Validity of markers of dilution in small volume lung lavage

Lung inflammation and pulmonary function in infants with meconium aspiration syndrome

OBJECTIVE

To evaluate the relationship between inflammation and pulmonary function, we quantified changes in inflammatory cellular profile, pro-inflammatory cytokines, and pulmonary function in intubated neonates with meconium aspiration syndrome (MAS).

METHODS

Sixteen term infants were studied. Tracheal aspirate fluids, obtained within the first 6, 24, 48, and 96 hr of life were used for measurements of: (1) cellular profile changes; (2) mRNA and protein levels for pro-inflammatory cytokines, IL-1beta, IL-6, IL-8, and TNF-alpha, using RT-PCR and ELISA. Using the same time points as above, we determined mean airway pressure, oxygenation index (OI), alveolar-arterial oxygen gradient, and arterial/alveolar oxygen ratio. Baseline tidal volume and pulmonary compliance were obtained.

RESULTS

Birth weight was 3,820 +/- 656 g, gestational age 39.8 +/- 1.4 weeks. Mean airway pressure and OI significantly decreased from the first 6-96 hr of age (P = 0.01, P = 0.027). Cell counts were elevated in the first 6 hr compared to 96 hr (17.4 x 10(6)/ml vs. 1.5 x 10(6)/ml, P < 0.05). Pro-inflammatory cytokines decreased from the first 6-96 hr: IL-1beta (187 vs. 37 pg/ml, P < 0.05); IL-6 (3,469 vs. 150 pg/ml, P < 0.05); IL-8 (16,230 vs. 6,334 pg/ml, P = 0.01).

CONCLUSIONS

MAS is associated with an inflammatory response characterized by the presence of elevated cell count and pro-inflammatory cytokines which significantly decreased by 96 hr of life. This decrease in lung inflammation has a positive correlation with corresponding decreases in mean airway pressure and oxygenation index, two parameters associated with improved pulmonary function.

Comparison of lung injury after normal or small volume optimized resuscitation in a model of hemorrhagic shock

OBJECTIVE

To compare lung injury induced by a hemorrhagic shock resuscitated with normal saline or with small volumes of a hypertonic/hyperoncotic solution.

DESIGN AND SETTING

Randomized, controlled, laboratory study in an animal research laboratory.

SUBJECTS

Nineteen pigs (43 +/- 4 kg).

INTERVENTIONS

After anesthesia and mechanical ventilation animals were bled to induce a 2-h deep shock and resuscitated for 2 h using normal saline (NS, 2 ml/kg per minute, n = 7) or the association of 7.2% NaCl with 6% hydroxyethylstarch 200/0.5 (HSHES, 4 ml/kg in 10 min followed by 0.2 ml/kg per minute, n = 7) to reach cardiac index and mixed venous oxygen saturation goals. Lungs were removed 6[Symbol: see text]h after the initiation of hemorrhage. Five animals were used as controls without hemorrhage.

MEASUREMENTS AND RESULTS

Resuscitation goals were achieved using 90 +/- 17 ml/kg NS or 6.8 +/- 1.9 ml/kg HSHES. Lung injury was noted in both hemorrhage groups but was not influenced by the type of resuscitation. Extravascular lung water was measured at 9.6 +/- 1.8 ml/kg in the NS group, 9.2 +/- 1.6 ml/kg in the HSHES, group and 6.4 +/- 1 m/kg in the control group. The degree of histological alveolar membrane focal thickening and interstitial neutrophil infiltration were significantly more pronounced in the hemorrhage groups with no difference between the two types of fluid loading. Finally, pulmonary levels of IL-8 were higher after hemorrhage regardless of the type of resuscitation.

CONCLUSIONS

When included in an optimized and goal directed resuscitation, the use of normal saline or a small volume of hypertonic/hyperoncotic solution does not result in a different early hemorrhage-induced lung injury.

Reliability of mini-bronchoalveolar lavage for the measurement of epithelial lining fluid concentrations of tobramycin in critically ill patients

OBJECTIVE

To evaluate the reliability of mini-bronchoalveolar lavage (mini-BAL) for the measurement of tobramycin concentrations in epithelial lining fluid (ELF) in comparison with conventional bronchoscopic bronchoalveolar lavage (BAL).

DESIGN

Prospective, open-label study.

SETTING

An intensive care unit and research ward in a university hospital.

PATIENTS

Twelve critically ill adult patients with ventilator-associated pneumonia (VAP).

INTERVENTIONS

All subjects received intravenous infusions of tobramycin 7-10 mg/kg once daily. After 2 days of therapy, the steady-state serum and ELF concentrations (obtained from BAL and mini-BAL) of tobramycin were determined by means of high-performance liquid chromatography.

