Background and aims Hypocarbia reduces cerebral blood flow, potentially impairing neurodevelopmental outcome. Avoiding hypocarbia in the ventilated infant during transport can be challenging. Physiology is changing with stabilisation, there are fewer opportunities for regular blood gas analysis, and transport ventilators are less sophisticated e.g. Babypac. We sought to determine the scale of the problem and characterise babies most at risk.

Methods Data from transports during the year 2011/12 were reviewed retrospectively. Babies with a pCO₂ less than 4 KPa at completion of transport were identified and their notes reviewed for additional data regarding diagnosis and respiratory status.

Results There were 256 ventilated patients transferred of whom 32 (12.5%) arrived at the receiving hospital with a pCO₂ below 4KPa, and 5 (2%) of those had a pCO₂ below 3KPa. The majority of affected patients had HIE (25%) or were premature (44%). The category of transport was important with a trend for over-ventilation in the resource rather than uplift subgroup (20.9% v 10.8%). Babies with hypocarbia had minimal ventilator requirements during the transfer (FiO₂ 21–28%, PEEP 56 mmHg, PIP 16–21 mmHg). Trajectory of pCO₂ from referral to departure was negative in 6/21 (29%) patients. There was no association with gestation, weight or age in days.

Conclusion Over-ventilation is a significant problem. We found no single factor identifying patients at risk. Until patient characteristics of at risk populations can be accurately defined any ventilated patient should be considered at risk of over-ventilation during transport. Clinical strategies to address this problem are required.