DECREASED IMPOSED WORK WITH A NEW NASAL CONTINUOUS POSITIVE AIRWAY PRESSURE DEVICE

This model study compared the imposed work of two nasal continuous pos itive airway pressure (NCPAP) devices for very low birthweight (VLBW) babies: a new NCPAP device, designed by Moa et al., (Grit Care Med 16: 1238, 1988), and a conventional NCPAP device. In addition, the variabi lities in the pressures of a simulated airway were compared. A continu ous flow (8 L/min) was used to generate CPAP. A Harvard ventilator was used to simulate breathing at a fixed volume (12.1 mt) and rate (45 b reaths/min). The pressure drop across and the flow rate through each d evice were measured, thus allowing the determination of imposed work, i.e., the work of breathing done by the patient to overcome frictional losses due to the NCPAP device. In addition, the pressure fluctuation s in the simulated airway were measured. The data presented are averag es of 36 breaths using the new device and 34 breaths using the convent ional device. The means of the imposed work in the new device and in t he conventional device were 0.135 (95% CI +/- 0.004) mJ/breath and 0.5 10 (95% CI +/- 0.004) mJ/breath (P < 0.01) respectively. The coefficie nts of variation for pressure in the simulated airway were: new 6.8% a nd conventional 15.3%. We conclude that the imposed work of the new NC PAP device for the VLBW baby is approximately one-fourth of that of th e conventional device. The airway pressure generated by the VLBW size of the new NCPAP device shows less variability during simulated breath ing than that found with the conventional device. The findings support the clinical use of the new NCPAP device in the very low birthweight baby. (C) 1996 Wiley-Liss, Inc.