Evaluation of bedside pulmonary function in the neonate: From the past to the future

Thoracic electrical impedance tomography for assessing progression of pulmonary dysfunction in ALS

Objective: We compared thoracic electrical impedance tomography (EIT) with slow vital capacity (SVC) to determine if EIT could monitor pulmonary function in ALS patients longitudinally. Methods: Of 32 ALS patients and 32 age- and sex-matched healthy controls (HCs) initially enrolled in the Pulmonary Function via Impedance Tomography (PuFIT) study, 22 ALS and 20 HCs returned for a follow-up visit ∼3.9 months later. All participants had thoracic EIT measurements performed simultaneously with standard SVC in upright and supine positions at both visits. EIT data from each measurement were summarized as a single parameter, the impedance-SVC (zSVC), representing an averaged impedance change across both lungs. We assessed alterations over time for both cohorts of participants. Results: Sufficient quality EIT and SVC data were available for 18 of the patients with ALS and 19 HCs. Over time, mean upright SVC significantly declined by 5% in the ALS group and did not change in the healthy group. Supine SVC showed no change in either group. Although mean trajectories of zSVC mirrored mean SVC trajectories in both participant cohorts, changes in zSVC in ALS patients did not reach significance, due to greater variability in the repeated measures. Conclusion: Despite strong cross-sectional correlations to SVC, EIT did not detect a decline in pulmonary function over approximately four months. Increased variability in EIT data explains the lack of sensitivity to change. Technological improvements and special care with electrode placement will be needed for EIT to reach its full potential in longitudinal assessment of pulmonary function in ALS.

Pulmonary function tests in the neonatal intensive care unit and beyond: a clinical review

Pulmonary function tests (PFTs) in the Neonatal Intensive Care Unit (NICU) have played a pivotal role in neonatal care. They have helped quantify the effects of therapeutic interventions, guide ventilator management, and serve as endpoints in clinical trials. Preterm delivery, the most common cause of altered lung development, establishes early lung function trajectories that persist into later life. Early PFTs in preterm infants can enhance our understanding of factors influencing these trajectories. This review summarizes techniques performed in the NICU and early infancy and the evolution of continuous lung function monitoring through the bedside ventilator. It provides examples incorporating PFTs in the NICU and early infancy to improve outcomes and identifies evolving technology in this area. This review does not include studies of control of breathing in newborn infants. Looking ahead, the field would greatly benefit from developing a sustainable, non-invasive PFT technique that can be applied across the lifespan.

Prediction of Tidal Volume in Newborns Through a Novel Three-Dimensional Model: A Viability Study

INTRODUCTION

Although noninvasive monitoring through quantifying rib cage movement has been useful in serial assessment of pulmonary function in newborns, measuring tidal volume (TV) is commonly performed invasively. As it is the most basic measure of pulmonary function, expanding its assessment to a noninvasive measure can contribute to clinical findings and interpretations in neonatal clinical practice.

OBJECTIVE

(1) Create a noninvasive measurement tool for TV for neonatal clinical use; (2) Evaluate the agreement between measured TV and predicted TV.

METHODS

Observational study with healthy newborns. Predicted TV was calculated based on the newborns' weight using the mid-range of the volumes usually set during mechanical ventilation of term infants (5 mL/kg). For measured TV, newborns were filmed in supine position using a digital camera, and their chest circumferences were measured with a nonelastic tape. Body markers delimited the segmentation of the area of interest, and a MATLAB software routine established their relationship with the area in cm² and generated a representative image of the thoracic and abdominal areas in a cylindrical, elliptical-based format, as well as a three-dimensional model to represent quantitative data of measured TV. Paired t-test assessed the means of measured and predicted TV, Pearson's correlation assessed level of association, and Kappa coefficient assessed the agreement between them.

