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Biomedical subjects

P H Jarreau

Publications and source records attributed to P H Jarreau.

At least 19 recordsLinked to original sources
PubMed2001

Dual assessment of airway area profile and respiratory input impedance from a single transient wave.

This report concerns the inference of geometric and mechanical airway characteristics based on information derived from a single transient planar wave recorded at the airway opening. We describe a new method to simultaneously measure upper airway area and respiratory input impedance by performing dual analysis of a single pressure wave. The algorithms required to reconstruct airway dimensions and mechanical characteristics were developed, implemented, and tested with reference to known physical models. Our method appears suitable to estimate, even under severe intensive care unit conditions, the respiratory system frequency response (above 10 Hz) in intubated patients and the patency of the endotracheal tube used to connect the patients to the ventilator.

Acoustics↗
PubMed2001

Pulmonary edema fluid from patients with acute lung injury augments in vitro alveolar epithelial repair by an IL-1beta-dependent mechanism.

Efficient alveolar epithelial repair is crucial for the restoration of the injured alveolar epithelial barrier in patients with acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS). We hypothesized that pulmonary edema fluid from patients with ALI /ARDS would inhibit alveolar epithelial repair as measured in an in vitro epithelial wound-repair model using the human alveolar epithelial-like cell line A549. In contrast to our initial hypothesis, pulmonary edema fluid from patients with ALI/ARDS increased alveolar epithelial repair by 33 +/- 3% compared with pooled plasma from healthy donors (p < 0.01). By contrast, the plasma and the pulmonary edema fluid from patients with hydrostatic pulmonary edema, and the plasma from patients with ALI/ARDS had similar effects on epithelial repair as pooled plasma from healthy donors. Inhibition of interleukin-1beta (IL-1beta) activity by IL-1 receptor antagonist reduced alveolar epithelial repair induced by ALI/ARDS edema fluid by 46 +/- 4% (p < 0.001), indicating that IL-1beta contributed significantly to the increased epithelial repair. In summary, pulmonary edema fluid collected early in the course of ALI/ARDS increased alveolar epithelial repair in vitro by an IL-1beta-dependent mechanism. These data demonstrate a novel role for IL-1beta in patients with ALI/ARDS, indicating that IL-1beta may promote repair of the injured alveolar epithelium.

Adult↗
PubMed2000

Impact of delayed repair and elective high-frequency oscillatory ventilation on survival of antenatally diagnosed congenital diaphragmatic hernia: first application of these strategies in the more "severe" subgroup of antenatally diagnosed newborns.

OBJECTIVE: a) To analyze the influence of a new management strategy on the outcome of neonates with antenatally diagnosed congenital diaphragmatic hernia (CDH); b) to determine early prognosis respiratory factors with the new strategy. DESIGN: Retrospective study. SETTING: Level III perinatal center. PATIENTS AND METHOD: Between 1985 and 1997, 51 consecutive neonates with antenatally diagnosed CDH were admitted to our level III neonatal intensive care unit. Before 1992 (period 1; n = 19), we used conventional mechanical ventilation and early surgery requiring transfer. Since 1992 (period 2; n = 32), we prospectively tested a new approach including (a) systematically use of high-frequency oscillatory ventilation (HFOV) regardless of the initial clinical severity, (b) delayed surgery following stabilization requiring transfer to a different surgical unit, but (c) no transfer of unstable patients with surgery under HFOV in our neonatal intensive care unit (n = 10). The two cohorts were comparable in terms of potential ante and postnatal prognostic indicators. RESULTS: Survival was improved with the new strategy: 21/32 (66%) vs. 5/19 (26%); P < 0.02. This improvement between periods 1 and 2 was due to a decrease in both preoperative and postoperative deaths in the later period. The better survival during period 2 was associated with the appearance of very late deaths, frequent pleural effusions, and the survival of more severe forms having evolved to a chronic respiratory insufficiency. Survivors were ventilated for longer time with longer duration of oxygen supplementation. The best oxygenation index (OI), alveolar arterial difference and oscillation amplitude (P/P) during the first 24 h, but not the best PaCO2, were the most reliable prognostic indicators during period 2. An OI < or = 10 with a P/P < or = 55 cmH2O was associated with a very good prognosis (94% survival). CONCLUSIONS: The prognosis of antenatally diagnosed CDH was improved by systematic HFOV on admission, no systematic transfer, and delayed surgery. This improvement is associated with modification of postnatal outcome.

