Site-specific and endothelial-mediated dysfunction of the alveolar-capillary barrier in response to lipopolysaccharides.

Infectious agents such as lipopolysaccharides (LPS) challenge the functional properties of the alveolar-capillary barrier (ACB) in the lung. In this study, we analyse the site-specific effects of LPS on the ACB and reveal the effects on the individual cell types and the ACB as a functional unit. Monocultures of H441 epithelial cells and co-cultures of H441 with endothelial cells cultured on Transwells® were treated with LPS from the apical or basolateral compartment. Barrier properties were analysed by the transepithelial electrical resistance (TEER), by transport assays, and immunostaining and assessment of tight junctional molecules at protein level. Furthermore, pro-inflammatory cytokines and immune-modulatory molecules were evaluated by ELISA and semiquantitative real-time PCR. Liquid chromatography-mass spectrometry-based proteomics (LS-MS) was used to identify proteins and effector molecules secreted by endothelial cells in response to LPS. In co-cultures treated with LPS from the basolateral compartment, we noticed a significant reduction of TEER, increased permeability and induction of pro-inflammatory cytokines. Conversely, apical treatment did not affect the barrier. No changes were noticed in H441 monoculture upon LPS treatment. However, LPS resulted in an increased expression of pro-inflammatory cytokines such as IL-6 in OEC and in turn induced the reduction of TEER and an increase in SP-A expression in H441 monoculture, and H441/OEC co-cultures after LPS treatment from basolateral compartment. LS-MS-based proteomics revealed factors associated with LPS-mediated lung injury such as ICAM-1, VCAM-1, Angiopoietin 2, complement factors and cathepsin S, emphasizing the role of epithelial-endothelial crosstalk in the ACB in ALI/ARDS.

Novel therapeutic roles for surfactant-inositols and -phosphatidylglycerols in a neonatal piglet ARDS model: a translational study.

The biological and immune-protective properties of surfactant-derived phospholipids and phospholipid subfractions in the context of neonatal inflammatory lung disease are widely unknown. Using a porcine neonatal triple-hit acute respiratory distress syndrome (ARDS) model (repeated airway lavage, overventilation, and LPS instillation into airways), we assessed whether the supplementation of surfactant (S; poractant alfa) with inositol derivatives [inositol 1,2,6-trisphosphate (IP3) or phosphatidylinositol 3,5-bisphosphate (PIP2)] or phosphatidylglycerol subfractions [16:0/18:1-palmitoyloleoyl-phosphatidylglycerol (POPG) or 18:1/18:1-dioleoyl-phosphatidylglycerol (DOPG)] would result in improved clinical parameters and sought to characterize changes in key inflammatory pathways behind these improvements. Within 72 h of mechanical ventilation, the oxygenation index (S+IP3, S+PIP2, and S+POPG), the ventilation efficiency index (S+IP3 and S+POPG), the compliance (S+IP3 and S+POPG) and resistance (S+POPG) of the respiratory system, and the extravascular lung water index (S+IP3 and S+POPG) significantly improved compared with S treatment alone. The inositol derivatives (mainly S+IP3) exerted their actions by suppressing acid sphingomyelinase activity and dependent ceramide production, linked with the suppression of the inflammasome nucleotide-binding domain, leucine-rich repeat-containing protein-3 (NLRP3)-apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)-caspase-1 complex, and the profibrotic response represented by the cytokines transforming growth factor-ß1 and IFN-γ, matrix metalloproteinase (MMP)-1/8, and elastin. In addition, IκB kinase activity was significantly reduced. S+POPG and S+DOPG treatment inhibited polymorphonuclear leukocyte activity (MMP-8 and myeloperoxidase) and the production of interleukin-6, maintained alveolar-capillary barrier functions, and reduced alveolar epithelial cell apoptosis, all of which resulted in reduced pulmonary edema. S+DOPG also limited the profibrotic response. We conclude that highly concentrated inositol derivatives and phosphatidylglycerol subfractions in surfactant preparations mitigate key inflammatory pathways in inflammatory lung disease and that their clinical application may be of interest for future treatment of the acute exudative phase of neonatal ARDS.

18:1/18:1-Dioleoyl-phosphatidylglycerol prevents alveolar epithelial apoptosis and profibrotic stimulus in a neonatal piglet model of acute respiratory distress syndrome.

