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Biomedical subjects

Francis Leclerc

Publications and source records attributed to Francis Leclerc.

18 recordsLinked to original sources
PubMed2006

Evaluation of a noninvasive cardiac output monitor in mechanically ventilated children.

OBJECTIVE: To compare measurements of cardiac output (CO) and cardiac index (CI) obtained by a recently developed noninvasive continuous cardiac output system, NICO (CONICO), and transthoracic Doppler echocardiography (COTTE) in mechanically ventilated children. DESIGN AND SETTING: Prospective study in a university-affiliated tertiary pediatric intensive care unit. PATIENTS: A total of 21 mechanically ventilated children, weighing >15 kg, in stable respiratory and hemodynamic condition. MEASUREMENTS: Sets of three successive measurements of CO with the NICO system and transthoracic Doppler echocardiography were obtained. Bland-Altman analysis was used to compare the agreement between the two methods. RESULTS: The mean +/- sd CO values were 4.06 +/- 1.43 L/min for CONICO and 4.67 +/- 1.78 L/min for COTTE. Bias +/- sd between the two methods was -0.61 +/- 0.94 L/min. The variability of the difference between the two methods increased as the magnitude of the CO measurement increased. Similar results were obtained for cardiac index: 4.01 +/- 1.40 L.min.m for CINICO and 4.59 +/- 1.48 L.min.m for CITTE. Bland-Altman analysis revealed a nonuniform relationship between CI difference and the magnitude (y = -0.299 - 0.0655 x mean). The variability of the differences did not increase as the magnitude of the CO measurement increased (sd of estimate was 0.827 L.min.m). With both CONICO and CINICO, each measurement was highly repeatable, with coefficient of variation of only 2.88% +/- 2.31%. Repeatability with Doppler echocardiography was 7.02% +/- 4.33%. CONCLUSIONS: The NICO system is a new device that measures CO easily and automatically in mechanically ventilated children weighing >15 kg. CO values obtained with this technique were in agreement with those obtained with Doppler echocardiography in children in respiratory and hemodynamic stable condition. The NICO system needs further investigation in children in unstable respiratory and hemodynamic condition.

Adolescent↗
PubMed2006

The moral experience of parents regarding life-support decisions for their critically-ill children: a preliminary study in France.

The common paediatric critical care practice in France is for physicians (rather than parents) to maintain the ultimate responsibility for lifesupport decisions in children. Some French literature asserts that it is inappropriate for parents to bear such responsibilities because they do not have the required knowledge and should be protected from feeling culpable for such decisions. The aim of this grounded theory preliminary study was to examine the moral experience of parents of critically-ill children that required life-support decisions in France. A convenience purposive sample of seven parents was recruited in Paris. Five principal themes emerged as significant from these interviews: (1) a need for more information; (2) physicians should be responsible for life-support decisions; (3) the child's concerns and wishes need to be better heard; (4) maternal guilt; and (5) physicians require better training in parent communication. These findings raise important issues for clinical practice and further research in France.

Adaptation, Psychological↗
PubMed2005

Does taking endurance into account improve the prediction of weaning outcome in mechanically ventilated children?

INTRODUCTION: We conducted the present study to determine whether a combination of the mechanical ventilation weaning predictors proposed by the collective Task Force of the American College of Chest Physicians (TF) and weaning endurance indices enhance prediction of weaning success. METHOD: Conducted in a tertiary paediatric intensive care unit at a university hospital, this prospective study included 54 children receiving mechanical ventilation (> or = 6 hours) who underwent 57 episodes of weaning. We calculated the indices proposed by the TF (spontaneous respiratory rate, paediatric rapid shallow breathing, rapid shallow breathing occlusion pressure [ROP] and maximal inspiratory pressure during an occlusion test [Pimax]) and weaning endurance indices (pressure-time index, tension-time index obtained from P(0.1) [TTI1] and from airway pressure [TTI2]) during spontaneous breathing. Performances of each TF index and combinations of them were calculated, and the best single index and combination were identified. Weaning endurance parameters (TTI1 and TTI2) were calculated and the best index was determined using a logistic regression model. Regression coefficients were estimated using the maximum likelihood ratio (LR) method. Hosmer-Lemeshow test was used to estimate goodness-of-fit of the model. An equation was constructed to predict weaning success. Finally, we calculated the performances of combinations of best TF indices and best endurance index. RESULTS: The best single TF index was ROP, the best TF combination was represented by the expression (0.66 x ROP) + (0.34 x Pimax), and the best endurance index was the TTI2, although their performance was poor. The best model resulting from the combination of these indices was defined by the following expression: (0.6 x ROP) - (0.1 x Pimax) + (0.5 x TTI2). This integrated index was a good weaning predictor (P < 0.01), with a LR+ of 6.4 and LR+/LR- ratio of 12.5. However, at a threshold value < 1.3 it was only predictive of weaning success (LR- = 0.5). CONCLUSION: The proposed combined index, incorporating endurance, was of modest value in predicting weaning outcome. This is the first report of the value of endurance parameters in predicting weaning success in children. Currently, clinical judgement associated with spontaneous breathing trials apparently remain superior.