Female↗
PubMed2000

Interleukin-1beta augments in vitro alveolar epithelial repair.

Biologically active interleukin (IL)-1beta is present in the pulmonary edema fluid obtained from patients with acute lung injury and has been implicated as an important early mediator of nonpulmonary epithelial wound repair. Therefore, we tested the hypothesis that IL-1beta would enhance wound repair in cultured monolayers from rat alveolar epithelial type II cells. IL-1beta (20 ng/ml) increased the rate of in vitro alveolar epithelial repair by 118 +/- 11% compared with that in serum-free medium control cells (P < 0.01). IL-1beta induced cell spreading and migration at the edge of the wound but not proliferation. Neutralizing antibodies to epidermal growth factor (EGF) and transforming growth factor-alpha or inhibition of the EGF receptor by tyrphostin AG-1478 or genistein inhibited IL-1beta-induced alveolar epithelial repair, indicating that IL-1beta enhances in vitro alveolar epithelial repair by an EGF- or transforming growth factor-alpha-dependent mechanism. Moreover, the mitogen-activated protein kinase pathway is involved in IL-1beta-induced alveolar epithelial repair because inhibition of extracellular signal-regulated kinase activation by PD-98059 inhibited IL-1beta-induced alveolar epithelial repair. In conclusion, IL-1beta augments in vitro alveolar epithelial repair, indicating a possible novel role for IL-1beta in the early repair process of the alveolar epithelium in acute lung injury.

Animals↗
PubMed2000

High-frequency oscillatory ventilation in the management of respiratory distress syndrome.

Early use of high-frequency oscillatory ventilation with a high volume strategy (HFOV-HVS) has been proposed to decrease the incidence of chronic lung disease following respiratory distress syndrome (RDS) in extremely immature infants. Despite encouraging results of animal experiments, clinical trials have provided discordant results. Our own multicenter trial showed that using HFOV-HVS, compared with conventional ventilation, decreased exogenous surfactant requirements, but did not modify pulmonary outcome, and increased the risk of severe intraventricular hemorrhage. This prompted us to change our management of RDS, by switching from elective use of HFOV to an 'early rescue' approach.

Animals↗
PubMed2000

Detection of positional airway obstruction in neonates by acoustic reflection.

In neonates intubated with an uncuffed endotracheal tube (ETT), positional changes of the head may induce obstruction (side position-related ETT obstruction [SPRO]) due to abutment of the beveled distal ETT orifice against the tracheal wall. We studied whether the acoustic reflection (ACR) method, a 4-s measurement that maps cross-sectional area as a function of the distance along the ETT and the airways, could detect SPRO. Eleven preterm newborns intubated with 2.5-mm ETTs and clinically suspected of having SPRO were studied with the head oriented to the left and to the right. In all patients there was a marked decrease in the ACR-measured area beyond the distal tip of the ETT in the presence of obstruction (decrease = 38 +/- 22% [mean +/- SD] of the ETT inside area), while the ACR-measured area increased markedly in the absence of obstruction (increase = 49 +/- 17%). For six of the 11 infants, we also recorded the maximal flow produced by a set mechanical inflation pressure. This maximal flow decreased in the presence of obstruction (decrease = 47 +/- 18%), and was constantly associated with a decrease in ACR-measured area beyond the ETT. In conclusion, ACR measurement is an efficient method for diagnosing positional ETT obstruction in intubated newborns.

Acoustics↗
PubMed2000

[Repetition of corticoid treatment for fetal lung maturation: clinical and experimental scientific data].

Before 34 weeks, one course of antenatal corticosteroids significantly decreases neonatal mortality and morbidity. Courses are repeated every week, because of their alleged loss of efficiency after 7 days, although the relative benefits and risks of repeated courses are poorly known. Data from the literature suggest that improvement in lung function after repeated courses depends on the reduction of the treatment/birth interval and not on the rise in the cumulative dose. These benefits must be balanced against the risk of decreased birth weight induced by repeated courses. Because of their effect on fetal growth, weekly courses of corticosteroids should no longer be given systematically. In clinical practice, pregnancies at high risk of preterm delivery must be reassessed every week before prescribing a new course. Both better understanding of treatment duration of corticosteroids and randomized controlled trials comparing one and multiple courses are needed to improve antenatal management of neonatal respiratory stress syndrome.

Adrenal Cortex Hormones↗
PubMed1999

Antenatal glucocorticoid treatment and cystic periventricular leukomalacia in very premature infants.

