Surfactant disaturated-phosphatidylcholine kinetics in acute respiratory distress syndrome by stable isotopes and a two compartment model

BACKGROUND: In patients with acute respiratory distress syndrome (ARDS), it is well known that only part of the lungs is aerated and surfactant function is impaired, but the extent of lung damage and changes in surfactant turnover remain unclear. The objective of the study was to evaluate surfactant disaturated-phosphatidylcholine turnover in patients with ARDS using stable isotopes. METHODS: We studied 12 patients with ARDS and 7 subjects with normal lungs. After the tracheal instillation of a trace dose of (13)C-dipalmitoyl-phosphatidylcholine, we measured the (13)C enrichment over time of palmitate residues of disaturated-phosphatidylcholine isolated from tracheal aspirates. Data were interpreted using a model with two compartments, alveoli and lung tissue, and kinetic parameters were derived assuming that, in controls, alveolar macrophages may degrade between 5 and 50% of disaturated-phosphatidylcholine, the rest being lost from tissue. In ARDS we assumed that 5–100% of disaturated-phosphatidylcholine is degraded in the alveolar space, due to release of hydrolytic enzymes. Some of the kinetic parameters were uniquely determined, while others were identified as lower and upper bounds. RESULTS: In ARDS, the alveolar pool of disaturated-phosphatidylcholine was significantly lower than in controls (0.16 ± 0.04 vs. 1.31 ± 0.40 mg/kg, p < 0.05). Fluxes between tissue and alveoli and de novo synthesis of disaturated-phosphatidylcholine were also significantly lower, while mean resident time in lung tissue was significantly higher in ARDS than in controls. Recycling was 16.2 ± 3.5 in ARDS and 31.9 ± 7.3 in controls (p = 0.08). CONCLUSION: In ARDS the alveolar pool of surfactant is reduced and disaturated-phosphatidylcholine turnover is altered

Surfactant disaturated-phosphatidylcholine kinetics in acute respiratory distress syndrome by stable isotopes and a two compartment model

BACKGROUND: In patients with acute respiratory distress syndrome (ARDS), it is well known that only part of the lungs is aerated and surfactant function is impaired, but the extent of lung damage and changes in surfactant turnover remain unclear. The objective of the study was to evaluate surfactant disaturated-phosphatidylcholine turnover in patients with ARDS using stable isotopes. METHODS: We studied 12 patients with ARDS and 7 subjects with normal lungs. After the tracheal instillation of a trace dose of (13)C-dipalmitoyl-phosphatidylcholine, we measured the (13)C enrichment over time of palmitate residues of disaturated-phosphatidylcholine isolated from tracheal aspirates. Data were interpreted using a model with two compartments, alveoli and lung tissue, and kinetic parameters were derived assuming that, in controls, alveolar macrophages may degrade between 5 and 50% of disaturated-phosphatidylcholine, the rest being lost from tissue. In ARDS we assumed that 5–100% of disaturated-phosphatidylcholine is degraded in the alveolar space, due to release of hydrolytic enzymes. Some of the kinetic parameters were uniquely determined, while others were identified as lower and upper bounds. RESULTS: In ARDS, the alveolar pool of disaturated-phosphatidylcholine was significantly lower than in controls (0.16 ± 0.04 vs. 1.31 ± 0.40 mg/kg, p < 0.05). Fluxes between tissue and alveoli and de novo synthesis of disaturated-phosphatidylcholine were also significantly lower, while mean resident time in lung tissue was significantly higher in ARDS than in controls. Recycling was 16.2 ± 3.5 in ARDS and 31.9 ± 7.3 in controls (p = 0.08). CONCLUSION: In ARDS the alveolar pool of surfactant is reduced and disaturated-phosphatidylcholine turnover is altered

Global perspective on training and staffing for paediatric cardiac critical care

AbstractThis manuscript provides a global perspective on physician and nursing education and training in paediatric cardiac critical care, including available resources and delivery of care models with representatives from several regions of the world including Africa, Israel, Asia, Australasia, Europe, South America, and the United States of America

Calibration Belt for Quality-of-Care Assessment Based on Dichotomous Outcomes

Prognostic models applied in medicine must be validated on independent samples, before their use can be recommended. The assessment of calibration, i.e., the model's ability to provide reliable predictions, is crucial in external validation studies. Besides having several shortcomings, statistical techniques such as the computation of the standardized mortality ratio (SMR) and its confidence intervals, the Hosmer–Lemeshow statistics, and the Cox calibration test, are all non-informative with respect to calibration across risk classes. Accordingly, calibration plots reporting expected versus observed outcomes across risk subsets have been used for many years. Erroneously, the points in the plot (frequently representing deciles of risk) have been connected with lines, generating false calibration curves. Here we propose a methodology to create a confidence band for the calibration curve based on a function that relates expected to observed probabilities across classes of risk. The calibration belt allows the ranges of risk to be spotted where there is a significant deviation from the ideal calibration, and the direction of the deviation to be indicated. This method thus offers a more analytical view in the assessment of quality of care, compared to other approaches

