Changes in phospholipid composition of tracheal aspirates from newborns with hyaline membrane disease or transient tachypnoea

Amniotic fluid lamellar body count as a novel biochemical marker for timing elective caesarean delivery

The aim of this study is to evaluate the performance of amniotic fluid lamellar body count (LBC) on the timing of elective caesarean delivery (CS) at ≥ 39 weeks. After allocating the study group (group I, transient tachypnoea of newborn (TTN), n = 14), an age-matched control group (group II, no TTN, n = 79) was selected for amniotic fluid LBC analysis. The median amniotic fluid LBC levels in group I were significantly lower than in the control group. Furthermore, the median values of mean lamellar body volume, median lamellar body distribution width and lamellar bodycrit in group I were also significantly lower than in group II. The best amniotic fluid LBC value to predict TTN was 40.15 × 10(3)/μl, with 82.3% sensitivity and 64.3% specificity. The favourable sensitivity and specificity values to predict the TTN for amniotic fluid LBC may suggest using it as an elective caesarean delivery-time scheduling marker.

Surfactant deficiency in transient tachypnea of the newborn

OBJECTIVE

To evaluate surfactant production and function in term neonates with transient tachypnea of the newborn (TTN).

STUDY DESIGN

Samples of gastric aspirates collected within 30 minutes of birth from 42 term newborns with gestational age ≥ 37 weeks (21 patients with TTN and 21 control subjects), delivered via elective cesarean delivery, were analyzed with lamellar body count and stable microbubble test.

RESULTS

Results of lamellar body counts and stable microbubble tests were significantly lower in the TTN group than in control subjects (P = .004 and .013, respectively). Lamellar body counts were significantly lower in infants with TTN requiring oxygen for ≥ 24 hours after birth than in infants requiring oxygen for < 24 hours (P = .029). When the cutoff point was 48 hours, the stable microbubble count was significantly lower in the group requiring oxygen for ≥ 48 hours than in the group requiring oxygen for < 48 hours (P = .047).

CONCLUSIONS

Term infants with TTN had low lamellar body counts associated with decreased surfactant function, suggesting that prolonged disease is associated with surfactant abnormalities.

Les déficits secondaires en surfactant

Preterm babies born before the 33rd week of gestation often exhibit primary surfactant deficiency responsible for the respiratory distress syndrome or hyaline membrane disease. In that situation, there is a limited and insufficient production of surfactant by type II alveolar cells of the lung due to immaturity. Secondary surfactant deficiencies occur in patients with prior normal surfactant synthesis and can be related to sepsis, hypoxia, ventilator induced lung injury or surfactant inhibition by a variety of substances reaching the alveolar spaces. They occur in full-term newborns with meconium aspiration syndrome, acute respiratory distress syndrome and congenital diaphragmatic hernia. In children and adults, acute respiratory distress syndrome and respiratory syncytial virus bronchiolitis can be responsible. In prematures they occur after the initial primary deficiency during pulmonary hemorrhage, pneumonia and bronchopulmonary dysplasia. Treatment with exogenous surfactant may be beneficial. There is a need for randomized controlled studies for evaluation of this treatment. Next generation of surfactants containing recombinant surfactant protein or synthetic peptides appear as promising agents in these situations of secondary surfactant deficiencies.

Disturbed surface properties in preterm infants with pneumonia

Congenital pneumonia in preterm infants is often associated with respiratory insufficiency requiring mechanical ventilation. This study was performed to show whether pneumonia in these infants is associated with an inhibition or deficiency of surfactant. The ratio of lecithin and sphingomyelin (L/S ratio) and minimal surface tension were determined in pharyngeal aspirates from 90 term born infants (healthy) and in tracheal aspirates from preterm infants with wet lung (n = 13), congenital pneumonia (n = 21) and respiratory distress syndrome (RDS) (n = 90). The L/S ratio was lower (p < 0.0001) in the RDS group (8.6) when compared with healthy (48.6), wet lung (42.9) and pneumonia (28.9). Surface tension was higher (p < 0.001) in RDS (37 mN/m) and pneumonia (33.7) when compared with healthy (22.9) or wet lung (21.2). For infants with RDS, L/S ratio <16.5 detects surfactant deficiency with 96% specificity and 70% sensitivity, surface tension >29 mN/m represents surfactant inhibition (specificity 97%, sensitivity 92%). Using these cut-off values in infants with pneumonia, 81% had a sufficient amount of surfactant but only 21% of infants with pneumonia had appropriate surface tension. Our study shows that lung effluent of respiratory insufficient infants with pneumonia, who need mechanical ventilation, has disturbed surface properties despite a sufficient amount of surfactant. In these infants, surfactant substitution could be beneficial.

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 glutathione (GL) content and the ratio of oxidized glutathione (GSSG) to reduced glutathione (GSH) in the tracheal aspirate (TA) of newborn infants with IRDS.

METHODS

The ST of the TA was determined by monitoring the fluid level pulsated in a capillary glass tube by means of a digitalized 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) concentration. Patients, Experimental Material: TA samples were collected from 32 intubated premature and newborn infants admitted to the NICU with IRDS during the first 2 weeks of their lives. Control samples were obtained from 11 children prior to elective surgery.

RESULTS

The ST relative to the PL content (surface tension index, STI) was significantly 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 GSH were significantly higher in the severe cases and in those with an unfavourable prognosis. Surfactant treatment had a protective effect against oxidative stress, it induced a decrease in both the GSSG concentration and in the GL redox ratio (GSSG/GSH) in the TA. There was a close correlation between the GSH content and the STI value of the samples studied.

CONCLUSION

Oxidation and consequent depletion of GSH in the TA may be an aggravating factor in the development of the insufficient surface activity in intubated newborns with IRDS.