BACKGROUND: Antenatal glucocorticoid therapy decreases the incidence of several complications among very premature infants. However, its effect on the occurrence of cystic periventricular leukomalacia, a major cause of cerebral palsy, remains unknown. METHODS: We retrospectively analyzed a cohort of 883 live-born infants, with gestational ages ranging from 24 to 31 weeks, who were born between January 1993 and December 1996 at three perinatal centers in the Paris area. The mothers of 361 infants had received betamethasone before delivery, the mothers of 165 infants had received dexamethasone before delivery, and the mothers of 357 infants did not receive glucocorticoids. We compared the rates of cystic periventricular leukomalacia among the three groups of infants in bivariate and multivariate analyses after adjustment for confounding factors. RESULTS: The rate of cystic periventricular leukomalacia was 4.4 percent among the infants whose mothers had received betamethasone, 11.0 percent among the infants whose mothers had received dexamethasone, and 8.4 percent among the infants whose mothers had not received a glucocorticoid. After adjustment for gestational age, the mode of delivery, and the presence or absence of chorioamnionitis, prolonged interval between the rupture of membranes and delivery (>24 hours), preeclampsia, and the use of tocolytic drugs, antenatal exposure to betamethasone was associated with a lower risk of cystic periventricular leukomalacia than was either the absence of glucocorticoid therapy (adjusted odds ratio, 0.5; 95 percent confidence interval, 0.2 to 0.9) or exposure to dexamethasone (adjusted odds ratio, 0.3; 95 percent confidence interval, 0.1 to 0.7). The adjusted odds ratio for the group of infants whose mothers had received dexamethasone as compared with the group of infants whose mothers had not received a glucocorticoid was 1.5 (95 percent confidence interval, 0.8 to 2.9). CONCLUSIONS: Antenatal exposure to betamethasone but not dexamethasone is associated with a decreased risk of cystic periventricular leukomalacia among very premature infants.

Betamethasone↗
PubMed1999

Corticosteroids and chronic lung disease in extremely immature infants: a dilemma.

What is the balance of benefits and risks of dexamethasone in extremely immature infants? The answer remains unclear. We feel that the risks of "early" treatment outweigh the benefits, because many infants who would not develop CLD will be treated. Treatment between day 7 and day 14 seems more appropriate to us, as it focuses on infants with a high risk of developing CLD. However, the lungs may be already somewhat damaged when starting treatment, whose expected benefit is a shortened duration of mechanical ventilation and a decreased incidence of CLD. The risks for growth and brain development are not clearly assessed. Both 7-day courses and pulse therapy are effective, but no comparison of these 2 schedules has been published. We therefore do not know whether pulse therapy provides the same benefits as 7-day courses with fewer risks for growth or cardiomyopathy.

Anti-Inflammatory Agents↗
PubMed1999

Estimation of inspiratory pressure drop in neonatal and pediatric endotracheal tubes.

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.

Adult↗
PubMed1997

Congenital adenomatoid malformation of the lung: when is active fetal therapy indicated?

OBJECTIVE: Although aggressive fetal therapies such as thoracoamniotic shunting can be applied to cystic adenomatoid malformations of the lung diagnosed in utero, there is no clear consensus regarding their indications. Our purpose was to evaluate a management policy in which aggressive fetal therapy was restricted to those cases complicated by major polyhydramnios or hydrops; all other cases were managed conservatively. STUDY DESIGN: A prospective cohort study of 33 cases with a prenatal diagnosis of cystic adenomatoid malformations of the lung was performed. Thoracoamniotic shunting was offered only in nine macrocystic cases with acute polyhydramnios or hydrops. RESULTS: Four cases were diagnosed postnatally as sequestrations. Of 12 cases complicated by acute polyhydramnios or hydrops, 5 survived (1 type III with spontaneous incomplete resolution in utero, 4 type I with substantial volume reduction after shunting). The 17 cases without acute polyhydramnios or hydrops were managed conservatively and survived. CONCLUSION: Conservative management is indicated in cases of cystic adenomatoid malformations of the lung without acute polyhydramnios or hydrops.

Cohort Studies↗
PubMed1996

Inspiratory work of breathing in ventilated preterm infants.

