Objective C reactive protein (CRP) is a sensitive marker of acute inflammation of infectious and non-infectious origin. Aim was to use near-infrared spectroscopy (NIRS) to analyse peripheral oxygenation and perfusion in term and preterm neonates with elevated CRP levels, at a time when routine haemodynamic variables are still normal.

Design Prospective observational study.

Settings Peripheral-muscle NIRS was performed in the first week of life. Tissue-oxygenation index (TOI), mixed venous oxygenation (SvO₂), fractional oxygen extraction (FOE), haemoglobin flow (Hbflow), oxygen delivery (DO₂) and oxygen consumption (VO₂) were assessed. Blood samples were taken within 3 h of the NIRS measurements.

Patients Cardiocirculatory stable term and preterm neonates with infection-related and infection-unrelated CRP elevations >10 mg/l were compared with neonates without CRP elevation. The two groups were matched for gestational and postnatal age.

Results 33 neonates with CRP elevation (gestational age 37.7±2.9 weeks) were compared with 33 controls (gestational age 37.3±2.9 weeks). In neonates with CRP elevation, TOI (68.9±6.6%), SvO₂ (66.9±7.3%) DO₂ (39.2±16.1 µmol/100ml/min) and VO₂ (10.9±3.4 µmol/100ml/min) were significantly lower compared with controls (TOI 72.9±3.8%, SvO₂ 70.2±4.7%, DO₂ 48.8±18.4 µmol/100ml/min, VO₂ 12.3±3.8 µmol/100ml/min). There was no significant difference in any other NIRS or routine haemodynamic parameter between the two groups.

Conclusion Inflammatory processes with CRP elevation cause impaired peripheral oxygenation and perfusion in neonates even when routine haemodynamic variables are still normal. NIRS might offer a new non-invasive tool for the early recognition and diagnosis of infectious and non-infectious inflammatory processes.