Hervé Walti

Prophylactic Administration of Porcine-Derived Lung Surfactant Is a Significant Factor in Reducing the Odds for Peri-Intraventricular Haemorrhage in Premature Infants

We hypothesized that prophylactic treatment with a porcine-modified lung surfactant (PLS) reduces the rate of peri-intraventricular haemorrhage (PIVH) more than rescue treatment. We performed a meta-analysis of three prophylactic versus rescue trials conducted with PLS in four countries using individual data. Overall (grades 1–4) or severe (grades 3 and 4) PIVH of 671 newborns was the outcome. A logistic regression analysis was performed. Prophylactic exposure to PLS was a significant independent factor in reducing the incidence of overall (OR 0.65; 95% CI 0.47–0.90) and severe (OR 0.56; 95% CI 0.35–0.89) PIVH. Moreover, for severe PIVH, the adjusted OR for outborn babies exposed to prophylactic treatment with PLS was highly significant (OR 0.11; 95% CI 0.02–to 0.49). The results we obtained show that prophylactic treatment with PLS reduces the rate of PIVH more than rescue treatment.

Functional Residual Capacity and Sleep States in the Premature Newborn

Functional residual capacity (FRC) variations in relation to sleep state changes were studied in 11 premature infants with birth weights of 1.68 +/- 0.48 kg and gestational ages of 32.7 +/- 2.2 weeks (mean +/- SD). Helium dilution was used to measure FRC, and sleep states were identified using neurophysiologic criteria. No significant difference in FRC could be demonstrated between data collected during active sleep (AS) and quiet sleep. However a relationship was shown between AS and paradoxical breathing (p less than 0.02) and between AS and irregular breathing (p less than 0.05). Several factors are discussed which might explain the discrepancy between the present data in premature infants and the previously published data in term infants. (1) Neurophysiologic identification of sleep states does not include breathing pattern whereas behavioral identification does. It is therefore possible that lung volume changes are related to breathing pattern changes and not to sleep state changes per se. (2) Maturational changes may occur among the mechanisms which control FRC, leading to a progressive stabilisation of FRC, the variation of which could become related to sleep state changes.

Pulmonary Functional Outcome at One Year of Age in Infants Treated with Natural Porcine Surfactant at Birth

This prospective study was designed to assess pulmonary function (functional residual capacity, FRC; dynamic lung compliance, CLdyn; and total pulmonary resistance, RL) at 1 year of corrected age in infants with neonatal respiratory distress syndrome treated with natural porcine surfactant (Curosurf) (n = 13), as compared to nontreated control infants (n = 9). Values from 21 healthy infants of similar age served as reference. We found similar pulmonary dysfunction (decreased CLdyn, elevated RL) in both patient groups. These results suggest that surfactant replacement therapy does not affect pulmonary function at 1 year of age in infants who survive respiratory distress syndrome.

Heliox® Tolerance in Spontaneously Breathing Neonates with Bronchopulmonary Dysplasia

The use of a gas mixture in which helium is substituted for nitrogen allows a decrease in pulmonary resistances and in resistive work of breathing. This treatment might allow a reduction in energy expenditure in infants with bronchopulmonary dysplasia (BPD) and spare calories for growth. In a preliminary study designed to assess tolerance to Heliox®, 4 infants with BPD and 4 controls were studied firstly when breathing air and secondly when breathing Heliox®, at 10, 20 and 30 min exposure (T10, T20, T30). The following parameters were recorded: respiratory and cardiac rates, room (RT) and skin temperatures (ST) and transcutaneous (Tc) blood gases. When breathing air, TcPO2 was normal in the two groups (mean ± SEM: 70 ± 4 mm Hg in BPD vs. 78 ±4 in controls). TcPCO2 was higher in the BPD group (41 ± 2 vs. 35 ± 1 mm Hg in controls; p = 0.028). Spontaneously breathing Heliox had immediate consequences such as wakening, crying, decrease in ST and hypoxia. Hypoxia was more serious and more rapid in the BPD group. At the 10-min exposure, mean TcPO2 was 39 ± 4 mm Hg in BPD vs. 69 ± 7 in controls (p = 0.042). Hypoxia was immediatly corrected when breathing room air. TcPCO2 was unchanged in both groups.

Prospective Randomized Multicenter Comparison of High-Frequency Oscillatory Ventilation (HFOV) and Conventional Ventilation (CV) in Preterm Infants <30 Weeks Gestational Age (GA) with RDS

Prospective Randomized Multicenter Comparison of High-Frequency Oscillatory Ventilation (HFOV) and Conventional Ventilation (CV) in Preterm Infants <30 Weeks Gestational Age (GA) with RDS

Effects of Exogenous Surfactant and Recombinant Human Copper-Zinc Superoxide Dismutase on Oxygen-Dependent Antimicrobial Defenses

The use of human recombinant CuZn superoxide dismutase (rhSOD) in addition to exogenous surfactant has been studied as a therapeutic strategy to prevent acute and chronic lung injury in premature infants with blood monocytes (MO). However, scavenging of superoxide by rhSOD may compromise bacterial killing by phagocytes. In the present study, we investigated the interaction of exogenous surfactant and rhSOD with the antibacterial activity of human blood MO. MO were preincubated in the presence or absence of: (1) modified natural surfactant (Curosurf®; 1 mg/ml); (2) rhSOD (2,500 U/ml) and (3) bovine catalase (25,000 U/ml). Bacteria (Legionella pneumophila or Escherichia coli) were then added and incubated for 6 h. Viable bacteria were determined by counting colony-forming units. The ability of the MO to generate superoxide anions (O–2) in response to bacterial infection was also investigated. The antibacterial capacity of MO was not impaired by the presence of rhSOD either alone or combined with Curosurf®. In some instances, bactericidal activity was even potentiated by the addition of rhSOD. Exposure of MO to catalase interfered with the increased bacterial killing of MO and rhSOD, suggesting that hydrogen peroxide (H2O2) production was critically important in the process of bacterial killing. Both bacterial species were also found to induce the generation of intra- and extracellular O–2 by MO. Data indicate that rhSOD potentiates the killing of bacteria by human MO. The mechanism of action appears to be related to the ability of bacteria to induce the generation of O–2, which in turn is converted to H2O2 in the presence of rhSOD. This has important implications in the development of therapeutic intervention strategies using antioxidant therapy in premature infants with respiratory distress syndrome.

Serum Angiotensin I-Converting Enzyme Activity in Premature and Full-Term Infants

Serum angiotensin I-converting enzyme activity (SCEA) was investigated in 15 healthy premature (gestational age ranging from 30 to 36 weeks) and in 14 healthy full-term (gestational age ranging from 37 to 41 weeks) newborns as well as in 16 healthy adults (32.0 +/- 2.6 years). SCEA mean values in the three groups, respectively, 23.3 +/- 1.3, 24.4 +/- 1.6 and 23.2 +/- 1.7 nM . min-1 . ml-1, did not differ significantly from each other and in the newborns there was no correlation between SCEA values and gestational age.