In ventilated newborns, part of the inspiratory work of breathing (WOB) may be due to the inspiratory efforts preceding inspiratory ventilator flow. This study was designed to quantify the contribution of these efforts to WOB. WOB was evaluated in six intubated preterm infants ventilated by the Dräger Babylog 8000. The ventilatory modes studied were intermittent mandatory ventilation (IMV), continuous positive airway pressure (CPAP), and assist-control ventilation at 10 (ACV10) and 15 (ACV15) cmH2O peak pressure. Mouth flow (V) and esophageal pressure (Pe) were recorded, and WOB was estimate from the area delineated by the esophageal pressure-volume curve, where volume is the time integral of V. Calculation of WOB started either at the onset of the infant's inspiratory flow (WOBi), or at the beginning of the infant's inspiratory muscle efforts, detected on Pe and confirmed on the V tracing (WOBm). WOBm was found to be significantly higher than WOBi under all ventilatory conditions studied. The difference in work of breathing (delta W) between WOBm and WOBi did not depend on the type of ventilatory mode. When delta W was related to WOBm, it amounted to about 30% of WOBm in IMV and CPAP, and 60% in ACV (P < 0.05, ACV15 vs. IMV). These results suggest that, in preterm infants connected to a ventilator, inspiratory efforts preceding flow inspiration might account for a large fraction of the inspiratory work of breathing.

Female↗
PubMed1996

Aerosolized tachykinin antagonists inhibit pentamidine-induce bronchoconstriction in guinea pigs.

To investigate the role of tachykinins in pentamidine-induced bronchoconstriction and airway microvascular leakage in the guinea pig, we examined the effects on bronchoconstriction and microvascular leakage of the nonpeptide antagonists of NK1 and NK2 tachykinin-receptors, respectively, CP-96,345 and SR 48968. Respiratory system resistance was measured by the occlusion method in anaesthetized, tracheotomized and mechanically ventilated guinea pigs. Airway microvascular permeability was evaluated by measuring the quantity of Evans blue dye in the trachea and main bronchi. Aerosolized CP-96,345 or SR 48968 partially abolished pentamidine-induced bronchoconstriction (at 5 to 30 mg/mL pentamidine; 60 breaths) whereas the combination of the two prevented it. In contrast, CP-96,345 and SR 48968 did not prevent the increase in airway microvascular permeability induced by pentamidine (50 mg/mL; 90 breaths) whether they were administered separately or together, by aerosol or intravenously. These results demonstrate that in the guinea pig, pentamidine-induced bronchoconstriction is mediated through both NK1 and NK2 tachykinin-receptor activation and that when directly administered into the airways, tachykinin antagonists effectively prevent pentamidine-induced bronchoconstriction.

Aerosols↗
PubMed1996

Unapparent systemic dissemination of Mycobacterium tuberculosis.

A healthy 6-week-old girl exposed to tuberculosis presented a positive DNA amplification for Mycobacterium tuberculosis complex in gastric aspirates and cerebrospinal fluid whereas she had no other clinical or biological symptoms. Cultures were negative. This report underlines the interest of polymerase chain reaction for early diagnosis of tuberculosis and suggests the importance of treating exposed neonates and young infants just as active tuberculosis.

Cerebrospinal Fluid↗
PubMed1996

Patient-triggered ventilation decreases the work of breathing in neonates.

During conventional intermittent mandatory ventilation (IMV) in neonates, asynchrony between mechanical and spontaneous breaths is frequent. We tested the hypothesis that patient-triggered ventilation (PTV) reduces the work of breathing (WOB) by providing synchronized assistance for each breath. Accordingly, six intubated preterm infants were studied at the median postnatal age of 34 days while they were being weaned from mechanical ventilation (MV). Patients were ventilated using the Draeger Babylog 8000 (software #3) and studied in four successive modes of MV with a constant level of positive end-expiratory pressure. They were randomly assigned to IMV, PTV with peak inspiratory pressure of either 10 cm H2O (PTV10) or 15 cm H2O (PTV15), and spontaneous ventilation with continuous positive airway pressure. PTV was achieved in the assist/control mode. During PTV, infants adapted their pattern of breathing in response to an increase in tidal volume (median 7.5 ml/kg in IMV versus 8.2 in PTV10 and 8.5 in PTV15, p<0.05) by decreasing their respiratory rate, thus maintaining minute ventilation (439 ml/min/kg in IMV versus 422 in PTV10 and 455 in PTV15, NS) and transcutaneous CO2. WOB fell significantly during PTV compared with its level during IMV (0.81 J/L in IMV versus 0.48 and 0.47 during PTV10 and PTV15, respectively, p<0.05). Power of breathing decreased in the same proportions. These results demonstrate that PTV mode allows reduction of the workload imposed on the respiratory muscles.

Adaptation, Physiological↗