Health worries of former Prime Minister Atal Behari Vajpayee continued today with AIIMS doctors putting him on "mechanical ventilation" after his respiratory infection worsened. "He (Vajpayee) continues to have lower respiratory track infection which has worsened since morning. He has been put on mechanical ventilation in ICU and is being monitored by a team of doctors," Dr Sampath Kumar, head of Cardiac Thoracic Vascular Sciences of AIIMS, said this evening while reading out a brief medical bulletin. All his basic parametres including blood pressure, liver and kidney functions were normal, Kumar said.