Safety and efficacy of high-frequency jet ventilation in neonatal transport.

OBJECTIVE: To evaluate the safety and efficacy of high-frequency jet ventilation for transporting critically ill hypoxic neonates to an extracorporeal membrane oxygenation (ECMO) center. STUDY DESIGN: We conducted a retrospective cohort study of 38 transported neonates. Safety was assessed by the comparison of cardiopulmonary variables before and after transport from referring hospital to our ECMO unit. Efficacy was assessed as the effect on ventilation and efficiency of pulmonary gas exchange after conversion from a conventional mechanical ventilator or a high-frequency oscillator to a high-frequency jet ventilator+/-inhaled nitric oxide. RESULT: The pre- and post transport vital signs remained stable, regardless of the type of ventilator used. Pre-transport pneumothorax was the main problem, but no transport-related deaths occurred. We found significant improvement in the ventilation of the neonates transported with a high frequency jet ventilation+/-inhaled nitric oxide that were deficient in those transported with conventional mechanical ventilation+inhaled nitric oxide (P<0.05). The improvement started before transport upon changing the mode of ventilation to a high-frequency jet ventilator. CONCLUSION: Independent of the use of inhaled nitric oxide, high frequency jet ventilation appears to provide better ventilation than conventional mechanical ventilation and is safe to transport pre-ECMO neonates.

Rapid identification of Helicobacter pylori by capillary electrophoresis: an overview.

Helicobacter pylori can cause gastritis and peptic ulcers and is directly associated with the development of gastric cancer. There are many types of diagnostic methods used to identification H. pylori (invasive and non-invasive), but these methods usually require time-consuming and laborious procedures and therefore are not capable of fast diagnosis in cases of emergency. This contribution describes the new achievements, interdisciplinary significance and some future directions in the application of capillary electrophoresis for determination of H. pylori.

Cardiac troponin T and cardiac dysfunction in extremely low-birth-weight infants.

Extremely low-birth-weight (ELBW) infants frequently manifest signs of cardiac dysfunction requiring inotropic support. It is not clear if this is due to cardiac injury, which can be monitored by measuring cardiac troponin T (cTnT). We performed a nested prospective cohort study at a university level III neonatal intensive care unit. The study included 27 infants weighing between 500 and 999 g. Exclusion criteria included evidence of sepsis, use of postnatal steroids, and cardiac anomalies. Measurements included serum cTnT and echocardiogram in the first 48 hours of life. The mean serum cTnT level of the study population was 0.52 +/- 0.38 ng/ml. It was higher in those with lower Apgar scores (0.89 +/- 0.37 if 5-minute Apgar < 4 vs 0.36 +/- 0.26 ng/ml, p < 0.001) and correlated to initial base deficit (r = -0.37, p < 0.05). Infants who required inotropic support had higher cTnT levels than those who did not (0.73 +/- 0.43 vs 0.39 +/- 0.29 ng/ml, p < 0.03). cTnT concentrations did not relate to simultaneous echocardiographic measures of cardiac function. In ELBW infants, serum cTnT levels are higher than normally seen in term infants and adults, and they are higher in infants with greater perinatal stress as well as those who show evidence of cardiac dysfunction requiring pressor support.

NF-kappaB in tracheal lavage fluid from intubated premature infants: association with inflammation, oxygen, and outcome.

OBJECTIVES: To determine if tracheal lavage concentrations of the transcription factor NF-kappaB, which is activated by risk factors associated with bronchopulmonary dysplasia (BPD) and induces expression of cytokines associated with BPD, is related to BPD in premature infants. DESIGN: Serial tracheal lavage samples from intubated premature infants were analysed for cell count and concentrations of interleukin (IL)8 and NF-kappaB, corrected for dilution by secretory component concentrations. SETTING: Level III university hospital neonatal intensive care unit. PATIENTS: Thirty three intubated infants (mean (SD) birth weight 903 (258) g, median gestation 27 weeks (range 24-31)) in the first 14 days of life. MAIN OUTCOME MEASURES: Tracheal effluent NF-kappaB, IL8, and cell counts, corrected for dilution by secretory component measurement. RESULTS: Square root transformed NF-kappaB concentrations were significantly related to signs of inflammation (cell count, p = 0.002; IL8, p = 0.019) and to simultaneous fraction of inspired oxygen in samples from the first 3 days of life (r = 0.512, p<0.003). Of the 32 subjects with samples in the first 3 days of life, the half who either died or had BPD had higher NF-kappaB concentrations than those without BPD (square root concentration 0.097 (0.043) v 0.062 (0.036) microg/microg protein/microg secretory component, p = 0.018). CONCLUSIONS: Tracheobronchial lavage NF-kappaB concentrations are related to lung inflammation, oxygen exposure, and pulmonary outcome in intubated preterm infants. NF-kappaB activation may be an early critical step leading to BPD.

