Clinical performance of a novel textile interface for neonatal chest electrical impedance tomography

Objective: Critically ill neonates and infants might particularly benefit from continuous chest electrical impedance tomography (EIT) monitoring at the bedside. In this study a textile 32-electrode interface for neonatal EIT examination has been developed and tested to validate its clinical performance. The objectives were to assess ease of use in a clinical setting, stability of contact impedance at the electrode–skin interface and possible adverse effects. Approach: Thirty preterm infants (gestational age: 30.3 ± 3.9 week (mean ± SD), postnatal age: 13.8 ± 28.2 d, body weight at inclusion: 1727 ± 869 g) were included in this multicentre study. The electrode–skin contact impedances were measured continuously for up to 3 d and analysed during the initial 20-min phase after fastening the belt and during a 10 h measurement interval without any clinical interventions. The skin condition was assessed by attending clinicians. Main results: Our findings imply that the textile electrode interface is suitable for long-term neonatal chest EIT imaging. It does not cause any distress for the preterm infants or discomfort. Stable contact impedance of about 300 Ohm was observed immediately after fastening the electrode belt and during the subsequent 20 min period. A slight increase in contact impedance was observed over time. Tidal variation of contact impedance was less than 5 Ohm. Significance: The availability of a textile 32-electrode belt for neonatal EIT imaging with simple, fast, accurate and reproducible placement on the chest strengthens the potential of EIT to be used for regional lung monitoring in critically ill neonates and infants

Effect of routine suction on lung aeration in critically ill neonates and young infants measured with electrical impedance tomography

Endotracheal suctioning is a widely used procedure to remove secretions from the airways of ventilated patients. Despite its prevalence, regional effects of this maneuver have seldom been studied. In this study, we explore its effects on regional lung aeration in neonates and young infants using electrical impedance tomography (EIT) as part of the large EU-funded multicenter observational study CRADL. 200 neonates and young infants in intensive care units were monitored with EIT for up to 72 h. EIT parameters were calculated to detect changes in ventilation distribution, ventilation inhomogeneity and ventilation quantity on a breath-by-breath level 5–10 min before and after suctioning. The intratidal change in aeration over time was investigated by means of regional expiratory time constants calculated from all respiratory cycles using an innovative procedure and visualized by 2D maps of the thoracic cross-section. 344 tracheal suctioning events from 51 patients could be analyzed. They showed no or very small changes of EIT parameters, with a dorsal shift of the center of ventilation by 0.5% of the chest diameter and a 7% decrease of tidal impedance variation after suctioning. Regional time constants did not change significantly. Routine suctioning led to EIT- detectable but merely small changes of the ventilation distribution in this study population. While still a measure requiring further study, the time constant maps may help clinicians interpret ventilationmechanics in specific cases

Compressive sensing in electrical impedance tomography for breathing monitoring

Continuous functional thorax monitoring using EIT has been extensively researched. A limiting factor in high temporal resolution, three dimensional, and fast EIT is the handling of the volume of raw impedance data produced for transmission and storage. Owing to the periodicity of breathing that may be reflected in EIT boundary measurements, data dimensionality may be reduced efficiently at the time of sampling using compressed sensing techniques. Measurements using a 32-electrode 48-frame-per-second EIT system from 30 neonates were post-processed to simulate random demodulation acquisition method on 2000 frames for compression ratios (CRs) ranging from 2-100. Sparse reconstruction was performed by solving the basis pursuit problem using SPGL1 package. The global impedance data was used in the subsequent studies. The signal to noise ratio (SNR) for the entire frequency band (0 Hz - 24 Hz) and three local frequency bands were analysed. A breath detection algorithm was applied to traces and the subsequent error-rates were calculated while considering the outcome of the algorithm applied to a down-sampled and linearly interpolated version of the traces as the baseline. SNR degradation was proportional with CR. The mean degradation for 0 Hz - 8 Hz was below ~15 dB for all CRs. The error-rates in the outcome of the breath detection algorithm in the case of decompressed traces were lower than those of the associated down-sampled traces for CR≥25, corresponding to sub-Nyquist rate for breathing. For instance, the mean error-rate associated with CR = 50 was ~60% lower than that of the corresponding down-sampled traces. To the best of our knowledge, no other study has evaluated compressive sensing on boundary impedance data in EIT. While further research should be directed at optimising the acquisition and decompression techniques for this application, this contribution serves as the baseline for future efforts. [Abstract copyright: Creative Commons Attribution license.

