Looking up you realise the breath sounds became louder because your paramedic had started external cardiac massage once the patient arrested.

A passing lawyer stops his car and shouts 'That guy was at the limit of his respiratory reserve and was hardly shifting any air. You couldn't have heard his breath sounds if you were in a soundproofed room, never mind the middle of the motorway. You never had control of the situation, and took way too long. Here's my card - you'll be needing it'