Age-dependent differences in pulmonary host responses in ARDS: a prospective observational cohort study.

BACKGROUND: Results from preclinical studies suggest that age-dependent differences in host defense and the pulmonary renin-angiotensin system (RAS) are responsible for observed differences in epidemiology of acute respiratory distress syndrome (ARDS) between children and adults. The present study compares biomarkers of host defense and RAS in bronchoalveolar lavage (BAL) fluid from neonates, children, adults, and older adults with ARDS. METHODS: In this prospective observational study, we enrolled mechanical ventilated ARDS patients categorized into four age groups: 20 neonates (< 28 days corrected postnatal age), 29 children (28 days-18 years), 26 adults (18-65 years), and 17 older adults (> 65 years of age). All patients underwent a nondirected BAL within 72 h after intubation. Activities of the two main enzymes of RAS, angiotensin converting enzyme (ACE) and ACE2, and levels of biomarkers of inflammation, endothelial activation, and epithelial damage were determined in BAL fluid. RESULTS: Levels of myeloperoxidase, interleukin (IL)-6, IL-10, and p-selectin were higher with increasing age, whereas intercellular adhesion molecule-1 was higher in neonates. No differences in activity of ACE and ACE2 were seen between the four age groups. CONCLUSIONS: Age-dependent differences in the levels of biomarkers in lungs of ARDS patients are present. Especially, higher levels of markers involved in the neutrophil response were found with increasing age. In contrast to preclinical studies, age is not associated with changes in the pulmonary RAS.

Pharmacokinetics of S-ketamine during prolonged sedation at the pediatric intensive care unit.

BACKGROUND: S-ketamine is the S(+)-enantiomer of the racemic mixture ketamine, an anesthetic drug providing both sedation and analgesia. In clinical practice, significant interpatient variability in drug effect of S-ketamine is observed during long-term sedation. AIMS: The aim of this study was to evaluate the pharmacokinetic variability of S-ketamine in children aged 0-18 years during long-term sedation. Twenty-five children (median age: 0.42 years, range: 0.02-12.5) received continuous intravenous administrations of 0.3-3.6 mg/kg/h S-ketamine for sedation during mechanical ventilation. Infusion rates were adjusted to the desired level of sedation and analgesia based on the COMFORT-B score and Visual Analog Scale. Blood samples were drawn once daily at random time-points, and at 1 and 4 hours after discontinuation of S-ketamine infusion. Time profiles of plasma concentrations of S-ketamine and active metabolite S-norketamine were analyzed using nonlinear mixed-effects modeling software. Clearance and volume of distribution were allometrically scaled using the ¾ power model. RESULTS: A total of 86 blood samples were collected. A 2-compartment and 1-compartment model adequately described the PK of S-ketamine and S-norketamine, respectively. The typical parameter estimates for clearance and central and peripheral volumes of distribution were: CLS-KETAMINE =112 L/h/70 kg, V1S-KETAMINE =7.7 L/70 kg, V2S-KETAMINE =545L/70 kg, QS-kETAMINE =196 L/h/70 kg, and CLS-NORKETAMINE =53 L/h/70 kg. Interpatient variability of CLS-KETAMINE and CLS-NORKETAMINE was considerable with values of 40% and 104%, respectively, leading to marked variability in steady-state plasma concentrations. CONCLUSION: Substantial interpatient variability in pharmacokinetics in children complicates the development of adequate dosage regimen for continuous sedation.

Age-Dependent Changes in the Pulmonary Renin-Angiotensin System Are Associated With Severity of Lung Injury in a Model of Acute Lung Injury in Rats.

