This happens in many nationalised (sic) systems: healthcare needs sometimes experience peaks and troughs, or a rare circumstance occurs for which any smaller population is not equipped. Happens in small towns and some States in the US as well. Rather than constructing capacity to handle every eventuality, it's more efficient to strike a deal with somebody else who has capacity: generally the private system. In Canada's case there's a good private system across the border. Others have an internal private system more than happy to do business.

From the article:

But Dr. Uwe Reinhardt, a Princeton University health economist who has studied the U.S. and Canadian health systems, said arrangements with cities like Detroit "are a terrific way to manage capacity" given Canada's smaller health care budget. "This is efficient," he said. "At least in Canada, you don't worry about going broke to pay for health care. You do here."

did you see this link on the same page? http://freep.com/article/20090820/COL04/908200430/Do+we+all+have+same+right+to+health+care?