RESULTS

Newborns' gestational ages ranged from 38 to 40 weeks and weights from 2190 to 4125 g. A total of 56 respiratory cycles were validated for analysis. The mean predicted TV according to weight was 5.06 mL/kg, and measured TV was 5 ml/kg (p = 0.31), with a correlation of 0.7 (p < 0.001) and a kappa coefficient of 0.39 (p = 0.01).

CONCLUSIONS

MATLAB software routine was a practical and easy-to-use tool to monitor noninvasive TV in a neonatal setting. There was no difference between predicted and estimated TV, with fair agreement between them.

Comparing ventilation modes by electrical impedance segmentography in ventilated children

Electrical impedance segmentography offers a new radiation-free possibility of continuous bedside ventilation monitoring. The aim of this study was to evaluate the efficacy and reproducibility of this bedside tool by comparing synchronized intermittent mandatory ventilation (SIMV) with neurally adjusted ventilatory assist (NAVA) in critically-ill children. In this prospective randomized case-control crossover trial in a pediatric intensive care unit of a tertiary center, including eight mechanically-ventilated children, four sequences of two different ventilation modes were consecutively applied. All children were randomized into two groups; starting on NAVA or SIMV. During ventilation, electric impedance segmentography measurements were recorded. The relative difference of vertical impedance between both ventilatory modes was measured (median 0.52, IQR 0-0.87). These differences in left apical lung segments were present during the first (median 0.58, IQR 0-0.89, p = 0.04) and second crossover (median 0.50, IQR 0-0.88, p = 0.05) as well as across total impedance (0.52 IQR 0-0.87; p = 0.002). During NAVA children showed a shift of impedance towards caudal lung segments, compared to SIMV. Electrical impedance segmentography enables dynamic monitoring of transthoracic impedance. The immediate benefit of personalized ventilatory strategies can be seen when using this simple-to-apply bedside tool for measuring lung impedance.

Tidal Breathing Parameters Measured by Structured Light Plethysmography in Newborns: Is It Feasible in Neonatal Intensive Care Unit?

OBJECTIVE

Structured light plethysmography (SLP) is a novel and noncontact respiratory assessment technique. It provides tidal breathing measurement in patients difficult to cooperate. In this study, we aimed to determine data for tidal breathing parameters measured by SLP in newborns.

STUDY DESIGN

Infants between 2 and 5 days of life without having any respiratory symptoms were eligible for this observational study. In total, 5 minutes of tidal breathing was recorded using SLP (Thora-3Di, PneumaCare Ltd, Cambridge, U.K.) in each infant. Various tidal breathing parameters including timing indices, flow-based parameters, and regional parameters were obtained from SLP data.

RESULTS

A total of 57 infants underwent measurements in the study. Evaluable recordings from 42 term and 11 late preterm infants were analyzed. Median gestational age and birthweight of the infants were 38 (37-39) weeks and 3,195 (2,790-3,585) g, respectively. In terms of flow-based parameters, "tidal inspiratory flow at 50% of inspiratory volume divided by tidal expiratory flow at 50% of expiratory volume" was 1.29 (1.13-1.53). Relative contribution of the thorax to each breath in percentage was measured as 38.67 (28.21-43.60). Median values of left-right hemithoracic asynchrony and thoraco-abdominal asynchrony were 6.92 (5.35-9.04) and 17.96 (12.98-36.44) degrees in the study population, respectively. There were no differences in tidal breathing parameters except "hemithoracic asynchrony" between term and late preterm infants. Hemithoracic asynchrony was significantly lower in term neonates than late preterms.

CONCLUSION

SLP was found to be feasible to obtain measures of tidal breathing parameters in newborns and it could be performed successfully even in the first days of life.

