Pressure-adjusted venting eliminates start-up delays and compensates for vertical position of syringe infusion pumps used for microinfusion

Microinfusions are commonly used for the administration of catecholamines, but start-up delays pose a problem for reliable and timely drug delivery. Recent findings show that venting of the syringe infusion pump with draining of fluid to ambient pressure before directing the flow towards the central venous catheter does not counteract start-up delays. With the aim to reduce start-up delays, this study compared fluid delivery during start-up of syringe infusion pumps without venting, with ambient pressure venting, and with central venous pressure (CVP)-adjusted venting. Start-up fluid delivery from syringe pumps using a microinfusion of 1 mL/h was assessed by means of liquid flow measurement at 10, 60, 180 and 360 s after opening the stopcock and starting the pump. Assessments were performed using no venting, ambient pressure venting or CVP-adjusted venting, with the pump placed either at zero, - 43 cm or + 43 cm level and exposed to a simulated CVP of 10 mmHg. Measured fluid delivery was closest to the calculated fluid delivery for CVP-adjusted venting (87% to 100% at the different timepoints). The largest deviations were found for ambient pressure venting (- 1151% to + 82%). At 360 s after start-up 72% to 92% of expected fluid volumes were delivered without venting, 46% to 82% with ambient pressure venting and 96% to 99% with CVP-adjusted venting. CVP-adjusted venting demonstrated consistent results across vertical pump placements (p = 0.485), whereas the other methods had significant variances (p < 0.001 for both). In conclusion, CVP-adjusted venting effectively eliminates imprecise drug delivery and start-up delays when using microinfusions.

Between hope and disillusionment: ECMO seen through the lens of nurses working in a neonatal and paediatric intensive care unit

BACKGROUND

Using extracorporeal membrane oxygenation (ECMO) in paediatric and neonatal intensive care units (PICU/NICU) creates ethical challenges and carries a high risk for moral distress, burn out and team conflicts.

AIM

The study aimed to gain a more comprehensive understanding of the underlying factors affecting moral distress when using ECMO for infants and children by examining the attitudes of ECMO nurses.

METHODS

Four focus groups discussions were conducted with 21 critical care nurses working in a Swiss University Children's Hospital. Purposive sampling was adopted to identify research participants. The data were analysed using reflexive thematic analysis.

RESULTS

Unlike "miracle machine" stories in online media reports, specialized nurses working in PICU/NICU expressed both their hopes and fears towards this technology. Their accounts also contained references to events and factors that triggered experiences of moral distress: the unspeakable nature of the death of a child or infant; the seemingly lack of honest and transparent communication with parents; the apparent loss of situational awareness among doctors; the perceived lack of recognition for the role of nurses and the variability in end-of-life decision-making; the length of time it takes doctors to take important treatment decisions; and the resource intensity of an ECMO treatment.

CONCLUSION

The creation of a multidisciplinary moral community with transparent information among all involved health care professionals and the definition of clear treatment goals as well as the implementation of paediatric palliative care for all paediatric ECMO patients should become a priority if we want to alleviate situations of moral distress.

RELEVANCE FOR CLINICAL PRACTICE

The creation of a multidisciplinary moral community, clear treatment goals and the implementation of palliative care for all paediatric ECMO patients are crucial to alleviate situations of moral distress for nurses, and thus to improve provider well-being and the quality of patient care in PICU/NICU.

Evaluation of the venting principle to reduce start-up delays in syringe infusion pumps used for microinfusions

Start-up delays of syringe pump assemblies can impede the timely commencement of an effective drug therapy when using microinfusions in hemodynamically unstable patients. The application of the venting principle has been proposed to eliminate start-up delays in syringe pump assemblies. However, effectively delivered infusion volumes using this strategy have so far not been measured. This invitro study used two experimental setups to measure the effect of the venting principle compared to a standard non-venting approach on delivered start-up infusion volumes at various timepoints, backflow volumes, flow inversion and zero drug delivery times by means of liquid flow measurements at flow rates of 0.5, 1.0 and 2.0 mL/h. Measured delivered initial start-up volumes were negative with all flow rates in the vented and non-vented setup. Maximum backflow volumes were 1.8 [95% CI 1.6 to 2.3] times larger in the vented setup compared to the non-vented setup (p < 0.0001). Conversely, times until flow inversion were 1.5 [95% CI 1.1 to 2.9] times shorter in the vented setup (p < 0.002). This led to comparable zero drug delivery times between the two setups (p = 0.294). Start-up times as defined by the achievement of at least 90% of steady state flow rate were achieved faster with the vented setup (p < 0.0001), but this was counteracted by the increased backflow volumes. The application of the venting principle to the start-up of microinfusions does not improve the timely delivery of drugs to the patient since the faster start-up times are counteracted by higher backflow volumes when opening the three-way stopcock.

Congenital syphilis in Switzerland: a retrospective cohort study, 2010 to 2019

AIMS OF THE STUDY

We previously reported a re-emergence of syphilis from 2006 to 2009 with detection of congenital syphilis in Switzerland. This study aimed to reassess the incidence of children exposed to maternal syphilis during pregnancy and congenital syphilis in a following 10-year period in the canton of Zurich, the most populous canton in Switzerland with the highest incidences of syphilis.

METHODS

Children were identified both by reviewing medical records at the four major neonatal and paediatric hospitals providing acute care in the canton of Zurich and by the serological database of the syphilis reference laboratory. Inclusion criteria for children were (a) date of birth in the period 2010-2019, (b) place of birth in the canton of Zurich, (c) evaluation for syphilis due to positive syphilis pregnancy screening and (d) age <1 year at diagnosis. Results were compared with epidemiological data provided by the Federal Office of Public Health (FOPH).