MEASUREMENTS AND RESULTS

We observed poor penetration of tobramycin in ELF of approximately approximately 12% with ELF peak concentrations of approximately approximately 3 mg/l with both methods. Good agreement in Bland-Altman analysis (mean +/- SD bias = 0.04 +/- 0.38 mg/l) was observed between the two methods of sampling.

CONCLUSION

Our results suggest that tobramycin 7-10 mg/kg once daily in critically ill patients with VAP might provide insufficient lung concentrations in the case of difficult-to-treat pathogens. Besides, mini-BAL, which is simple, non-invasive and easily repeatable at the bedside, appears to be a reliable method for the measurement of antibiotic concentrations in ELF in comparison with bronchoscopic BAL in critically ill patients with VAP.

Inflammatory markers and mediators in tracheal fluid of premature infants treated with inhaled nitric oxide

OBJECTIVE

We compared serial measurements of inflammatory mediators and markers in infants treated with inhaled nitric oxide or placebo to assess the effects of inhaled nitric oxide therapy on lung inflammation during bronchopulmonary dysplasia. We investigated relationships between respiratory severity scores and airway concentrations of inflammatory markers/mediators.

METHODS

As part of the Nitric Oxide (to Prevent) Chronic Lung Disease trial, a subset of 99 infants (52 placebo-treated infants and 47 inhaled nitric oxide-treated infants; well matched at baseline) had tracheal aspirate fluid collected at baseline, at 2 to 4 days, and then weekly while still intubated during study gas treatment (minimum of 24 days). Fluid was assessed for interleukin-1beta, interleukin-8, transforming growth factor-beta, N-acetylglucosaminidase, 8-epi-prostaglandin F2alpha, and hyaluronan. Results were normalized to total protein and secretory component of immunoglobulin A.

RESULTS

At baseline, there was substantial variability of each measured substance and no correlation between tracheal aspirate fluid levels of any substance and respiratory severity scores. Inhaled nitric oxide administration did not result in any time-matched significant change for any of the analytes, compared with the placebo-treated group. There was no correlation between any of the measured markers/mediators and respiratory severity scores throughout the 24 days of study gas administration. In the posthoc analysis of data for inhaled nitric oxide-treated infants, there was a difference at baseline in 8-epi-prostaglandin F2alpha levels for infants who did (n = 21) and did not (n = 26) develop bronchopulmonary dysplasia at postmenstrual age of 36 weeks.

CONCLUSIONS

Inhaled nitric oxide, as administered in this study, seemed to be safe. Its use was not associated with any increase in airway inflammatory substances.

Neuromuscular blocking agents decrease inflammatory response in patients presenting with acute respiratory distress syndrome*

OBJECTIVE

To evaluate the effects of neuromuscular blocking agents (NMBAs) on pulmonary and systemic inflammation in patients with acute respiratory distress syndrome ventilated with a lung-protective strategy.

DESIGN

Multiple-center, prospective, controlled, and randomized trial.

SETTING

One medical and two medical-surgical intensive care units.

PATIENTS

A total of 36 patients with acute respiratory distress syndrome (Pao2/Fio2 ratio of < or =200 at a positive end-expiratory pressure of > or =5 cm H2O) were included within 48 hrs of acute respiratory distress syndrome onset.

INTERVENTIONS

Patients were randomized to receive conventional therapy plus placebo (n = 18) or conventional therapy plus NMBAs (n = 18) for 48 hrs. Both groups were ventilated with a lung-protective strategy (tidal volume between 4 and 8 mL/kg ideal body weight, plateau pressure of < or =30 cm H2O).

MEASUREMENTS AND MAIN RESULTS

Bronchoalveolar lavages and blood samples were performed, before randomization and at 48 hrs, to determine the concentrations of tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, and IL-8. Pao2/Fio2 ratio was evaluated before randomization and at 24, 48, 72, 96, and 120 hrs. A decrease over time in IL-8 concentrations (p = .034) was observed in the pulmonary compartment of the NMBA group. At 48 hrs after randomization, pulmonary concentrations of IL-1beta (p = .005), IL-6 (p = .038), and IL-8 (p = .017) were lower in the NMBA group as compared with the control group. A decrease over time in IL-6 (p = .05) and IL-8 (p = .003) serum concentrations was observed in the NMBA group. At 48 hrs after randomization, serum concentrations of IL-1beta (p = .037) and IL-6 (p = .041) were lower in the NMBA group as compared with the control group. A sustained improvement in Pao2/Fio2 ratio was observed and was reinforced in the NMBA group (p < .001).

CONCLUSION

Early use of NMBAs decrease the proinflammatory response associated with acute respiratory distress syndrome and mechanical ventilation.

Evaluation of the concentration of marbofloxacin in alveolar macrophages and pulmonary epithelial lining fluid after administration in dogs

OBJECTIVE

To determine concentrations of marbofloxacin in alveolar macrophages (AMs) and epithelial lining fluid (ELF) and compare those concentrations with plasma concentrations in healthy dogs.

