From single-case analysis of neonatal deaths toward a further reduction of the neonatal mortality rate.

Background The infant mortality rate (IMR), a key indicator of the quality of a healthcare system, has remained at approximately 3.5‰ for the past 10 years in Germany. Generic quality indicators (QIs), as used in Germany since 2010, greatly help in ensuring such a good value but do not seem to be able to further reduce the IMR. The neonatal mortality rate (NMR) contributes to 65-70% of the IMR. We therefore propose single-case analysis of neonatal deaths as an additional method and show an efficient way to implement this approach. Methods We used the Nordic-Baltic classification (NBC) to detect avoidable neonatal deaths. We applied this classification to a sample of 1968 neonatal death records, which represent over 90% of all neonatal deaths in East Berlin from 1973 to 1989. All cases were analyzed as to their preventability based on the complete perinatal and clinical data by a special commission of different experts. The NBC was automatically applied through natural language processing and an ontology-based terminology server. Results The NBC was used to select the group of cases that had a high potential of avoidance. The selected group represented 6.0% of all cases, and 60.4% of the cases within that group were judged avoidable or conditionally avoidable. The automatic detection of malformations showed an F1 score of 0.94. Conclusion The results show that our method can be applied automatically and is a powerful and highly specific tool for selecting potentially avoidable neonatal deaths and thus for supporting efficient single-case analysis.

Dead space reduction by Kolobow's endotracheal tube does not justify the waiving of volume monitoring in small, ventilated lungs.

In ventilated preterm infants the flow sensor contributes significantly to the total apparatus dead space, which may impair gas exchange. The aim of the study was to quantify to which extent a dead space reduced Kolobow tube (KB) without flow sensor improves the gas exchange compared with a conventional ventilator circuit with flow sensor [Babylog 8000 (BL)]. In a cross-over trial in 14 tracheotomized, surfactant-depleted (saline lavage) and mechanically ventilated newborn piglets (age <12 h; body weight 705-1200 g) BL and KB was applied alternately for 15 min and blood gases were recorded. The inner diameter of the endotracheal tube was 3.6 mm and the apparatus dead space of BL and KB including the endotracheal tube were 3.0 and 1.34 mL. Despite a 50 % apparatus dead space reduction with KB compared to BL statistically significant improvements were only observed for body weights <900 g. In this weight group median paCO2 was decreased by 5 mmHg (p < 0.01), whereas the improvement decreased with decreasing baseline paCO2. Furthermore, median paO2 was increased by 4 mmHg (p < 0.05) and O2 saturation was increased by 2.5 % (p < 0.05). No significant changes were seen in the circulatory parameters. In very small, ventilated lungs the use of KB improved the gas exchange; however, the improvement was moderate and does not justify the waiving of volume monitoring.

Standardized diaper care regimen: a prospective, randomized pilot study on skin barrier function and epidermal IL-1α in newborns.

Adaptation of skin barrier function and interleukin-1α (IL-1α) content in diapered and nondiapered skin are poorly characterized in newborns receiving standard skin care. In a monocentric, prospective pilot study 44 healthy, full-term neonates were randomly assigned to skin care with baby wipes (n = 21) or water-moistened washcloth (n = 23) at each diaper change. Transepidermal water loss (TEWL), skin hydration, skin-pH, IL-1α, and epidermal desquamation were measured on days 2, 14, and 28 postpartum. Microbiological colonization was evaluated at baseline and on day 28. Significantly lower TEWL was found on the buttock in the group using baby wipes compared to water. IL-1α and skin hydration significantly increased and pH decreased independent of skin care regimen. IL-1α was significantly higher in diapered skin compared to nondiapered skin. Although skin care with wipes seems to stabilize TEWL better than using water, the skin condition and microbiological colonization were comparable using both cleansing procedures. Increase of epidermal IL-1α may reflect postnatal skin barrier maturation. These data suggest that neither of the two cleansing procedures harms skin barrier maturation within the first four weeks postpartum. Longer observations on larger populations could provide more insight into postnatal skin barrier maturation.

