This study evaluates the efficacy of 2 different NIV strategies for RDS treatment in very low birth weight ( VLBW ) infants : nasal synchronized intermittent positive pressure ventilation ( NSIPPV ) , which is a modality of conventional ventilation with intermittent peak inspiratory pressure , and bilevel continuous positive airway pressure ( BiPAP ) , not synchronized , with 2 alternate levels of continuous positive airway pressure .