Relationship between Arterial and End-Tidal Carbon Dioxide Pressure during Controlled Ventilation in Porcine Neonates

Abstract

To investigate the validity of ETCO₂ in porcine neonates, which have been frequently used as an experimental model for human neonates, the relationship between arterial (PaCO₂) and end-tidal PCO₂ (ETCO₂) in porcine neonates was examined under different respiratory conditions by regulating both inspiratory flow and positive end expiratory pressure (PEEP). The difference between PaCO₂ and ETCO₂ widened significantly, according to the significant decrease in tidal volume/body weight ratio (TV/BW) caused by the increase of PEEP. A lower correlation between PaCO₂ and ETCO₂ was observed in <6 ml/kg than in ≥ 6 ml/kg TV/BW. It therefore seems reasonable to conclude that, in porcine neonates, the valid ETCO₂ measurements corresponding to PaCO₂ would be obtained at ≥ 6 ml/kg TV/BW.