Effect of standardized skin care regimens on neonatal skin barrier function in different body areas.

The effect of topical skin care products on neonatal skin barrier during first 8 weeks of life has not been scientifically evaluated. In a prospective, randomized clinical study, we compared the influence of three skin care regimens to bathing with water on skin barrier function in newborns at four anatomic sites. A total of 64 healthy, full-term neonates (32 boys and 32 girls) aged <48 hours were randomly assigned to four groups receiving twice-weekly: WG, bathing with wash gel (n = 16); C, bathing and cream (n = 16); WG + C, bathing with wash gel plus cream (n = 16); and B, bathing with water (n = 16). Transepidermal water loss, stratum corneum hydration, skin pH, sebum were measured on day 2, week 2, 4, 8 of life on front, abdomen, upper leg, and buttock. Skin condition was scored and microbiologic colonization was documented. After 8 weeks, group WG + C showed significantly lower transepidermal water loss on front, abdomen, and upper leg as well as higher stratum corneum hydration on front and abdomen compared with group B. Similarly, group C showed lower transepidermal water loss and higher stratum corneum hydration on these body regions. Group WG revealed significantly lower pH on all sites compared with group B at week 8. No differences in sebum level, microbiologic colonization and skin condition score were found. Skin care regimens did not harm physiologic neonatal skin barrier adaptation within the first 8 weeks of life. However, significant influence of skin care on barrier function was found in a regional specific fashion.

Comparison of lung volume measurements by multiple-breath heptafluoropropane washout and computed tomography in small ventilated piglets.

BACKGROUND: Knowledge of lung volume is essential for monitoring and optimizing mechanical ventilation. The aim of this study was to compare lung volume measurements by multiple-breath heptafluoropropane (HFP) washout (MBW) and by respiratory gated computed tomography (CT) in ventilated newborn piglets. MATERIAL/METHODS: In 6 ventilated piglets (age: <12 h, median weight: 945 g) blood gases, respiratory mechanics, and lung volumes were measured in both the supine and prone positions. The measurements were performed in random order. Functional residual capacity (FRC) was measured simultaneously by HFP MBW (FRC(HFP)) using a new infrared mainstream sensor and by CT (FRC(CT)) at the end of inspiration and expiration (multi-slice Toshiba Aquilon 16, Otawara, Japan). Tidal volume (V(T)) was measured both by the Dräger Babylog 8000 ventilator (V(T BL)) and the volume difference of the CT scans (V(T CT)). RESULTS: FRC(HFP) (25.2+/-8.5 ml) and FRC(CT) (24.9+/-7.6 ml) correlated strongly (r=0.97) without significant bias. Bland-Altman limits of agreement showed differences between the two methods that ranged from -19.7 to +19.5%. A similar strong correlation without statistically significant bias was found between V(T BL) (8.5+/-2.0 ml) and V(T CT) (9.0+/-2.4 ml) with r=0.91. The limits of agreement were -24.4 and +14.0%. Body position (prone vs. supine) had no significant effect on blood gases, respiratory mechanics, or lung volumes. CONCLUSIONS: Lung volumes measured in small ventilated lungs by HFP washout and CT are highly correlated and independent of body position. However, the relatively large limits of agreement indicate differences in the two techniques.

Variations of Apgar score of very low birth weight infants in different neonatal intensive care units.