RESULTS

We identified and evaluated 17 children after potential exposure to maternal syphilis. Residual antibodies of a past infection were found in 11 mothers. Six children were identified as having had real exposure to asymptomatic maternal syphilis. From an epidemiological perspective, the distribution of the cases followed a similar pattern as confirmed syphilis cases in women of childbearing age reported to the FOPH. No cases of congenital syphilis were observed.

CONCLUSIONS

In contrast to the rise in syphilis infections, this study identified no cases of congenital syphilis in the canton of Zurich, Switzerland, in the period 2010-2019. Syphilis pregnancy screening may have prevented congenital syphilis by diagnosing and allowing adequate treatment of asymptomatic maternal syphilis.

Effect of central venous pressure on fluid delivery during start-up of syringe infusion pumps for microinfusion

BACKGROUND

Intravenous administration of highly concentrated and potent drugs at low flow rates is common practice, particularly in critically ill children. Drug delivery during infusion start-up can be considerably delayed by intrinsic factors of syringe infusion pump assemblies. The impact of central venous pressures on the course of start-up fluid delivery of such microinfusions remains unknown.

METHODS

Infusion volumes delivered after activation of the start button in a conventional 50 mL syringe infusion pump assembly equilibrated (representing classical in vitro testing) and not equilibrated (representing real clinical conditions) to central venous pressure levels of 0, 10 and 20 mmHg at a set infusion flow rate of 1 mL/h were measured using a fluidic flow sensor.

RESULTS

The experimental setup mimicking real life conditions demonstrated considerable differences in fluid delivery during pump start-up depending on central venous pressure. A central venous pressure of 0 mmHg resulted in massive fluid delivery at infusion start-up, while central venous pressure levels of 10 and 20 mmHg resulted in retrograde flows with related mean (95% CI) zero-drug delivery times of 3.22 (2.98-3.46) min and 4.51 (4.33-4.69) min, respectively (p < .0001).

CONCLUSION

Depending on central venous pressure level, connection and starting a new syringe pump can result in significant antegrade or retrograde fluid volumes. In clinical practice, this can lead to hemodynamic instability and hence requires clinical alertness. Further research and methods to improve start-up performance in syringe infusion pump systems are desirable.

Copeptin Release in Arterial Hypotension and Its Association with Severity of Disease in Critically Ill Children

Low copeptin levels may indicate inadequate arginine-vasopressin release promoting arterial hypotension, whereas high copeptin concentrations may reflect disease severity. This single-center prospective non-randomized clinical trial analyzed the course of blood copeptin in critically ill normo- and hypotensive children and its association with disease severity. In 164 patients (median age 0.5 years (interquartile range 0.1, 2.9)), the mean copeptin concentration at baseline was 43.5 pmol/L. Though not significantly different after 61 h (primary outcome, mean individual change: −12%, p = 0.36, paired t-test), we detected 1.47-fold higher copeptin concentrations during arterial hypotension when compared to normotension (mixed-effect ANOVA, p = 0.01). In total, 8 out of 34 patients (23.5%) with low copeptin concentrations <10 pmol/L were hypotensive. Copeptin was highest in the adjusted mixed-effect regression analysis within the first day (+20% at 14 h) and decreased significantly at 108 h (−27%) compared to baseline (p = 0.002). Moreover, we found a significant association with vasopressor-inotrope treatment intensity, infancy (1−12 months) and cardiopulmonary bypass (all p ≤ 0.001). In conclusion, high copeptin values were associated with arterial hypotension and severity of disease in critically ill children. This study does not support the hypothesis that low copeptin values might be indicative of arginine-vasopressin deficiency.

Macitentan attenuates cardiovascular remodelling in infant rats with chronic lung disease

Background

Cardiovascular impairment contributes to increased mortality in preterm infants with chronic lung disease. Macitentan, an endothelin-1 receptor antagonist, has the potential to attenuate pulmonary and cardiovascular remodelling.

Methods

In a prospective randomized placebo-controlled intervention trial, Sprague–Dawley rats were exposed to 0.21 or 1.0 fraction of inspired oxygen (FiO2) for 19 postnatal days. Rats were treated via gavage with placebo or macitentan from days of life 5 to 19. Alveoli, pulmonary vessels, α-smooth muscle actin content in pulmonary arterioles, size of cardiomyocytes, right to left ventricular wall diameter ratio, and endothelin-1 plasma concentrations were assessed.

Results

FiO2 1.0 induced typical features of chronic lung disease with significant alveolar enlargement (p = 0.012), alveolar (p = 0.048) and pulmonary vessel rarefaction (p = 0.024), higher α-smooth muscle actin content in pulmonary arterioles (p = 0.009), higher right to left ventricular wall diameter ratio (p = 0.02), and larger cardiomyocyte cross-sectional area (p < 0.001). Macitentan treatment significantly increased pulmonary vessel count (p = 0.004) and decreased right to left ventricular wall diameter ratios (p = 0.002). Endothelin-1 plasma concentrations were higher compared to placebo (p = 0.015). Alveolar number and size, α-smooth muscle actin, and the cardiomyocyte cross-sectional area remained unchanged (all p > 0.05).

Conclusion

The endothelin-1 receptor antagonist macitentan attenuated cardiovascular remodelling in an infant rat model for preterm chronic lung disease. This study underscores the potential of macitentan to reduce cardiovascular morbidity in preterm infants with chronic lung disease.

Lung-borne systemic inflammation in mechanically ventilated infant rats due to high PEEP, oxygen, and hypocapnia

BACKGROUND

Intensive care practice calls for ventilator adjustments due to fast-changing clinical conditions in ventilated critically ill children. These adaptations include positive end-expiratory pressure (PEEP), fraction of inspired oxygen (FiO₂), and respiratory rate (RR). It is unclear which alterations in ventilator settings trigger a significant systemic inflammatory response.