Child↗
PubMed2004

Cumulative influence of organ dysfunctions and septic state on mortality of critically ill children.

The interaction between sepsis and multiple organ dysfunction syndrome is poorly defined in children. We analyzed by Cox regression models the cumulative influence of organ dysfunctions, using the pediatric logistic organ dysfunction (PELOD) score, and septic state (systemic inflammatory response syndrome or sepsis, severe sepsis, and septic shock) on mortality of critically ill children. We included 593 children (mortality rate: 8.6%) from three pediatric intensive care units; 514 patients had at least a systemic inflammatory response syndrome and 269 had two or more organ dysfunctions. Hazard ratio of death significantly increased with the severity of organ dysfunction, as estimated by the PELOD score, and the worst diagnostic category of septic state. Each increase of one unit in the PELOD score multiplied the hazard ratio by 1.096 (p < 0.0001); hazard ratio of diagnostic category was 9.039 (p = 0.031) for systemic inflammatory response syndrome or sepsis, 18.797 (p = 0.007) for severe sepsis and 32.572 (p < 0.001) for septic shock. Cumulative hazard ratio of death = (hazard ratio of PELOD score) x (hazard ratio of diagnostic category). We conclude that there is a cumulative accrual of the risk of death both with an increasing severity of organ dysfunction and an increasing severity of the diagnostic category of septic state.

Child↗
PubMed2004

Can generic paediatric mortality scores calculated 4 hours after admission be used as inclusion criteria for clinical trials?

INTRODUCTION: Two generic paediatric mortality scoring systems have been validated in the paediatric intensive care unit (PICU). Paediatric RISk of Mortality (PRISM) requires an observation period of 24 hours, and PRISM III measures severity at two time points (at 12 hours and 24 hours) after admission, which represents a limitation for clinical trials that require earlier inclusion. The Paediatric Index of Mortality (PIM) is calculated 1 hour after admission but does not take into account the stabilization period following admission. To avoid these limitations, we chose to conduct assessments 4 hours after PICU admission. The aim of the present study was to validate PRISM, PRISM III and PIM at the time points for which they were developed, and to compare their accuracy in predicting mortality at those times with their accuracy at 4 hours. METHODS: All children admitted from June 1998 to May 2000 in one tertiary PICU were prospectively included. Data were collected to generate scores and predictions using PRISM, PRISM III and PIM. RESULTS: There were 802 consecutive admissions with 80 deaths. For the time points for which the scores were developed, observed and predicted mortality rates were significantly different for the three scores (P < 0.01) whereas all exhibited good discrimination (area under the receiver operating characteristic curve >or=0.83). At 4 hours after admission only the PIM had good calibration (P = 0.44), but all three scores exhibited good discrimination (area under the receiver operating characteristic curve >or=0.82). CONCLUSIONS: Among the three scores calculated at 4 hours after admission, all had good discriminatory capacity but only the PIM score was well calibrated. Further studies are required before the PIM score at 4 hours can be used as an inclusion criterion in clinical trials.

Adolescent↗
PubMed2004

[Meningococcal purpura fulminans in children].

In France, the incidence of meningococcal infections is increasing and the most severe presentation, called purpura fulminans, has still a death rate of 20-25%. Diagnosis of invasive meningococcal infection must be evoked in any child presenting with febrile purpura (vasculitic rash not disappearing with "tumbler test"); a fulminating form must be suspected in the presence of only one ecchymosis and signs of infection, remembering that recognition of shock is difficult in children. The Health Authority recommend to administer a third generation cephalosporin promptly for any child with signs of infection and an ecchymotic purpura (>3 mm of diameter), and then to refer the patient to the hospital. Children with purpura fulminans should be referred to a paediatric intensive care unit. Management includes antibiotics, steroids, fluid resuscitation and catecholamines (be aware of hypoglycaemia, particularly in infants, and hypocalcaemia). Treatment of cutaneous necrosis and distal ischemia is difficult and still controversial: antithrombin, protein C, tissue plasminogen activator and vasodilator infusion have no proved efficacy. Cases must be rapidly notified to the Public Health Service who will institute chemoprophylaxis for close contacts. Given the predominance of serogroup B in France, we hope that an efficient vaccine will soon become available.

