RESUMO
OBJECTIVE: The aim of the study was to assess the influence of nasal continuous positive airway pressure (NCPAP) on breathing pattern in preterm newborns. DESIGN: Prospective study. SETTING: Neonatal intensive care unit. PATIENTS: Ten premature newborn infants on NCPAP (gestational age range from 27 to 32 weeks, mean birth weight 1300+/-460 g) admitted in our neonatal intensive care unit (NICU) for respiratory distress syndrome. METHODS: Breathing patterns and changes in lung volumes level were obtained using respiratory inductive plethysmography (RIP), at random CPAP levels (0, 2, 4, 6 and 8 cmH2O). Raw data were analysed for end-expiratory lung volume level (EELV-level), tidal volume (Vt), respiratory rate, phase angle and labour breathing index (LBI). RESULTS: CPAP increased EELV-level by 2.1+/-0.3xVt from 0 to 8 cmH2O ( p<0.01). Vt increased by 43% from CPAP of 0 cmH2O to CPAP of 8 cmH2O ( p<0.01). We also found that CPAP lowered the phase angle (from 76+/-21 degrees at CPAP of 0 cmH2O to 30+/-15 degrees at CPAP of 8 cmH2O; p<0.01 ) and LBI (from 1.7+/-0.8 at CPAP of 0 cmH2O to 1.2+/-0.3 at CPAP of 8 cmH2O; p<0.05). CONCLUSION: NCPAP improves the breathing strategy of premature infants with respiratory failure, as reflected by improved thoraco-abdominal synchrony, increased Vt and reduction of the LBI. This effect is associated with an increase in EELV-level with CPAP level. However, further investigations are necessary to establish the best CPAP level that ensures both safety and efficiency.