METHODS

Fourteen-day old Wistar rat pups were randomized to the following groups: (a) "control" with tidal volume ~8 mL/kg, PEEP 5 cmH₂O, FiO₂ 0.4, RR 90 min^-1, (b) "PEEP 1", (c) "PEEP 9" (d) "FiO₂ 0.21", (e) "FiO₂ 1.0", (f) "hypocapnia" with RR of 180 min^-1, and (g) "hypercapnia" with RR of 60 min^-1. Following 120 min of mechanical ventilation, plasma for inflammatory biomarker analyses was obtained by direct cardiac puncture at the end of the experiment.

RESULTS

Interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were driven by FiO₂ 0.4 and 1.0 (P=0.02, P<0.01, respectively), tissue plasminogen activator inhibitor type-1 (tPAI-1) was increased by high PEEP (9 cmH₂O, P<0.05) and hypocapnia (P<0.05), and TNF-α was significantly lower in hypercapnia (P<0.01). Tissue inhibitor of metalloproteinase-1 (TIMP-1), cytokine-induced neutrophil chemoattractant 1 (CINC-1), connective tissue growth factor (CTGF), and monocyte chemoattractant protein-1 (MCP-1) remained unaffected.

CONCLUSION

Alterations of PEEP, FiO₂, and respiratory frequency induced a significant systemic inflammatory response in plasma of infant rats. These findings underscore the importance of lung-protective ventilation strategies. However, future studies are needed to clarify whether ventilation induced systemic inflammation in animal models is pathophysiologically relevant to human infants.

Strain-specific differences in lung tissue viscoelasticity of mechanically ventilated infant Sprague-Dawley and Wistar rats

Rats are often used in ventilator-induced lung injury (VILI) models. However, strain-specific susceptibility for VILI has not been elucidated yet. The aim of this study was to demonstrate strain-specific differences in VILI in infant Sprague-Dawley and Wistar rats. VILI was compared in 2-wk-old pups after 8 h of protective or injurious ventilation. Pups were ventilated with tidal volumes (V_T) of ∼7 mL/kg and positive end-expiratory pressures (PEEP) of 6 cmH₂O (V_T7 PEEP6) or with V_T of ∼21 mL/kg and PEEP 2 cmH₂O (V_T21 PEEP2). Interleukin-6, macrophage inflammatory protein-2 (MIP-2), inflammatory cells, and albumin in bronchoalveolar lavage fluid (BALF); histology; and low-frequency forced oscillation technique (LFOT) and pressure-volume (PV) maneuvers were assessed. Alveolar macrophages, neutrophils, and MIP-2 derived from BALF revealed more pronounced VILI after V_T21 PEEP2 in both strains. LFOT and PV analyses demonstrated rat strain-specific differences both at baseline and particularly in response to V_T21 PEEP2 ventilation. Sprague-Dawley rats showed higher airway and tissue resistance and elastance values with no difference in hysteresivity between ventilation strategies. Wister rats challenged by V_T21 PEEP2 experienced significantly more energy dissipation when compared with V_T7 PEEP6 ventilation. In conclusion, both rat strains are useful for VILI models. The degree of VILI severity depends on ventilation strategy and selected strain. However, fundamental and time-dependent differences in respiratory system mechanics exist and reflect different lung tissue viscoelasticity. Hence, strain-specific characteristics of the respiratory system need to be considered when planning and interpreting VILI studies with infant rats.

Impact of high tidal volume ventilation on surfactant metabolism and lung injury in infant rats

The poorly understood tolerance toward high tidal volume (V_T) ventilation observed in critically ill children and age-equivalent animal models may be explained by surfactant homeostasis. The aim of our prospective animal study was to test whether high V_T with adequate positive end-expiratory pressure (PEEP) is associated with surfactant de novo synthesis and secretion, leading to improved lung function, and whether extreme mechanical ventilation affects intracellular lamellar body formation and exocytosis. Rats (14 days old) were allocated to five groups: nonventilated controls, PEEP 5 cmH₂O with V_T of 8, 16, and 24 mL/kg, and PEEP 1 cmH₂O with V_T 24 mL/kg. Following 6 h of ventilation, lung function, surfactant proteins and phospholipids, and lamellar bodies were assessed by forced oscillation technique, quantitative real-time polymerase chain reaction, mass spectrometry, immunohistochemistry, and transmission electron microscopy. High V_T (24 mL/kg) with PEEP of 5 cmH₂O improved respiratory system mechanics and was not associated with lung injury, elevated surfactant protein expression, or surfactant phospholipid content. Extreme ventilation with V_T 24 mL/kg and PEEP 1 cmH₂O produced a mild inflammatory response and correlated with higher surfactant phospholipid concentrations in bronchoalveolar lavage fluid without affecting lamellar body count and morphology. Elevated phospholipid concentrations in the potentially most injurious strategy (V_T 24 mL/kg, PEEP 1 cmH₂O) need further evaluation and might reflect accumulation of biophysically inactive small aggregates. In conclusion, our data confirm the resilience of infant rats toward high V_T-induced lung injury and challenge the relevance of surfactant synthesis, storage, and secretion as protective factors.

Evaluation of Incompatible Coadministration of Continuous Intravenous Infusions in a Pediatric/Neonatal Intensive Care Unit

OBJECTIVES We aimed to evaluate and quantify incompatible coadministrations of continuous intravenous medication in the daily clinical practice of a PICU/NICU.

METHODS We conducted a retrospective, observational study in the setting of an 18-bed PICU/NICU. All concurrently administered continuous infusions, including blood products and parenteral nutrition, were analyzed for 2 months. Raw electronic data were retrieved and subjected to quality controls. Infusion combinations were classified as compatible, incompatible, no data, or variable according to the internal hospital charts, Trissel's database, and the Swiss summary of product characteristics. For situations with incompatible coadministrations, we assessed alternative distributions of infusions among the currently available lumen.

