He had been referred to a respiratory specialist in London.
“Francesco remains comfortable in hospital and is receiving excellent care and treatment,” read a Swansea statement.
“He is making good progress and is in good spirits following last night’s result at Arsenal.
“The club is in close contact with Francesco and his consultant and his progress is being reviewed on a regular basis.
“No release date from hospital has been confirmed at present.”
The Welsh club earlier said Guidolin was “comfortable” and his full recovery was expected within a few days, adding: “The specialist felt the best course of action was for Guidolin to remain in hospital for a few days to receive further treatment.