OBJECTIVES: A growing body of evidence suggests that age affects the main pathophysiologic mechanisms of the acute respiratory distress syndrome. This may imply the need for developing age-tailored therapies for acute respiratory distress syndrome. However, underlying molecular mechanisms governing age-related susceptibility first need to be unraveled. In a rat model of acute lung injury, we investigated whether age affects the balance between the two key enzymes of the pulmonary renin-angiotensin system, angiotensin-converting enzyme, and angiotensin-converting enzyme 2. We hypothesized that aging shifts the balance toward the lung injury-promoting angiotensin-converting enzyme, which may form an explanation for the differences in severity of lung injury between different age groups. DESIGN: Prospective, randomized controlled animal study. SETTING: University medical research laboratory. SUBJECTS: Infant (15 ± 2 d), juvenile (37 ± 2 d), adult (4 ± 0.2 mo), and elderly (19.5 ± 0.5 mo) male RCCHan Wistar rats. INTERVENTIONS: Lung injury was induced by intratracheal administration of lipopolysaccharide (5 mg/kg) and 4 hours of mechanical ventilation (15 mL/kg). MEASUREMENTS AND MAIN RESULTS: In lipopolysaccharide-exposed and mechanical ventilated rats, angiotensin-converting enzyme activity in bronchoalveolar lavage fluid increased 3.2-fold in elderly when compared with infants. No changes in bronchoalveolar lavage fluid angiotensin-converting enzyme 2 activity were found. In addition, membrane-bound angiotensin-converting enzyme activity decreased. Together with the presence of angiotensin-converting enzyme-sheddase ADAM9 (a disintegrin and metalloproteinase domain-containing protein 9) and an age-dependent increase in tumor necrosis factor-α, an activator of ADAM9, these results indicate increased shedding of angiotensin-converting enzyme in the alveolar compartment, thereby shifting the balance toward the injurious pathway. This imbalance was associated with an increased inflammatory mediator response and more lung injury (wet-to-dry ratio and histology) in elderly rats. CONCLUSIONS: Increasing age is associated with an imbalance of the pulmonary renin-angiotensin system, which correlates with aggravated inflammation and more lung injury. These changes might form the ground for new therapeutic strategies in terms of dosing and effectiveness of renin-angiotensin system-modulating agents for treatment of acute respiratory distress syndrome.

Incidence and Mortality of Acute Respiratory Distress Syndrome in Children: A Systematic Review and Meta-Analysis.

OBJECTIVES: Our understanding of the acute respiratory distress syndrome in children is limited, and literature is dominated by investigations in adult patients. Recent preclinical studies suggest that the susceptibility to and severity of acute respiratory distress syndrome in children could differ from that in adults. We assessed the incidence and mortality of acute respiratory distress syndrome reported in children in studies published in the last two decades. DATA SOURCES: Medline, Embase, and CINAHL databases were searched up to August 2014. STUDY SELECTION: Articles reporting study data on population- or PICU-based incidence and mortality of acute respiratory distress syndrome in children (> 36 wk gestation and < 18 yr old) were selected. DATA EXTRACTION: Two authors independently collected data and assessed methodological quality and risk of bias of selected studies. Pooled estimates of incidence and mortality were calculated using random-effects models. To explore heterogeneity, influence of study characteristics, including median year of conduct, study location, inclusion and exclusion criteria, and study design and quality, was assessed by meta-regression analysis. DATA SYNTHESIS: Twenty-nine studies reported on incidence and 32 on mortality. Pooled weighted estimate of the population-based and PICU-based incidence of pediatric acute respiratory distress syndrome was 3.5 (95% CI, 2.2-5.7) cases per 100,000 person years and 2.3% (95% CI, 1.9-2.9), respectively. Pooled weighted mortality was 33.7% (95% CI, 28.6-39.7). There were no trends over time, but mortality was significantly associated with study location. CONCLUSIONS: This systematic review and meta-analysis shows a low incidence but a high mortality. Its results also indicate that both incidence and mortality of pediatric acute respiratory distress syndrome have not changed over the last two decades and that mortality depends on the geographic location of studies.

The effect of short-term high versus normal protein intake on whole-body protein synthesis and balance in children following cardiac surgery: a randomized double-blind controlled clinical trial.