RESULTS Data for 100 patients were analyzed. Patients were exposed to a mean of 6.9 ± 3.6 individual continuous infusions administered through 3.8 ± 1.8 lumina. Among the 1447 coadministered continuous infusions, we detected 146 incompatible combinations (10%), resulting in 105 individually relevant incompatible situations. Furthermore, 185 combinations (13%) were not covered by internal compatibility charts, and for 207 combinations (15%) no data on compatibility were available. We found that 58% of the incompatible situations could have been avoided by a redistribution of the infusions among the available lumina.

CONCLUSIONS Most infusion combinations in the studied PICU/NICU were compatible and covered by the internal compatibility charts. However, we also identified concurrent administrations of incompatible infusions or for which compatibility data are not available. A significant reduction of coadministrations of incompatible infusions could be achieved through optimal use of available lumina.

Mediterranean diet as a natural supplemental resource for athletes and physical activity

The WHO Global Action Plan on physical activity underlines the binomial "diet and physical activity" for the maintenance of well-being state. The adequate nutritional intake is required for sport and can be achieved by a well-adjusted diet without adding artificial food supplements, whose abuse can even represent a risk and appear as an antechamber of doping. Within a national doping prevention project, a peer education tool was realized in the form of a book and e-book, based on the principle of the Mediterranean Diet as an effective nutritional support in sport and physical activity. This health-literacy book contains recipes from all Italian regions revised for their capability to satisfy sport nutritional needs.

Comparison of postoperative chylothorax in infants and children with trisomy 21 and without dysmorphic syndrome: Is there a difference in clinical outcome?

INTRODUCTION

Children with trisomy 21 are prone to postoperative chylothorax, caused by malformation of the lymphatic system, after cardiac surgery. The clinical course of patients diagnosed with postoperative chylothorax and trisomy 21 was compared to that of patients without dysmorphic syndromes. Additionally, differences between the groups in composition, amount, and duration of chyle were analyzed to better understand chylothorax in patients with trisomy 21.

MATERIALS AND METHODS

Retrospective cohort study using inpatient clinical databases during a 10-year period.

RESULTS

A total of 2255 patients underwent cardiac operations during the period, of whom 160 (7.1%) patients were diagnosed with trisomy 21. Chylothorax developed in 122 children; 89 patients were included in our study. Of 160 trisomy 21 patients, 27 (16.9%) developed postoperative chylothorax compared to 62 (3%) of 2095 patients without dysmorphic syndromes (p = <0.001). Time on ventilation, stay in intensive care, hospital stay, mortality, and composition of chylous effusion did not differ between groups. The rate of thrombosis was significantly lower (p = 0.02) in the trisomy 21 group.

CONCLUSION

Children with trisomy 21 and congenital heart disease are more prone to developing chylothorax after heart surgery than those without dysmorphic syndromes. However if they develop this postoperative complication, mortality, chylous composition, time in ICU, and duration of hospital stay is not different to from that of other infants or children with this complication. This is important information for the medical specialists involved and is helpful in counseling parents of children with trisomy 21 undergoing heart surgery.

LEVEL OF EVIDENCE

This is a treatment study evidence level III.

Hyperoxia-induced lung structure-function relation, vessel rarefaction, and cardiac hypertrophy in an infant rat model

BACKGROUND

Hyperoxia-induced bronchopulmonary dysplasia (BPD) models are essential for better understanding and impacting on long-term pulmonary, cardiovascular, and neurological sequelae of this chronic disease. Only few experimental studies have systematically compared structural alterations with lung function measurements.

METHODS

In three separate and consecutive series, Sprague-Dawley infant rats were exposed from day of life (DOL) 1 to 19 to either room air (0.21; controls) or to fractions of inspired oxygen (FiO2) of 0.6, 0.8, and 1.0. Our primary outcome parameters were histopathologic analyses of heart, lungs, and respiratory system mechanics, assessed via image analysis tools and the forced oscillation technique, respectively.

RESULTS

Exposure to FiO2 of 0.8 and 1.0 resulted in significantly lower body weights and elevated coefficients of lung tissue damping (G) and elastance (H) when compared with controls. Hysteresivity (η) was lower due to a more pronounced increase of H when compared with G. A positive structure-function relation was demonstrated between H and the lung parenchymal content of α-smooth muscle actin (α-SMA) under hyperoxic conditions. Moreover, histology and morphometric analyses revealed alveolar simplification, fewer pulmonary arterioles, increased α-SMA content in pulmonary vessels, and right heart hypertrophy following hyperoxia. Also, in comparison to controls, hyperoxia resulted in significantly lower plasma levels of vascular endothelial growth factor (VEGF). Lastly, rats in hyperoxia showed hyperactive and a more explorative behaviour.

CONCLUSIONS

Our in vivo infant rat model mimics clinical key features of BPD. To the best of our knowledge, this is the first BPD rat model demonstrating an association between lung structure and function. Moreover, we provide additional evidence that infant rats subjected to hyperoxia develop rarefaction of pulmonary vessels, augmented vascular α-SMA, and adaptive cardiac hypertrophy. Thus, our model provides a clinically relevant tool to further investigate diseases related to O2 toxicity and to evaluate novel pharmacological treatment strategies.

Mechanical ventilation strategies alter cardiovascular biomarkers in an infant rat model

Mechanical ventilation (MV) is routinely used in pediatric general anesthesia and critical care, but may adversely affect the cardiocirculatory system. Biomarkers are increasingly measured to assess cardiovascular status and improve clinical treatment decision-making. As the impact of mechanical ventilation strategies on cardiovascular biomarkers in ventilated infants is largely unknown, we conducted this retrospective study in a healthy in vivo infant rat ventilation model using 14-days old Wistar rats. We hypothesized that 2 h of mechanical ventilation with high and low positive end-expiratory pressure (PEEP), hyperoxemia, hypoxemia, hypercapnia, and hypocapnia would significantly impact B-type natriuretic peptide (BNP), vascular endothelial growth factor (VEGF), and endothelin-1 (ET-1). We found BNP to be driven by both high (9 cmH₂ O) and low (1 cmH₂ O) PEEP compared to ventilated control animals (P < 0.05). VEGF concentrations were associated with high PEEP, hyperoxemia, hypoxemia, and hypocapnia (P < 0.05), whereas ET-1 levels were changed only in response to hypoxemia (P < 0.05). In conclusion, the mode of mechanical ventilation alters plasma biomarker concentrations. Moreover, BNP and VEGF might serve as surrogate parameters for ventilation induced cardiovascular compromise and lung tissue damage. Furthermore, our data support the hypothesis, that sudden onset of hyperoxemia may trigger a quick VEGF release as a possible cellular survival reflex.