Biodistribution, inter-/intra-cellular localization and respiratory dysfunction induced by Ti3C2 nanosheets: Involvement of surfactant protein down-regulation in alveolar epithelial cells

Two-dimensional Ti₃C₂ nanosheets have been extensively used in biomedical fields and are mostly designed to enter the circulatory system. However, few studies have focused on the in vivo anatomical location and physiological function of major organs on exposure to Ti₃C₂ nanosheets. This study attempts to determine whether and how Ti₃C₂ nanosheets disrupt the physiological function of the involved organs. Our studies demonstrated that Ti₃C₂ nanosheets were mainly distributed in the lungs and liver after entering circulation. In the lungs, they were retained in the cytoplasm of alveolar epithelial cells and endothelial cells, and inhibited pulmonary surfactant protein B (SP-B) expression on alveolar epithelial cell, causing increased airway resistance-induced respiratory disorder following a 28-day Ti₃C₂ nanosheet exposure. Furthermore, our data showed that Ti₃C₂ nanosheets did not cause abnormal proinflammatory cytokines and histopathological changes. These findings demonstrated that Ti₃C₂ nanosheets might disturb respiration without inflammatory responses and pathological lesions, suggesting that these effects may occur by decreasing SP-B-mediated airway resistance. This indicates that organ function maintenance differs from biological safety for Ti₃C₂ nanosheets, an important consideration during potential clinical application and human exposure.

Point-of-care lung ultrasound in neonatology: classification into descriptive and functional applications

Lung ultrasound (LUS) is the latest amongst imaging techniques: it is a radiation-free, inexpensive, point-of-care tool that the clinician can use at the bedside. This review summarises the rapidly growing scientific evidence on LUS in neonatology, dividing it into descriptive and functional applications. We report the description of the main ultrasound features of neonatal respiratory disorders and functional applications of LUS aiming to help a clinical decision (such as surfactant administration, chest drainage etc). Amongst the functional applications, we propose SAFE (Sonographic Algorithm for liFe threatening Emergencies) as a standardised protocol for emergency functional LUS in critical neonates. SAFE has been funded by a specific grant issued by the European Society for Paediatric Research. Future potential development of LUS in neonatology might be linked to its quantitative evaluation: we also discuss available data and research directions using computer-aided diagnostic techniques. Finally, tools and opportunities to teach LUS and expand the research network are briefly presented.

Changes in pulmonary oxygen content are detectable with laser absorption spectroscopy: proof of concept in newborn piglets

BACKGROUND

Using an optical method based on tunable diode laser absorption spectroscopy, we previously assessed oxygen (O₂) and water vapor (H₂O) content in a tissue phantom of the preterm infant lung. Here we applied this method on newborn piglets with induced lung complications.

METHODS

Five mechanically ventilated piglets were subjected to stepwise increased and decreased fraction of inspired oxygen (FiO₂), to atelectasis using a balloon catheter in the right bronchus, and to pneumothorax by injecting air in the pleural cavity. Two diode lasers (764 nm for O₂ gas absorption and 820 nm for H₂O absorption) were combined in a probe delivering light either externally, on the skin, or internally, through the esophagus. The detector probe was placed dermally.

RESULTS

Calculated O₂ concentrations increased from 20% (IQR 17-23%) when ventilated with room air to 97% (88-108%) at FiO₂ 1.0. H₂O was only detectable with the internal light source. Specific light absorption and transmission patterns were identified in response to atelectasis and pneumothorax, respectively.

CONCLUSIONS

The optical method detected FiO₂ variations and discriminated the two induced lung pathologies, providing a rationale for further development into a minimally invasive device for real-time monitoring gas changes in the lungs of sick newborn infants.

IMPACT

Optical spectroscopy can detect pulmonary complications in an animal model. Oxygen concentrations can be evaluated in the lungs. Presents a novel minimally invasive method to detect lung oxygenation and complications. Potential to be developed into a lung monitoring method in newborn infants. Potential for bed-side detection of pulmonary complications in newborn infants.

Thoracoabdominal motion in newborns: Reliability between two interactive computing environments

BACKGROUND

Quantifying the chest wall is useful in documenting thoracoabdominal synchrony during the neonatal period. Subjective measures are often used rather than gold-standard methods due to their practicality in clinical practice. The aim of the present study is to compare the reliability between a newly proposed method (video analysis in MATLAB) and image analysis using AutoCad tools, both applied to assess thoracoabdominal motion in newborns (NBs).