BACKGROUND: Infants undergoing cardiac surgery are at risk of a negative protein balance, due to increased proteolysis in response to surgery and the cardiopulmonary bypass circuit, and limited intake. The aim of the study was to quantify the effect on protein kinetics of a short-term high-protein (HP) diet in infants following cardiac surgery. METHODS: In a prospective, double-blinded, randomized trial we compared the effects of a HP (5 g · kg(-1) · d(-1)) versus normal protein (NP, 2 g · kg(-1) · d(-1)) enteral diet on protein kinetics in children <24 months, on day 2 following surgical repair of congenital heart disease. Valine kinetics and fractional albumin synthesis rate (FSRalb) were measured with mass spectrometry using [1-(13)C]valine infusion. The Mann-Whitney U test was used to investigate differences between group medians. Additionally, the Hodges-Lehmann procedure was used to create a confidence interval with a point estimate of median differences between groups. RESULTS: Twenty-eight children (median age 9 months, median weight 7 kg) participated in the study, of whom in only 20 subjects isotopic data could be used for final calculations. Due to underpowering of our study, we could not draw conclusions on the primary outcome parameters. We observed valine synthesis rate of 2.73 (range: 0.94 to 3.36) and 2.26 (1.85 to 2.73) µmol · kg(-1) · min(-1) in the HP and NP diet, respectively. The net valine balance was 0.54 (-0.73 to 1.75) and 0.24 (-0.20 to 0.63) µmol · kg(-1) · min(-1) in the HP and NP group. Between groups, there was no difference in FSRalb. We observed increased oxidation and BUN in the HP diet, compared to the NP diet, as a plausible explanation of the metabolic fate of surplus protein. CONCLUSIONS: It is plausible that the surplus protein in the HP group has caused the increase of valine oxidation and ureagenesis, compared to the NP group. Because too few patients had completed the study, we were unable to draw conclusions on the effect of a HP diet on protein synthesis and balance. We present our results as new hypothesis generating data. TRIAL REGISTRATION: Dutch Trial Register NTR2334.

Association between Maturation and Aging and Pulmonary Responses in Animal Models of Lung Injury: A Systematic Review.

BACKGROUND: Advanced age is associated with an increased susceptibility and mortality of the acute respiratory distress syndrome. This may be due to the progressive changes in innate immune responses and intrinsic properties of the lung that occur during the process of aging. Therefore, this study assesses the association between maturation and aging and pulmonary responses to injury in animal models of lung injury. METHODS: A systematic search was conducted in PubMed, EMBASE (up to June 2014) and in the references of relevant articles to identify the studies using in vivo models of lung injury caused by an acute pulmonary insult, in which at least two age groups were compared. Because methodological diversity precluded combining these studies in a quantitative meta-analysis, data are presented based on the qualitative comparison with the adult group. RESULTS: Of the 2,840 identified studies, 51 were included in this review. Most studies showed that, in response to a pulmonary insult, increasing age is associated with more pulmonary inflammation, edema, alveolar damage, and higher mortality. In addition, results indicate the existence of age-dependent changes in key components of the intracellular signaling pathways involved in the inflammatory response. CONCLUSIONS: Increasing age seems to be correlated with exaggerated pulmonary responses to injury, ultimately leading to more severe lung injury. Pulmonary inflammation seems relatively suppressed in infants/juveniles, whereas in the middle aged/elderly, the inflammatory response seems delayed but aggravated. This implies that investigators and clinicians need to use caution about extrapolating results from adolescent or youngadult animals to pediatric or elderly patients in clinical practice.

The caspase inhibitor zVAD increases lung inflammation in pneumovirus infection in mice.

Severe respiratory syncytial virus (RSV) disease is a frequent cause of acute respiratory distress syndrome (ARDS) in young children, and is associated with marked lung epithelial injury and neutrophilic inflammation. Experimental studies on ARDS have shown that inhibition of apoptosis in the lungs reduces lung epithelial injury. However, the blockade of apoptosis in the lungs may also have deleterious effects by hampering viral clearance, and importantly, by enhancing or prolonging local proinflammatory responses. The aim of this study was to determine the effect of the broad caspase inhibitor Z-VAD(OMe)-FMK (zVAD) on inflammation and lung injury in a mouse pneumovirus model for severe RSV disease. Eight- to 11-week-old female C57BL/6OlaHsd mice were inoculated with the rodent-specific pneumovirus pneumonia virus of mice (PVM) strain J3666 and received multiple injections of zVAD or vehicle (control) during the course of disease, after which they were studied for markers of apoptosis, inflammation, and lung injury on day 7 after infection. PVM-infected mice that received zVAD had a strong increase in neutrophil numbers in the lungs, which was associated with decreased neutrophil apoptosis. Furthermore, zVAD treatment led to higher concentrations of several proinflammatory cytokines in the lungs and more weight loss in PVM-infected mice. In contrast, zVAD did not reduce apoptosis of lung epithelial cells and did not affect the degree of lung injury, permeability, and viral titers in PVM disease. We conclude that zVAD has an adverse effect in severe pneumovirus disease in mice by enhancing the lung proinflammatory response.