ANIMALS

12 adult mixed-breed and purebred hounds.

PROCEDURE

10 dogs received orally administered marbofloxacin at a dosage of 2.75 mg/kg every 24 hours for 5 days. Two dogs served as nontreated controls. Fiberoptic bronchoscopy and bronchoalveolar lavage procedures were performed while dogs were anesthetized with propofol, approximately 6 hours after the fifth dose. The concentrations of marbofloxacin in plasma and bronchoalveolar fluid (cell and supernatant fractions) were determined by use of high-performance liquid chromatography with detection of fluorescence.

RESULTS

Mean +/- SD plasma marbofloxacin concentrations 2 and 6 hours after the fifth dose were 2.36 +/- 0.52 microg/mL and 1.81 +/- 0.21 microg/mL, respectively. Mean +/- SD marbofloxacin concentration 6 hours after the fifth dose in AMs (37.43 +/- 24.61 microg/mL) was significantly greater than that in plasma (1.81 +/- 0.21 microg/mL) and ELF (0.82 +/- 0.34 microg/mL), resulting in a mean AM concentration-to-plasma concentration ratio of 20.4, a mean AM:ELF ratio of 60.8, and a mean ELF-to-plasma ratio of 0.46. Marbofloxacin was not detected in any samples from control dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Marbofloxacin concentrations in AMs were greater than the mean inhibitory concentrations of major bacterial pathogens in dogs. Results indicated that marbofloxacin accumulates in AMs at concentrations exceeding those reached in plasma and ELF The accumulation of marbofloxacin in AMs may facilitate treatment for susceptible intracellular pathogens or infections associated with pulmonary macrophage infiltration.

Potential Impact of Vancomycin Pulmonary Distribution on Treatment Outcomes in Patients with Methicillin-ResistantStaphylococcus aureusPneumonia

Vancomycin as the drug of choice for treatment of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia has been called into question on the basis of therapeutic failures. In patients with MRSA pneumonia, treatment failures are probably due to the complex interplay of variables affecting the host-antimicrobial-pathogen interrelationship. However, it has been suggested that decreased penetration of vancomycin into the lungs may contribute. This review explores physiochemical and physiologic variables that affect pulmonary penetration and describes methods used in quantifying pulmonary vancomycin concentrations. Most important, findings are evaluated in the clinical context of the chemotherapeutic options available for treatment of MRSA pneumonia. The possibility of increased serum vancomycin concentrations as a method to optimize current treatment outcomes is also explored.

Method for improved accuracy in endogenous urea recovery marker calibrations for microdialysis in tumors

INTRODUCTION

Urea has been proposed as an endogenous recovery marker for microdialysis for absolute concentration calculations of analytes in microdialysis samples. Previously we demonstrated a linear relationship between urea concentrations in a rat mammary carcinoma and that in plasma, validating its use as a recovery marker for that particular tumor. In this paper, we have extended the validation to two other tumor lines, thereby providing confidence that the calibration is constant across tumor types. To improve the accuracy in the determination of the plasma/tumor urea relationship from no net flux calibrations, we extended the range of the calibration by adding exogenous urea to tumor bearing animals. This method enabled more accurate calculations of absolute recovery from plasma and dialysate urea concentrations. We confirm that by using this method the calibration is valid across three different tumor lines. The existence of a common calibration between tumors provides rationale for using plasma urea as a recovery marker for clinical trials. The existence of a common calibration between tumor types bypasses the need to perform time consuming calibrations for each patient. This makes the procedure much more practical for clinical studies.

METHODS

The no net flux technique was used to determine the plasma vs. tumor urea relationship for the R3230Ac mammary carcinoma, 9 L glioma, and a fibrosarcoma (FSa), grown in Fischer 344 rats. Plasma urea was stably increased beyond the normally occurring concentration for some of the data points by subcutaneous bolus administration to extend the range of data for the no net flux calibration.

RESULTS

Urea recovery was unaffected by plasma urea concentration and was consistent with other reported values. The relationship between plasma and tumor urea was fit by a line, and linear regressions of the data with the extended plasma urea range had better R2 values than we reported previously. Statistical comparison of the regressions suggests that within reasonable uncertainty limits, they are the same for the different tumor types.

DISCUSSION

Increasing the plasma urea concentration range for no net flux calibrations of urea as an endogenous recovery marker in tumors resulted in more accurate determination of the plasma/tumor urea relationship. A single linear regression may describe the relationship between plasma and tumor urea concentration across tumor lines for a given set of microdialysis parameters.

[Bronchial exudate of serum proteins during asthma attack]

OBJECTIVE

Although altered vascular permeability and edema of the bronchial mucosa are associated with asthma attack, their influence on its severity remains unknown. We address this issue by comparing relative indices for the concentration of albumin (RIAlb) and alpha2-macroglobulin (RIalpha2M) in induced sputum and peripheral blood from patients with exacerbated asthma, patients with stable asthma, and control subjects.

