What is the purpose of a reservoir bag?

The purpose of a reservoir bag is to provide storage for gases that are delivered to a patient during anesthesia and to confirm the placement of the endotracheal (ET) tube. It allows for the collection and mixing of fresh gas from the anesthesia machine with the exhaled gases from the patient, ensuring that there is a supply of oxygen available for the patient to inhale. When the patient inhales, they draw from the bag, and when they exhale, the bag inflates, which allows for the visualization of breath and provides a means to confirm that the ET tube is placed correctly in the trachea. This confirmation is critical during anesthesia to ensure proper ventilation and oxygenation of the patient.

Additionally, the reservoir bag provides a way to administer positive pressure ventilation if necessary, and the size of the bag helps to ensure that there is enough reserve of anesthetic gases available for each breath.