OBJECTIVE: The Apgar score should be an objective method to assess the state of newborns; however, its applicability in preterm infants is hampered by large variations among different observers. The study tested whether physicians that give low scores to written case descriptions also apply lower scores to preterm infants. PATIENTS AND METHODS: Descriptions (BMJ 2004; 329: 143-4) were sent to 14 neonatal units. Physicians were asked to evaluate the Apgar (case score). From seven units Apgar scores of all very low birth weight infants (VLBW) born between January 2004 and December 2006 were obtained from charts (clinical score). RESULTS: In total, 121 physicians from 14 institutions (median 9, range 3-15) replied: 24 residents with <6-month and 28 with >6-month neonatal experience, and 69 consultants. The assessment of the case scores was very heterogeneous with large variations in respiration, muscle tone and reflexes. Clinical scores were obtained from 1000 VLBW infants. The score depended on the gestational age, with a median of 4 at 24 and 7 at 27 weeks. With one exception, centres that assigned low case scores had also low clinical scores. CONCLUSION: There is considerable variation in assigning Apgar scores. Definitions are required to apply the Apgar score to infants under clinical conditions such as preterm delivery, resuscitation or artificial ventilation.

Integrating terminologies into standard SQL: a new approach for research on routine data.

BACKGROUND: Most electronic medical records still contain large amounts of free-text data. Semantic evaluation of such data requires the data to be encoded with sufficient classifications or transformed into a knowledge-based database. METHODS: We present an approach that allows databases accessible via SQL (Structured Query Language) to be searched directly through semantic queries without the need for further transformations. Therefore, we developed I) an extension to SQL named Ontology-SQL (O-SQL) that allows to use semantic expressions, II) a framework that uses a standard terminology server to annotate free-text containing database tables and III) a parser that rewrites O-SQL to SQL, so that such queries can be passed to the database server. RESULTS: I) We compared several semantic queries published to date and were able to reproduce them in a reduced, highly condensed form. II) The quality of the annotation process was measured against manual annotation, and we found a sensitivity of 97.62% and a specificity of 100.00%. III) Different semantic queries were analyzed, and measured with F-scores between 0.91 and 0.98. CONCLUSIONS: We showed that systematic analysis of free-text-containing medical records is possible with standard tools. The seamless connection of ontologies and standard technologies from the database field represents an important constituent of unstructured data analysis. The developed technology can be readily applied to relationally organized data and supports the increasingly important field of translational research.

Impact of maternal angiotensinogen M235T polymorphism and angiotensin-converting enzyme insertion/deletion polymorphism on blood pressure, protein excretion and fetal outcome in pregnancy.

OBJECTIVE: To test the hypothesis that genetically determined alterations of the renin-angiotensin system are associated with hypertensive disorders in pregnancy. METHODS: A genetic association study was conducted at the obstetrics department of the Charité university hospital, Berlin, Germany. A total of 1068 Caucasian women were consecutively included after delivery and genotyped for the angiotensinogen M235T polymorphism and the angiotensin-converting enzyme (ACE) insertion/deletion polymorphism. RESULTS: Women homozygous for the angiotensinogen T allele have significantly elevated mean systolic and diastolic blood pressures in the third trimester (118.4 +/- 1.1/71.5 +/- 0.7 versus 116.9 +/- 0.3/70.4 +/- 0.2 mmHg, n = 128 versus 940; P < 0.05). This finding is especially pronounced in the subgroup of primigravid women. The ACE polymorphism is not associated with blood pressure during pregnancy. None of the polymorphisms is associated with urinary protein excretion or oedema during pregnancy. Maternal polymorphisms do not influence fetal growth and birth weight. There is, however, an interesting trend towards an increased incidence of circulatory system malformations in newborns carrying alleles that are known to be associated with decreased intrinsic renin-angiotensin system activity. CONCLUSION: We demonstrate for the first time in a large Caucasian population that a common maternal polymorphism of the angiotensinogen gene is related to a blood pressure increase during pregnancy. The angiotensinogen M235T polymorphism might contribute to the multifactorial pathogenesis of gestational hypertension and pre-eclampsia.

Alterations of alveolar type II cells and intraalveolar surfactant after bronchoalveolar lavage and perfluorocarbon ventilation. An electron microscopical and stereological study in the rat lung.

