A man complaining of breathing difficulties punched a paramedic, possibly breaking his jaw, then drove off and collided with an ambulance.
The "sickening attack" occurred when crews were called to Winifred Avenue, in Coventry on Sunday evening.
The patient attacked the paramedic while demanding an inhaler and then collided with the ambulance as he drove away, West Midlands Police said.
A 21-year-old man was arrested on Monday, the force said.
He was detained on suspicion of wounding and driving off from the scene of a collision as well as criminal damage.
It is also suspected that he damaged a door at a GP's surgery in Baliol Road, in the Stoke area of the city on 31 March, the spokesman added.
The paramedic remains in hospital with a suspected broken jaw.
West Midlands Police was called to the scene after the ambulance crew reported they were dealing with a violent patient.
Mike O'Hara from Coventry Police said: "Attacks on any emergency services staff will never be tolerated but this is a particularly sickening incident right now given that NHS workers are on the frontline of our national efforts to tackle coronavirus.
"I think I speak for the whole of Coventry in wishing the paramedic well and ... a speedy recovery."
West Midlands Ambulance Service chief executive, Anthony Marsh, added: "This was a horrendous assault on one of my staff.
"At a time when the NHS is under more pressure than at any time in its history, to lose an experience paramedic from a cowardly act like this, beggars belief.
"I am determined that we will work with police colleagues to bring anyone who attacks my staff to justice."
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