MATERIALS AND METHODS

This is an observational cross-sectional study of full-term NBs. A digital camera was used to film thoracoabdominal motion for 2 minutes in the supine position, with movements measured by the two aforementioned methodologies.

RESULTS

A total of 139 images were used, showing agreement between AutoCAD and MATLAB (BIAS = -1.68; CI = -6.59:3.22, Bland-Altman plot).

CONCLUSION

The programs were interchangeable and the routine developed in MATLAB was simpler and faster, allowing dynamic analysis and suggesting its clinical utility in quantifying respiratory motion in NBs.

Tools to assess lung aeration in neonates with respiratory distress syndrome

AIM

Respiratory distress syndrome is a common condition among preterm neonates, and assessing lung aeration assists in diagnosing the disease and helping to guide and monitor treatment. We aimed to identify and analyse the tools available to assess lung aeration in neonates with respiratory distress syndrome.

METHODS

A systematic review and narrative synthesis of studies published between January 1, 2004, and August 26, 2019, were performed using the OVID Medline, PubMed, Embase and Scopus databases.

RESULTS

A total of 53 relevant papers were retrieved for the narrative synthesis. The main tools used to assess lung aeration were respiratory function monitoring, capnography, chest X-rays, lung ultrasound, electrical impedance tomography and respiratory inductive plethysmography. This paper discusses the evidence to support the use of these tools, including their advantages and disadvantages, and explores the future of lung aeration assessments within neonatal intensive care units.

CONCLUSION

There are currently several promising tools available to assess lung aeration in neonates with respiratory distress syndrome, but they all have their limitations. These tools need to be refined to facilitate convenient and accurate assessments of lung aeration in neonates with respiratory distress syndrome.

Electrical impedance segmentography: A promising tool for respiratory monitoring?

BACKGROUND

Non-invasive, radiation free bedside monitoring methods have gained increased popularity in the respiratory field. The aim of our study was to report the experience with electrical impedance segmentography (EIS), a rather new technique, which allows continuous visual and quantitative monitoring of regional lung ventilation.

METHODS

Prospective, pilot trial in spontaneously breathing, healthy, non-sedated term neonates between 24 and 72 hours post-delivery using a commercially available EIS-device. Systematic review of the literature.

RESULTS

A total of 12 neonates were eligible for complete data analysis in our study. EIS was found to be a safe and easy to perform method. The median duration of the study time was 25 minutes (16-40). Individual total and regional impedance values, given in arbitrary units and it's percentage of distribution in the upper and lower right and left lung segments (UR, UL, LR, LL), were variable (median total impedance 207 arbitrary units (AU), UR% 17, LR 27%,UL 28%, LL 23%). A number of influencing factors such as body movements, sucking, jawing, and electrode issues have to be considered for correct data interpretation. The literature search revealed two small experimental studies in neonatal piglets and two human studies (one study in preschool children with bronchopulmonary dysplasia and one case report in a neonate with respiratory distress).

CONCLUSIONS

EIS is an innovative technique and a potentially useful tool in studying regional lung ventilation in research and clinical care.

Lung-protective ventilatory strategies in intubated preterm neonates with RDS

This article provides a narrative review of lung-protective ventilatory strategies (LPVS) in intubated preterm infants with RDS. A description of strategies is followed by results on short-and long-term respiratory and neurodevelopmental outcomes. Strategies will include patient-triggered or synchronized ventilation, volume targeted ventilation, the technique of intubation, surfactant administration and rapid extubation to NCPAP (INSURE), the open lung concept, strategies of high-frequency ventilation, and permissive hypercapnia. Based on this review single recommendations on optimal LPVS cannot be made. Combinations of several strategies, individually applied, most probably minimize or avoid potential serious respiratory and cerebral complications like bronchopulmonary dysplasia and cerebral palsy.