BACKGROUND: Repeated bronchoalveolar lavage (BAL) has been used in animals to induce surfactant depletion and to study therapeutical interventions of subsequent respiratory insufficiency. Intratracheal administration of surface active agents such as perfluorocarbons (PFC) can prevent the alveolar collapse in surfactant depleted lungs. However, it is not known how BAL or subsequent PFC administration affect the intracellular and intraalveolar surfactant pool. METHODS: Male wistar rats were surfactant depleted by BAL and treated for 1 hour by conventional mechanical ventilation (Lavaged-Gas, n = 5) or partial liquid ventilation with PF 5080 (Lavaged-PF5080, n = 5). For control, 10 healthy animals with gas (Healthy-Gas, n = 5) or PF5080 filled lungs (Healthy-PF5080, n = 5) were studied. A design-based stereological approach was used for quantification of lung parenchyma and the intracellular and intraalveolar surfactant pool at the light and electron microscopic level. RESULTS: Compared to Healthy-lungs, Lavaged-animals had more type II cells with lamellar bodies in the process of secretion and freshly secreted lamellar body-like surfactant forms in the alveoli. The fraction of alveolar epithelial surface area covered with surfactant and total intraalveolar surfactant content were significantly smaller in Lavaged-animals. Compared with Gas-filled lungs, both PF5080-groups had a significantly higher total lung volume, but no other differences. CONCLUSION: After BAL-induced alveolar surfactant depletion the amount of intracellularly stored surfactant is about half as high as in healthy animals. In lavaged animals short time liquid ventilation with PF5080 did not alter intra- or extracellular surfactant content or subtype composition.

Observational study to compare the clinical efficacy of the natural surfactants Alveofact and Curosurf in the treatment of respiratory distress syndrome in premature infants.

INTRODUCTION: Natural surfactants have been shown to be superior to synthetic surfactants in the treatment of neonatal respiratory distress syndrome (RDS). In Germany, Alveofact (A) and Curosurf (C) are the most frequently used natural surfactant preparations. The aim of this retrospective, observational study was to compare the effects of A and C on gas exchange and outcome in premature infants. METHODS: During a 5-year period in our neonatal intensive care unit (NICU), 187 premature infants were treated with surfactant, with 82 receiving A and 105 receiving C. We recorded F(I)O(2) and gas exchange (PaO(2)/F(I)O(2) ratio, PaCO(2), SaO(2)) during the first 72h after surfactant application and the incidence of outcome parameters at day 28 (bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH grade III or IV), patent ductus arteriosus (PDA), pneumothorax, necrotizing enterocolites (NEC) and death). The differences between the patient groups were assessed by ANOVA or the calculation of relative risks. Bonferroni correction was used for multiple comparisons. RESULTS: There were no statistically significant differences between infants treated with A and C in mean gestational age (28.4 vs. 28.4 weeks), birth weight (1210 vs.1258 g) and time of first surfactant application (60 vs. 90 min postnatal). We observed no significant between group differences in course of F(I)O(2) and blood gases, or in incidence at day 28 of BPD (41.7% vs. 42.8%), IVH III/IV (18.3% vs. 14.3%), pneumothorax (9.8% vs. 4.8%), PDA (23.2% vs. 21.9%), PVL (7.3% vs. 9.5%) and death (17% vs. 17.1%). There were also no statistically significant differences in the subgroup of infants <28 weeks. The lower incidence of NEC in A compared with C (1.2% vs. 10.5%, P=0.01) was not statistically significant after Bonferroni correction. CONCLUSION: Independent of gestational age no significant difference in the clinical efficacy of A and C was observed.

Ingeborg Syllm-Rapoport (1912-2017): An Exemplary Life for Children and Paediatrics.

