Positional effects on lung mechanics of ventilated preterm infants with acute and chronic lung disease.

BACKGROUND: The role of prone position in preterm infants has not been completely clarified. We investigated prone versus supine posture-related changes in respiratory system resistance (Rrs) and reactance (Xrs) measured by the Forced Oscillation Technique (FOT) in mechanically ventilated preterm newborns. METHODS: Patients were studied in the supine versus prone positions in random order. Oxygen saturation, transcutaneous partial pressure of oxygen (ptcO2 ), carbon dioxide (ptcCO2 ), Rrs and Xrs were measured in each position. RESULTS: Nine patients with respiratory distress syndrome (RDS) and nine with evolving broncho-pulmonary dysplasia (BPD) were studied. Rrs was, on average, 9.8 (1.3, 18.3 as 95%CI) cmH2 O*s/l lower in the prone compared to the supine position (P = 0.02), while no differences in Xrs, ptcO2 , ptcCO2 , and breathing pattern were observed between postures. Only patients with evolving BPD showed a significant reduction of Rrs from 69.0 ± 27.4 to 53.0 ± 16.7 cmH2 O*s/l, P = 0.01. No significant correlations were found between changes in lung mechanics and ptcO2 , ptcCO2 , or breathing pattern. CONCLUSIONS: On short-term basis, prone positioning does not offer significant advantages in lung mechanics in mechanically ventilated infants with RDS, while it is associated with lower Rrs values in patients with evolving BPD.

Relationship between respiratory impedance and positive end-expiratory pressure in mechanically ventilated neonates.

PURPOSE: To evaluate the feasibility of forced oscillation technique (FOT) measurements at the bedside and to describe the relationship between positive end-expiration pressure (PEEP) and lung mechanics in different groups of ventilated infants. METHODS: Twenty-eight infants were studied: 5 controls, 16 newborns with respiratory distress syndrome (RDS) and 7 chronically ventilated newborns that developed bronchopulmonary dysplasia. An incremental/decremental PEEP trial was performed by changing PEEP in 1-min steps of 1 cmH(2)O between 2 and 10 cmH(2)O. Forced oscillations at 5 Hz were superimposed on the ventilator waveform. Pressure and flow, measured at the inlet of the ETT, were used to compute resistance (Rrs) and reactance (Xrs). RESULTS: In controls Rrs and Xrs were on average 41 ± 21 and -22 ± 6 cmH(2)O s/l respectively and were almost unaffected by PEEP. RDS infants presented similar Rrs (48 ± 25 cmH(2)O s/l) and reduced Xrs (-71 ± 19 cmH(2)O s/l) at the beginning of the trial. Two behaviours were observed as PEEP was increased: in extremely low birth weight infants Xrs decreased with PEEP with marked hysteresis; in very low and low birth weight infants Xrs and Rrs were less PEEP dependent. Chronically ventilated infants had very high Rrs and very negative Xrs values at very low PEEPs (121 ± 41 and -95 ± 13 cmH(2)O s/l at PEEP = 2 cmH(2)O) that markedly changed as PEEP exceeded 3-4 cmH(2)O. CONCLUSIONS: Rrs and Xrs measurement in preterm newborns is feasible, and data are representative of the lung mechanics and very sensitive to its changes with PEEP, making FOT a promising technique for the non-invasive bedside titration of mechanical ventilation in preterm newborns.

Epithelial lining fluid neutrophil-gelatinase-associated lipocalin levels in premature newborns with bronchopulmonary dysplasia and patency of ductus arteriosus.