Regional lung ventilation pattern in preschool children with bronchopulmonary dysplasia is modified by bronchodilator response

BACKGROUND

Bronchopulmonary dysplasia (BPD) remains a significant long-term complication of prematurity. A standardized method of pulmonary function testing is still not available in preschool children with BPD. We investigated the feasibility of Electrical Impedance Segmentography (EIS) monitoring in this group and the impact of bronchodilator response (BDR) to salbutamol on the pattern of lung ventilation.

METHODS

We conducted a follow-up study of 4-year-old premature children who had been treated in the tertiary NICU. The cohort was divided into two groups based on the presence of BPD. EIS monitoring was performed before and 15 min after the administration of 400 µg of salbutamol (pMDI with spacer) in all subjects during spontaneous tidal breathing in upright position. Data were expressed as median segmental impedance amplitude differences and segmental ventilation inhomogeneity index (II) changes.

RESULTS

We included 51 children in our analysis: 33 with BPD (median birth weight-840 g; median gestational age-27 weeks) and 18 without BPD (1,290 g; 30 weeks, respectively). There was a significant increase in median segmental impedance amplitude after salbutamol in gravity non-dependent segments in children with BPD: upper left (UL): 462 versus 534 AU; (P = 0.003); upper right (UR): 481 versus 595 AU (P < 0.001) and II in these segments: UL: 0.046 versus 0.078 (P = 0.003) UR: 0.049 versus 0.064 (P = 0.006). There were no changes in the lower segments. There were no changes in ventilation pattern in children without BPD.

CONCLUSION

BDR to salbutamol increases breath amplitude in gravity non-dependent segments of the lungs during spontaneous tidal breathing in preschool children with BPD. Pediatr Pulmonol. 2017;52:353-359. © 2016 Wiley Periodicals, Inc.

Electromagnetic inductance plethysmography is well suited to measure tidal breathing in infants

Reliable, accurate and noninvasive methods for measuring lung function in infants are desirable. Electromagnetic inductance plethysmography has been used to perform infant spirometry and VoluSense Pediatrics (VSP) (VoluSense, Bergen, Norway) represents an updated version of this technique. We aimed to examine its accuracy compared to a validated system measuring airflow via a facemask using an ultrasonic flowmeter.

We tested 30 infants with postmenstrual ages between 36 to 43 weeks and weights from 2.3 to 4.8 kg, applying both methods simultaneously and applying VSP alone. Agreement between the methods was calculated using Bland–Altman analyses and we also estimated the effect of applying the mask.

Mean differences for all breathing parameters were within ±5.5% and limits of agreement between the two methods were acceptable, except perhaps for peak tidal expiratory flow (PTEF). Application of the facemask significantly increased tidal volume, minute ventilation, PTEF, the ratio of inspiratory to expiratory time and the ratio of expiratory flow at 50% of expired volume to PTEF.

VSP accurately measured tidal breathing parameters and seems well suited for tidal breathing measurements in infants under treatment with equipment that precludes the use of a facemask.

Accuracy of VoluSense Pediatricshttp://ow.ly/BIFS304sheG

Basic principles of respiratory function monitoring in ventilated newborns: A review

Respiratory monitoring during mechanical ventilation provides a real-time picture of patient-ventilator interaction and is a prerequisite for lung-protective ventilation. Nowadays, measurements of airflow, tidal volume and applied pressures are standard in neonatal ventilators. The measurement of lung volume during mechanical ventilation by tracer gas washout techniques is still under development. The clinical use of capnography, although well established in adults, has not been embraced by neonatologists because of technical and methodological problems in very small infants. While the ventilatory parameters are well defined, the calculation of other physiological parameters are based upon specific assumptions which are difficult to verify. Incomplete knowledge of the theoretical background of these calculations and their limitations can lead to incorrect interpretations with clinical consequences. Therefore, the aim of this review was to describe the basic principles and the underlying assumptions of currently used methods for respiratory function monitoring in ventilated newborns and to highlight methodological limitations.