This is a prospective randomized cross over study of healthy volunteers undergoing continuous positive airway pressure ventilation via a noninvasive ventilation (NIV) mask with and without the addition of nasal cannulas. Mask leak will be measured by the ventilator after 60 seconds of spontaneous resting ventilation, with each subject serving as his or her own control.

This is a randomized cross over study. A convenience sample of staff and resident physicians and physician assistants from the San Antonio Military Medical Center (SAMMC) Department of Emergency Medicine will be used to assess NIPPV mask seal during CPAP administration with and without nasal cannula. Volunteers will be solicited via Grand Rounds and staff meetings at San Antonio Military Medical Center. Subjects will undergo permuted block randomization by random number generator to the order of intervention, mask alone or mask with nasal cannula at 15L/min of oxygen. An emergency medicine trained physician will place equipment and operate the ventilator. After placement of the NIPPV mask and prior to each study intervention period, appropriate adjustments to enhance mask seal will be made as would happen in a therapeutic setting and the volunteer will be allowed up to two minutes to acclimate to continuous noninvasive positive pressure ventilation. Mask leak will be measured by the ventilator unit and will be recorded after 60 seconds of spontaneous restful ventilation.

Inclusion Criteria:

• 18 years of age
• Volunteer for study

Exclusion Criteria:

• Known cardiac disease
• Known pulmonary disease (to include respiratory infections)