PATIENTS AND METHODS

Forty-six volunteers participated in the study: 14 with exacerbated asthma (forced expiratory volume in the first second [FEV1] 74.3% [SD, 20.8%] of reference), 23 with stable asthma (FEV1 93.6% [7.5%]), and 9 controls (FEV1 101.1% [9.9%]). The concentrations of albumin and alpha2-macroglobulin were quantified by immunoturbidimetry and immunonephelometry, respectively. The relative index was then calculated by dividing the concentration in sputum supernatant by the concentration in peripheral blood.

RESULTS

The mean RIAlb was 1.2 (1.1) in the control group, 2.9 (3.1) in the stable asthma group, and 6.0 (6.7) in the exacerbated asthma group. The RIalpha2M values were 11.7 (10.9), 11.9 (14.7), and 3.2 (3.8) for the control group and stable and exacerbated asthma groups, respectively. The increases in the RIAlb values between all groups, and the decrease in the RIalpha2M value between the exacerbated asthma and control groups were statistically significant (P<.05). The percentage of neutrophils, but not of eosinophils, in sputum was correlated with the RIAlb (r=0.39; P=.008) but not the RIalpha2M (r=-0.035; P=.82). FEV1 displayed an inverse relationship with the RIAlb (r=-0.43; P=.009) but not with the RIalpha2M (r=-0.206; P=.24). No correlation was found between oxyhemoglobin saturation and either the RIAlb (r=-0.33; P=.19) or the RIalpha2M (r=-0.12; P=.84).

CONCLUSIONS

Vascular permeability is altered during asthma exacerbations and appears to be correlated with the presence of neutrophils and the degree of bronchial obstruction.

Association of interleukin-8 with inflammatory and innate immune components in bronchoalveolar lavage of children with chronic respiratory diseases

BACKGROUND

The host inflammatory response and innate immunity play a complex role in respiratory diseases.

METHODS

We evaluated the levels of inflammatory mediators and antibacterial proteins in children who required bronchoscopy and bronchoalveolar lavage fluid (BALF) for clinical indications such as chronic tracheostomy (n=15) and chronic suppurative lung disease (n=8).

RESULTS

Our results suggested the presence of interleukin-1beta (IL-1beta) and IL-8 as major inflammatory mediators in BALF samples. The level of the antibacterial protein sIgA was higher than lactoferrin and lysozyme. BALF IL-8 levels significantly correlated with the presence of IL-1beta, IL-6, IL-10, IL-16, sIgA and lysozyme. BALF IL-8 levels did not correlate with the levels of immunomodulatory and anti-inflammatory clara cell 10 kDa protein (CC10) or lactoferrin.

CONCLUSION

This study suggests that patients with high levels of BALF IL-8 could potentially have high levels of IL-6, IL-10, IL-16, lysozyme and sIgA. Evaluating the inflammatory mediators (IL-8) in relation to other BALF protein components provides insight into understanding the role of inflammatory mediators in the regulation of host defense and the response to lung inflammation and injury.

Blood transfusion and pulmonary lipid peroxidation in ventilated premature babies

Urinary malondialdehyde (MDA; a biochemical marker of lipid peroxidation) is increased following the receipt of blood transfusions in premature babies. This indicates an increased level of oxidative damage somewhere in the body. The aim of this study was to determine whether the lung may be a site of increased oxidative damage following blood transfusions. This was achieved by examining the relationship between blood transfusion and levels of MDA in bronchoalveolar lavage (BAL) fluid from ventilated premature babies. The study was a retrospective analysis of data obtained from a group of 42 ventilated premature babies of less than 32 weeks' gestation. Twenty-seven babies received blood transfusions, and 9 received at least one transfusion during the first week of life when daily BAL samples were being taken. Pulmonary epithelial lining fluid (ELF) was sampled by BAL daily during the first week of life and weekly thereafter. MDA was measured by an established high performance liquid chromatography (HPLC) technique. There was a significant positive correlation between volume of blood transfusions received and peak and mean ELF MDA levels (r=0.810, peak; r=0.740, mean; n=21). During the first week of life, when daily samples were being taken, the mean ELF MDA level after blood transfusion (1.829 microM; SE, 0.529) was significantly greater than before transfusion (0.928 microM; SE, 0.297) (n=9). In babies who received 2 transfusions within the first week (n=5), the MDA level was elevated further following the second transfusion (2.825 microM; SE, 0.346). The results of this study indicate that pulmonary oxidative damage increases after the receipt of blood transfusions. Babies receiving blood transfusions show a greater incidence of pulmonary oxidative stress and poor clinical outcome. This may simply reflect that the sickest babies are those most in need of blood transfusion, and that there is no causal relationship. However, the possibility of a causal relationship between blood transfusions and oxidative damage exists and should be investigated.

