BACKGROUND: The OxyMask is a new face mask for oxygen delivery that uses a small 'diffuser' to concentrate and direct oxygen toward the mouth and nose. The authors hypothesized that this unique design would enable the OxyMask to deliver oxygen more efficiently than a Venturi mask in patients with chronic hypoxemia. AIM AND OBJECTIVE: To determine if the OxyMask can deliver oxygen safely and more efficiently than the Venturi system in this patient population. METHODS: Oxygendependent patients with chronic, stable respiratory disease were recruited to compare the OxyMask and Venturi mask in a randomized, single-blind, cross-over design. Baseline blood oxygen saturation (SaO2) was established by breathing room air, followed in a random order by supplemental oxygen through the OxyMask or Venturi mask. Oxygen delivery was titrated to maintain SaO2 4% to 5% and 8% to 9% above baseline for two separate 30-minute periods of stable breathing. Oxygen flow rate, partial pressure of inspired and expired oxygen (PO2) and carbon dioxide (PCO2), minute ventilation, heart rate, nasal and oral breathing, SaO2, and transcutaneous PCO2 were collected continuously. The study was repeated following alterations to the OxyMask design, which improved clearance of carbon dioxide. RESULTS: Using the original OxyMask, 16 patients between the ages of 30 and 70 were initially investigated. When utilizing the OxyMask, there was a decrease in oxygen flow rate, an increase in inspired PO2, and a decrease in expired PO2. While utilizing the OxyMask, minute ventilation as well as inspired and expired PCO2 were significantly greater. However, transcutaneous PCO2, heart rate, and the ratio of nasal to oral breathing did not alter significantly during the course of the trial. 16 additional patients, ranging in age from 30 to 70, were investigated utilizing the same technique after the OxyMask was modified. Without exhibiting any signs of carbon dioxide retention, the improved OxyMask produced a greater amount of inspired PO2 at a lower flow rate. CONCLUSIONS: Oxygen is delivered safely and more efficiently by the OxyMask than by the Venturi mask in stable oxygen-dependent patients.

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