C reactive protein: impact on peripheral tissue oxygenation and perfusion in neonates

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.

Prospective observational study.

Peripheral-muscle NIRS was performed in the first week of life. Tissue-oxygenation index (TOI), mixed venous oxygenation (SvO(2)), fractional oxygen extraction (FOE), haemoglobin flow (Hbflow), oxygen delivery (DO(2)) and oxygen consumption (VO(2)) were assessed. Blood samples were taken within 3 h of the NIRS measurements.

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.

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%), SvO(2) (66.9±7.3%) DO(2) (39.2±16.1 µmol/100ml/min) and VO(2) (10.9±3.4 µmol/100ml/min) were significantly lower compared with controls (TOI 72.9±3.8%, SvO(2) 70.2±4.7%, DO(2) 48.8±18.4 µmol/100ml/min, VO(2) 12.3±3.8 µmol/100ml/min). There was no significant difference in any other NIRS or routine haemodynamic parameter between the two groups.

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.