Work of breathing for cuffed and uncuffed pediatric endotracheal tubes in an in vitro lung model setting

BACKGROUND

Over the last decade, cuffed endotracheal tubes are increasingly used in pediatric anesthesia and also in pediatric intensive care. However, the smaller inner diameter of cuffed endotracheal tubes and, implicitly, the increased endotracheal tube resistance is still a matter of debate.

AIMS

This in vitro study investigated work of breathing and inspiratory airway pressures in cuffed and uncuffed endotracheal tubes and the impact of pressure support ventilation and automatic tube compensation.

METHODS

In 5 simulated neonatal and pediatric lung models, the Active Servo Lung 5000 and an intensive care ventilator were used to quantify the differences in work of breathing under spontaneous breathing (with and without pressure support ventilation and automatic tube compensation) between cuffed and uncuffed endotracheal tubes. Additionally, differences in inspiratory airway pressures, measured either proximal or distal of the endotracheal tube, between cuffed and uncuffed endotracheal tubes under mechanical ventilation were investigated.

RESULTS

Work of breathing was overall 10.27% [95% confidence interval 9.01-11.94] higher with cuffed than with uncuffed endotracheal tubes and was dramatically reduced by 34.19% [95% confidence interval 31.61-35.25] with the application of pressure support. Automatic tube compensation almost diminished work of breathing differences between the 2 endotracheal tube types in nearly all pediatric lung models. Peak inspiratory and mean airway pressures measured at the proximal endotracheal tube end revealed significantly higher values in cuffed than in uncuffed endotracheal tubes. However, these differences measured at the distal end of the endotracheal tube became minimal.

CONCLUSION

This in vitro study confirmed significant differences in work of breathing and inspiratory pressures between cuffed and uncuffed endotracheal tubes. Work of breathing, however, is almost neutralized by pressure support ventilation with automatic tube compensation and distal inspiratory airway pressures that, from a clinical perspective, are not significantly increased.

Prognostic Evaluation of Mortality after Pediatric Resuscitation Assisted by Extracorporeal Life Support

To improve survival rates during cardiopulmonary resuscitation (CPR), some patients are put on extracorporeal life support (ECLS) during active resuscitation (ECPR). Our objective was to assess the clinical outcomes after pediatric ECPR in Switzerland and to determine pre-ECPR prognostic factors for mortality. The present study is a retrospective analysis. The study setting included three pediatric intensive care units in Switzerland that use ECPR. All patients (<16 years old) undergoing ECPR from 2008 to 2016 were included in the study. There were no interventions. Data before ECLS initiation and clinical outcomes were collected. An ECPR score was designed to predict mortality, based on variables significantly different between survivors and non-survivors. Fifty-five patients were included, with a median age of 13.5 months. Eighty percent were cardiac patients. The mortality rate was 75%. Mortality was significantly associated with CPR duration ( p  = 0.02), last lactate ( p  = 0.05), and last pH ( p  = 0.01) before ECLS initiation. Based on these three variables, an ECPR score was designed as follows: CPR duration (in minutes): 1 point if < 40; 2 points if ≥ 40; 3 points if ≥ 60; 6 points if ≥ 105. Lactate (in mmol/L): 1 point if < 8; 2 points if ≥ 8; 3 points if ≥ 14; 6 points if ≥ 18. pH: 1 point if > 7.00; 2 points if ≤ 7.00; 3 points if ≤ 6.85; 6 points if ≤ 6.60. The area under the receiver-operating characteristic curve was 0.74. The positive predictive value of a score ≥ 9 was 94%. In our population, a score based on three variables easily available prior to ECLS initiation had good discrimination and could appropriately predict mortality. This score now needs validation in a larger population.

Accuracy of near-patient vs. inbuilt spirometry for monitoring tidal volumes in an in-vitro paediatric lung model

Spirometric monitoring provides precise measurement and delivery of tidal volumes within a narrow range, which is essential for lung-protective strategies that aim to reduce morbidity and mortality in mechanically-ventilated patients. Conventional anaesthesia ventilators include inbuilt spirometry to monitor inspiratory and expiratory tidal volumes. The GE Aisys CS² anaesthesia ventilator allows additional near-patient spirometry via a sensor interposed between the proximal end of the tracheal tube and the respiratory tubing. Near-patient and inbuilt spirometry of two different GE Aisys CS² anaesthesia ventilators were compared in an in-vitro study. Assessments were made of accuracy and variability in inspiratory and expiratory tidal volume measurements during ventilation of six simulated paediatric lung models using the ASL 5000 test lung. A total of 9240 breaths were recorded and analysed. Differences between inspiratory tidal volumes measured with near-patient and inbuilt spirometry were most significant in the newborn setting (p < 0.001), and became less significant with increasing age and weight. During expiration, tidal volume measurements with near-patient spirometry were consistently more accurate than with inbuilt spirometry for all lung models (p < 0.001). Overall, the variability in measured tidal volumes decreased with increasing tidal volumes, and was smaller with near-patient than with inbuilt spirometry. The variability in measured tidal volumes was higher during expiration, especially with inbuilt spirometry. In conclusion, the present in-vitro study shows that measurements with near-patient spirometry are more accurate and less variable than with inbuilt spirometry. Differences between measurement methods were most significant in the smallest patients. We therefore recommend near-patient spirometry, especially for neonatal and paediatric patients.