Clinical performance of a novel textile interface for neonatal chest electrical impedance tomography

Objective: Critically ill neonates and infants might particularly benefit from continuous chest electrical impedance tomography (EIT) monitoring at the bedside. In this study a textile 32-electrode interface for neonatal EIT examination has been developed and tested to validate its clinical performance. The objectives were to assess ease of use in a clinical setting, stability of contact impedance at the electrode–skin interface and possible adverse effects. Approach: Thirty preterm infants (gestational age: 30.3 ± 3.9 week (mean ± SD), postnatal age: 13.8 ± 28.2 d, body weight at inclusion: 1727 ± 869 g) were included in this multicentre study. The electrode–skin contact impedances were measured continuously for up to 3 d and analysed during the initial 20-min phase after fastening the belt and during a 10 h measurement interval without any clinical interventions. The skin condition was assessed by attending clinicians. Main results: Our findings imply that the textile electrode interface is suitable for long-term neonatal chest EIT imaging. It does not cause any distress for the preterm infants or discomfort. Stable contact impedance of about 300 Ohm was observed immediately after fastening the electrode belt and during the subsequent 20 min period. A slight increase in contact impedance was observed over time. Tidal variation of contact impedance was less than 5 Ohm. Significance: The availability of a textile 32-electrode belt for neonatal EIT imaging with simple, fast, accurate and reproducible placement on the chest strengthens the potential of EIT to be used for regional lung monitoring in critically ill neonates and infants

Initial observations on the effect of repeated surfactant dose on lung volume and ventilation in neonatal respiratory distress syndrome [Brief Report]

Background: Exogenous surfactant administration is an essential part of respiratory distress syndrome treatment in preterm infants. Current guidelines recommend the first dose to be given as early as possible, followed by an additional dose if symptoms persist. The effect of additional dosing on regional ventilation and lung volume has not been investigated so far. Objectives: The aim of this study was to assess changes in ventilation distribution, lung volume, and gas exchange following repeated surfactant dosing in invasively ventilated neonates. Method: Preterm infants requiring invasive ventilation and repeated surfactant treatment, and participating in the prospective observational multicenter trial “Continuous Regional Analysis Device for neonate Lung (CRADL)” were included in this analysis. Ventilation distribution, end-expiratory lung impedance (EELZ), and tidal impedance variation were determined by electrical impedance tomography together with clinical parameters before and after repeat endotracheal surfactant treatment. Results: Nine neonates (gestational age 32.7 ± 2.7 weeks, weight 1,724 ± 691 g) received an additional dose of surfactant at a median postnatal age of 33.5 h (IQR 9.1–46.6). One patient was excluded from the analysis due to simultaneous interventions confounding data analysis. Repeated surfactant dose did not significantly affect ventilation distribution. There were no significant changes in EELZ or tidal impedance variation. SpO2/FiO2 increased from 248 ± 104 to 367 ± 92 (p = 0.001), while FiO2 was reduced from 0.41 ± 0.20 to 0.27 ± 0.10 (p = 0.004). Expiratory tidal volume fell from 4.3 ± 0.6 to 3.0 ± 1.2 mL/kg (p = 0.03), while other ventilator and clinical parameters remained stable. Conclusions: Repeated surfactant dose during invasive ventilation improves oxygenation without measurable changes in EELZ or ventilation distribution

Initial observations on the effect of repeated surfactant dose on lung volume and ventilation in neonatal respiratory distress syndrome [Brief Report]