Adolescent↗
PubMed2003

Validation of the paediatric logistic organ dysfunction (PELOD) score: prospective, observational, multicentre study.

BACKGROUND: Multiple organ dysfunction syndrome is more frequent than death in paediatric intensive care units. Estimation of the severity of this syndrome could be a useful additional outcome measure in clinical trials in such units. We aimed to validate the paediatric logistic organ dysfunction (PELOD) score and estimate its validity when recorded daily (dPELOD). METHODS: We did a prospective, observational, multicentre cohort study in seven multidisciplinary, tertiary-care paediatric intensive care units of university-affiliated hospitals (two French, three Canadian, and two Swiss). We included 1806 consecutive patients (median age 24 months; IQR 5-90). PELOD score includes six organ dysfunctions and 12 variables and was recorded daily. For each variable, the most abnormal value each day and during the whole stay were used in calculating the dPELOD and PELOD scores, respectively. Outcome was vital status at discharge. We used Hosmer-Lemeshow goodness-of-fit tests to evaluate calibration and areas under receiver operating characteristic curve (AUC) to estimate discrimination. FINDINGS: 370 (21%) patients had no organ dysfunction, 471 (26%) had one, 457 (25%) had two, and 508 (28%) had three or more. Case fatality rate was 6.4% (115 deaths). PELOD score was significantly higher in non-survivors (mean 31.0 [SE 1.2]) than survivors (9.4 [0.2]; p<0.0001). Calibration (p=0.54) and discrimination (AUC=0.91, SE=0.01) of PELOD and dPELOD (p> or =0.39; AUC> or =0.79) scores were good. INTERPRETATION: PELOD and dPELOD scores are valid outcome measures of the severity of multiple organ dysfunction syndrome in paediatric intensive care units; their use should significantly reduce the sample size required to complete clinical trials in critically ill children.

Adolescent↗
PubMed2003

Combined antithrombin and protein C supplementation in meningococcal purpura fulminans: a pharmacokinetic study.

PURPOSE: To document in patients with meningococcal purpura fulminans (PF), the effects of a combined supplementation with antithrombin (AT) and protein C (PC) plasma concentrates and to estimate the pharmacokinetics and dose requirements of each inhibitor. DESIGN: Retrospective study of 15 patients. SETTING. One paediatric and one adult ICU in a university hospital. INTERVENTIONS: In addition to standard intensive care, all patients received a 100 IU/kg loading dose of AT and PC concentrates, followed by a continuous infusion (AT: 100-150 IU.kg.day; PC: 100 IU.kg.day in adults, and 400 IU/kg in infants). MEASUREMENTS: Clinical data, coagulation, and fibrinolysis parameters, AT and PC activities, and free protein S (PS) levels were sequentially measured. Restitution ratio, median increment after supplementation, and half-life of clearance from plasma were calculated for the two plasma substitutes. RESULTS. At admission, all patients had a severe decrease in AT, PC, and PS levels. The supplementation regimen induced a substantial increase in AT and PC activities, peaking at H18 and H48, respectively. The supplementation procedure did not modify free PS levels. The median values of AT and PC restitution ratio, increment in plasma activity observed after 100 IU/kg concentrate, and apparent half-life of clearance from plasma were 0.85 U.ml.U.kg and 0.59 U.ml.U.kg, 23% and 21%, 16 h and 6 h, respectively. CONCLUSION: If AT and PC concentrates are to be given in fulminant meningococcemia, the doses of supplementation should be at least 150 IU/kg AT and 250 IU/kg PC as loading dose and 150 IU/kg AT and 200 IU/kg PC as daily maintenance therapy. Taking into account the individual variability in inhibitor deficiency and restitution ratio, repeated measurements of plasma levels are mandatory to obtain a patient-based adjustment of the supplementation.

Antithrombins↗
PubMed2003

Influence of respiratory system impedance on volume and pressure delivered at the Y piece in ventilated infants.