Impact of endotracheal tube shortening on work of breathing in neonatal and pediatric in vitro lung models

BACKGROUND

Work of breathing accounts for a significant proportion of total oxygen consumption in neonates and infants. Endotracheal tube inner diameter and length significantly affect airflow resistance and thus work of breathing. While endotracheal tube shortening reduces endotracheal tube resistance, the impact on work of breathing in mechanically ventilated neonates and infants remains unknown.

AIM

The objective of this in vitro study was to quantify the effect of endotracheal tube shortening on work of breathing in simulated pediatric lung settings. We hypothesized that endotracheal tube shortening significantly reduces work of breathing.

METHODS

We used the Active-Servo-Lung 5000 to simulate different clinical scenarios in mechanically ventilated infants and neonates under spontaneous breathing with and without pressure support. Endotracheal tube size, lung resistance, and compliance, as well as respiratory settings such as respiratory rate and tidal volume were weight and age adapted for each lung model. Work of breathing was measured before and after maximal endotracheal tube shortening and the reduction of the daily energy demand calculated.

RESULTS

Tube shortening with and without pressure support decreased work of breathing to a maximum of 10.1% and 8.1%, respectively. As a result, the calculated reduction of total daily energy demand by endotracheal tube shortening was between 0.002% and 0.02%.

CONCLUSION

In this in vitro lung model, endotracheal tube shortening had minimal effects on work of breathing. Moreover, the calculated percentage reduction of the total daily energy demand after endotracheal tube shortening was minimal.

Two case reports of unexpected tracheal agenesis in the neonate: 3 C's beyond algorithms for difficult airway management

Background

Handling neonates with postnatal respiratory failure due to congenital airway malformations implies knowledge about emergency management of unexpected difficult airway. In these stressful situations both technical and communication skills of the caretakers are essential.

Case presentation

Two cases with prenatally unknown tracheal agenesis are reported.

Conclusion

In the presented cases, airway malformation and subsequent difficulties upon endotracheal intubation were not adequately communicated between caretakers. We discuss the aspects of culture, communication, and capnography.

Determinants of plasma copeptin: a systematic investigation in a pediatric mechanical ventilation model

Copeptin, the C-terminal part of the arginine vasopressin precursor peptide, holds promise as a diagnostic and prognostic plasma biomarker in various acute clinical conditions. Factors influencing copeptin response in the critical care setting are only partially established and have not been investigated systematically. Using an in vivo infant ventilation model (Wistar rats, 14 days old), we studied the influence of commonly occurring stressors in critically ill children. In unstressed ventilated rats basal median copeptin concentration was 22pmol/L. In response to respiratory alkalosis copeptin increased 5-fold, while exposure to hypoxemia, high PEEP, hemorrhage, and psycho-emotional stress produced a more than 10-fold increase. Additionally, we did not find a direct association between copeptin and acidosis, hypercapnia, and hyperthermia. Clinicians working in the acute critical care setting should be aware of factors influencing copeptin plasma concentrations. Moreover, our results do have implications for animal studies in the field of stress research.

Linking lung function and inflammatory responses in ventilator-induced lung injury

Despite decades of research, the mechanisms of ventilator-induced lung injury are poorly understood. We used strain-dependent responses to mechanical ventilation in mice to identify associations between mechanical and inflammatory responses in the lung. BALB/c, C57BL/6, and 129/Sv mice were ventilated using a protective [low tidal volume and moderate positive end-expiratory pressure (PEEP) and recruitment maneuvers] or injurious (high tidal volume and zero PEEP) ventilation strategy. Lung mechanics and lung volume were monitored using the forced oscillation technique and plethysmography, respectively. Inflammation was assessed by measuring numbers of inflammatory cells, cytokine (IL-6, IL-1β, and TNF-α) levels, and protein content of the BAL. Principal components factor analysis was used to identify independent associations between lung function and inflammation. Mechanical and inflammatory responses in the lung were dependent on ventilation strategy and mouse strain. Three factors were identified linking 1) pulmonary edema, protein leak, and macrophages, 2) atelectasis, IL-6, and TNF-α, and 3) IL-1β and neutrophils, which were independent of responses in lung mechanics. This approach has allowed us to identify specific inflammatory responses that are independently associated with overstretch of the lung parenchyma and loss of lung volume. These data provide critical insight into the mechanical responses in the lung that drive local inflammation in ventilator-induced lung injury and the basis for future mechanistic studies in this field.

Protective mechanical ventilation does not exacerbate lung function impairment or lung inflammation following influenza A infection

The degree to which mechanical ventilation induces ventilator-associated lung injury is dependent on the initial acute lung injury (ALI). Viral-induced ALI is poorly studied, and this study aimed to determine whether ALI induced by a clinically relevant infection is exacerbated by protective mechanical ventilation. Adult female BALB/c mice were inoculated with 104.5 plaque-forming units of influenza A/Mem/1/71 in 50 μl of medium or medium alone. This study used a protective ventilation strategy, whereby mice were anesthetized, tracheostomized, and mechanically ventilated for 2 h. Lung mechanics were measured periodically throughout the ventilation period using a modification of the forced oscillation technique to obtain measures of airway resistance and coefficients of tissue damping and tissue elastance. Thoracic gas volume was measured and used to obtain specific airway resistance, tissue damping, and tissue elastance. At the end of the ventilation period, a bronchoalveolar lavage sample was collected to measure inflammatory cells, macrophage inflammatory protein-2, IL-6, TNF-α, and protein leak. Influenza infection caused significant increases in inflammatory cells, protein leak, and deterioration in lung mechanics that were not exacerbated by mechanical ventilation, in contrast to previous studies using bacterial and mouse-specific viral infection. This study highlighted the importance of type and severity of lung injury in determining outcome following mechanical ventilation.