Talking with parents about end-of-life decisions for their children.

BACKGROUND AND OBJECTIVE: Retrospective studies show that most parents prefer to share in decisions to forgo life-sustaining treatment (LST) from their children. We do not yet know how physicians and parents communicate about these decisions and to what extent parents share in the decision-making process. METHODS: We conducted a prospective exploratory study in 2 Dutch University Medical Centers. RESULTS: Overall, 27 physicians participated, along with 37 parents of 19 children for whom a decision to withhold or withdraw LST was being considered. Forty-seven conversations were audio recorded, ranging from 1 to 8 meetings per patient. By means of a coding instrument we quantitatively and qualitatively analyzed physicians' and parents' communicative behaviors. On average, physicians spoke 67% of the time, parents 30%, and nurses 3%. All physicians focused primarily on providing medical information, explaining their preferred course of action, and informing parents about the decision being reached by the team. Only in 2 cases were parents asked to share in the decision-making. Despite their intense emotions, most parents made great effort to actively participate in the conversation. They did this by asking for clarifications, offering their preferences, and reacting to the decision being proposed (mostly by expressing their assent). In the few cases where parents strongly preferred LST to be continued, the physicians either gave parents more time or revised the decision. CONCLUSIONS: We conclude that parents are able to handle a more active role than they are currently being given. Parents' greatest concern is that their child might suffer.

Incidence, risk factors, and outcome of transfusion-related acute lung injury in critically ill children: a retrospective study.

PURPOSE: Acute lung injury (ALI) that develops within 6 hours after transfusion (TRALI) is the leading cause of transfusion-related morbidity and mortality. Both incidence and patient and transfusion-related risk factors are well studied in the adult critically ill patient population. Clinical data on TRALI in the pediatric population are sparse and are mainly limited to case reports and hemovigilance reporting systems. The objective of this study was to determine incidence, risk factors, and outcome of TRALI in critically ill children. MATERIALS AND METHODS: In a retrospective cohort study, all first-time admissions to the pediatric intensive care unit from January 1, 2009, until December 31, 2012, were screened for onset of TRALI using the consensus criteria. RESULTS: Of 2294 admitted patients, 304 were transfused, of whom 21 (6.9%) developed TRALI. Compared with transfused control subjects, risk factors for TRALI were mechanical ventilation (odds ratio, 18.94 [2.38-2452.56]), sepsis (odds ratio, 7.20 [2.69-19.69]), and high Pediatric Risk of Mortality III score (odds ratio, 1.05 [1.01-1.10]). Patients with TRALI had a higher mortality and a longer duration of mechanical ventilation when compared with transfused control subjects. CONCLUSIONS: Transfusion-related ALI is relatively common in critically ill children. The incidence in the pediatric intensive care unit population is similar to that in adult intensive care unit patients. High PRISM score on admission, mechanical ventilation and sepsis were identified as independent risk factors, which may help to assess the risks and benefits of transfusion in critically ill patients.

Parents who wish no further treatment for their child.

BACKGROUND: In the ethical and clinical literature, cases of parents who want treatment for their child to be withdrawn against the views of the medical team have not received much attention. Yet resolution of such conflicts demands much effort of both the medical team and parents. OBJECTIVE: To discuss who can best protect a child's interests, which often becomes a central issue, putting considerable pressure on mutual trust and partnership. METHODS: We describe the case of a 3-year-old boy with acquired brain damage due to autoimmune-mediated encephalitis whose parents wanted to stop treatment. By comparing this case with relevant literature, we systematically explored the pros and cons of sharing end-of-life decisions with parents in cases where treatment is considered futile by parents and not (yet) by physicians. CONCLUSIONS: Sharing end-of-life decisions with parents is a more important duty for physicians than protecting parents from guilt or doubt. Moreover, a request from parents on behalf of their child to discontinue treatment is, and should be, hard to over-rule in cases with significant prognostic uncertainty and/or in cases with divergent opinions within the medical team.