BACKGROUND: 18:1/18:1-Dioleoyl-phosphatidylgycerol (DOPG) is a surfactant phospholipid that is nearly non-detectable in neonatal surfactant films. When alveolar macrophages are exposed to DOPG in vitro, secretory phospholipase A2 (sPLA2) production is blocked, resulting in suppressed macrophage activity and improved surfactant function. We investigated whether the addition of DOPG to a commercially available surfactant preparation would improve lung function in a neonatal piglet model of acute respiratory distress syndrome. MATERIALS AND METHODS: Respiratory failure was achieved by triple-hit lung injury (repeated broncho-alveolar lavage, injurious ventilation, tracheal lipopolysaccharide instillation, each intervention 24 h apart) in twenty-four domestic piglets aged 2-6 days and subject to mechanical ventilation. Following each lung injury protocol the piglets were treated with surfactant alone or with surfactant + DOPG. RESULTS: Within 72 h of mechanical ventilation, we observed significantly improved gas exchange (oxygenation and ventilation), lung mechanics (compliance and resistance of the respiratory system), and pulmonary oedema (extra-vascular lung water index) in the surfactant + DOPG group. This favourable clinical effect could be attributed to improved surfactant function, reduced sPLA2 secretion, inhibition of macrophage migration, reduced alveolar epithelial apoptosis, and suppression of amphiregulin and TGF-ß1 expression in pulmonary tissues as a prerequisite for fibrous lung repair. CONCLUSIONS: We conclude that surfactant fortified by DOPG preserves lung function, and prevents alveolar epithelial injury and fibrous stimulus by reduction of sPLA2 in a neonatal model of acute respiratory distress syndrome without any relevant discernable side effects. Hence, DOPG supplementation in a neonatal lung exerts important function protecting effects and seems to be justified in cases of overwhelming pulmonary inflammation.

Inositol-trisphosphate reduces alveolar apoptosis and pulmonary edema in neonatal lung injury.

D-myo-inositol-1,2,6-trisphosphate (IP3) is an isomer of the naturally occurring second messenger D-myo-inositol-1,4,5-trisphosphate, and exerts anti-inflammatory and antiedematous effects in the lung. Myo-inositol (Inos) is a component of IP3, and is thought to play an important role in the prevention of neonatal pulmonary diseases such as bronchopulmonary dysplasia and neonatal acute lung injury (nALI). Inflammatory lung diseases are characterized by augmented acid sphingomyelinase (aSMase) activity leading to ceramide production, a pathway that promotes increased vascular permeability, apoptosis, and surfactant alterations. A novel, clinically relevant triple-hit model of nALI was developed, consisting of repeated airway lavage, injurious ventilation, and lipopolysaccharide instillation into the airways, every 24 hours. Thirty-five piglets were randomized to one of four treatment protocols: control (no intervention), surfactant alone, surfactant + Inos, and surfactant + IP3. After 72 hours of mechanical ventilation, lungs were excised from the thorax for subsequent analyses. Clinically, oxygenation and ventilation improved, and extravascular lung water decreased significantly with the S + IP3 intervention. In pulmonary tissue, we observed decreased aSMase activity and ceramide concentrations, decreased caspase-8 concentrations, reduced alveolar epithelial apoptosis, the reduced expression of interleukin-6, transforming growth factor-ß1, and amphiregulin (an epithelial growth factor), reduced migration of blood-borne cells and particularly of CD14(+)/18(+) cells (macrophages) into the airspaces, and lower surfactant surface tensions in S + IP3-treated but not in S + Inos-treated piglets. We conclude that the admixture of IP3 to surfactant, but not of Inos, improves gas exchange and edema in our nALI model by the suppression of the governing enzyme aSMase, and that this treatment deserves clinical evaluation.

Topical application of phosphatidyl-inositol-3,5-bisphosphate for acute lung injury in neonatal swine.

