The efficacy of a custom-fabricated nasal mask on gas exchange during nasal intermittent positive pressure ventilation

Commercially available nasal masks have a large mask volume and give rise t o considerable air leaks around the mask during nasal intermittent positive pressure ventilation (NIPPV) which may reduce alveolar ventilation (VA per breath). The effects of a custom-fabricated nasal mask (F-mask) versus a commerciall y Rt sr arch Institute available mask (C-mask) on arterial blood gas measur ements, dead space including both physiological and apparatus dead spare (V D). air leak and VA per breath were compared in patients with restrictive t horacic disease during short-term NIPPV sessions while using a volume cycle d ventilator with equivalent settings for both masks. The mask volume of the C-mask was significantly larger than that of the F-m ask (p<0.003). The arterial carbon dioxide tension (Pa,CO2) during NIPPV wi th either the F-mask (5.56+/-1.35 kPa) (mean+/-SD) or the C-mask (6.87+/-0. 96 kPa) was significantly lower than during spontaneous breathing (7.75+/-0 .81 kPa; p<0.003), but the Pa,CO2 decreased more during NIPPV with the F-ma sk than with the C-mask (p<0.003). The VD was significantly smaller (p<0.03 ). the air leak was significantly less (p<0.03), and the VA per breath was significantly larger (p<0.03) during NIPPV with the F-mask than with the C- mask. In conclusion, nasal intermittent positive pressure ventilation with the F- mask was more effective than nasal intermittent positive pressure ventilati on with the commercially available mask due to its smaller dead space and l ess air leak. Further studies are needed to extend these results to all the commercially available-masks.