Patency of the ductus arteriosus (PDA) and bronchopulmonary dysplasia (BPD) development represent severe affections for premature newborns, therefore the research of early markers for these two conditions is really important. The aim of this study is to analyze epithelial lining fluid (ELF) Neutrophil-gelatinase-associated lipocalin (NGAL) levels for prediction of lung injury or possible involvement of this molecule in PDA. Only scarce and contrasting results have previously been published in this field. In contrast, this molecule, included in a large macromolecular complex together with matrix metalloproteinase-9 (MMP-9), is considered an acceptable marker of infectious/inflammatory processes, cancer monitoring and induction of apoptotic pathway. NGAL was detected in 28 pre-term newborns by means of a commercially available kit in bronchoalveolar lavage fluid (BALF). The results have been corrected to ELF levels, by the urea method, to eliminate bias due to BALF collection. ELF NGAL levels were found significantly increased both in infants developing BPD or in those affected by PDA. By means of multivariate logistic regression analysis the significances were confirmed after adjusting for possible interfering variables such as gestational age and concomitant presence of both PDA and BPD. Our results stress the involvement of NGAL in the mechanisms leading to BPD and also suggest a possible association with PDA, which is often linked to prematurity and BPD development, probably due to the involvement of inflammatory and angiogenetic processes in both pathologies.

[Use of Meropenem in preterm newborns. Survey of the literature and case series]. / L'uso del Meropenem nel neonato prematuro. Revisione della letteratura e casistica clinica.

AIM: The aim of this paper was to evaluate usefulness and safety of Meropenem in severe infections in neonatal intensive care unit (NICU) patients. New broad spectrum carbapenem class of -lactam antibiotics has been investigated for the treatment of a wide range of infections, including nosocomial infections with cephalosporin-resistant pathogens, an emergent problem in NICU, and meningitis. Meropenem represents the first cabapenem-class that has received Food and Drug Administration (FDA) approval for use in children 3 months of age and older. The pharmacokinetics of Meropenem has been well studied in preterm neonates. METHODS: We report the use of Meropenem in 26 neonates with median gestational age (GA) of 27 weeks (25-32) and median birth weight of 940 g (510-1900), with severe infections due to Gram-negative or Gram-positive organisms, from 2001 to 2004. The median postnatal age was 21 days (4-75). Meropenem was administrated intravenously in 30 min at dosage of 20 mg/kg every 12 h (every 8 h in Pseudomonas Aeruginosa infections). RESULTS: In all cases Meropenem has been used as second choice. No adverse effects (eosinophilia, trombocytosis or thrombocytopenia, increase in liver enzyme, increase in creatinine, diarrhea, vomiting and seizures) were observed. Clinical and bacterial response was ontaine in all cases but one. CONCLUSIONS: This report suggests that Meropenem may be a useful and safe antimicrobial agent in neonatal infections caused by resistant organisms and in meningitis. Further studies are needed to confirm these results.

[Pulmonary infections in preterm newborns]. / Infezioni polmonari nel neonato prematuro.

AIM: The aim of this study was to evaluate retrospectively the incidence and etiology of connatal pneumonia and ventilator-associated pneumonia (VAP) in preterm newborns who had birth weight = or < 1250 g and required intubation for at least 12 h. METHODS: We have reported data about preterm newborns who had birth weight = or < 1250 g and required intubation for at least 12 h with diagnosis of connatal pneumonia and VAP, admitted to the neonatal intensive care unit from 1994 to 2004. We divided these 11 years into 4 periods. For each period we determined etiology associated with connatal pneumonia or VAP. RESULTS: A total of 417 patients were studied; 311 (74.6%) required mechanical ventilation (MV) for more than 48 h (the least for the diagnosis of VAP). Connatal pneumonia occurred in 35/417 patients (8.4%). VAP incidence did not change over time showing a slight increase in the last 2 years (from 27% to 33%). Mycoplasma and Chlamydia as causative organisms of connatal pneumonia dissapear during years. Gram-negative micro-organisms were isolated more frequently in last years in VAP episodes. CONCLUSIONS: The incidence of VAP does not decrease over time although length of MV was reduced. Additional studies are needed to improve criteria for the diagnosis and prevention of VAP in NICU patients.