Hypoxemic respiratory failure of the neonatal organism involves increased acid sphingomyelinase (aSMase) activity and production of ceramide, a second messenger of a pro-inflammatory pathway that promotes increased vascular permeability, surfactant alterations and alveolar epithelial apoptosis. We comparatively assessed the benefits of topical aSMase inhibition by either imipramine (Imi) or phosphatidylinositol-3,5-bisphosphate (PIP2) when administered into the airways together with surfactant (S) for fortification. In this translational study, a triple-hit acute lung injury model was used that entails repeated airway lavage, injurious ventilation and tracheal lipopolysaccharide instillation in newborn piglets subject to mechanical ventilation for 72 hrs. After randomization, we administered an air bolus (control), S, S+Imi, or S+PIP2. Only in the latter two groups we observed significantly improved oxygenation and ventilation, dynamic compliance and pulmonary oedema. S+Imi caused systemic aSMase suppression and ceramide reduction, whereas the S+PIP2 effect remained compartmentalized in the airways because of the molecule's bulky structure. The surfactant surface tensions improved by S+Imi and S+PIP2 interventions, but only to a minor extent by S alone. S+PIP2 inhibited the migration of monocyte-derived macrophages and granulocytes into airways by the reduction of CD14/CD18 expression on cell membranes and the expression of epidermal growth factors (amphiregulin and TGF-ß1) and interleukin-6 as pro-fibrotic factors. Finally we observed reduced alveolar epithelial apoptosis, which was most apparent in S+PIP2 lungs. Exogenous surfactant "fortified" by PIP2, a naturally occurring surfactant component, improves lung function by topical suppression of aSMase, providing a potential treatment concept for neonates with hypoxemic respiratory failure.

IKK NBD peptide inhibits LPS induced pulmonary inflammation and alters sphingolipid metabolism in a murine model.

Airway epithelial NF-κB is a key regulator of host defence in bacterial infections and has recently evolved as a target for therapeutical approaches. Evidence is accumulating that ceramide, generated by acid sphingomyelinase (aSMase), and sphingosine-1-phosphate (S1-P) are important mediators in host defence as well as in pathologic processes of acute lung injury. Little is known about the regulatory mechanisms of pulmonary sphingolipid metabolism in bacterial infections of the lung. The objective of this study was to evaluate the influence of NF-κB on sphingolipid metabolism in Pseudomonas aeruginosa LPS-induced pulmonary inflammation. In a murine acute lung injury model with intranasal Pseudomonas aeruginosa LPS we investigated TNF-α, KC (murine IL-8), IL-6, MCP-1 and neutrophilic infiltration next to aSMase activity and ceramide and S1-P lung tissue concentrations. Airway epithelial NF-κB was inhibited by topically applied IKK NBD, a cell penetrating NEMO binding peptide. This treatment resulted in significantly reduced inflammation and suppression of aSMase activity along with decreased ceramide and S1-P tissue concentrations down to levels observed in healthy animals. In conclusion our results confirm that changes in sphingolipid metabolim due to Pseudomonas aeruginosa LPS inhalation are regulated by NF-κB translocation. This confirms the critical role of airway epithelial NF-κB pathway for the inflammatory response to bacterial pathogens and underlines the impact of sphingolipids in inflammatory host defence mechanisms.

Characterization of phospholipid-modified lung surfactant in vitro and in a neonatal ARDS model reveals anti-inflammatory potential and surfactant lipidome signatures.

A strong inflammatory immune response drives the lung pathology in neonatal acute respiratory distress syndrome (nARDS). Anti-inflammatory therapy is therefore a promising strategy for improved treatment of nARDS. We demonstrate a new function of the anionic phospholipids POPG, DOPG, and PIP2 as inhibitors of IL-1ß release by LPS and ATP-induced inflammasome activation in human monocyte-derived and lung macrophages. Curosurf® surfactant was enriched with POPG, DOPG, PIP2 and the head-group derivative IP3, biophysically characterized and applicability was evaluated in a piglet model of nARDS. The composition of pulmonary surfactant from piglets was determined by shotgun lipidomics screens. After 72 h of nARDS, levels of POPG, DOPG, and PIP2 were enhanced in the respective treatment groups. Otherwise, we did not observe changes of individual lipid species in any of the groups. Surfactant proteins were not affected, with the exception of the IP3 treated group. Our data show that POPG, DOPG, and PIP2 are potent inhibitors of inflammasome activation; their enrichment in a surfactant preparation did not induce any negative effects on lipid profile and reduced biophysical function in vitro was mainly observed for PIP2. These results encourage to rethink the current strategies of improving surfactant preparations by inclusion of anionic lipids as potent anti-inflammatory immune regulators.