The effect of TIP on pneumovirus-induced pulmonary edema in mice.

BACKGROUND: Pulmonary edema plays a pivotal role in the pathophysiology of respiratory syncytial virus (RSV)-induced respiratory failure. In this study we determined whether treatment with TIP (AP301), a synthetic cyclic peptide that mimics the lectin-like domain of human TNF, decreases pulmonary edema in a mouse model of severe human RSV infection. TIP is currently undergoing clinical trials as a therapy for pulmonary permeability edema and has been shown to decrease pulmonary edema in different lung injury models. METHODS: C57BL/6 mice were infected with pneumonia virus of mice (PVM) and received TIP or saline (control group) by intratracheal instillation on day five (early administration) or day seven (late administration) after infection. In a separate set of experiments the effect of multiple dose administration of TIP versus saline was tested. Pulmonary edema was determined by the lung wet-to-dry (W/D) weight ratio and was assessed at different time-points after the administration of TIP. Secondary outcomes included clinical scores and lung cellular response. RESULTS: TIP did not have an effect on pulmonary edema in different dose regimens at different time points during PVM infection. In addition, TIP administration did not affect clinical severity scores or lung cellular response. CONCLUSION: In this murine model of severe RSV infection TIP did not affect pulmonary edema nor course of disease.

FiO2 predicts outcome in infants with respiratory syncytial virus-induced acute respiratory distress syndrome.

OBJECTIVE: Respiratory syncytial virus (RSV) infection can progress to acute respiratory distress syndrome (ARDS) in infants. ARDS is a life-threatening condition that is characterized by severe hypoxemia, defined as PaO(2)/FiO(2) ratio <300 mmHg. This ratio is used in many trials as the sole oxygenation criterion for ARDS. Recently, however, it has been shown in adults with ARDS that FiO(2), independently of the PaO(2)/FiO(2) ratio predicts mortality. Because epidemiology and outcome of ARDS differ strongly between children and adults, we determined if FiO(2) on admission (baseline FiO(2)) independently predicted the duration of mechanical ventilation (MV) and length of stay (LOS) in the pediatric intensive care unit (PICU) in infants with RSV-induced ARDS. DESIGN: Retrospective observational study. SETTING: A 14-bed pediatric intensive care unit. PATIENTS: One hundred twenty-nine mechanically ventilated infants with RSV-induced ARDS. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Independent predictors for outcome, including baseline FiO(2) and PEEP, were analyzed using the cox regression model. Endpoints were duration of MV and LOS in the PICU. A higher baseline FiO(2) was independently associated with a longer duration of MV (HR 0.12, CI 0.02-0.87, P = 0.036) and increased LOS in the PICU (HR 0.09, CI 0.01-0.57, P = 0.023). Neither baseline PEEP nor PaO(2)/FiO(2) ratio correlated with outcome. CONCLUSIONS: FiO(2) level independently predicted outcome in infants with RSV-induced ARDS, whereas both PEEP and the PaO(2)/FiO(2) ratio did not. This suggests that FiO(2) should be taken into account in defining disease severity in infants with RSV-induced ARDS.

Imbalance between pulmonary angiotensin-converting enzyme and angiotensin-converting enzyme 2 activity in acute respiratory distress syndrome.