Protein fingerprinting as a complementary tool for the classification of Pseudomonas bacteria.

A collection of total 42 bacterial strains belonging to the genus Pseudomonas were characterised based on protein fingerprinting using sodium dodecyl sulphate polyacrylamide gel electrophoregrams of cell-free extracts. Densitometrical analysis revealed unique and distinct profiles characteristic of the studied species. This comparison differentiated the isolates into four main clusters and twelve subclusters. The obtained protein patterns have proved to be an effective and reliable method both for the classification of bacteria and for showing similarities and variability among them.

Utilization of different carbon sources by bacteria isolated from the roots of pine seedlings (Pinus silvestris L.) inoculated with root-free, rhizosphere and mycorrhizosphere soil.

Studies were carried out on the utilization of different sugars (glucose, fructose, arabinose, xylose, sucrose) and organic acids (acetic, citric, fumaric, propionic, succinic) by fast and slow growing bacteria isolated from the roots of pine seedlings (P. silvestris L.) inoculated with root-free, rhizosphere and mycorrhizosphere soil from nursery and mature pine forest. Sucrose among sugars and propionic acid among organic acids were the less frequently utilized compounds. Sugars were better carbon sources than organic acids. Proportion of isolates utilizing respective sugars or organic acids was, in general, significantly higher among fast growing bacteria as compared with slow growing ones. No significant differences in number of strains assimilating the appropiate sugars depending on their original habitat or kind of soil were observed. Such differences were noted for utilization of some organic acids. 3-factor ANOVA confirmed that the growth speed of bacteria at the moment of their isolation had the strongest effect on utilization of the compounds studied.

Plasma intestinal fatty acid binding protein in neonates with necrotizing enterocolitis: a pilot study.

BACKGROUND/PURPOSE: Intestinal fatty acid-binding protein (IFABP) is found within cells at the tip of the intestinal villi, an area commonly injured when necrotizing enterocolitis (NEC) occurs. This study was undertaken to determine if measuring IFABP concentrations in the bloodstream early in the course of NEC would differentiate patients by severity before clinical findings made it clear who had stage 3 NEC and who had milder stages. METHODS: Three plasma samples from newborn infants evaluated for NEC were obtained at symptom onset and after 8 and 24 hours. IFABP concentration was measured by radioimmunoassay. Infants were classified by the final and most severe stage of NEC, and IFABP levels were compared between groups at each sampling. RESULTS: IFABP was detectable in blood samples from all 7 infants with stage 3 NEC compared with 3 of 24 with stages 1 or 2 NEC. Elevated plasma IFABP concentrations were detectable before clinical staging could be made in 5 of the 7 subjects with stage 3 NEC. CONCLUSION: IFABP may be a specific marker for early identification of severe NEC.

Circulating pro- and counterinflammatory cytokine levels and severity in necrotizing enterocolitis.

OBJECTIVES: To evaluate the relationship between the severity of necrotizing enterocolitis (NEC) and circulating concentrations of proinflammatory cytokines interleukin (IL)-1beta and IL-8 and counterinflammatory cytokines IL-1 receptor antagonist (IL-1ra) and IL-10. These cytokines have been associated with bowel injury or inflammation and may be released more slowly or later than previously examined cytokines. Also, to determine if any one of these cytokines will predict the eventual severity of NEC when measured at symptom onset. METHOD: Serial blood samples at onset, 8, 24, 48, and 72 hours were obtained from newborn infants with predefined signs and symptoms of NEC. Normal levels were defined from weight-, gestation-, and age-matched controls. Concentrations of the four cytokines were determined by enzyme-linked immunosorbent assay and compared throughout the time period by stage of NEC, using sepsis as a co-factor. Mean concentrations of each cytokine at onset were compared with the controls. Threshold values were obtained with the best combination of high sensitivity and high specificity for defining stage 1 NEC or for diagnosing stage 3 NEC at onset. RESULTS: There were 12 cases of stage 1, 18 cases of stage 2, and 6 cases of stage 3 NEC included in the study, as well as 20 control infants. Concentrations of IL-8 and IL-10 were significantly higher in infants with stage 3 NEC from onset through 24 hours compared with infants with less severe NEC. At onset, concentrations of all four cytokines were significantly higher in stage 3 NEC. To identify, at onset, the infants with a final diagnosis of stage 3 NEC, an IL-1ra concentration of >130 000 pg/mL had a sensitivity of 100% and a specificity of 92%. At 8 hours, an IL-10 concentration of >250 pg/mL had a sensitivity of 100% and a specificity of 90% in identifying stage 3 NEC in infants with symptoms suggestive of NEC at onset. CONCLUSIONS: The severity of NEC and its systemic signs and symptoms are not due to a deficiency of counterregulatory cytokines. In fact, mean concentrations of IL-1ra in NEC are higher than what has been reported in other populations. The cytokines IL-8, IL-1ra, and IL-10 are released later or more slowly after a stimulus and may be more useful in identifying, within hours of symptom onset, which infant will develop significant NEC.