OBJECTIVES: Tidal volume (VT) delivered to infants' airways are overestimated and pressure underestimated when measured in the ventilator and not at the Y piece. This study aimed at evaluating the influence of respiratory system impedance on expiratory VT (VTE) and pressure measurement difference. DESIGN: Prospective observational study. SETTING: Pediatric intensive care unit at a university hospital. PATIENTS: Data were collected between February 2000 and October 2001 for 30 infants (range, 1-23 months) ventilated in the pressure-controlled or volume-controlled mode. INTERVENTIONS: Measurements of VTE, pressure obtained at the same time at the Y piece and on the ventilator Servo 300, were collected in ventilated infants. Respiratory system impedance was calculated from data obtained at the Y piece. Circuit compliance was measured in vitro. VTEs were corrected for compressible volume. MEASUREMENTS AND RESULTS: VTEs were overestimated by the Servo 300 in the pressure-controlled and volume-controlled modes (from 5% to 62% of the value displayed on Servo 300). Maximal inspiratory pressures were underestimated by the Servo 300 in the pressure-controlled mode (difference from -2 to +19 cm H(2)O). Measurement difference increased with increasing respiratory system impedance. Ventilator VTE corrected for circuit compliance did not offer a sufficiently accurate estimation of VTE at the Y piece. CONCLUSIONS: VT and pressure measurements must be performed at the Y piece, especially in infants with increased respiratory system impedance (i.e., decreased respiratory system compliance or increased resistance). Correcting VTE for circuit compliance cannot replace measurement of VT at the Y piece.

Airway Resistance↗
PubMed2002

Prediction of outcome after hypoxic-ischemic encephalopathy: a prospective clinical and electrophysiologic study.

OBJECTIVES: To evaluate and compare the predictive value of history, clinical examination, and biologic and electrophysiologic data regarding the prognosis of children with acute hypoxic-ischemic encephalopathy (HIE). STUDY DESIGN: Prospective cohort of 57 consecutive children who were mechanically ventilated for HIE throughout a 3-year period in a tertiary pediatric intensive care unit at a university hospital in France. RESULTS: At 24 hours after admission, 12 patients had died, 3 were awake and 42 showed impaired consciousness or were in a coma, of whom 38% had a favorable outcome. In this group, an initial cardiopulmonary resuscitation duration longer than 10 minutes and a Glasgow Coma Scale <5 at 24 hours after admission were associated with an unfavorable outcome (positive predictive value [PPV] 91%, 100%; sensitivity 50%, 54%). A discontinuous electroencephalogram (EEG), the presence of spikes or epileptiform discharges were associated with an unfavorable outcome (PPV 100% for the 2 criteria; sensitivity 27%, 54%). The bilateral absence of the N20 wave on short-latency sensory evoked potentials (SEPs) had a PPV for unfavorable outcome of 100% (sensitivity 63%). CONCLUSIONS: The clinical assessment combined with EEG and SEPs allow an early prediction of the prognosis of children with HIE.

Adolescent↗
PubMed2002

Effect of increasing inspiratory time on respiratory mechanics in mechanically ventilated neonates.

OBJECTIVE: To investigate the effect of inspiratory time and inspiratory flow on the respiratory mechanics of intubated and ventilated neonates. DESIGN: Physiology study. SETTING: Tertiary university neonatal intensive care unit. PATIENTS: Neonates requiring mechanical ventilation with (group 1, n = 9) and without lung disease (group 2, n = 6). INTERVENTIONS: All infants were ventilated with a Servo 900C Siemens ventilator in the volume-controlled constant-flow mode. Flow and pressure were measured at the Y-piece, while different inspiratory times (25%, 33%, 50%, and 67% of the respiratory cycle) were applied randomly without changing tidal volume. MEASUREMENTS: The constant flow end-inspiratory airway occlusion technique allowed partitioning of the total respiratory system resistance (R(tot,rs)) into a standard intrinsic flow resistance (R(int,rs)) and a lung/thorax tissue viscoelastic component (DeltaR(rs)), and it allowed partitioning of the dynamic respiratory system elastance (E(dyn,rs)) into a static (E(st,rs)) and a lung/thorax tissue viscoelastic component (DeltaE(rs)). A two-compartment model of the respiratory system was applied to the experimental data. MAIN RESULTS: All respiratory mechanics components were significantly higher in group 1 compared with group 2. Both groups showed increasing R(int,rs) with increasing flow and increasing DeltaR(rs) with increasing inspiratory time. DeltaR(rs) represented 40% to 75% of R(tot,rs) whatever the group. E(dyn,rs) and E(st,rs) changed with inspiratory time in the very low (<0.4 secs) and the very long inspiratory time range (>1.0 secs). No change was found when clinically, commonly used inspiratory times were applied (0.4-1.0 secs). DeltaE(rs) represented 17% to 19% of E(dyn,rs). The relationship between DeltaR(rs) and increasing inspiratory time fitted the exponential two-compartment model (r =.99, p <.001). CONCLUSIONS: Total respiratory mechanics and its components in ventilated newborns with and without lung disease showed inspiratory time dependence. DeltaR(rs) increased with increasing inspiratory time as predicted by the two-compartment lung model, whereas standard R(int,rs) and E(dyn,rs) decreased.

Clinical Trial↗