OBJECTIVE: Angiotensin-converting enzyme and its effector peptide angiotensin II have been implicated in the pathogenesis of acute respiratory distress syndrome. Recently, angiotensin-converting enzyme 2 was identified as the counter-regulatory enzyme of angiotensin-converting enzyme that converts angiotensin II into angiotensin-(1-7). The aim of this study was to determine pulmonary angiotensin-converting enzyme and angiotensin-converting enzyme 2 activity in patients with acute respiratory distress syndrome. DESIGN: Prospective observational pilot study. SETTING: A PICU of a university hospital. PATIENTS: Fourteen patients admitted, requiring mechanical ventilation for respiratory syncytial virus lower respiratory tract infection. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Two groups of patients were distinguished at admission: a group fulfilling the criteria for acute respiratory distress syndrome and a non-acute respiratory distress syndrome group. Angiotensin-converting enzyme and angiotensin-converting enzyme 2 activity were measured in bronchoalveolar lavage fluid. Patients with acute respiratory distress syndrome had increased angiotensin-converting enzyme activity and decreased angiotensin-converting enzyme 2 activity (p < 0.001) compared with the control group. CONCLUSION: It is shown for the first time that in acute respiratory distress syndrome, enhanced angiotensin-converting enzyme activity is paralleled by a reduced angiotensin-converting enzyme 2 activity, similar to that found in an experimental rat model of acute respiratory distress syndrome. The reduced angiotensin-converting enzyme 2 activity may be counteracted by restoring angiotensin-(1-7) level, thereby offering a novel treatment modality for this syndrome.

Are central line bundles and ventilator bundles effective in critically ill neonates and children?

Central line-associated bloodstream infections (CLABSI) and ventilator-associated pneumonia (VAP) are common problems in adult, pediatric (PICU) and neonatal (NICU) intensive care unit patients. Care bundles have been developed to prevent these hospital-acquired infections and to provide best possible care. Studies in adults have proven that care bundles contribute to a decrease in CLABSI and VAP rates. The purpose of this literature review was to critically appraise the known evidence of the effectiveness of central line bundles and ventilator bundles in PICU and NICU patients. The number of publications of central line bundles and ventilator bundles in PICU and NICU patients is limited compared to adults. Ten studies in PICU patients demonstrated a significant decrease in the CLABSI or VAP rate after implementation of the bundle. Two studies in neonates demonstrated a reduction in the CLABSI rate after implementation of the central line bundle. No studies on the effectiveness of the ventilator bundle in neonates were found. Bundle elements differed between studies, and their scientific basis was not as robust as in adults. Monitoring of compliance to bundle elements seems required for optimal reduction of CLABSI and VAP. Bundle components that focus on maintenance of a central line probably are important to prevent CLABSI in children.

Effect of oxidative stress on respiratory epithelium from children with Down syndrome.

Children with Down syndrome are at high risk for acute respiratory distress syndrome. In Down syndrome, both regulation of inflammation and apoptosis, important in acute respiratory distress syndrome pathophysiology, are abnormal. This has been linked to an imbalance in free radical scavengers. We investigated the expression of free radical scavengers and the effect of oxidative stress in terms of apoptosis and inflammation in respiratory epithelium from children with Down syndrome compared with control subjects. We cultured primary nasal epithelial cells from Down syndrome children (n=12) and controls (n=17) and exposed them to oxidative stress by supplementing superoxide. First we showed that the expression of the free radical scavengers CuZn-superoxide dismutase was 28% higher (p=0.06), catalase was 36% lower (p=0.04) and glutathione peroxidase was 73% lower (p=0.004) in Down syndrome children compared with controls. We found no significant difference in apoptosis, between Down syndrome and control subjects after exposure to oxidative stress. We also found no significant difference in levels of interleukin (IL)-1ß, IL-6, IL-8, vascular endothelial growth factor and granulocyte colony-stimulating factor in primary nasal epithelial cell supernatant after exposure to oxidative stress between Down syndrome and control subjects. We found an imbalance in free radical scavengers in respiratory epithelial cells from children with Down syndrome, but this did not result in increased levels of either apoptosis or inflammation upon exposure to oxidative stress.

Pulmonary epithelial apoptosis in fetal down syndrome: not higher than normal.