Lung volume recruitment maneuvers and respiratory system mechanics in mechanically ventilated mice

The study aim was to establish how recruitment maneuvers (RMs) influence lung mechanics and to determine whether RMs produce lung injury. Healthy BALB/c mice were allocated to receive positive end-expiratory pressure (PEEP) at 2 or 6 cmH(2)O and volume- (20 or 40 mL/kg) or pressure-controlled (25 cmH(2)O) RMs every 5 or 75 min for 150 min. The low-frequency forced oscillation technique was used to measure respiratory input impedance. Large RMs resulting in peak airway opening pressures (P(ao))>30 cmH(2)O did not increase inflammatory response or affect transcutaneous oxygen saturation but significantly lowered airway resistance, tissue damping and tissue elastance; the latter changes are likely associated with the bimodal pressure-volume behavior observed in mice. PEEP increase alone and application of RMs producing peak P(ao) below 25 cmH(2)O did not prevent or reverse changes in lung mechanics; whereas frequent application of substantial RMs on top of elevated PEEP levels produced stable lung mechanics without signs of lung injury.

Impact of supplemental oxygen in mechanically ventilated adult and infant mice

The aim of the present study was to determine the short-term effects of hyperoxia on respiratory mechanics in mechanically ventilated infant and adult mice. Eight and two week old BALB/c mice were exposed to inspired oxygen fractions [Formula: see text] of 0.21, 0.3, 0.6, and 1.0, respectively, during 120 min of mechanical ventilation. Respiratory system mechanics and inflammatory responses were measured. Using the low-frequency forced oscillation technique no differences were found in airway resistance between different [Formula: see text] groups when corrected for changes in gas viscosity. Coefficients of lung tissue damping and elastance were not different between groups and showed similar changes over time in both age groups. Inflammatory responses did not differ between groups at either age. Hyperoxia had no impact on respiratory mechanics during mechanical ventilation with low tidal volume and positive end-expiratory pressure. Hence, supplemental oxygen can safely be applied during short-term mechanical ventilation strategies in infant and adult mice.

Longtime performance and reliability of two different PtcCO2 and SpO2 sensors in neonates

OBJECTIVES

Blood gas monitoring is necessary in treatment of critically ill neonates. Whereas SaO2 can be estimated by pulse oximetry, PaCO2 is still most often assessed from blood samples.

AIM

To compare long time performance of an ear sensor for combined assessment of transcutaneous carbon dioxide (PtcCO2) and oxygen saturation (SpO2) (TOSCA Monitor; Radiometer, Switzerland) with a conventional PtcCO2 monitor (MicroGas 7650-500 rapid, Radiometer, Switzerland) in critically ill neonates.

METHODS

Prospective, observational study. Twenty critically ill neonates were monitored for PtcCO2 and SpO2 using the Tosca and the MicroGas monitor for 24 h. TOSCA ear sensor was changed to the other ear lobe after 12 h and the MicroGas sensor four hourly on the trunk. Values obtained were compared with SaO2 and PaCO2 from arterial blood gas analysis using Bland-Altman analysis. Data are presented as median (range).

RESULTS

Eighty-two paired measurements were obtained. Median age of the 20 patients was 4.5 days (1-26 days) and weight was 3.05 kg (0.98-3.95 kg). Bias and precision between PaCO2 and PtcCO2 were 0.14 and 1.45 kPa for the Tosca monitor and -0.08 and 1.2 kPa for the MicroGas monitor, respectively. The two biases were significantly different (P = 0.0036). SpO2 assessment by TOSCA was comparable to SaO2 values (bias 0.26% and precision 4.14%).

CONCLUSION

The TOSCA monitor allows safe estimation of PtcCO2 and SaO2 in neonates. Measurements of PtcCO2 were less reliable with TOSCA compared with conventional monitoring but still allow assessing a trend of ventilation status in newborn patients.

The bimodal quasi-static and dynamic elastance of the murine lung

The double sigmoidal nature of the mouse pressure-volume (PV) curve is well recognized but largely ignored. This study systematically examined the effect of inflating the mouse lung to 40 cm H2O transrespiratory pressure (Prs) in vivo. Adult BALB/c mice were anesthetized, tracheostomized, and mechanically ventilated. Thoracic gas volume was calculated using plethysmography and electrical stimulation of the intercostal muscles. Lung mechanics were tracked during inflation-deflation maneuvers using a modification of the forced oscillation technique. Inflation beyond 20 cm H2O caused a shift in subsequent PV curves with an increase in slope of the inflation limb and an increase in lung volume at 20 cm H2O. There was an overall decrease in tissue elastance and a fundamental change in its volume dependence. This apparent “softening” of the lung could be recovered by partial degassing of the lung or applying a negative transrespiratory pressure such that lung volume decreased below functional residual capacity. Allowing the lung to spontaneously recover revealed that the lung required ∼1 h of mechanical ventilation to return to the original state. We propose a number of possible mechanisms for these observations and suggest that they are most likely explained by the unfolding of alveolar septa and the subsequent redistribution of the fluid lining the alveoli at high transrespiratory pressure.

Congenital prothrombotic disorders in children with peripheral venous and arterial thromboses

AIMS

To evaluate the prevalence of congenital prothrombotic disorders in children with peripheral venous and arterial thromboses.

METHODS

Deficiencies in antithrombin (AT), proteins C (PC) and S (PS), and increased lipoprotein (a), and the presence of factor V (FV) G1691A, prothrombin G20210A and methylenetetrahydrofolate reductase (MTHFR) mutations were investigated.

