Transcutaneous CO 2 Monitoring in Extremely Low Birth Weight Premature Infants.

Extremely low birth weight (ELBW) premature infants are particularly susceptible to hypocarbia and hypercarbia, which are associated with brain and lung morbidities. Transcutaneous CO 2 (TcCO 2 ) monitoring allows for continuous non-invasive CO 2 monitoring during invasive and non-invasive ventilation and is becoming more popular in the NICU. We aimed to evaluate the correlation and agreement between CO 2 levels measured by a TcCO 2 monitor and blood gas CO 2 (bgCO 2 ) among ELBW infants. This was a prospective observational multicenter study. All infants < 1000 g admitted to the participating NICUs during the study period were monitored by a TcCO 2 monitor, if available. For each bgCO 2 measured, a simultaneous TcCO 2 measurement was documented. In total, 1828 pairs of TcCO 2 -bgCO 2 values of 94 infants were collected, with a median (IQR) gestational age of 26.4 (26.0, 28.3) weeks and birth weight of 800 (702, 900) g. A moderate correlation (Pearson: r = 0.64) and good agreement (bias (95% limits of agreement)):(2.9 [-11.8, 17.6] mmHg) were found between the TcCO 2 and bgCO 2 values in the 25-70 mmHg TcCO 2 range. The correlation between the TcCO 2 and bgCO 2 trends was moderate. CO 2 measurements by TcCO 2 are in good agreement (bias < 5 mmHg) with bgCO 2 among premature infants < 1000 g during the first week of life, regardless of day of life, ventilation mode (invasive/non-invasive), and sampling method (arterial/capillary/venous). However, wide limits of agreement and moderate correlation dictate the use of TcCO 2 as a complementary tool to blood gas sampling, to assess CO 2 levels and trends in individual patients.