Continuous positive airway pressure (CPAP) systems for preterm infants work with conventional ventilators or use a jet ventilation system. It is assumed that the most important advantage of jet-CPAP systems is a lower expiratory resistance (R(E) ). We investigated the R(E) of seven different CPAP systems. We studied two primary-care CPAP systems, three jet-CPAP generators, and two conventional CPAP devices. All devices were adjusted at 6 mbar and connected with a test lung simulating a standardized expiration volume. Maximum pressure increase during expiration was measured and maximum R(E) was calculated. In primary-care CPAP devices, the maximum R(E) of the Benveniste valve was 9.7 mbar/L/s (SD 1.2) while that of the Neopuff was 102.8 mbar/L/s (SD 7.9) (P < 0.01). In jet-CPAP devices, the R(E) of the Infant Flow was 6.8 mbar/L/s (SD 1.7), the one of the Medijet REF 1000 was 43.5 mbar/L/s (SD 1.5), and that of the Medijet REF 1010 was 36.7 mbar/L/s (SD 0.3) (P < 0.01). In conventional CPAP systems, the R(E) of the Baby Flow was 29.7 mbar/L/s (SD 1.1) and that of the Bubble CPAP was 37.1 mbar/L/s (SD 4.3) (P < 0.01). All CPAP devices created an R(E). Jet-CPAP devices did not produce lower R(E) than conventional CPAP devices.

Introduction: CPAP systems for preterm infantswork with conventional ventilators or use a jetventilation system. It is assumed that the mostimportant advantage of jet-CPAP systems is a lowerexpiratory resistance. We investigated the expiratoryresistance of seven different CPAP systems. Methods: We studied two primary-care CPAPsystems, 3 jet-CPAP generators and 2 conventionalCPAP devices. All devices were adjusted at 6mbar and connected with a test lung simulating astandardized expiration volume. Maximum pressureincrease during expiration was measured andmaximum expiratory resistance was calculated. Results: In primary-care CPAP devices themaximum expiratory resistance of the Benvenistevalve was 9.7mbar/l/s (SD 1.2) while that of theNeopuff was 102.8mbar/l/s (SD 7.9) (p< 0.01). Injet-CPAP devices the expiratory resistance of theInfant Flow was 6.8mbar/l/s (SD 1.7), the one ofthe Medijet REF 1000 was 43.5mbar/l/s (SD 1.5)and that of the Medijet REF 1010 was 36.7mbar/l/s(SD 0.3) (p< 0.01). In conventional CPAP systemsthe expiratory resistance of the Baby-Flow was29.7mbar/l/s (SD 1.1) and that of the Bubble-CPAPwas 37.1mbar/l/s (SD 4.3) (p< 0.01). Conclusion: All CPAP devices created an expiratoryresistance. Jet-CPAP devices did not produce lowerexpiratory resistance than conventional CPAPdevices.