Ingeborg Syllm-Rapoport, the first Chair in neonatology in Europe, passed away on March 23. Her biography illustrates how medical and scientific work has been influenced by social, ideological, and economic frames and boundaries in the 20th century. Regarded as a "Half-Jew" by the Nazi racist laws, she was denied her medical doctorate. She went to the USA, where she trained in paediatrics and met her husband, the biochemist Samuel Mitja Rapoport. During the "McCarthy Era" both were persecuted as communists. They returned to Europe and became two of the most influential figures at the Charité Hospital in East Berlin. She had to wait until 2015 to finally undergo the doctoral examination at the age of 102 years, making her the oldest person in history to receive a doctorate. We describe Syllm-Rapoport's life and the challenges she had to face living in several countries under different political systems in the 20th century.

Contact of Chlamydophila pneumoniae with type II cell triggers activation of calcium-mediated NF-kappa B pathway.

Nuclear factor-kappa B (NF-kappa B) plays an important role in inflammation, proliferation and regulation of apoptosis. The purpose of the present study on type II cells was to investigate whether Chlamydophila pneumoniae contact induces (I) a Ca2+ release, that (II) disrupts F-actin/beta-tubulin cytoskeletal association with NF-kappa B/I kappa B alpha, leading to (III) a subsequent NF-kappa B activation. Incubation of rat type II pneumocytes with C. pneumoniae caused an intracellular calcium release within seconds. Confocal laser scanning microscopy (CLSM) revealed that bacterial contact with cell surface leads to a disappearance of the microvilli and disturbs the co-localization between F-actin and NF-kappa B (p65). Using semi-quantitative CLSM, we show that at 10-30 min I kappa B alpha was decreased and p65 or p50 was simultaneously translocated from cytoplasm to the nucleus, resulting in a 19-fold and 17-fold increase versus control cells. During this time no bacteria were internalized into type II cells. The pre-treatment of cells with BAPTA-AM inhibited C. pneumoniae-mediated calcium release. BAPTA-AM or SN50 prevented the C. pneumoniae-induced changes in F-actin cytoskeleton and inhibited NF-kappa B activation. Paclitaxel reduced C. pneumoniae-mediated changes of beta-tubulin cytoskeleton and activation of NF-kappa B. These results suggest that calcium-mediated cytoskeleton reorganization is involved in C. pneumoniae-induced NF-kappa B activation in type II cells.

Somatostatin or octreotide as treatment options for chylothorax in young children: a systematic review.

OBJECTIVE: Chylothorax is a rare but life-threatening condition in children. To date, there is no commonly accepted treatment protocol. Somatostatin and octreotide have recently been used for treating chylothorax in children. We set out to summarise the evidence on the efficacy and safety of somatostatin and octreotide in treating young children with chylothorax. DESIGN: Systematic review: literature search (Cochrane Library, EMBASE and PubMed databases) and literature hand search of peer reviewed articles on the use of somatostatin and octreotide in childhood chylothorax. PATIENTS: Thirty-five children treated for primary or secondary chylothorax (10/somatostatin, 25/octreotide) were found. RESULTS: Ten of the 35 children had been given somatostatin, as i.v. infusion at a median dose of 204 microg/kg/day, for a median duration of 9.5 days. The remaining 25 children had received octreotide, either as an i.v. infusion at a median dose of 68 microg/kg/day over a median 7 days, or s.c. at a median dose of 40 microg/kg/day and a median duration of 17 days. Side effects such as cutaneous flush, nausea, loose stools, transient hypothyroidism, elevated liver function tests and strangulation-ileus (in a child with asplenia syndrome) were reported for somatostatin; transient abdominal distension, temporary hyperglycaemia and necrotising enterocolitis (in a child with aortic coarctation) for octreotide. CONCLUSIONS: A positive treatment effect was evident for both somatostatin and octreotide in the majority of reports. Minor side effects have been reported, however caution should be exercised in patients with an increased risk of vascular compromise as to avoid serious side effects. Systematic clinical research is needed to establish treatment efficacy and to develop a safe treatment protocol.

