Premature lungs are highly susceptible to lung injuries, leading to bronchopulmonary dysplasia (BPD). Keratinocyte growth factor (KGF) is produced by the developing lung and may reduce the risk of BPD by preventing injury to the lung epithelium and enhancing its repair. To determine whether KGF concentrations in the airways during the initial phase of hyaline membrane disease are correlated with subsequent development of BPD defined as the need for supplemental oxygen at a postconceptional age of 36 weeks, we obtained tracheal aspirates within 3 hours of birth (Day 0) from 91 intubated neonates with a gestational age of 30 weeks or less. Repeat samples were obtained from 42 neonates within 5 days after birth. KGF in aspirate supernatants was measured by enzyme-linked immunosorbent assay. On Day 0, KGF was detected in all but six neonates. A significant increase in KGF concentration was found from the first to the second samples. The highest KGF concentration within 5 days after birth (KGF(max)) was significantly higher in survivors without BPD than in those with BPD. A KGF(max) value higher than 110 pg/ml had a positive predictive value of 95% for absence of BPD. KGF may hold promise for the treatment of very premature neonates.

2002.-Matrix-degrading metalloproteinases may play a role in the pathophysiology of bronchopulmonary dysplasia (BDP). We, therefore, evaluated correlations between gelatinase activities [metalloproteinase (MMP)-2 and MMP-9] or tissue inhibitor of metalloproteinase (TIMP)-1 levels present in the airways during the initial phase of hyaline membrane disease and the onset of BPD. Tracheal aspirates were obtained within 6 h of birth (day 0) from 64 intubated neonates with a gestational age Յ30 wk. Forty-five neonates were resampled on day 3 or 5. Total MMP-2 level measured by zymography fell with time, whereas total MMP-9 level and TIMP-1 levels, assayed by ELISA, increased; the MMP-9 increase correlated with the increase in airway inflammatory cell numbers. Among the parameters measured on day 0, 3, or 5, lower total MMP-2 level, lower birth weight, and higher fraction of inspired oxygen on day 0 were significantly and independently associated with the development of BPD. In conclusion, MMP-9 level and TIMP-1 levels increased after birth but are not linked to BPD outcome. In contrast, low MMP-2 level at birth is strongly associated with the development of BPD. metalloproteinase; lung development; newborn; extracellular matrix PREMATURE NEONATES WITH HYALINE membrane disease are at risk of developing bronchopulmonary dysplasia (BPD), as a sequel of both the disease and its treatment. The pathogenesis is unclear, but BPD is thought to result from damage to an immature lung. Mechanical ventilation, oxygen therapy, and airway inflammatory responses have all been implicated in the development of BPD (19). These insults appear to interfere with normal lung maturation, which is incomplete at birth. In particular, they appear to alter alveolar formation, on the basis of morphometric studies of severe BPD (3, 24). Alveolar formation is characterized by the multiplication of alveolar septa and the thinning of interalveolar walls, both of which require intense remodeling of the pulmonary extracellular matrix (4). Changes in matrix turnover have been experimentally linked to abnormal alveolar formation (20). The proteinase-antiproteinase balance in the lung is a key factor in harmonious matrix turnover. In particular, matrix metalloproteinases (MMPs), which can synergistically digest the major macromolecules of connective tissue matrices, have been implicated in physiological regulation of lung growth. The MMP gelatinase A (MMP-2) has been shown to play a role in the major collagen turnover that occurs during early postnatal rat lung growth (1, 2). We postulated that MMP-2 might also participate in human lung development and that inadequate MMP-2 levels in premature lungs exposed to insults could contribute to impaired lung growth and thus to BPD. We also postulated that MMPs may be secreted in excess during the inflammatory response associated with hyaline membrane disease and may, therefore, lead to tissue degradation. Gelatinase B (MMP-9) is the main MMP released by inflammatory cells such as neutrophils and alveolar macroph...