HFOV in premature neonates: effects on pulmonary mechanics and epithelial lining fluid cytokines. A randomized controlled trial

OBJECTIVE

Ventilation strategies for preterm neonates may influence the severity of pulmonary dysfunction and later development of chronic lung disease. The objective of this report is to compare the effects of high-frequency oscillatory ventilation (HFOV) versus synchronized intermittent mandatory ventilation (sIMV) from the points of views of biochemical and functional variables.

DESIGN

Randomized controlled trial.

SETTING

Third level NICU.

PATIENTS AND PARTICIPANTS

Forty preterm neonates with a gestational age of 24-29 weeks were randomly assigned to one of the two above-mentioned ventilation strategies within 30 min from birth.

MEASUREMENTS AND RESULTS

At 1, 3, 5, and 7 days, the babies were monitored by means of ventilator indices, pulmonary function, and eight pro-inflammatory or anti-inflammatory cytokines measured in bronchoalveolar lavage fluid. The neonates assigned to the HFOV procedure benefited from early and sustained improvement in pulmonary mechanics and gas exchange-significantly higher dynamic respiratory compliance values, significantly lower expiratory airway resistance and oxygenation index values-with earlier extubation as compared to the neonates assigned to sIMV treatment, and showed significantly lower transforming growth factor-beta1 concentrations in bronchoalveolar lavage fluid.

CONCLUSIONS

The results of this randomized clinical trial support the hypothesis that early and exclusive use of HFOV, combined with optimum volume strategy, has a beneficial effect during the acute phase of lung injury.

Expression and Activity of β-Defensins and LL-37 in the Developing Human Lung

Immaturity of innate immunity contributes to the increased susceptibility of human neonates to infection. The lung is a major portal of entry for potential pathogens in the neonate, and human beta-defensins (HBDs) and LL-37 participate in pulmonary innate immunity. We hypothesized that these antimicrobial factors would be developmentally regulated, expressed by neonatal pulmonary tissues, and participate in neonatal innate immunity. We found HBD-2 to be the predominant beta-defensin in human neonatal lung. HBD-2 mRNA expression was developmentally regulated, induced by the proinflammatory factor IL-1beta, and decreased by dexamethasone. Additionally, HBD-2 abundance in neonatal tracheal aspirates increased as a function of gestational age. HBD-1 had a lower level of expression compared with HBD-2 and was induced by dexamethasone. HBD-3 and LL-37 messages were not detected in airway epithelial cultures. Additionally, each antimicrobial peptide exhibited a unique spectrum of antimicrobial activity and salt sensitivity against bacteria commonly causing sepsis in the neonate. Lower levels of HBD-2 may be one factor contributing to the increased susceptibility of premature infants to pulmonary infections.

Interleukin-1 balance in the lungs of preterm infants who develop bronchopulmonary dysplasia

BACKGROUND

The local pulmonary balance between the agonist and antagonist of interleukin-1 (IL-1) may influence the development of inflammatory disease and resultant structural damage in a variety of human diseases including adult respiratory distress syndrome and asthma.

OBJECTIVES

We tested the hypothesis that IL-1 cytokines are early markers for bronchopulmonary dysplasia (BPD), when measured in tracheal aspirates (TAs) obtained from premature infants being ventilated for respiratory distress syndrome during the first week of life.

METHODS

Serial TAs were collected on days 1, 3, 5 and 7 from 35 preterm infants (16 BPD, 19 non-BPD) in the absence of chorioamnionitis, and were assayed for IL-1 cytokines and leukocytes.

RESULTS

In spite of comparable maternal demographic and clinical characteristics, premature infants who developed BPD had higher levels of IL-1 receptor antagonist (Ra) in their airways on the first day of life. This antagonist IL-1Ra was an early and persistent marker for BPD during the first week of life. The agonist IL-1beta also increased significantly for BPD patients early, both compared to non-BPD patients, and also within the BPD group. While the early (day 1) IL-1 antagonist/agonist molar balance offered protection, by days 5 and 7, a threshold for IL-1Ra in the presence of increasing IL-1beta expression-favored pro-inflammation in the BPD group.

CONCLUSIONS

We conclude that a strong and early expression of airway antagonist (IL-1Ra) proves ultimately to be sub-optimal and non-protective due to the robust expression of airway agonist (IL-1beta) seen by day 5 in premature infants who develop BPD.

Increased Levels of Albumin in Bronchial Washing Fluid of Patients with Bronchial Carcinoma. Could Albumin be Considered as a Tumor Marker?

Background

The aim of this study was to evaluate the significance of albumin in bronchial washing fluid (BWF) and its relationship to three tumor markers (CEA, CA 19–9 and NSE).