Dynamic computed tomography of the neonatal lung: volume calculations and validation in an animal model.

PURPOSE: The purpose of this study was to evaluate and validate dynamic volume calculation by respiratory-gated multislice computed tomography (CT) in small neonatal animals. MATERIALS AND METHODS: Six mechanically ventilated newborn piglets were imaged in a multislice CT with 0.5-mm slice thickness (4:16 pitch, 0.5-second rotation time, 120 kV). The respirator was connected to the CT unit for recording the respiratory signal. Simultaneously, tidal volume was measured by the respirator and functional residual capacity (FRC) using a multiple-breath washin-washout technique (MBW) with heptafluoropropane (HFP) as tracer gas. Complete volume datasets were reconstructed throughout the respiratory cycle in increments of 10% using retrospective half-scan gating. All animals were scanned in 3 different ventilator settings. Dynamic lung volumes (tidal volumes) were calculated by means of segmentation of the lung parenchyma during the respiratory cycle using work-in-progress software. RESULTS: The mean (+/-standard deviation) FRC determined by CT was 24.7+/-8.6 mL versus 24.8+/-7.3 mL for the MBW technique. There was no statistically significant difference (P=0.555). Pearson's correlation coefficient showed a strong correlation between the data obtained with CT and that obtained with the MBW technique (r=0.886). After exclusion of one outlier, tidal volumes showed a similar correlation (r=0.837) without significant differences in the mean values (CT: 8.9+/-2.4 mL and respirator: 8.7+/-2.4 mL, P=0.566). CONCLUSION: Dynamic multislice CT with respiratory gating allows for calculation of lung volumes and may be useful for future CT applications in human neonatal lung imaging.

A survey of transcutaneous blood gas monitoring among European neonatal intensive care units.

BACKGROUND: PCO2 and PO2 are important monitoring parameters in neonatal intensive care units (NICU). Compared to conventional blood gas measurements that cause significant blood loss in preterms, transcutaneous (tc) measurements allow continuous, non-invasive monitoring of blood gas levels. The aim of the study was to survey the usage and opinions among German speaking NICUs concerning tc blood gas monitoring. METHODS: A questionnaire was developed and sent to 56 head nurses of different NICUs in Germany, Switzerland and Austria. RESULTS: A completely answered questionnaire was obtained from 41 NICUs. In two of these units tc measurements are not performed. In most NICUs (77%), both PtcO2 and PtcCO2 are measured simultaneously. Most units change the sensors every 3 hours; however, the recommended temperature of 44 degrees C is used in only 15% of units. In only 8% of units are arterial blood gases obtained to validate tc values. Large variations were found concerning the targeted level of oxygen saturation [median upper limit: 95% (range 80-100%); median lower limit: 86% (range 75-93%)] and PO2 [median upper limit: 70 mmHg (range 45-90 mmHg); median lower limit: 44 mmHg (range 30-60 mmHg)]. CONCLUSION: Our survey shows that the use of tc monitors remains widespread among German speaking NICUs, despite earlier data suggesting that their use had been abandoned in many NICUs worldwide. In addition, we suggest that the current method of monitoring oxygenation may not prevent hyperoxemia in preterm infants.

Determination of 1,1,1,2,3,3,3-heptafluoropropane (HFP) in blood by headspace gas chromatography-mass spectrometry.

The inert and certified medical gas 1,1,1,2,3,3,3-heptafluoropropane (HFP) is commonly used as a propellant in medical sprays. HFP is also of interest as tracer gas for lung function measurements. In this work a sensitive method for quantitative determination of HFP in blood was developed using headspace gas chromatography-mass spectrometry with N2 as internal standard. The limits of detection and quantification were 0.005 and 0.016 mg/L, respectively. The method was applied to blood samples from newborn piglets that were ventilated with air containing 0.8% HFP (v/v) for 30 min. This was done to assess accumulation of HFP during measurement of functional residual lung capacity by wash-in and wash-out techniques. A saturation concentration in blood between 2.0 and 2.5 mg/L was attained after 3 min ventilation and decreased with a half-life below 1 min after termination of the HFP supply. No relevant accumulation of HFP was observed.

