Abstract: A mask for delivery of gas, such as oxygen, to a patient and useable in a naso-gastric intubation procedure without disruption of the seal between the mask and the face of the patient. The body of the mask includes a fenestration or opening through which the naso-gastric tube may be inserted. The fenestration is preferably shaped to support the tube in manner which is comfortable for the patient and which eliminates or minimizes the amount of gas lost to the atmosphere outside the mask. In at least some embodiments, the fenestration is closed when a tube is not inserted therethrough so that the mask may be used normally without loss of the gas through the fenestration.