Children with Down syndrome (DS) are at high risk for acute lung injury (ALI). Pulmonary epithelial apoptosis is an important factor in the pathophysiology of ALI. Whether the risk of ALI in DS is associated with a high level of pulmonary epithelial apoptosis is not known. We hypothesized that the percentage of apoptotic epithelial cells is higher in DS than in control lungs. Lung tissue sections from autopsies of 21 fetuses with DS and 12 controls were stained with antibodies against the epithelial marker pan-cytokeratin (CK) and apoptosis marker activated caspase-3 (aC3). Spectral imaging software was used to quantify the mean percentage of pixels that showed colocalization of CK and aC3. Mean (standard deviation [SD]) gestational age in weeks was 18.7 (1.4) in DS and 18.9 (2.0) in controls (P  =  0.67). The mean (SD) percentage of CK-positive pixels was 27.2% (4.7%) in DS compared to 27.1% (6.2%) in controls (P  =  0.97). The median (interquartile range [IQR]) percentage of CK-positive pixels that showed colocalization of aC3 was 0.16% (0.18%) in DS compared to 0.27% (0.24%) in controls (P  =  0.45). The mean (SD) number of CK-positive pixels increased from 22.5% (5.2%) to 30.4% (4.6%) with the appearance of saccular morphology in controls but not in DS (P  =  0.01). The percentage of apoptotic epithelial cells in DS fetal lungs does not differ from that in controls. However, we did find a difference in the development of epithelial structures between DS and controls that may be associated with anomalies in alveolar development found at birth in DS.

High-carbohydrate/low-protein-induced hyperinsulinemia does not improve protein balance in children after cardiac surgery.

OBJECTIVE: In pediatric cardiac surgery, fluid-restricted low-protein (LoProt) diets account for cumulative protein deficits with increased morbidity. In this setting, we aimed to inhibit proteolysis by a high-carbohydrate (HiCarb)-intake-induced hyperinsulinemia and improve protein balance. METHODS: The effect of a HiCarb/LoProt (glucose 10 mg · kg(-1) · min(-1)/protein 0.7 g · kg(-1) · d(-1)) versus a normal-carbohydrate (NormCarb)/LoProt (glucose 7.5 mg · kg(-1) · min(-1)/protein 0.3 g · kg(-1) · d(-1)) enteral diet on whole-body protein breakdown and balance was compared in a prospective, randomized, single-blinded trial in 24 children after cardiac surgery. On the second postoperative day, plasma insulin and amino acid concentrations, protein breakdown (endogenous rate of appearance of valine), protein synthesis (non-oxidative disposal of valine), protein balance, and the rate of appearance of urea were measured by using an isotopic infusion of [1-(13)C]valine and [(15)N(2)]urea. RESULTS: The HiCarb/LoProt diet led to a serum insulin concentration that was three times higher than the NormCarb/LoProt diet (596 pmol/L, 80-1833, and 198 pmol/L, 76-1292, respectively, P = 0.02), without differences in plasma glucose concentrations. There were no differences in plasma amino acid concentrations, non-oxidative disposal of valine, and endogenous rate of appearance of valine between the groups, with a negative valine balance in the two groups (-0.65 µmol · kg(-1) · min(-1), -1.91 to 0.01, and -0.58 µmol · kg(-1) · min(-1), -2.32 to -0.07, respectively, P = 0.71). The serum cortisol concentration in the HiCarb/LoProt group was lower compared with the NormCarb/LoProt group (204 nmol/L, 50-544, and 532 nmol/L, 108-930, respectively, P = 0.02). CONCLUSION: In children with fluid restriction after cardiac surgery, a HiCarb/LoProt diet compared with a NormCarb/LoProt diet stimulates insulin secretion but does not inhibit proteolysis further and therefore cannot be advocated for this purpose.

New tools for systematic evaluation of teaching qualities of medical faculty: results of an ongoing multi-center survey.