Robotic infant surgery with 3 mm instruments: a study in piglets of less than 10 kg body weight.

No data exist concerning the appication of a new robotic system with 3 mm instruments (Senhance®, Transenterix) in infants and small children. Therefore, the aim of this study was to test the system for its feasibility, performance and safety of robotic pediatric abdominal and thoracic surgery in piglets simulating infants with a body weight lower than 10 kg. 34 procedures (from explorative laparoscopy to thoracoscopic esophageal repair) were performed in 12 piglets with a median age of 23 (interquartile range: 12-28) days and a median body weight of 6.9 (6.1-7.3) kg. The Senhance® robotic system was used with 3 mm instruments, a 10 mm 3D 0° or 30° videoscope and advanced energy devices, the setup consisted of the master console and three separate arms. The amount, size, and position of the applied ports, their distance as well as the distance between the three operator arms of the robot, external and internal collisions, and complications of the procedures were recorded and analyzed. We were able to perform all planned surgical procedures with 3 mm robotic instruments in piglets with a median body weight of less than 7 kg. We encountered two non-robot associated complications (bleeding from the inferior caval and hepatic vein) which led to termination of the live procedures. Technical limitations were the reaction time and speed of robotic camera movement with eye tracking, the excessive bending of the 3 mm instruments and intermittent need of re-calibration of the fulcrum point. Robotic newborn and infant surgery appears technically feasible with the Senhance® system. Software adjustments for camera movement and sensitivity of the fulcrum point calibration algorithm to adjust for the increased compliance of the abdominal wall of infants, therefore reducing the bending of the instruments, need to be implemented by the manufacturer as a result of our study. To further evaluate the Senhance® system, prospective trials comparing it to open, laparoscopic and other robotic systems are needed.

Selective NF-kappaB inhibition, but not dexamethasone, decreases acute lung injury in a newborn piglet airway inflammation model.

Acute respiratory failure in neonates (e.g. ARDS, meconium aspiration pneumonitis, pneumonia) is characterized by an excessive inflammatory response, governing the migration of polymorpho-nuclear leukocytes (PMNLs) into lung tissue and causing consecutive impairment of gas exchange and lung function. Critical to this inflammatory response is the activation of nuclear factor-kappaB (NF-kappaB) that is required for transcription of the genes for many pro-inflammatory mediators. We asked whether the inhibition of NF-kappaB activity using either a selective inhibitor (IKK-NBD peptide) or dexamethasone would be more effective in decreasing NF-kappaB activity and chemokine expression in pulmonary cells. Changes in lung function were repeatedly assessed for 24h following induction of acute respiratory failure and therapeutic intervention. We conducted a randomized, controlled, prospective animal study with mechanically ventilated newborn piglets which underwent repeated airway lavage (20+/-2 [SEM]) to remove surfactant and to induce lung inflammation. Admixed to 100 mg kg(-1) surfactant, piglets then received either IKK-NBD peptide (S+IKK), a selective inhibitor of NF-kappaB activation, its control peptide without intrinsic activity, dexamethasone (S+Dexa), its solvent aqua, or an air bolus only (all groups n=8). After 24h of mechanical ventilation, the following differences were measured: PaO(2)/FiO(2) (S+IKK 230+/-9 mm Hg vs. S+Dexa 188+/-14, p<0.05); ventilation efficiency index (0.18+/-0.01 [3800/(PIP-PEEP)(*)f(*)PaCO(2)] vs. 0.14+/-0.01, p<0.05); extravascular lung water (24+/-1 ml kg(-1) vs. 29+/-2, p<0.05); PMNL in BAL fluid (112+/-21 cells microl(-1) vs. 208+/-34, p<0.05), IL-8 (351+/-117 pg ml(-1) vs. 491+/-144, p=ns) and leukotriene B(4) (23+/-7 pg ml(-1) vs. 71+/-11, p<0.01) in BAL fluid. NF-kappaB activity in the nucleus of pulmonary cells differed by 32+/-5% vs. 55+/-3, p<0.001. Differences between these two intervention groups were more pronounced in the second half of the observation period (hours 12-24). At 24h of mechanical ventilation, inhibition of NF-kappaB activity by IKK-NBD peptide admixed to surfactant as a carrier caused improved gas exchange, lung function and reduced pulmonary inflammation, as evidenced by reduction in PMNL migration into lung tissue due to reduced nuclear NF-kappaB activity. We conclude that IKK-NBD admixture to surfactant in acute neonatal respiratory failure is superior to dexamethasone administration within the first 24h.

