Near infrared spectroscopy tissue oxygenation in infants with bronchiolitis during mechanical ventilation and spontaneous breathing

Introduction. Near-infrared spectroscopy (NIRS) was used in infants with acute bronchiolitis as a noninvasive indicator of tissue oxygenation to determine regional tissue oxygen saturation (rStO(2)) and fractional tissue oxygen extraction (FTOE) during mechanical ventilation and spontaneous breathing. Methods. Twenty-seven infants with bronchiolitis that needed mechanical ventilation were included in a prospective study. Regional StO(2) in brain, liver, kidney and skeletal muscle tissue was measured on admission to the Intensive Care Unit (ICU), on day 1 (D1); after two to three days of mechanical ventilation (D2); on the last day of mechanical ventilation (D3) and during spontaneous breathing (D4). Measurements were conducted by in-vivo optical spectroscopy. For research purposes we divided the infants according to C-reactive protein (CRP) levels, with a cut-off value of 10 mg/ml on admission, into low (l-CRP) and high (h-CRP) groups. Results. During mechanical and spontaneous breathing we found lower StO2 and higher FTOE for skeletal muscle at D4 compared to D1-D2 in the h-CRP group of patients. Differences between l-and h-CRP groups in rStO2 were found for brain tissue on D3, D4, and in rStO2 and FTOE for liver tissue on D3. A strong negative correlation was found between rStO2 and FTOE in all tissues. A positive correlation was found between CRP and rStO2 and negative between CRP and FTOE in skeletal muscle among all patients combined. Conclusion. Only Infants with acute bronchiolitis in the h-CRP group have significant changes in rStO2 and FTOE in skeletal muscles during mechanical ventilation and spontaneous breathing. Regional StO2 and FTOE in all the other measured tissues never decreased below normal values.