Compare the Efficacy and Outcome Between Fentanyl and Morphine as Analgo-sedation in Mechanically Ventilated Patients

Researchers will randomize patients into 2 groups (Fentanyl and Morphine) and will start study drug accordingly for sedation in ICU.Proportion of patients from each group achieving targeted sedation score at 12 and 24 hours following initiation of the drug and proportion of patients from each group requiring rescue sedation dose will be recorded and analyzed. Furthemore duration of mechanical ventilation, length of ICU stay and 14 days mortality rate will recorded and compared between this 2 groups of patients.