Ambulance bosses in the West Midlands have sent out an SOS to owners of 4x4s to drive nurses around and "help patients receive vital treatment".
West Midlands Ambulance Service made the urgent call as nurses struggled to get out into the community because of treacherous snow and ice.
The appeal, backed by NHS Warwickshire, related to members of the public in Coventry, Warwick, Nuneaton and Rugby.
So far, 86 volunteers have come forward but another 20 are needed urgently, said Martin Turner, NHS director of communications.
"In rural Warwickshire many of the roads are impassable," said Mr Turner. "This morning it got to the stage where you couldn't get over a simple humped back bridge without slipping."
He added that a large number of elderly housebound patients had become extra vulnerable because of the community nurses' inability to get out to them.
The patients require a range of treatments from renal dialysis to blood pressure tests.
Mr Turner said the ambulance service and hospitals were seeing a large increase in calls and volunteers would be able to prevent patients needing emergency care.
Volunteers able to help West Midlands Ambulance Service should call 01926 310 310.