BACKGROUND: Tools for the evaluation, improvement and promotion of the teaching excellence of faculty remain elusive in residency settings. This study investigates (i) the reliability and validity of the data yielded by using two new instruments for evaluating the teaching qualities of medical faculty, (ii) the instruments' potential for differentiating between faculty, and (iii) the number of residents' evaluations needed per faculty to reliably use the instruments. METHODS AND MATERIALS: Multicenter cross-sectional survey among 546 residents and 629 medical faculty representing 29 medical (non-surgical) specialty training programs in The Netherlands. Two instruments--one completed by residents and one by faculty--for measuring teaching qualities of faculty were developed. Statistical analyses included factor analysis, reliability and validity exploration using standard psychometric methods, calculation of the numbers of residents' evaluations needed per faculty to achieve reliable assessments and variance components and threshold analyses. RESULTS: A total of 403 (73.8%) residents completed 3575 evaluations of 570 medical faculty while 494 (78.5%) faculty self-evaluated. In both instruments five composite-scales of faculty teaching qualities were detected with high internal consistency and reliability: learning climate (Cronbach's alpha of 0.85 for residents' instrument, 0.71 for self-evaluation instrument, professional attitude and behavior (0.84/0.75), communication of goals (0.90/0.84), evaluation of residents (0.91/0.81), and feedback (0.91/0.85). Faculty tended to evaluate themselves higher than did the residents. Up to a third of the total variance in various teaching qualities can be attributed to between-faculty differences. Some seven residents' evaluations per faculty are needed for assessments to attain a reliability level of 0.90. CONCLUSIONS: The instruments for evaluating teaching qualities of medical faculty appear to yield reliable and valid data. They are feasible for use in medical residencies, can detect between-faculty differences and supply potentially useful information for improving graduate medical education.

Acute respiratory distress syndrome leads to reduced ratio of ACE/ACE2 activities and is prevented by angiotensin-(1-7) or an angiotensin II receptor antagonist.

Acute respiratory distress syndrome (ARDS) is a devastating clinical syndrome. Angiotensin-converting enzyme (ACE) and its effector peptide angiotensin (Ang) II have been implicated in the pathogenesis of ARDS. A counter-regulatory enzyme of ACE, ie ACE2 that degrades Ang II to Ang-(1-7), offers a promising novel treatment modality for this syndrome. As the involvement of ACE and ACE2 in ARDS is still unclear, this study investigated the role of these two enzymes in an animal model of ARDS. ARDS was induced in rats by intratracheal administration of LPS followed by mechanical ventilation. During ventilation, animals were treated with saline (placebo), losartan (Ang II receptor antagonist), or with a protease-resistant, cyclic form of Ang-(1-7) [cAng-(1-7)]. In bronchoalveolar lavage fluid (BALF) of ventilated LPS-exposed animals, ACE activity was enhanced, whereas ACE2 activity was reduced. This was matched by enhanced BALF levels of Ang II and reduced levels of Ang-(1-7). Therapeutic intervention with cAng-(1-7) attenuated the inflammatory mediator response, markedly decreased lung injury scores, and improved lung function, as evidenced by increased oxygenation. These data indicate that ARDS develops, in part, due to reduced pulmonary levels of Ang-(1-7) and that repletion of this peptide halts the development of ARDS.

Role of the Fas/FasL system in a model of RSV infection in mechanically ventilated mice.

Infection with respiratory syncytial virus (RSV) in children can progress to respiratory distress and acute lung injury necessitating mechanical ventilation (MV). MV enhances apoptosis and inflammation in mice infected with pneumonia virus of mice (PVM), a mouse pneumovirus that has been used as a model for severe RSV infection in mice. We hypothesized that the Fas/Fas ligand (FasL) system, a dual proapoptotic/proinflammatory system involved in other forms of lung injury, is required for enhanced lung injury in mechanically ventilated mice infected with PVM. C57BL/6 mice and Fas-deficient ("lpr") mice were inoculated intratracheally with PVM. Seven or eight days after PVM inoculation, the mice were subjected to 4 h of MV (tidal volume 10 ml/kg, fraction of inspired O(2) = 0.21, and positive end-expiratory pressure = 3 cm H(2)O). Seven days after PVM inoculation, exposure to MV resulted in less severe injury in lpr mice than in C57BL/6 mice, as evidenced by decreased numbers of polymorphonuclear neutrophils in the bronchoalveolar lavage (BAL), and lower concentrations of the proinflammatory chemokines KC, macrophage inflammatory protein (MIP)-1α, and MIP-2 in the lungs. However, when PVM infection was allowed to progress one additional day, all of the lpr mice (7/7) died unexpectedly between 0.5 and 3.5 h after the onset of ventilation compared with three of the seven ventilated C57BL/6 mice. Parameters of lung injury were similar in nonventilated mice, as was the viral content in the lungs and other organs. Thus, the Fas/FasL system was partly required for the lung inflammatory response in ventilated mice infected with PVM, but attenuation of lung inflammation did not prevent subsequent mortality.