Methods

Serum and BWF samples were collected in a group of 60 patients. Albumin and tumor markers in the BWF and serum of three groups: a control group (CG), a chronic bronchitis group (CBG) and a lung cancer group (CaG), were analyzed in a prospective cross-sectional study. The diagnostic yields of the tests in each environment (serum and BWF) were evaluated by using as cutoff points the values of the corresponding 90th percentile of CG and CBG taken together.

Results

A significant difference in albumin level (p<0.001) was noted in the BWF of patients with cancer compared with the other two groups. In addition, a significant difference in CEA level (p<0.001) was observed in the serum of cancer patients compared with the other two groups. The cutoff values for CEA in serum and albumin in BWF were 2.20 ng/mL and 2.00 g/dL, respectively. The areas under the corresponding ROC curves were 93% and 97%. Combination of CEA-serum and albumin-BWF by logistic regression analysis increased their diagnostic value.

Conclusion

Measurement of albumin levels in BWF could be a useful additional diagnostic tool to differentiate malignant from non-malignant lung diseases. Moreover, the combined measurement of CEA in serum and albumin in BWF could be of aid in the follow-up of lung cancer patients.

Pulmonary surfactant disaturated-phosphatidylcholine (DSPC) turnover and pool size in newborn infants with congenital diaphragmatic hernia (CDH)

In animal CDH models, surfactant deficiency contributes to the pathophysiology of the condition but information on human disease is very limited. The aim of our study was to investigate surfactant kinetics in CDH newborns. We studied surfactant disaturated-phosphatidylcholine (DSPC) half-life, turnover and apparent pool size by stable isotope methodology in CDH newborns with no ExtraCorporeal Membrane Oxygenation (ECMO) support (n = 13, birth weight (BW) 3.2 +/- 2.2 kg, gestational age (GA) 39 +/- 0.4 wks, postnatal age 43 +/- 11 h) and in 8 term infants with no lung disease (CONTROLS, BW 2.7 +/- 0 kg, GA 38 +/- 0.8 wks, postnatal age 96 +/- 26 h). We administered a trace dose of 13C-palmitic acid dipalmitoyl-phosphatidylcholine (DPPC) through the endotracheal (ET) tube and we measured DSPC kinetics by gas chromatography-mass spectrometry from DSPC13C-enrichment decay curves obtained from sequential tracheal aspirates. DSPC amount from tracheal aspirates (TA-DSPC) was measured by gas chromatography. In CDH infants DSPC half-life was shorter (24 +/- 4 and 53 +/- 11 h, p = 0.01), turnover faster (0.6 +/- 0.1 and 1.5 +/- 0.3 d-1 p = 0.01), apparent pool size smaller (34 +/- 6 and 57 +/- 7 mg/kg body weight, p = 0.02) and tracheal aspirates DSPC amount lower (2.4 +/- 0.4 and 4.6 +/- 0.5 mg/mL Epithelial Lining Fluid (ELF), p = 0.007) than in CONTROLS. In conclusion surfactant kinetics is grossly abnormal in mechanically ventilated CDH. Whether alterations of DSPC kinetics in CDH infants are caused by a primary surfactant deficiency or are secondary to oxygen therapy and ventilator support has still to be determined.

Adenosine triphosphate is released during injurious mechanical ventilation and contributes to lung edema

BACKGROUND

Extracellular nucleotides mediate many cellular functions and are released in response to mechanical stress in vitro. It is unknown whether adenosine triphosphate (ATP) is released in vivo during mechanical ventilation (MV). We hypothesized that stress from high-pressure MV would increase airway ATP, contributing to MV-associated lung edema.

METHODS

Rats were randomized to nonventilated control (n = 6) or 30 minutes of MV with low (15 cm H(2)0, n = 7) or high (40 cm H(2)0, n = 6) pressure. Additional groups received intratracheal ATP (n = 7) or saline (n = 7) before low-pressure MV.

RESULTS

Low-pressure MV did not affect lung edema or bronchoalveolar lavage (BAL) ATP levels. In contrast, high-pressure MV significantly increased BAL ATP and produced alveolar edema; lactate dehydrogenase was unchanged. Intratracheal ATP administration significantly increased lung water during low-pressure MV.

CONCLUSION

High-pressure MV increases BAL ATP concentration without altering lactate dehydrogenase, suggesting that release is not from cell lysis. Intratracheal ATP increases lung water, implicating nucleotides in MV-associated lung edema.

Effects of chronic alcohol abuse on alveolar epithelial barrier function and glutathione homeostasis

BACKGROUND

An association between the development and severity of the acute respiratory distress syndrome has been described in individuals who abuse alcohol chronically, possibly through a mechanism involving the deficiency of pulmonary glutathione. In a rodent model of chronic alcohol abuse, this antioxidant contributes to the maintenance of alveolar-capillary membrane integrity. We postulated that humans who chronically abuse alcohol will have similar alterations in alveolar-capillary barrier function.

