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.