Exposed tissue or bone looks alarming, but the management principle is straightforward. If there is no serious arterial bleeding, pack into the wound cavity with gauze so there is no space beneath the bandage, then wrap firmly around the outside.
Avoid over-tightening, you should be able to fit two fingers under each end of the bandage. Over-tightening, particularly with a long transport time, can cause complications including compartment syndrome.
Get the person to hospital for proper assessment and wound management.
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