Improved pulmonary function by acid sphingomyelinase inhibition in a newborn piglet lavage model.

RATIONALE: In acute inflammatory lung disease in newborn infants, exogenous surfactant only transiently improves lung function. We hypothesized that the transient nature of this protection is in part explained by elevated acid sphingomyelinase (a-SMase) activity that may inactivate surfactant and promote proinflammatory responses. OBJECTIVES: We investigated the intermediate-term effects (>12 h) of a-SMase inhibition in a neonatal piglet model of repeated airway lavage by the intratracheal use of the a-SMase inhibitor imipramine, together with exogenous surfactant as a carrier substance. METHODS: After surfactant washout and induction of pulmonary inflammation, lung function was monitored over 24 hours of mechanical ventilation and followed by ex vivo analyses. In addition, we studied the effect of lipopolysaccharide inhalation in a-SMase-deficient mice at 48 hours. MEASUREMENTS AND MAIN RESULTS: Surfactant washout increased both pulmonary a-SMase activity and ceramide content; this was attenuated by surfactant and prevented in the surfactant plus imipramine group. Compared with surfactant alone, Pa(O(2)), dynamic compliance, and extravascular lung water were improved in the final 12 hours in the surfactant plus imipramine group. At 24 hours, lavage fluid leukocyte counts and IL-8 concentrations decreased, and physical surfactant film properties improved. In the mouse model at 48 hours, a-SMase-deficient mice showed reduced pulmonary ceramide levels and attenuated leukocyte influx into the alveolar space. CONCLUSIONS: We conclude that stabilization of exogenous surfactant by adding imipramine to create a "fortified surfactant preparation" improves lung function in a clinically relevant piglet model, and that this effect can be attributed to the inhibition of a-SMase as evidenced in the mouse model.

An Unsettled Promise: The Newborn Piglet Model of Neonatal Acute Respiratory Distress Syndrome (NARDS). Physiologic Data and Systematic Review.

Despite great advances in mechanical ventilation and surfactant administration for the newborn infant with life-threatening respiratory failure no specific therapies are currently established to tackle major pro-inflammatory pathways. The susceptibility of the newborn infant with neonatal acute respiratory distress syndrome (NARDS) to exogenous surfactant is linked with a suppression of most of the immunologic responses by the innate immune system, however, additional corticosteroids applied in any severe pediatric lung disease with inflammatory background do not reduce morbidity or mortality and may even cause harm. Thus, the neonatal piglet model of acute lung injury serves as an excellent model to study respiratory failure and is the preferred animal model for reasons of availability, body size, similarities of porcine and human lung, robustness, and costs. In addition, similarities to the human toll-like receptor 4, the existence of intraalveolar macrophages, the sensitivity to lipopolysaccharide, and the production of nitric oxide make the piglet indispensable in anti-inflammatory research. Here we present the physiologic and immunologic data of newborn piglets from three trials involving acute lung injury secondary to repeated airway lavage (and others), mechanical ventilation, and a specific anti-inflammatory intervention via the intratracheal route using surfactant as a carrier substance. The physiologic data from many organ systems of the newborn piglet-but with preference on the lung-are presented here differentiating between baseline data from the uninjured piglet, the impact of acute lung injury on various parameters (24 h), and the follow up data after 72 h of mechanical ventilation. Data from the control group and the intervention groups are listed separately or combined. A systematic review of the newborn piglet meconium aspiration model and the repeated airway lavage model is finally presented. While many studies assessed lung injury scores, leukocyte infiltration, and protein/cytokine concentrations in bronchoalveolar fluid, a systematic approach to tackle major upstream pro-inflammatory pathways of the innate immune system is still in the fledgling stages. For the sake of newborn infants with life-threatening NARDS the newborn piglet model still is an unsettled promise offering many options to conquer neonatal physiology/immunology and to establish potent treatment modalities.