Background: Exogenous surfactant administration is an essential part of respiratory distress syndrome treatment in preterm infants. Current guidelines recommend the first dose to be given as early as possible, followed by an additional dose if symptoms persist. The effect of additional dosing on regional ventilation and lung volume has not been investigated so far. Objectives: The aim of this study was to assess changes in ventilation distribution, lung volume, and gas exchange following repeated surfactant dosing in invasively ventilated neonates. Method: Preterm infants requiring invasive ventilation and repeated surfactant treatment, and participating in the prospective observational multicenter trial “Continuous Regional Analysis Device for neonate Lung (CRADL)” were included in this analysis. Ventilation distribution, end-expiratory lung impedance (EELZ), and tidal impedance variation were determined by electrical impedance tomography together with clinical parameters before and after repeat endotracheal surfactant treatment. Results: Nine neonates (gestational age 32.7 ± 2.7 weeks, weight 1,724 ± 691 g) received an additional dose of surfactant at a median postnatal age of 33.5 h (IQR 9.1–46.6). One patient was excluded from the analysis due to simultaneous interventions confounding data analysis. Repeated surfactant dose did not significantly affect ventilation distribution. There were no significant changes in EELZ or tidal impedance variation. SpO2/FiO2 increased from 248 ± 104 to 367 ± 92 (p = 0.001), while FiO2 was reduced from 0.41 ± 0.20 to 0.27 ± 0.10 (p = 0.004). Expiratory tidal volume fell from 4.3 ± 0.6 to 3.0 ± 1.2 mL/kg (p = 0.03), while other ventilator and clinical parameters remained stable. Conclusions: Repeated surfactant dose during invasive ventilation improves oxygenation without measurable changes in EELZ or ventilation distribution

Effect of sternal electrode gap and belt rotation on the robustness of pulmonary electrical impedance tomography parameters

Objective: Non-adhesive textile electrode belts offer several advantages over adhesive electrodes and are increasingly used in neonatal patients during continuous electrical impedance tomography (EIT) lung monitoring. However, non-adhesive belts may rotate in unsedated patients and discrepancies between chest circumference and belt sizes may result in a gap between electrodes near the sternum. This project aimed to determine the effects of belt rotation and sternal electrode gap on commonly used lung EIT parameters. Approach: We developed a simulation framework based on a 3D finite-element model and introduced lung regions with little or no ventilation that could be changed according to a decremental positive end-expiratory pressure (PEEP) trial. Four degrees of sternal gap and belt rotation were simulated and their effect on the EIT parameters silent spaces, centre of ventilation, global inhomogeneity index and overdistension/collapsed lung (OD/CL) analysed. Additionally, seven premature infants were examined to assess the influence of leftward and rightward belt rotations in a clinical setting. Main results: Small violations of the electrode equidistance criterion and rotations of the belts less than one electrode space exert only minor effects on the EIT parameters and do not impede the interpretation. Rotations of two and three electrode spaces induce non-negligible effects that might lead to flawed interpretations. The 'best PEEP' determined with the OD/CL approach was robust and identifiable with all studied sternal gaps and belt rotations. Significance: We revealed an important challenge for neonatal EIT applications related to a wide electrode gap at the sternum and belt rotation, which should be avoided in clinical application

First outbreak of nosocomial legionella infection in term neonates caused by a cold mist ultrasonic humidifier

Background To date, all descriptions of legionellosis in neonates have emerged from a small number of isolated case reports in newborns with unusually severe pneumonia. In December 2008, a large outbreak of Legionella infection occurred in term neonates in Cyprus, providing new information on the epidemiological and clinical features of Legionellosis in this age group.Methods An environmental investigation was performed at a small private hospital where the infected neonates were delivered. The medical records of the infected neonates were retrospectively reviewed to obtain clinical data on presentation, complications, and course of disease.Results Nine of the 32 (28%) newborns who were exposed to the contaminated source at the private nursery were infected with Legionella. Six subjects had pulmonary infiltrates, but in 3 cases there were no abnormal radiological findings and clinical presentation was mild. In 4 neonates, pulmonary infiltrates at presentation were bilateral and extensive and 3 died, conferring a mortality rate of 50% in subjects with pulmonary infiltrates and an overall mortality of 33.3%. Legionella pneumophila serogroup 3 was recovered in neonatal biological samples, although in some patients there was implication of a second strain, serogroup 1. It was determined that the neonates were infected while in the nursery at the private hospital by aerosol produced by a recently installed cold-mist humidifier that was filled with contaminated water.Conclusions Use of humidifiers in nursery units must be avoided as the risk of disseminating Legionella in neonates is very high. In neonates legionellosis should be suspected when signs of infection first appear and take an unusual course, even when no pulmonary infiltrates appear

Effect of sternal electrode gap and belt rotation on the robustness of pulmonary electrical impedance tomography parameters

