Background: Mechanically ventilating is frequently performed life-saving procedure in the emergency room (ER). With the duration of stay of ventilated patients in ERs rising, it is critical for emergency physicians to have a firm grasp on procedures for optimizing mechanical ventilation and minimizing consequences. Numerous positively pressured ventilation techniques are available; they are derived from different permutations of triggered volume- and pressure-cycled ventilations and supply ventilation at a variety of rates, pressures and volumes. Inadequate ventilatory treatment may result in significant respiratory and extrapulmonary injury that may go undetected. Objective: The aim of this review article was to highlight mechanical ventilation in critically ill patients in ICU. Conclusion: Non-invasive ventilation is an excellent first-line therapy for hypoxemic or hypercapnic respiratory failure in critically ill patients, failure of non-invasive ventilation necessitates introduction of intubation and invasive mechanical ventilation as second line therapy.