what kind of tertiary injury from a blast would cause a character to be conscious but out of it for a couple of minutes and then die
Hey there @flowerjaia!
First, a super-quick review of blast injury causes:
Primary blast injury: This is damage done to the body by the pressure of the blast. Eardrum ruptures, blast lung (a form of TRALI, trauma-related acute lung injury), and tears in the GI system could all come from this.
Secondary blast injury: the boom produces shrapnel, and the shrapnel hits your character. This is almost always penetrating trauma with lots of small projectiles at high speeds, though larger projectiles are of course possible.
Tertiary blast injury: Your character is thrown by the blast and hits something: a car, the ground, a wall, anything. This is the direct force of the explosion acting on your character’s body.
Quaternary blast injury: other items, affected by the blast, injure your character; e.g., the building falls on them.
So you want your character conscious, dazed, and then dead a few minutes later, eh?
The problem with your specified injury type – tertiary – is that being thrown by the blast is usually either instantly lethal (ie blown off a cliff or out of a window), or more slowly lethal (head injuries, hepatic or splenic lacerations).
Honestly, I think you need two injuries. I think an amputation from the explosion (secondary injury) and a concussion (tertiary injury) could work together. Characters who have been explosed (hah – that was supposed to be “exposed”) to blasts are often dazed, and shock from blood loss sets in quickly; I would believe someone sitting near an explosion who’s dazed and then dies.
You may not even need the concussion. Pressure from blasts is notorious for rupturing eardrums, which affects balance and hearing. (Yes, people do bleed from the ears.)
And if they’re thrown on some impaling object that’s sticking up out of the ground, or if they took a significant amount of the shrapnel with their back, whoever sees them might not realize that they have such a significant injury.
So my suggestions are:
1) Eardrum rupture (1*) + impalement on some object on the ground (3*)
2) Eardrum rupture (1*) + shrapnel in the back that’s hit something important, like nicking the aorta (2*)
3) Traumatic amputation (2*)
4) Concussion + any of the lethal components.
Hope this was what you needed!