Simultaneous quantitation from infrared spectra of glucose concentrations, lactate concentrations, and lecithin/sphingomyelin ratios in amniotic fluid.

OBJECTIVE: The purpose of this study was to assess the feasibility of using infrared spectroscopy to simultaneously predict preterm infection, fetal distress, and fetal lung maturity. STUDY
DESIGN: A total of 189 infrared spectra were acquired from amniotic fluid obtained by amniocentesis. The concentrations of glucose and lactate and the lecithin/sphingomyelin ratios were determined separately by accepted clinical chemistry methods for each sample. Infrared spectra were recorded with a commercial spectrometer and 35 microL amniotic fluid was used for each spectrum. Calibration models (partial least squares) were derived from the correlation between 102 infrared spectra and clinical standard analyses; the model was then validated with the remaining 87 spectra.
RESULTS: By means of the multivariate technique of partial least squares regression, calibration models for glucose and lactate were developed that had excellent correlation coefficients (r = 0.97 for glucose and r = 0. 91 for lactate); the SEs of calibration were 0.04 mmol/L for glucose and 0.09 mmol/L for lactate. The validation sets for the quantitation of glucose and lactate predicted by the calibration models also yielded good outcomes (r = 0.95 for glucose and r = 0.71 for lactate, with SEs of prediction of 0.06 mmol/L and 0.18 mmol/L, respectively).
CONCLUSION: Infrared spectroscopy has the potential to become the clinical method of choice for simultaneously predicting preterm infection, fetal distress, and fetal lung maturity.