Effectivity of ventilation by measuring expired CO2 and RIP during stabilisation of preterm infants at birth

Abstract

Objective: To measure tidal volume, plethysmography changes and gas exchange during respiratory support at birth.

Design: The following parameters were measured: (1) expired tidal volumes (Vte (mL/kg)) using respiratory function monitoring, (2) changes in plethysmography (AU/kg) per breath using respiratory inductance plethysmography (bands placed around rib cage (RC) and abdomen (AB)) and (3) expired CO2 (ECO2) levels using a volumetric CO2 monitor. For respiratory support, a T-piece resuscitator and facemask were used with peak inspiratory pressure (PIP) 25 cm H2O and positive end expiratory pressure 5 cm H2O. Data were analysed during the sustained inflation (SI), positive pressure ventilation (PPV) and breathing on continuous positive airway pressure (CPAP).

Setting: The delivery rooms of the Leiden University Medical Center, Leiden, and V. Buzzi, Milan.

Patients: 15 preterm infants with a gestational age 28 (27-31) weeks and a birth weight of 1080 (994-1300) g.

Results: Vte for PPV inflations, PPV inflations with breathing and spontaneous breathing were significantly different (4.4 (2.5-8.6) vs 8.8 (5.7-11.4) vs 5.7 (3.3-9.8); p<0.0001)). Spontaneous breathing led to the highest ECO2 levels and during PPV, ECO2 levels were higher when the inflations coincided with breathing (32 (23-38) vs 20 (13-25) vs 2 (3-11) mm Hg; p<0.0001). Little change in plethysmography amplitude occurred during the SI, PPV and breathing at the RC. There was gain in plethysmography amplitude at the AB during the SI, PPV, but most with breathing.

Conclusions: While Vte during breathing on CPAP was lower compared with PPV coinciding with breathing, breathing on CPAP was most effective in gas exchange and plethysmography amplitude gain compared with PPV and PPV coinciding with breathing.

Keywords: CO2; breathing; expiratory tidal volume; neonatal transition; respiratory inductance plethysmography.