METHODS

Bronchoalveolar lavage was performed in 18 healthy chronic alcoholics and 18 control subjects; total protein and glutathione concentrations were measured within the epithelial lining fluid. To examine possible protracted effects of alcohol abuse, a subset of 11 chronic alcoholic subjects underwent a second bronchoalveolar lavage after a week of abstinence.

RESULTS

Chronic alcoholic subjects had significantly elevated protein concentrations compared with controls (8.64 microg protein/ng immunoglobulin A vs. 5.91 microg protein/ng immunoglobulin A, p = 0.01). After a week of abstinence, no significant increase in either the glutathione levels or normalization of the protein concentrations in the epithelial lining fluid was demonstrable.

CONCLUSIONS

Increased protein levels in the epithelial lining fluid of individuals who abuse alcohol chronically may signify abnormal alveolar epithelial barrier function that does not appear to readily reverse after a period of abstinence.

Detectable IL-8 and IL-10 in bronchoalveolar lavage fluid from preterm infants ventilated for respiratory distress syndrome

Pro-inflammatory cytokines such as IL-8 play an important role in the inflammatory response to neonatal airway injury. Difficulty in detecting counter-regulatory cytokines such as IL-10 in lavage fluid from preterm infants led to the suggestion that its deficit may be a factor in the etiology of chronic lung disease of prematurity (CLD). The aim of the study was to determine IL-8 and IL-10 concentrations in lavage fluid from preterm infants ventilated for respiratory distress syndrome. Fifty infants <30 wk gestation were studied who had been randomized to receive a natural or synthetic surfactant. Lavage samples were collected daily for the first week and twice weekly thereafter. Samples were immediately centrifuged and stored at -70 degrees C. Cytokine concentrations were quantified in duplicate using commercially available sandwich ELISA kits. Lavage IL-10 concentration, at a minimum initially, rose significant over the first five postnatal days (p = 0.009). In the same samples, lavage IL-8 concentrations rose significantly over the first postnatal week (p < 0.001), the rise preceding that of IL-10. Infants dying or developing CLD had a significant early rise in both cytokine concentrations. Compared with infants developing CLD, lavage IL-10 concentrations were significantly higher on d 1 among those not developing CLD but significantly lower on d 4 (p < 0.05). To conclude, IL-10 is detectable in lavage fluid from ventilated preterm infants and its concentrations rise significantly over the first five postnatal days. In the same samples, IL-8 concentration also rises and this increase precedes the rise in IL-10.

Surfactant synthesis and kinetics in infants with congenital diaphragmatic hernia

In animal models of congenital diaphragmatic hernia (CDH), surfactant deficiency contributes to the pathophysiology of the disease; however, information on CDH in humans is limited. We compared surfactant disaturated phosphatidylcholine (DSPC) synthesis and metabolism, by stable isotope technology, in newborn infants with CDH and in control subjects. DSPC amount, total proteins, and surfactant protein-A (SP-A) from tracheal aspirates were also measured. DSPC and SP-A were significantly lower in 14 infants with CDH than in the eight control subjects. Mean DSPC was 2.3 +/- 1.3 mg/ml of epithelial lining fluid (ELF) in infants with CDH and 4.6 +/- 1.5 mg/ml of ELF in control subjects (p = 0.001). Mean SP-A in infants with CDH and in control subjects was 16.2 +/- 9.3 and 61.2 +/- 30.6 microg/ml of ELF, respectively (p = 0.03). DSPC kinetics was measured in 12 of 14 infants with CDH and in 5 of 8 control subjects. Secretion time was 8.3 +/- 5.5 and 8.5 +/- 2.5 hours and peak time 51.9 +/- 15.2 and 51 +/- 13 hours in infants with CDH and in control subjects, respectively. Fractional synthesis rate was not different for infants with CDH and control subjects (p = 0.4). In conclusion, surfactant DSPC synthesis and kinetics were not significantly deranged in infants with CDH compared with control subjects. Other factors, such as lower surface area or increased DSPC catabolism, may contribute to surfactant pool alteration in CDH.

Partial liquid ventilation reduces release of leukotriene B4 and interleukin-6 in bronchoalveolar lavage in surfactant-depleted newborn pigs