PICU mortality of children with cancer admitted to pediatric intensive care unit a systematic review and meta-analysis.

BACKGROUND: Outcomes for children diagnosed with cancer have improved dramatically over the past 20 years. However, although 40% of pediatric cancer patients require at least one intensive care admission throughout their disease course, PICU outcomes and resource utilization by this population have not been rigorously studied in this specific group. METHODS: Using a systematic strategy, we searched Medline, Embase, and CINAHL databases for articles describing PICU mortality of pediatric cancer patients admitted to PICU. Two investigators independently applied eligibility criteria, assessed data quality, and extracted data. We pooled PICU mortality estimates using random-effects models and examined mortality trends over time using meta-regression models. RESULTS: Out of 1218 identified manuscripts, 31 studies were included covering 16,853 PICU admissions with the majority being retrospective in nature. Overall pooled weighted mortality was 27.8% (95% confidence interval (CI), 23.7-31.9%). Mortality decreased slightly over time when post-operative patients were excluded. The use of mechanical ventilation (odds ratio (OR): 18.49 [95% CI 13.79-24.78], p < 0.001), inotropic support (OR: 14.05 [95% CI 9.16-21.57], p < 0.001), or continuous renal replacement therapy (OR: 3.24 [95% CI 1.31-8.04], p = 0.01) was significantly associated with PICU mortality. CONCLUSIONS: PICU mortality rates of pediatric cancer patients are far higher when compared to current mortality rates of the general PICU population. PICU mortality has remained relatively unchanged over the past decades, a slight decrease was only seen when post-operative patients were excluded. This compared infavorably with the improved mortality seen in adults with cancer admitted to ICU, where research-led improvements have led to the paradigm of unlimited, aggressive ICU management without any limitations on resuscitations status, for a time-limited trial.

Altered pulmonary interleukin-6 signaling in preterm infants developing bronchopulmonary dysplasia.

Interleukin (IL)-6 signaling depends on the soluble IL-6 receptor (sIL-6R) and the soluble glycoprotein 130 (sgp130). To investigate the impact of IL-6 signaling on the pathogenesis of bronchopulmonary dysplasia of prematurity (BPD), IL-6, sIL-6R, and sgp130 were measured by enzyme-linked immunosorbent assay (ELISA) technique in tracheal aspirates of mechanically ventilated preterm infants. Infants developing BPD showed increased concentrations of IL-6, sIL-6R, and sgp-130 in their first week of life. These infants also had significantly higher molar ratios for IL-6/sIL-6R and IL-6/sgp130. The authors conclude that altered interleukin-6 signaling via the soluble receptors sIL-6R and sgp130 may play an important role in pulmonary inflammation of preterm infants.

Bronchoscopic surfactant administration in pediatric patients with persistent lobar atelectasis.

Persistent lobar atelectasis in pediatric patients on mechanical ventilation results in impaired gas exchange and lung mechanics and contributes to a further need for mechanical ventilation. The most common types of atelectasis in children are resorption atelectasis following airway obstruction, and atelectasis due to surfactant deficiency or dysfunction. We aimed to determine whether bronchoscopic suctioning and surfactant application to atelectatic lung segments would result in improved oxygenation, ventilation, chest X-ray scoring, and early extubation. Five children with heterogeneous lung diseases (aged between 7 months and 15 years) were treated with a diluted surfactant preparation (Curosurf) in a concentration of 5-10 mg/ml (total dose 120-240 mg) which was instilled into the affected segments. Outcome parameters were gas exchange, radiographic resolution of atelectasis and extubation. All mechanically ventilated patients could be extubated within 24 h following the intervention. Bronchoscopic surfactant application could be carried out without adverse effects and brought improvements in oxygenation, respiratory rate, and partial or complete resolution of atelectases without recurrence.

Supine vs. Prone Position With Turn of the Head Does Not Affect Cerebral Perfusion and Oxygenation in Stable Preterm Infants ≤32 Weeks Gestational Age.

