Weaning is the process of putting the patient off the ventilator. There are three types of ventilation modes that can be used for the weaning process. Spontaneous breathing trials (SBTs): Type of weaning method where patient's capacity to breathe with minimum ventilator support is evaluated. Pressure-support ventilation (PSV): Assisted type of ventilation that can be activated by the patient itself. It is a commonly used method in weaning especially in critical patients in ICU. Synchronized intermittent mandatory ventilation (SIMV): Volume control method where preset breaths along with the predetermined volume is provided to help in natural breathing. It prevents the patient from developing respiratory alkalosis but at the same time increases the work of breathing. This method is considered as the least effective one.