Perfluorocarbons have been shown to reduce the inflammatory process generated by alveolar macrophages in vitro. The aim of this study was to evaluate the impact of different ventilator modalities such as partial liquid ventilation (PLV), conventional ventilation (CV), and high-frequency oscillatory ventilation (HFOV) on the release of inflammatory mediators in vivo. Acute lung injury was induced in 30 male piglets by repeated saline lavage (arterial oxygen tension, <60 mm Hg; fraction of inspired oxygen, 1.0). Thereafter, animals were randomly assigned to one of five groups of six animals each: 1) 24 h of CV; 2) 24 h of CV plus surfactant therapy (S+CV); 3) 24 h of HFOV plus surfactant therapy (S+HFOV); 4) 1 h of PLV followed by 23 h of CV (PLV); and 5) 24 h of CV without previous lung injury (control group). Piglets randomized to S+CV or S+HFOV received natural surfactant (100 mg/kg). PLV with FC-77 was started in an initial dose of 30 mL/kg over 30 min followed by 0.5 mL x kg(-1) x min(-1) for another 30 min. After 1 h of PLV the animals were conventionally ventilated for 23 h. Before acute lung injury and after 24 h the number of inflammatory cells and the levels of IL-6, leukotriene B4, and tumor necrosis factor-alpha were measured in the bronchoalveolar lavage fluid. Additionally, the oxygenation index and the histopathologic damage were evaluated. Before acute lung injury, the number of inflammatory cells and the levels of mediators in bronchoalveolar lavage fluid were not different among the groups. After 24 h, the number of granulocytes in the PLV group was as low as in the control group. leukotriene B4 and IL-6 levels were found to be elevated in all groups except the control group (p < 0.01). The release of leukotriene B4 and IL-6 was lowest in the PLV group when compared with S+HFOV, S+CV, or CV (p < 0.05). No differences among the groups were detected for tumor necrosis factor-alpha. Although the concentrations of leukotriene B4 and IL-6 after PLV were lowest in the PLV group, histopathologic evidence of damage and the oxygenation index in the PLV group did not differ from that found in the S+CV or S+HFOV groups. In conclusion, PLV with perfluorocarbons may protect the lung from acute pulmonary inflammation more effectively than CV or HFOV does.

Ozone, but not nitrogen dioxide, exposure decreases glutathione peroxidases in epithelial lining fluid of human lung

Antioxidants, such as glutathione peroxidases (GPxs), in epithelial lining fluid (ELF) protect against health effects of oxidant pollutants, which includes O(3) or NO(2). We hypothesized that GPxs concentration in ELF is responsive to O(3) or NO(2) exposure. Subjects underwent two 4-h exposures to O(3) (0.22 ppm) and one to air. In another experiment, subjects underwent 3-h exposures to air and NO(2) (0.6 and 1.5 ppm). Bronchoalveolar lavage (BAL) was performed immediately or 18 h after O(3) exposure and 3.5 h after each NO(2) exposure. GPx activity and extracellular GPx (eGPx) protein concentrations were determined in ELF, and their relationships to markers of lung function, inflammation, and epithelial permeability were examined. Although the total amounts were not changed, basal (air) GPx activity (223.6 +/- 24.4 mU/ml), basal eGPx protein concentration (2.62 +/- 0.25 microg/ml), and basal ELF dilution factor (152.3 +/- 8.4) decreased 40% immediately after O(3) exposure and remained 30% decreased 18 h after exposure (p = 0.0001). No effect of NO(2) exposure on GPxs concentration was detected. There was an inverse correlation between baseline ELF eGPx protein concentration and the change in PMN 18 h after O(3) exposure (p = 0.04). Thus, O(3), a strong oxidant, decreases both GPx activity and eGPx protein in ELF, whereas NO(2), a weaker oxidant, does not. eGPx in ELF may protect against O(3)-induced airway inflammation.

Elevated protein carbonyls and lipid peroxidation products correlating with myeloperoxidase in tracheal aspirates from premature infants

The purpose of this study is to determine whether the oxidative injury markers, protein carbonyls and malondialdehyde (MDA), are elevated in tracheal aspirates from very low birth weight (< 1500 g) infants; to determine whether levels correlate with myeloperoxidase as a marker of neutrophil inflammation; and to assess whether high levels are associated with poor respiratory outcome. Tracheal aspirates (144 samples) were collected from 86 infants < 1500 g at times of routine suctioning. Aspirates (82 samples) from 54 infants > or = 1500 g who required intubation for a variety of diagnoses were analyzed for comparison. Analyses were performed for protein carbonyls by ELISA, total malondialdehyde by HPLC, and myeloperoxidase activity. Respiratory outcome was assessed as oxygen requirement at 28-d or 36-wk postmenstrual age, and as the number of days of oxygen requirement. Protein carbonyls were significantly higher in infants < 1500 g than larger infants, and were highest close to birth. MDA concentrations were also higher in the earlier samples. There was a strong positive correlation between protein carbonyls and myeloperoxidase, suggesting a link between protein oxidation and neutrophil activation. A similar but weaker correlation was seen for MDA. Carbonyls in samples taken after steroid administration were less than for controls with a similar age distribution. We did not see significant associations between oxidant marker levels and development of chronic lung disease. Our findings of higher amounts of protein and lipid oxidation products in tracheal aspirates with high myeloperoxidase activity, taken together with other studies showing a link between neutrophil accumulation and chronic lung disease, suggest a possible contribution by neutrophil-derived reactive oxygen species to the injury.