ATR based infrared spectroscopy for the diagnosis of neonatal respiratory distress syndrome

Optical spectroscopy offers a potential non-invasive, label free and rapid method to assist clinicians to diagnose diseases for which biomarkers are known. Neonatal respiratory distress syndrome (nRDS) diagnosis in preterm infants is known to be correlated with the lecithin/sphingomyelin ratio (LS ratio) in gastric aspirates, with a ratio less than 2.2 indicating that surfactant replacement therapy is needed. Currently no widespread method exists that can give clinically relevant answers in less than 2 hours from the point of sample collection as it is difficult to identify those who could benefit from prompt surfactant treatment. Various LS ratios were generated using pure dipalmitoylphosphatidylcholine (DPPC) and sphingomyelin (SM) dissolved in dichloromethane and infrared spectra generated using Attenuated Total Reflection (ATR) assisted Fourier Transform InfraRed spectrometry (FTIR). Subsequent analysis obtained the LS ratio using the spectra alone. Further, we demonstrate the application of principal component regression (PCR) and partial least squares (PLS) fits to measured spectra to assist in the determination of the LS ratio using a model trained with multiple runs of the different batches of the same concentration.