The health condition of music maestro Ustad Rashid Khan, who is undergoing treatment in a Kolkata-based hospital for prostate cancer, remained critical on Sunday, said an official. The 55-year-old Khan is still on ventilation, he added. ‘His condition remained critical. Our doctors are keeping him under watch,’ the official of the hospital, where Khan is undergoing treatment, told PTI. The musician’s health condition deteriorated following a cerebral attack on Friday, he added. Khan, who belongs to the Rampur-Sahaswan Gharana, is the great-grandson of gharana founder Inayat Hussain Khan.