How can an ISS of 75 be achieved?

Achieving an Injury Severity Score (ISS) of 75 is a significant indication of extreme injury severity and is usually computed based on the Abbreviated Injury Scale (AIS). The correct pathway for obtaining an ISS of 75 involves summing the squares of the highest AIS scores assigned to injuries in the three most severely injured body regions.

When considering an AIS of 5 in three different body regions, the calculation for the ISS would be:

• AIS 5 (first body region) squared is 25,

• AIS 5 (second body region) squared is 25,

• AIS 5 (third body region) squared is 25.

Adding these values together gives an ISS of 75 (25 + 25 + 25 = 75).

This calculation reflects the extreme severity associated with three separate, highly critical injuries, which aligns with the established methodology for determining the ISS. Thus, the combination of an AIS of 5 across three body regions demonstrates the potential for a catastrophic outcome, validating the choice.

Other scenarios, such as those with lower scores or fewer regions, do not provide the same level of injury severity as required to reach an ISS of 75. For instance, an AIS of 4 or combinations with lower scores