Mainstream end-tidal carbon dioxide monitoring in the neonatal intensive care unit.

BACKGROUND: Continuous noninvasive monitoring of arterial carbon dioxide (CO2) in neonatal intensive care unit (NICU) patients would help clinicians avoid complications of hypocarbia and hypercarbia. End-tidal CO2 monitoring has not been used in this population to date, but recent technical advances and the introduction of surfactant therapy, which improves ventilation-perfusion matching, might improve the clinical utility of end-tidal monitoring. OBJECTIVE: To determine the accuracy and precision of end-tidal CO2 monitoring in NICU patients. DESIGN: Nonrandomized recording of simultaneous end-tidal and arterial CO2 pairs. SETTING: Two university NICUs. PATIENTS: Forty-five newborn infants receiving mechanical ventilation who had indwelling arterial access, and a predefined subsample of infants who were <1000 g birth weight, <8 days of age, and who received surfactant therapy (extremely low birth weight -ELBW- <8). OUTCOME MEASURES: The correlation coefficient, degree of bias, and 95% confidence interval were determined for both the overall population and the ELBW <8 subgroup. Those factors which significantly influenced the bias were identified. The ability of the end-tidal monitor to alert the clinician to instances of hypocarbia or hypercarbia was determined. RESULTS: There were 411 end-tidal/arterial pairs analyzed from 45 patients. The correlation coefficient was 0.833 and the bias was -6. 9 mm Hg (95% confidence interval, +/-11.5 mm Hg). The results did not differ markedly in the ELBW <8 infants. Measures of the degree of lung disease, the ventilation index and the oxygenation index, had small influences on the degree of bias. This type of capnometry identified 91% of the instances when the arterial CO2 pressure was between 34 and 54 mm Hg using an end-tidal range of 29 to 45 mm Hg. End-tidal values outside this range had a 63% accuracy in predicting hypocarbia or hypercarbia. CONCLUSION: End-tidal CO2 monitoring in NICU patients is as accurate as capillary or transcutaneous monitoring but less precise than the latter. It may be useful for trending or for screening patients for abnormal arterial CO2 values.

Early versus late identification of infants at high risk of developing moderate to severe bronchopulmonary dysplasia.

We developed a simple method to identify neonates at high risk of bronchopulmonary dysplasia (BPD) and determined whether early (8 hours) and late (14 days) risk assessment is equally useful. A retrospective cohort design was utilized of subjects enrolled in multi-dose surfactant trials to develop each risk identification model. Prospective testing of the late 14-day model was done to determine accuracy. The primary outcome variable (moderate to severe BPD) was defined as the need for oxygen and mechanical ventilation beyond 28 days of life and significant chest X-ray changes. Variables were screened for inclusion in the models by univariate and multiple regression analysis of data available at 14 days or 8 hours of life, converted to yes-no variables by the use of receiver-operator curves; the final model was based on those variables that gave the highest sensitivity and specificity for identifying BPD risk. Thirty-eight out of 116 of the 14-day model subjects developed BPD. The 14-day model (F1O2 > or = 0.30 and ventilation index (defined as 10,000/peak pressure x rate x PCO2) < 0.510 (or < 0.800 if previously septic)] had a sensitivity of 82% and specificity of 89%. It accurately identified 83% of cases (51/61) during at 1-year prospective test. The positive predictive value was 81% and negative predictive value 88%. Forty-four of the 698 early 8-hour model subjects developed BPD. The 8-hour model [gestational age < 31 weeks, 5-minute Apgar < 9, ventilator rate > 23 breaths/min, and ventilation index < 0.895] had a sensitivity of 73%, specificity of 83%, negative predictive value of 98% but positive predictive value of only 22%. These observation indicated that clinical data can create an accurate and simple model to classify infants into high- or low-risk groups for BPD. Using such models very early in life (e.g., at 8 hours) may lead to a high number of false-positive identifications.

