Contraindications to Noninvasive Positive Pressure Ventilation Absolute contraindications Cardiac or respiratory arrest, or impending arrest Hemodynamic or dysrhythmic instability Severe upper gastrointestinal bleeding Facial deformity or trauma Upper airway obstruction Copious secretions or inability to clear secretions Vomiting (which may result in life-threatening aspiration) or impaired gastric emptying (as occurs with ileus, bowel obstruction, or pregnancy), which increases risk of vomiting Imminent indication for surgery or need to be in a setting inaccessible for close monitoring for prolonged procedures Obtundation or inability to cooperate with instructions Complications of Noninvasive Positive Pressure Ventilation Possible aspiration into the unprotected airway Barotrauma, including simple pneumothorax and tension pneumothorax Equipment for Noninvasive Positive Pressure Ventilation BPAP machine (or a full-featured ventilator) Face mask or nasal mask Head strap, to secure the mask against the patient's face Fitting wheel, used to determine the optimal mask size for the patient Additional Considerations for Noninvasive Positive Pressure Ventilation IPAP must be set below esophageal opening pressure (20 cm water) to avoid gastric insufflation.