Inertance measurements by jet pulses in ventilated small lungs after perfluorochemical liquid (PFC) applications.

Perfluorochemical liquid (PFC) liquids or aerosols are used for assisted ventilation, drug delivery, lung cancer hyperthermia and pulmonary imaging. The aim of this study was to investigate the effect of PFC liquid on the inertance (I) of the respiratory system in newborn piglets using partial liquid ventilation (PLV) with different volumes of liquid. End-inspiratory (I(in)) and end-expiratory (I(ex)) inertance were measured in 15 ventilated newborn piglets (age < 12 h, mean weight 724 +/- 93 g) by brief flow pulses before and 80 min after PLV using a PFC volume (PF5080, 3 M) of 10 ml kg(-1) (N = 5) or 30 ml kg(-1) (N = 10). I was calculated from the imaginary part of the measured respiratory input impedance by regression analysis. Straight tubes with 2-4 mm inner diameter were used to validate the equipment in vitro by comparison with the analytically calculated values. In vitro measurements showed that the measuring error of I was <5% and that the reproducibility was better than 1.5%. The correlation coefficient of the regression model to determine I was >0.988 in all piglets. During gas ventilation, I(in) and I(ex) (mean +/- SD) were 31.7 +/- 0.8 Pa l(-1) s(2) and 33.3 +/- 2.1 Pa l(-1) s(2) in the 10 ml group and 32.4 +/- 0.8 Pa l(-1) s(2) and 34.0 +/- 2.5 Pa l(-1) s(2) in the 30 ml group. However, I of the 3 mm endotracheal tube (ETT) used was already 26.4 Pa l(-1) s(2) (about 80% of measured I). During PLV, there was a minimal increase of I(in) to 33.1 +/- 2.5 Pa l(-1) s(2) in the 10 ml group and to 34.5 +/- 2.7 Pa l(-1) s(2) in the 30 ml group. In contrast, the increase of I(ex) was dramatically larger (p < 0.001) to 67.7 +/- 13.3 Pa l(-1) s(2) and to 74.8 +/- 9.3 Pa l(-1) s(2) in the 10 ml and 30 ml groups, respectively. Measurements of I by jet pulses in intubated small animals are reproducible. PFC increases the respiratory inertance, but the magnitude depends considerably on its spatial distribution which changes during the breathing cycle. Large differences between I(in) and I(ex) are an indicator for liquid in airways or the ETT.

Changes in FiO2 affect PaO2 with minor alterations in cerebral concentration of oxygenated hemoglobin during liquid ventilation in healthy piglets.

OBJECTIVE: To measure the impact of changes in the fraction of inspired oxygen (FiO2) on systemic and cerebral oxygen supply in gas and liquid ventilated healthy animals. DESIGN: Interventional prospective animal study. SETTING: University research laboratory. PARTICIPANTS: Ten healthy, new-born piglets. INTERVENTIONS: Variations in FiO2 during conventional mechanical ventilation (CMV) followed by partial liquid ventilation (PLV) with two different filling volumes of PF 5080 (10 vs. 30 ml/kg). MEASUREMENTS AND RESULTS: Arterial blood gases were obtained 15 min after changing FiO2 and concentrations of cerebral oxygenated and total hemoglobin were determined with near infrared spectroscopy. During CMV an increase in FiO2 1.0 was associated with a constant rise in PaO2 but only a small increase in the cerebral concentration of oxygenated Hb. Initiation of PLV (at FiO2 of 1.0) caused a rapid drop in PaO2 towards values that were similar to CMV at FiO2 of 0.5. At FiO2 of 0.5 a reduction in oxygenated Hb was found in the 30 ml/kg filling group. Complete filling of the lungs with PFC caused a significant drop in total cerebral Hb concentration. CONCLUSIONS. According to our data, PLV in healthy lungs should be performed with a FiO2 of 1.0 and a small filling volume to avoid deterioration in cerebral oxygen supply.

