Objective Hypocarbia, defined as a PCO₂<4.7 kPa, is associated with the development of chronic lung disease (CLD). Our objective was to investigate the incidence of early hypocarbia in ELBW infants following transfer from the delivery suite.

Methods Retrospective chart review of ventilated preterm infants <1.5 kg and gestational age <32 weeks admitted to the NICU. All documented blood gases taken while on mechanical ventilation were reviewed and infants with hypocarbia (<4.7 kPa) and low CO₂ (<5.3 kPa) were identified. Cranial ultrasound and, where available, MRI findings of IVH, severe IVH and PVL were noted. This study was performed as an audit of current unit practice.

Results Ventilated ELBW infants admitted to the NICU between January and December 2006 were identified. Notes were obtained on 50 infants, only 3 had a PCO₂ <4.7 kPa (8%) on arrival to the NICU. 2 infants (4%) had a CO₂ <3.8 kPa on arrival and a further 3 infants (6%) had a low normal CO₂ (4 to 5.2 kPa).

Of the infants with hypocarbia (<4.7 kPa), 2 of 3 were oxygen dependent at 36 weeks’ corrected age. Of infants with a CO₂ between 4.7 and 5.3 kPa on admission, two died and the other did not develop CLD.

Conclusion 6 infants (12%) were exposed to increase risk of CLD because of low, and low to normal, early CO₂ values. However the incidence of hypocarbia on admission was only 6%, less than previously reported. Of 3 infants who were hypocarbic on admission, 2 developed subsequent CLD.