RESULTS

Forty-eight patients (mean age, 3.4 years) were investigated. Of these patients, 23 had venous thrombosis, 22 had arterial thrombosis, and 3 had both. No patients had AT, PC or PS deficiency. FV G1691A mutation was present in 2 (7.6%) and 3 (12%) patients with venous and arterial thromboses, respectively. The prothrombin G20210A mutation was present in 1 (4%) patient with arterial thrombosis. Homozygous MTHFR C677T mutation was detected in 4 (18%) and 2 (9%) patients with venous and arterial thromboses, respectively. Increased lipoprotein (a) was present in 2 (10%) and 1 (4.5%) patients with venous and arterial thromboses, respectively. Regarding acquired risk factors, 79% of all thrombotic events were related to catheter usage. An underlying disease was present in 96% of the patients.

CONCLUSIONS

Compared to acquired risk factors, congenital prothrombotic disorders are rarely present in children with peripheral venous and arterial thromboses. These results do not support general screening of children with venous and arterial thromboses for congenital prothrombotic disorders.

An in vitro study of the compliance of paediatric tracheal tube cuffs and tracheal wall pressure

Cuff volume-pressure curves and cuff pressure-tracheal wall pressure relationships were investigated in eight brands of currently available cuffed, paediatric tracheal tubes with internal diameters of 5.0 mm. Cuff volume-pressure curves were measured with the cuff unrestricted and with the cuff placed within a tracheal model with wall pressure measurements. With the tracheal tube cuffs, unrestricted cuff compliance at 20 cmH(2)O cuff pressure varied between 0.06 and 0.3 ml x cmH(2)O(-1). With the cuff restricted within the model trachea, all tracheal tube cuffs became considerably less compliant (0.01-0.09 ml x cmH(2)O(-1)). We found tracheal wall pressure was similar to the cuff pressure as long as the resulting cuff diameter was sufficiently large freely to drape the inner tracheal wall. We found that, regardless of whether a higher or lower compliant tube cuff was used, cuff hyperinflation uniformly resulted in potentially compromised tracheal mucosal blood flow; cuff pressure monitoring using cuff pressure limitation is therefore strongly recommended.

The role of somatostatin in the treatment of persistent chylothorax in children

OBJECTIVE

To analyze the success rate of somatostatin in children with persistent chylothorax who failed dietary treatment options (fat-free nutrition, total parenteral nutrition) and to work out predictive factors for a successful therapy with somatostatin.

METHODS

Retrospective cohort study over a 5-year period (2000-2004) in a neonatal and pediatric intensive care unit of a tertiary university hospital. We analyzed the data of 85 neonatal and pediatric patients. Treatment of chylothorax occurred according to a multistage protocol with progressing invasiveness: (1) fat-free enteral nutrition, (2) total parenteral nutrition, (3) somatostatin infusion, (4) surgery. The percentages of patients successfully treated at the progressing steps were recorded. The somatostatin group was analyzed regarding to physiologic, diagnostic, treatment and outcome parameters. Somatostatin-responders were compared with non-responders.

RESULTS

Seventy-six of the 85 patients had chylothorax after cardiac surgery. Sixty-six percent could be treated with fat-free nutrition alone, 19% needed treatment with total parenteral nutrition and in 15% somatostatin was added. Of the whole sample, 4.7% required a surgical intervention. Of the 13 patients treated with somatostatin, all had bilateral chylothorax. Six patients (46%) responded to somatostatin. Responders and non-responders did not differ significantly regarding age, day of postoperative diagnosis of chylothorax, amount of chylous effusion before somatostatin infusion, triglyceride concentration and lymphocyte percentage in chylous, and central venous pressure (p=0.066).

CONCLUSIONS

Somatostatin, integrated in a treatment algorithm, was successful in resolving persistent chylothorax in around 50% of patients. With this strategy, some children may be prevented from undergoing an operation. However, factors predicting successful therapy with somatostatin could not be elicited.

Antithrombin activity in children with chylothorax

OBJECTIVE

To determine whether increased antithrombin loss is present in children with chylothorax after cardiac surgery.

METHODS

Plasma and pleural effusion samples of children with chylous and non-chylous pleural effusion were assayed for antithrombin activity.

RESULTS

Ten children with chylothorax and five children with non-chylous pleural effusion were investigated. There was statistically significant increase in mean antithrombin activity in chylous samples (32.2+/-11.4%) compared to non-chylous samples (14.4+/-13.9%), and significant decrease in plasma of children with chylothorax (44.6+/-15.4%) compared to children with non-chylous pleural effusion (69.9+/-22.4%). Seven of 10 children with chylous and none of the children without chylous developed thrombosis (p<0.007).

CONCLUSIONS

Increased loss of antithrombin is present in children with chylothorax, potentially predisposing these children to an increased risk of thrombosis. Repeated antithrombin substitution should be considered in critically ill children with chylothorax.

Thrombolysis of venous and arterial thrombosis by catheter-directed low-dose infusion of tissue plasminogen activator in children

Thrombolytic therapy is a well-defined treatment option for arterial and venous thrombosis in adults. In contrast, uniform recommendations regarding the indication, route of administration, and dosing of thrombolytic therapy in children are not available. The authors report the successful resolution of bilateral pulmonary embolism and popliteal artery thrombosis in an 11-year-old girl and 13-year-old girl, respectively, by catheter-directed thrombolysis with low-dose recombinant tissue plasminogen activator. Catheter-directed low-dose thrombolysis is an efficient treatment option for severe venous and arterial thrombosis in children.

Integrated luminometer for the determination of trace metals in seawater using fluorescence, phosphorescence and chemiluminescence detection

The paper describes an integrated luminometer able to perform fluorescence (FL), room temperature phosphorescence (RTP) and chemiluminescence (CL) measurements on seawater samples. The technical details of the instrumentation are presented together with flow injection (FI) manifolds for the determination of cadmium and zinc (by FL), lead (RTP) and cobalt (CL). The analytical figures of merit are given for each manifold and results are presented for the determination of the four trace metals in seawater reference materials (NASS-5, SLEW-2) and Scheldt estuarine water samples.