
Abrasions destroy the stratum corneum, the skin's primary barrier, allowing bacterial entry and increasing infection risk.
Question 7: When coding a patient with both a partial-thickness burn and a laceration on the same body segment, the AIS coder should:
- Code only the burn as it is more severe
- Code only the laceration
- Code both injuries separately (Correct answer)
- Combine them into one code
Correct answer: Code both injuries separately
Each distinct injury must receive its own AIS code; combining injuries into a single code is not permitted under AIS methodology.
CAISS External and Thermal 4
A chemical burn from concentrated hydrofluoric acid to 5% TBSA is particularly dangerous because it also causes: