Comparación de la reinhalación de anhídrido carbónico originada por 3 mascarillas nasales durante la aplicación de CPAP

A comparison is made between the end-tidal fractional concentration of carbon dioxide (FETCO2) obtained during application of varying levels of continuous positive airway pressure (CPAP) with a prototype mask (from Carburos Metálicos) and FETCO2 obtained with 2 commonly used nasal masks (Profile Lite and ComfortClassic from Respironics). The nasal FETCO2 was measured on 3 consecutive days in 11 healthy volunteers, 12 patients with severe obstructive sleep apnea-hypopnea syndrome, and 12 hypercapnic patients. A different mask was randomly assigned on each day and the FETCO2 was measured after 3 minutes of CPAP at 4, 5, 6, 8, 10, 15, and 20 cm H2O. Although in all cases a progressive reduction in FETCO2 was observed with increasing CPAP, the effect was greatest with the prototype mask at all pressures. In the 3 different study groups the pressures obtained with the prototype mask were similar to those generated by the CPAP machine. In conclusion, the lower concentration of nasal CO2 obtained using the prototype mask suggests that it causes less rebreathing.