Intraventricular hemorrhage (IVH) is a frequent major damage to the brain of premature babies ≤32 weeks gestational age, and its incidence (20-25%) has not significantly changed lately. Because of the intrinsic fragility of germinal matrix blood vessels, IVH occurs following disruption of subependymal mono-layer arteries and is generally attributed to ischemia-reperfusion alterations or venous congestion, which may be caused by turn of the head. Therefore, supine position with the head in a midline position is considered a standard position for preterm infants during their first days of life. We asked whether a change in body position (supine vs. prone) linked with a turn of the head by 90° in the prone position would change blood flow velocities and resistance indices in major cerebral arteries and veins of stable premature babies at two different time points (t0, day of life 2, vs. t1, day 9). Moreover, we assessed cerebral tissue oxygenation (cStO2) by near-infrared spectroscopy and determined correlations for changes in velocities and oxygenation. Twenty one premature infants [gestational age 30 (26-32) weeks] with sufficiently stable gas exchange and circulation were screened by ultrasonography and near-infrared spectroscopy. Peak systolic and end-diastolic blood flow velocities in the anterior cerebral arteries (29 ± 6 m/s vs. 28 ± 7 peak flow at t0, 36 ± 8 vs. 35 ± 7 at t1), the basilar artery, the right and the left internal carotid artery, and the great cerebral vein Galen (4.0 ± 0.8 m/s vs. 4.1 ± 1.0 maximum flow at t0, 4.4 ± 0.8 vs. 4.4 ± 1.0 at t1) did not show significant differences following change of body and head position. Also, there were no differences in cStO2 (83 ± 7% vs. 84 ± 7 at t0, 76 ± 10 vs. 77 ± 11 at t1) and in vital signs such as heart rate and blood pressure. We conclude that change in body position with turn of the head in the prone position does not elicit significant alterations in cerebral blood flow velocities or in oxygenation of cerebral tissues. Maturational changes in arterial flow velocities and cStO2 are not correlated. For this subgroup of premature infants at low risk of IVH our data do not support the concept of exclusive preterm infant care in supine position.

Intrapulmonary application of a 5-lipoxygenase inhibitor using surfactant as a carrier reduces lung edema in a piglet model of airway lavage.

Leukotriene-generated effects on microvascular integrity and polymorphonuclear leukocytes (PMNL) play a key role in the inflammatory process of the alveolar-capillary unit in neonatal acute respiratory distress syndrome. We asked if intrapulmonary application of MK886, a 5-lipoxygenase inhibitor, and the use of a porcine surfactant preparation (Curosurftrade mark) as a carrier substance would improve lung function in a neonatal piglet model of airway lavage. Anesthetized, mechanically ventilated newborn piglets (n = 19) underwent repeated airway lavage to induce acute lung injury. Piglets then received either surfactant alone (S, n = 6), or MK886 admixed with surfactant (S + MK, n = 7), or an air-bolus injection as control (C, n = 6). Measurements of gas exchange, lung function, extravascular lung water (EVLW), cell counts, and leukotriene B(4) (LTB(4)) concentrations in bronchoalveolar lavage fluid (BAL) were performed during 6 hr of mechanical ventilation. Arterial oxygen partial pressure (PaO(2)) (S, 13.8 +/- 4.2 kPa, vs. S + MK, 20 +/- 6.6; P < 0.05), functional residual capacity (S, 15.1 +/- 6.8 ml/kg, vs. S + MK, 18.8 +/- 3.7 ml/kg; P < 0.05), and EVLW (S, 29 +/- 14 ml/kg, vs. S + MK 24 +/- 4 ml/kg; P < 0.05) were significantly improved in the MK886 group. This clinical effect was linked with a decrease in LTB(4) concentration in BAL (S, 3.5 (1.9-5.4) pg/ml, vs. S + MK, 1.6 (0.7-4.7) pg/ml; P < 0.05) and an increase in IL-8 (S, 2,103 (852-4,243) pg/ml, vs. S + MK, 3,815 (940-26,187) pg/ml; P < 0.05). PMNL counts in BAL were reduced (S, 570 +/- 42 cells/ml, vs. 275 +/- 35 cells/ml; P < 0.05). In conclusion, intrapulmonary application of the 5-lipoxygenase inhibitor MK886 with surfactant as a carrier improves lung function by decreasing EVLW as the main response to LTB(4) reduction.

