He was critically injured and on the verge of death.
The company is in a moribund state.
He suffered life-threatening injuries in a traffic accident.
The patient briefly fell into a critical, near-death state.
虫の息 is a vivid, idiomatic way to say someone is barely breathing and near death, whereas 瀕死 is the more formal, general term for being on the verge of death.
moribund state; near-death; barely alive
Standard kanji form; used in news and formal writing.
Mixed kanji-kana spelling; less common but still encountered.
From Chinese 瀕死 (bīnsǐ), composed of 瀕 'to approach, to be on the brink of' and 死 'death'. The reading ひんし is the on'yomi of the characters.