RESUMO
One of the most convenient ways to determine fetal lung maturity is by measuring the fluorescence polarization (P) of the amniotic fluid at room temperature. With sensitivity fixed on 100%, specificity is relatively unsatisfactory. The present study compared the predictive power of fluorescence polarization measured at temperatures 25C (P25), 37C (P37), and 40C (P40) among 195 consecutive samples tested at both 25C and 37C, with a subgroup of 86 samples tested also at 40C. A better separation between the results for fetuses with and without hyaline membrane disease is attained at P37, demonstrated by a greater mean standardized distance (distance between P values for those patients with and the mean P value for those patients without hyaline membrane disease in unit of standard deviation of the latter; 1.597 +/- 0.528 for P25 versus 2.332 +/- 0.591 for P37). Fixing the sensitivity at 100%, the specificity of P25 and P37, were 68.9 and 94.9%, respectively; a highly significant difference (P less than .001). The specificity of P40 was 90.5%, lower than that of P37. P37 is the best predictor and adding either P25 or P40 does not improve the prediction of lung maturity. It is concluded that P37 should replace P25 as the definite index for fetal lung maturity.
Assuntos
Líquido Amniótico/fisiologia , Temperatura Corporal , Maturidade dos Órgãos Fetais , Viscosidade , Feminino , Polarização de Fluorescência , Idade Gestacional , Humanos , Doença da Membrana Hialina/diagnóstico , Recém-Nascido , Pulmão/embriologia , Gravidez , Complicações na Gravidez/fisiopatologia , Diagnóstico Pré-Natal , Viscosidade/instrumentação , Viscosidade/métodosAssuntos
Líquidos Corporais , Elasticidade/instrumentação , Viscosidade/instrumentação , Alcenos , Clara de Ovo , Pulmão , Muco , Polímeros , Pressão , Reologia , SalivaAssuntos
Viscosidade Sanguínea , Viscosidade/instrumentação , Sedimentação Sanguínea , Humanos , Plasma , ReologiaRESUMO
A viscometer was tested and the results were found to be accurate and reproducible for the ranges encountered in neonates. The viscosity was determined in 80 cord blood samples and the mean and 2 standard deviations (2SD) were calculated at each shear rate. Changes in viscosity increased from birth to 12 hours, and then gradually decreased over the next 72 hours. The results are in keeping with the accepted normal values in the newborn.
Assuntos
Viscosidade Sanguínea , Recém-Nascido , Sangue Fetal , Hematócrito , Humanos , Veias , Viscosidade/instrumentaçãoRESUMO
Inexpensive electronic components were adapted to a miniaturized version of a falling-ball viscometer. This allowed automatic determination of relative viscosities of Newtonian fluids with 1% accuracy and employing only 10 to 30 microliters of sample or about 1 microgram of some biological materials. The electronic microviscometer was tested with bidistilled water at several temperatures, with CS2SO4 and glycerol solutions, several organic liquids, and some preparations of high-molecular-weight hyaluronic acid. Details of construction, circuitry, temperature control, operating procedure, and calculations are given as well as an evaluation of the instrument's performance in terms of previously established criteria.