One guard was knocked out and another hurt when Anthony Ferrie, 33, jumped from the G4S vehicle near Livingston's St John's Hospital on Thursday.
Police said efforts to trace the prisoner were centred on his home town of Bellshill and the surrounding area.
The have appealed for anyone with information to come forward.
Ferrie was being held at Addiewell Prison in West Lothian.
He is described as white, 6ft tall and of slim build. He was wearing a blue sweater, jeans and trainers.
Members of the public have been warned not to approach him.
Det Insp Paul Batten said: "Ferrie is from Bellshill and whilst we are carrying out some inquiries in West Lothian, most of our work is happening in Lanarkshire.
"The investigation is using both local and national Police Scotland resources, and liaison with partners, to try to locate Ferrie as quickly as possible and return him to custody.
"I would urge anyone who may know of his whereabouts to contact police immediately."
The police search for a prisoner who escaped from a private security firm's van after a hospital visit is focussing on the Lanarkshire area.