Fatal Naegleria fowleri Meningoencephalitis, Italy

We report the first case of primary amebic meningoencephalitis in Italy, in a 9-year-old boy. Clinical course was fulminant, and diagnosis was made by identifying amebas in stained brain sections and by indirect immunofluorescence analysis. Naegleria fowleri was characterized as genotype I on the basis of polymerase chain reaction test results

WHO standards-based tools to measure service providers' and service users' views on the quality of hospital child care: development and validation in Italy

Objectives Evidence showed that, even in high-income countries, children and adolescents may not receive high quality of care (QOC). We describe the development and initial validation, in Italy, of two WHO standards-based questionnaires to conduct an assessment of QOC for children and young adolescents at inpatient level, based on the provider and user perspectives. Design Multiphase, mixed-methods study. Setting, participants and methods The two questionnaires were developed in four phases equally conducted for each tool. Phase 1 which included the prioritisation of the WHO Quality Measures according to predefined criteria and the development of the draft questionnaires. In phase 2 content face validation of the draft questionnaires was assessed among both experts and end-users. In phase 3 the optimised questionnaires were field tested to assess acceptability, perceived utility and comprehensiveness (N=163 end-users). In phase 4 intrarater reliability and internal consistency were evaluated (N=170 and N=301 end-users, respectively). Results The final questionnaires included 150 WHO Quality Measures. Observed face validity was excellent (kappa value of 1). The field test resulted in response rates of 98% and 76% for service users and health providers, respectively. Among respondents, 96.9% service users and 90.4% providers rated the questionnaires as useful, and 86.9% and 93.9%, respectively rated them as comprehensive. Intrarater reliability was good, with Cohen's kappa values exceeding 0.70. Cronbach alpha values ranged from 0.83 to 0.95, indicating excellent internal consistency. Conclusions Study findings suggest these tools developed have good content and face validity, high acceptability and perceived utility, and good intrarater reliability and internal consistency, and therefore could be used in health facilities in Italy and similar contexts. Priority areas for future research include how tools measuring paediatric QOC can be more effectively used to help health professionals provide the best possible care

Surfactant phosphatidylcholine half-life and pool size measurements in premature baboons developing bronchopulmonary dysplasia

Because minimal information is available about surfactant metabolism in bronchopulmonary dysplasia, we measured half-lives and pool sizes of surfactant phosphatidylcholine in very preterm baboons recovering from respiratory distress syndrome and developing bronchopulmonary dysplasia, using stable isotopes, radioactive isotopes, and direct pool size measurements. Eight ventilated premature baboons received (2)H-DPPC (dipalmitoyl phosphatidylcholine) on d 5 of life, and radioactive (14)C-DPPC with a treatment dose of surfactant on d 8. After 14 d, lung pool sizes of saturated phosphatidylcholine were measured. Half-life of (2)H-DPPC (d 5) in tracheal aspirates was 28 +/- 4 h (mean +/- SEM). Half-life of radioactive DPPC (d 8) was 35 +/- 4 h. Saturated phosphatidylcholine pool size measured with stable isotopes on d 5 was 129 +/- 14 micro mol/kg, and 123 +/- 11 micro mol/kg on d 14 at autopsy. Half-lives were comparable to those obtained at d 0 and d 6 in our previous baboon studies. We conclude that surfactant metabolism does not change during the early development of bronchopulmonary dysplasia, more specifically, the metabolism of exogenous surfactant on d 8 is similar to that on the day of birth. Surfactant pool size is low at birth, increases after surfactant therapy, and is kept constant during the first 2 wk of life by endogenous surfactant synthesis. Measurements with stable isotopes are comparable to measurements with radioactive tracers and measurements at autopsy

Surfactant Metabolism in Neonatal Lung Diseases

2noreservedmixedCarnielli, V.P.; Cogo, P.E.Carnielli, V. P.; Cogo, Paol

BALLOON ATRIAL SEPTOSTOMY AND PREOPERATIVE BRAIN INJURY IN NEONATES WITH TRANSPOSITION OF GREAT ARTERIES: A SYSTEMATIC REVIEW AND A META-ANALYSIS

4no22 Annual Congress of the European Society of Paediatric and Neonatal Intensive Care Hannover (Germany) 2-5 November 2011reservedmixedPolito, A; Ricci, Z; Fragasso, T; Cogo, PePolito, A; Ricci, Z; Fragasso, T; Cogo, Paol