Quantitative assessment of intrathoracic airway collapse in infants and children with tracheobronchomalacia.

Tracheobronchomalacia (TBM) is increasingly recognized in infants, children, and adults with acquired chronic lung diseases as the use of flexible bronchoscopy has become widely established in spontaneously breathing patients. However, the lack of a reliable method to quantify the severity of the airway collapse has made serial studies, evaluation of therapies, and comparisons between patients difficult. The purpose of this study was to describe a method of quantifying airway collapse in TBM. The degree of airway collapse was quantitated by measuring the ratio of the smallest to the largest airway area during a respiratory cycle. The videotape of flexible bronchoscopy was run through a video monitor and frozen at the appropriate times. The airway circumference was then traced onto plastic overlays and the area measured. The videotapes of seven infants and children with TBM and eight with normal airways were reviewed by investigators who did not know the diagnosis. Intra-observer variability was 2.2%, and inter-observer variability was 1.4%. The mean smallest/largest airway ratio was 0.34 + or - 0.14 (SD) in the subjects with known TBM, compared with a ratio of 0.82 + or - 0.08 (SD) in children with a normal airway (P< 0.0001). The range in the children with TBM was 0.22-0.61, whereas for the control children it was 0.73-0.93. In this series, there was no overlap in the ratios between affected and unaffected patients. In addition to the manual method of calculating airway area ratios, a computer-assisted method is described that could be adapted to real-time use. This way of analyzing the degree of airway collapse could be used to assess patients with TBM quantitatively and reproducibly.

Effect of IL-1 blockade on inflammatory manifestations of acute ventilator-induced lung injury in a rabbit model.

Ventilator-induced lung injury in children and adults is characterized by an initial inflammatory phase. To investigate whether the inflammatory cytokine, IL-1, plays a role in this process, a rabbit model of ventilator-induced injury was created. Animals maintained under pentobarbital anesthesia were primed for injury by undergoing lung lavage with 22 mL/kg of saline and then ventilated for 8 h with either FIO2 0.21 and normal pressures or FIO2 1.0 and high ventilator pressures. The animals exposed to hyperoxia/hyperventilation demonstrated a greater increase in lung lavage neutrophil counts and a higher histological injury score, as well as a faster decline in oxygenation compared to the control animals. A third group of rabbits received 800 micrograms of recombinant IL-1 receptor antagonist after lung lavage and prior to the exposure to FIO2 1.0 and high ventilator pressures. These animals had significantly lower concentrations of albumin and elastase and lower neutrophil counts in their lungs after the 8-h ventilatory period compared to hyperoxia/hyperventilation rabbits. IL-1 blockade had no effect on the decline in dynamic compliance and oxygenation seen in saline-treated hyperoxic/hyperventilated rabbits. IL-1 is a mediator of acute inflammation due to ventilator-induced lung injury.

Bronchoalveolar interleukin-1 beta in infants on day 1 of life.

Interleukin-1 beta (IL-1 beta) a proinflammatory cytokine associated with adult lung diseases, may play a role in the development of bronchopulmonary dysplasia (BPD). Concentrations of IL-1 beta were measured in bronchoalveolar lavage fluid from 17 infants on day 1 of life and in 18 infants intubated until day 14. IL-1 beta was detected in 31 of 35 samples. Day 14 concentrations were significantly higher than those obtained on day 1. The four infants who had BPD had significantly higher IL-1 beta levels than those who received oxygen for less than a week or for 1 to 4 weeks. Day 1 IL-1 beta concentration was related to the neutrophil count and inversely to gestational age. IL-1 beta is present in the majority of newborn infants intubated on day 1 or at 2 weeks of life and is elevated during the first 24 hours in infants who will subsequently require longer ventilatory support. It is also elevated in infants who have a stronger pulmonary inflammatory response.

Elevated production of interleukin-1-beta from alveolar macrophages isolated from newborn rabbits.

Alveolar macrophage (AM) production of pro-inflammatory cytokines has been associated with the development of acute and chronic lung injury. However, the role of AM-derived IL-1 beta in the development of bronchopulmonary dysplasia has not been extensively examined. To determine if in vitro production of IL-1 beta by AM is influenced by maturity, cells were isolated by lung lavage from litters of newborn rabbits and from adults. After overnight incubation in serum-supplemented medium, newborn AM produced more IL-1 beta than cells from adults. When these AM were then exposed for 2 h to endotoxin in serum-free medium, adult cells increased their IL-1 beta secretion while the newborn cells did not. Newborn AM IL-1 beta response to LPS returned by 24 h. AM from newborn rabbits also demonstrated increased spontaneous production and increased LPS-induced production of IL-1 beta during overnight incubation in serum-free medium. The newborn rabbit AM appears to be up-regulated in its IL-1 beta production compared to the adult.