Comparison of two different CPAP systems by tidal breathing parameters.

OBJECTIVE: Comparison of tidal breathing and pressure fluctuation of the continuous positive airway pressure (CPAP) associated with the use of the valveless Infant Flow System versus the conventional constant-flow CPAP (Babylog 8000) in preterm infants. DESIGN: Randomized cross-over trial. SETTING: Neonatal intensive care unit level III. PATIENTS: Twenty infants; median (range): birth weight 1,035 g (640-4,110 g), actual weight 1,165 g (820-4,250 g), gestational age at birth 27 (26-40) weeks. INTERVENTIONS: After extubation two CPAP devices (Infant Flow System vs Babylog 8000) were applied in a random order to the same infant. Fluctuations of the applied pressure during the breathing cycle and tidal breathing parameters were measured by the flow-through technique. MAIN RESULTS: Using the Infant Flow System the mean (standard deviation) inspiratory flow [1.5 (0.1) vs 1.3 (0.1) l.min(-1).kg(-1), P<0.05] and tidal volume were significantly increased [5.3 (1.3) vs 4.7 (1.3) ml/kg(-1), P<0.05] compared to Babylog 8000. The fluctuations of the applied pressure of the Infant Flow System during the breathing cycle were significantly lower [0.1 (0.03) kPa vs 0.15 (0.08) kPa, P<0.05] compared to Babylog 8000. No differences were seen in the duration of inspiration and expiration and the time to peak tidal flow. In the Infant Flow System pressures during expiration remained stable whereas they increased during the use of Babylog 8000. CONCLUSIONS: Within-subject comparisons of tidal breathing parameters of the two CPAP devices Infant Flow System and Babylog 8000 show: (1) a significant influence of the system used; and (2) that the valveless Infant Flow System increases air flow and tidal volume with less fluctuations in CPAP pressures during the breathing cycle.

Aerosolization of perfluorocarbons during mechanical ventilation: an in vitro study.

OBJECTIVE: Inhalation of perfluorocarbons (PFC) has been suggested as a new and promising technique of PFC delivery in animal models of severe lung injury. However, no in vitro data were available on the efficacy of PFC aerosolization during mechanical ventilation. Therefore, the aim of the in vitro study was to investigate the influence of physical properties of PFC and the ventilatory settings on the amount of PFC delivered into the lung. DESIGN: In vitro lung model study. SETTING: University research laboratory. MEASUREMENTS AND RESULTS: Two different PFC (PF 5080 and PFOB) were aerosolized with a PariBoy jet nebulizer. Using a PFC selective adsorber, the effect of endotracheal tube size (2 mm and 3 mm diameter) on delivery of PFC was investigated. PFC delivery was estimated by continuous measurement of weight gain of the adsorber (adsorption rate). Finally, the influence of respiratory rate and tidal volume on adsorption rate (AR) was studied. AR was significantly reduced by a decreasing tube diameter and ranged from 1.45+/-0.03 ml/min (no tube) to 0.93+/-0.03 ml/min (2.0 mm) for PF 5080 (vapor pressure 51 mmHg) and from 0.49+/-0.06 ml/min to 0.32+/-0.04 ml/min for PFOB (11 mmHg). PFC-aerosolization into a ventilatory circuit with simulation of spontaneous tidal breathing (minute volume 600 ml) reduced AR to 0.16+/-0.02 ml/min. During mechanical ventilation, changes in respiratory rate and tidal volume, which reduce minute ventilation, caused a decrease in AR. CONCLUSION: The amount of PFC that can be delivered into the lung by aerosolization is very small and is influenced by PFC properties, tube size, and ventilatory settings.