Objective: Non-adhesive textile electrode belts offer several advantages over adhesive electrodes and are increasingly used in neonatal patients during continuous electrical impedance tomography (EIT) lung monitoring. However, non-adhesive belts may rotate in unsedated patients and discrepancies between chest circumference and belt sizes may result in a gap between electrodes near the sternum. This project aimed to determine the effects of belt rotation and sternal electrode gap on commonly used lung EIT parameters. Approach: We developed a simulation framework based on a 3D finite-element model and introduced lung regions with little or no ventilation that could be changed according to a decremental positive end-expiratory pressure (PEEP) trial. Four degrees of sternal gap and belt rotation were simulated and their effect on the EIT parameters silent spaces, centre of ventilation, global inhomogeneity index and overdistension/collapsed lung (OD/CL) analysed. Additionally, seven premature infants were examined to assess the influence of leftward and rightward belt rotations in a clinical setting. Main results: Small violations of the electrode equidistance criterion and rotations of the belts less than one electrode space exert only minor effects on the EIT parameters and do not impede the interpretation. Rotations of two and three electrode spaces induce non-negligible effects that might lead to flawed interpretations. The 'best PEEP' determined with the OD/CL approach was robust and identifiable with all studied sternal gaps and belt rotations. Significance: We revealed an important challenge for neonatal EIT applications related to a wide electrode gap at the sternum and belt rotation, which should be avoided in clinical application

Sedation and Analgesia Practices in Neonatal Intensive Care Units (EUROPAIN): Results from a Prospective Cohort Study

BACKGROUND: Neonates who are in pain or are stressed during care in the intensive care unit (ICU) are often given sedation or analgesia. We investigated the current use of sedation or analgesia in neonatal ICUs (NICUs) in European countries. METHODS: EUROPAIN (EUROpean Pain Audit In Neonates) was a prospective cohort study of the management of sedation and analgesia in patients in NICUs. All neonates admitted to NICUs during 1 month were included in this study. Data on demographics, methods of respiration, use of continuous or intermittent sedation, analgesia, or neuromuscular blockers, pain assessments, and drug withdrawal syndromes were gathered during the first 28 days of admission to NICUs. Multivariable linear regression models and propensity scores were used to assess the association between duration of tracheal ventilation (TV) and exposure to opioids, sedatives-hypnotics, or general anaesthetics in neonates (O-SH-GA). This study is registered with ClinicalTrials.gov, number NCT01694745. FINDINGS: From Oct 1, 2012, to June 30, 2013, 6680 neonates were enrolled in 243 NICUs in 18 European countries. Mean gestational age of these neonates was 35.0 weeks (SD 4.6) and birthweight was 2384 g (1007). 2142 (32%) neonates were given TV, 1496 (22%) non-invasive ventilation (NIV), and 3042 (46%) were kept on spontaneous ventilation (SV). 1746 (82%), 266 (18%), and 282 (9%) neonates in the TV, NIV, and SV groups, respectively, were given sedation or analgesia as a continuous infusion, intermittent doses, or both (p<0.0001). In the participating NICUs, the median use of sedation or analgesia was 89.3% (70.0-100) for neonates in the TV group. Opioids were given to 1764 (26%) of 6680 neonates and to 1589 (74%) of 2142 neonates in the TV group. Midazolam was given to 576 (9%) of 6680 neonates and 536 (25%) neonates of 2142 neonates in the TV group. 542 (25%) neonates in the TV group were given neuromuscular blockers, which were administered as continuous infusions to 146 (7%) of these neonates. Pain assessments were recorded in 1250 (58%) of 2138, 672 (45%) of 1493, and 916 (30%) of 3017 neonates in the TV, NIV, and SV groups, respectively (p<0.0001). In the univariate analysis, neonates given O-SH-GA in the TV group needed a longer duration of TV than did those who were not given O-SH-GA (mean 136.2 h [SD 173.1] vs 39.8 h [94.7] h; p<0.0001). Multivariable and propensity score analyses confirmed this association (p<0.0001). INTERPRETATION: Wide variations in sedation and analgesia practices occur between NICUs and countries. Widespread use of O-SH-GA in intubated neonates might prolong their need for mechanical ventilation, but further research is needed to investigate the therapeutic and adverse effects of O-SH-GA in neonates, and to develop new and safe approaches for sedation and analgesia. FUNDING: European Community's Seventh Framework Programme