Endotracheal tubes (ETTs) constitute a resistive extra load for intubated patients. The ETT pressure drop (DeltaP(ETT)) is usually described by empirical equations that are specific to one ETT only. Our laboratory previously showed that, in adult ETTs, DeltaP(ETT) is given by the Blasius formula (F. Lofaso, B. Louis, L. Brochard, A. Harf, and D. Isabey. Am. Rev. Respir. Dis. 146: 974-979, 1992). Here, we also propose a general formulation for neonatal and pediatric ETTs on the basis of adimensional analysis of the pressure-flow relationship. Pressure and flow were directly measured in seven ETTs (internal diameter: 2.5-7.0 mm). The measured pressure drop was compared with the predicted drop given by general laws for a curved tube. In neonatal ETTs (2.5-3.5 mm) the flow regime is laminar. The DeltaP(ETT) can be estimated by the Ito formula, which replaces Poiseuille's law for curved tubes. For pediatric ETTs (4.0-7.0 mm), DeltaP(ETT) depends on the following flow regime: for laminar flow, it must be calculated by the Ito formula, and for turbulent flow, by the Blasius formula. Both formulas allow for ETT geometry and gas properties.

The prosthetic dead space makes a significant contribution to the total dead space in low-birth-weight premature newborns receiving artificial ventilation in response to respiratory distress. Use of an endotracheal tube with capillaries molded into the tube wall enables washout of the dead space without insertion of a tracheal catheter. In 10 premature newborns (mean gestational age, 27.5 +/- 2.2 wk; mean weight, 890 +/- 260 g) receiving continuous positive-pressure ventilation (Paw = 12.7 +/- 1.8 cm H2O; FIO2 = 39 +/- 17%), tracheal gas insufflation (TGI) for CO2 washout was conducted using this technique. The flow of tracheal insufflation (0.5 L/min) was derived from the inspiratory line of the ventilator circuit and blown into the trachea. Intratracheal pressures showed little or no TGI-related modification ( < 1 cm H2O). A control system enabled TGI discontinuation in the event of a pressure rise. At constant ventilation pressure, PaCO2 decreased by 12.1 +/- 5.9 mm Hg (delta PaCO2 = -26 +/- 12%) under TGI, whereas PaO2 remained unchanged. While maintaining PaCO2 constant, peak inspiratory pressure (PIP) was decreased by 5.4 +/- 1.7 cm H2O (delta PIP = -22.0 +/- 8.3%). TGI showed immediate efficacy (PCO2 reduction of at least 5 mm Hg) in nine of the 10 newborns who then received chronic TGI (14 to 138 h). TGI appears to be an effective method, suitable for long-term clinical application, enabling a reduction in the aggressive nature of conventional ventilation.

CTGI may be a useful adjunct to conventional ventilation in preterm neonates with respiratory disease, enabling an increase in CO2 clearance or a reduction in ventilatory pressure.

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Adding 36 hr of optimized mechanical ventilation before first extubation does not improve the rate of successful extubation but has no adverse effects.

BackgroundPremedication before neonatal intubation is heterogeneous and contentious. The combination of a short acting, rapid onset opioid with a muscle relaxant is considered suitable by many experts. The purpose of this study was to describe the tolerance and conditions of intubation following anaesthesia with atropine, sufentanil and atracurium in very premature infants.MethodsMonocentric, prospective observational study in premature infants born before 32 weeks of gestational age, hospitalised in the NICU and requiring semi-urgent or elective intubation. Intubation conditions, heart rate, pulse oxymetry (SpO2), arterial blood pressure and transcutaneous PCO2 (TcPCO2) were collected in real time during 30 minutes following the first drug injection. Repeated physiological measurements were analysed using mixed linear models.ResultsThirty five intubations were performed in 24 infants with a median post conceptional age of 27.6 weeks and a median weight of 850 g at the time of intubation. The first attempt was successful in 74% and was similar for junior (75%) and senior (74%) operators. The operator rated conditions as “excellent” or “good” in 94% of intubations. A persistent increase in TcPCO2 as compared to baseline was observed whereas other vital parameters showed no significant variations 5, 10, 15 and 30 minutes after the first drug injection. Eighteen (51%) desaturations (SpO2 less than or equal to 80% for more than 60 seconds) and 2 (6%) bradycardia (heart rate less than100 bpm for more than 60 seconds) were observed.ConclusionThis drug combination offers satisfactory success rate for first attempt and intubation conditions for the operator without any significant change in heart rate and blood pressure for the patient. However it is associated with frequent desaturations and a possible persistent hypercapnia. SpO2 and PCO2 can be significantly modified during neonatal intubation and should be cautiously followed in this high-risk population.