73yr old pneumonia patient on ventilator

My father who is a smoker and suffering from sugar and bp had severe fever and weakness since past 5 days but there was no dengue or typhoid detected then we admitted him to hospital where suddenly he started having breathlessness and sweating. his oxygen level were down with high bp and dr moved him to icu and put him on ventilator, was later diagonosed with pneumonia with xray suggesting his left lung affected, the sample was given for culture report but which will take 3-5 days as per dr. and now he is there on ventilator for past 20hrs with no signs of improvement. in between his bp went low which was controlled through high dose of bp medicine. we are quite worried and want to know what is the expected procedure for recovery from here.