Topical interleukin-8 antibody attracts leukocytes in a piglet lavage model.

OBJECTIVE: Acute respiratory distress syndrome (ARDS) in young infants is linked with a pulmonary inflammatory response part of which are increased interleukin-8 (IL-8) levels and migration of polymorphonuclear leukocytes (PMNL) into lung tissue. A topical application of an antibody against IL-8 might therefore decrease PMNL migration and improve lung function. DESIGN: Randomized, controlled, prospective animal study. SETTING: Research laboratory of a university children's hospital. SUBJECTS AND INTERVENTIONS: Anesthetized, mechanically ventilated newborn piglets (n=22) underwent repeated airway lavage to remove surfactant and to induce lung inflammation. Piglets then received either surfactant alone (S, n=8), or a topical antibody against IL-8 admixed to surfactant (S+IL-8, n=8), or an air bolus injection (control, n=6). MEASUREMENTS AND RESULTS: After 6 h of mechanical ventilation following intervention, oxygenation [S 169+/-51 (SD) vs S+IL-8 139+/-61 mmHg] and lung function (compliance: S 1.3+/-0.4 vs S+IL-8 0.9+/-0.4 ml/cmH(2)O/kg; extra-vascular lung-water: S 27+/-9 vs S+IL-8 52+/-28 ml/kg) were worse in the S+IL-8 group because reactive IL-8 production [S 810 (median, range 447-2323] vs S+IL-8 3485 (628-16180) pg/ml; P<0.05) with facilitated migration of PMNL into lung tissue occurred. Moreover, antibody application caused augmented chemotactic potency of IL-8 [linear regression of migrated PMNL and IL-8 levels: S r(2)=0.30 (P=ns) vs S+IL-8 r(2)=0.89 (P=0.0002)]. CONCLUSION: Topical anti-IL-8 treatment after lung injury increases IL-8 production, PMNL migration, and worsens lung function in our piglet lavage model. This effect is in contrast to current literature using pre-lung injury treatment protocols. Our data do not support anti-IL-8 treatment in young infants with ARDS.

Functional residual capacity determines the effect of inhaled nitric oxide on intrapulmonary shunt and gas exchange in a piglet model of lung injury.

OBJECTIVE: Hypoxemic respiratory failure in the newborn infant due to severe parenchymal lung disease is caused by large, intrapulmonary, right-to-left shunting. Nitric oxide (NO) has been shown to reduce shunting and improve oxygenation-however inconsistently-in a variety of neonatal lung diseases such as meconium aspiration pneumonitis, bacterial pneumonia, surfactant deficiency, and others. The aim of this study was to determine whether lung expansion, as determined by functional residual capacity (FRC), by means of increasing levels for positive end-expiratory pressure (PEEP) would augment the effect of NO on reducing right-to-left shunting. DESIGN: Prospective, randomized, controlled, animal laboratory investigation. SETTING: University laboratory. SUBJECTS: Newborn piglets (n = 8), anesthetized and mechanically ventilated. INTERVENTIONS: The piglets were made surfactant deficient by repeated airway lavage aiming at a Pao(2) of 45 mm Hg (6 kPa) while using an Fio(2) of.6. Two hours after lavage, different PEEP levels of 4, 6, 8, 10, and 12 cm H(2)O (.4,.6,.8, 1.0, and 1.2 kPa) were used in a random order, keeping tidal volumes strictly at 8 mL/kg. All measurements were made with or without NO at 10 ppm in a random order, thus each animal served as its own control. A nitrogen washout method was used to measure FRC and alveolar volume, in addition to tidal volume, and compliance and resistance of the respiratory system. MEASUREMENTS AND MAIN RESULTS: Improvement in oxygenation and reduction of right-to-left shunting was optimal while achieving FRC values comparable with those values before airway lavage (approximately 25 mL/kg) while using PEEP levels of 6 to 8 cm H(2)O (.6 to.8 kPa). Further lung expansion did not augment the NO effect. In addition, alveolar volume and compliance of the respiratory system were positively influenced by NO, resulting in a small, but significant, decrease in Paco(2). CONCLUSION: We conclude that improvement in oxygenation by the administration of inhaled NO can be optimized by achieving FRC values comparable with those of the undiseased lung before airway lavage.