Production of B-group vitamins by Azospirillum spp. grown in media of different pH at different temperatures.

Studies were carried out on B-group vitamin (thiamine, biotin, nicotinic acid, riboflavin, pantothenic acid) production by 3 strains of Azospirillum (one derived from coniferous ectomycorrhizae and two--from sporocarps of ectomycorrhizal fungi) grown in media of different pH (5.5, 6.5, 7.5) at different temperatures (10 degrees C, 20 degrees C, 26 degrees C). Riboflavin was produced in largest amounts by all the strains studied; biotin was not detected in culture filtrates at all. Qualitative-quantitative composition of vitamins in post culture liquids of azospirilla depended on the temperature of growth, pH of the medium and on the strain studied. Thiamine was synthesized in largest quantities at pH 5.5 by all strains of Azospirillum--independently of the temperature of growth. In media of higher pH this vitamin was detected in considerably smaller amounts or was not detected at all. The smallest quantities--and the smallest numbers of vitamins produced were observed at temperature 10 degrees C and pH 5.5.

Growth of mycorrhizal fungi in dixenic cultures with bacteria in media of different composition.

Studies were carried out on the effect of bacteria: Arthrobacter globiformis, Bacillus subtilis and Pseudomonas fluorescens on biomass production by three important ectomycorrhizal fungi: Laccaria laccata, Hebeloma crustuliniforme and Rhizopogon vinicolor in media of different composition. It was shown that bacteria stimulated, inhibited or did not affect significantly the biomass production by mycorrhizal fungi. 3-factor ANOVA have shown that although effect of bacteria was statistically significant (p < or = 0.05), composition of medium and its pH affected mycelial growth stronger than bacteria.

A rapid agar-diffusion test for quantifying the toxic effects of copper on microorganisms.

The rapid agar diffusion test for quantifying the toxic effects of copper on microorganisms was elaborated. The assay was run in standard Petri dishes containing Czapek Solution Agar (Difco). Immediately after inoculation with the organism tested 3.2 mm diameter wells were punched in the agar. Wells were filled (20 microliters) with distilled water (control) and a range of solutions containing 128 to 4096 ppm Cu2+ (as CuSO4). After incubation (2-5 days, 26 degrees C) the diameters of Cu-inhibition zones were measured. Cu-sensitivity indices (ICu's) were calculated according to the formula: ICu = a2/(3.2-b), where: a--slope of the linear regression equation: log [Cu] (x)--inhibition zone diameter (y), b--intercept of the same equation. Additionally for characterization of Cu-sensitivity of the organism tested the predicted highest non-inhibitory Cu concentration (10c) was calculated, where: c = (3.2-b)/a. Both ICu's and adjusted average diameters of Cu-inhibition zones characterized well the Cu-sensitivity in organisms tested, as indicated by the statistical analyses. ICu's correlated very well (negative correlation) with 50% effective doses (Ed50's) of Cu2+ for mycelial growth of Cylindrocarpon destructans. The applicability of the elaborated assay in ecotoxicological studies was discussed.

Evaluation of a system for the delivery of inhaled beclomethasone dipropionate to intubated neonates.

Since systemic dexamethasone therapy for bronchopulmonary dysplasia is associated with numerous side effects, a simple system to deliver aerosolized beclomethasone dipropionate (BDP) directly to the lungs of intubated neonates was developed and evaluated in vitro. The system consists of a self-inflating bag, metered dose inhaler (MDI) adapter, Tygon spacer and endotracheal tube (ETT). A dose is delivered by discharging the MDI into the system and giving 3 'breaths' with the bag. Different sizes of ETT do not affect the drug output (1.17 +/- 0.29 vs. 1.32 +/- 0.34 micrograms of BDP per dose using a 3.0-mm or 3.5-mm ETT, respectively; means +/- SD). However, a shorter system spacer substantially reduces the drug output. The majority (54.0%) of the particles exiting the ETT and available to the patient are in the respirable range (0.5-5.5 microns). Based on adult doses and delivery of BDP and the relative sizes of the adult and neonatal lung, it is estimated that a neonate will require 1-6 doses/day. Replacing dexamethasone in the treatment of bronchopulmonary dysplasia with aerosol topical steroids delivered by this system may improve both the safety and efficacy.