SURFACE-TENSION, GLUTATHIONE CONTENT AND REDOX RATIO OF THE TRACHEAL ASPIRATE FLUID OF PREMATURE-INFANTS WITH IRDS

Objective: Determination of the surface tension (ST), the total glutat hione (GL) content and the ratio of oxidized glutathione (GSSG) to red uced glutathione (GSH) in the tracheal aspirate (TA) of newborn infant s with IRDS. Methods: The ST of the TA was determined by monitoring th e fluid level pulsated in a capillary glass tube by means of a digital ized videocomputerized picture analysis program, a technique developed in our laboratory. The concentrations of GSSG and total GL in the TA were determined enzymatically with glutathione reductase. All results of laboratory tests were referred to the total phospholipid (PL) conce ntration. Patients, Experimental Material: TA samples were collected f rom 32 intubated premature and newborn infants admitted to the NICU wi th IRDS during the first 2 weeks of their lives. Control samples were obtained from 11 children prior to elective surgery. Results: The ST r elative to the PL content (surface tension index, STI) was significant ly lower in the newborns with IRDS than in the control group, and the concentration of GSH in the TA was also markedly decreased in all IRDS infants studied. The concentration of GSSG and the ratio of GSSG to G SH were significantly higher in the severe cases and in those with an unfavourable prognosis. Surfactant treatment had a protective effect a gainst oxidative stress, it induced a decrease in both the GSSG concen tration and in the GL redox ratio (GSSG/GSH) in the TA. There was a cl ose correlation between the GSH content and the STI value of the sampl es studied. Conclusion: Oxidation and consequent depletion of GSH in t he TA may be an aggravating factor in the development of the insuffici ent surface activity in intubated newborns with IRDS.