ROME — Pope Francis remained in critical condition Sunday and blood tests show early kidney failure but he remains alert and “well-oriented,” and attended Mass, the Vatican said, as the 88-year-old pontiff battles pneumonia and a complex lung infection.

Francis remains in critical condition but has not suffered any additional crises, the Vatican said Sunday evening, after reporting Saturday the pope suffered a “long asthmatic respiratory crisis” days after he was hospitalized for pneumonia.