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 ventilation mechanics in specific cases.

Maternal and neonatal risk factors for neonatal respiratory distress syndrome in term neonates in Cyprus: a prospective case-control study

Background

Neonatal respiratory distress syndrome (NRDS) is strongly associated with premature birth, but it can also affect term neonates. Unlike the extent of research in preterm neonates, risk factors associated with incidence and severity of NRDS in term neonates are not well studied. In this study, we examined the association of maternal and neonatal risk factors with the incidence and severity of NRDS in term neonates admitted to Neonatal Intensive Care Unit (NICU) in Cyprus.

Methods

In a prospective, case-control design we recruited term neonates with NRDS and non-NRDS admitted to the NICU of Archbishop Makarios III hospital, the only neonatal tertiary centre in Cyprus, between April 2017–October 2018. Clinical data were obtained from patients’ files. We used univariate and multivariate logistic and linear regression models to analyse binary and continuous outcomes respectively.

Results

During the 18-month study period, 134 term neonates admitted to NICU were recruited, 55 (41%) with NRDS diagnosis and 79 with non-NRDS as controls. In multivariate adjusted analysis, male gender (OR: 4.35, 95% CI: 1.03–18.39, p = 0.045) and elective caesarean section (OR: 11.92, 95% CI: 1.80–78.95, p = 0.01) were identified as independent predictors of NRDS. Among neonates with NRDS, early-onset infection tended to be associated with increased administration of surfactant (β:0.75, 95% CI: − 0.02-1.52, p = 0.055). Incidence of pulmonary hypertension or systemic hypotension were associated with longer duration of parenteral nutrition (pulmonary hypertension: 11Vs 5 days, p < 0.001, systemic hypotension: 7 Vs 4 days, p = 0.01) and higher rate of blood transfusion (pulmonary hypertension: 100% Vs 67%, p = 0.045, systemic hypotension: 85% Vs 55%, p = 0.013).

Conclusions

This study highlights the role of elective caesarean section and male gender as independent risk factors for NRDS in term neonates. Certain therapeutic interventions are associated with complications during the course of disease. These findings can inform the development of evidence-based recommendations for improved perinatal care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13052-021-01086-5.

Compressive sensing in electrical impedance tomography for breathing monitoring

OBJECTIVE

Electrical impedance tomography (EIT) is a functional imaging technique in which cross-sectional images of structures are reconstructed based on boundary trans-impedance measurements. Continuous functional thorax monitoring using EIT has been extensively researched. Increasing the number of electrodes, number of planes and frame rate may improve clinical decision making. Thus, a limiting factor in high temporal resolution, 3D and fast EIT is the handling of the volume of raw impedance data produced for transmission and its subsequent storage. Owing to the periodicity (i.e. sparsity in frequency domain) of breathing and other physiological variations that may be reflected in EIT boundary measurements, data dimensionality may be reduced efficiently at the time of sampling using compressed sensing techniques. This way, a fewer number of samples may be taken.

APPROACH

Measurements using a 32-electrode, 48-frames-per-second EIT system from 30 neonates were post-processed to simulate random demodulation acquisition method on 2000 frames (each consisting of 544 measurements) for compression ratios (CRs) ranging from 2 to 100. Sparse reconstruction was performed by solving the basis pursuit problem using SPGL1 package. The global impedance data (i.e. sum of all 544 measurements in each frame) 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.

MAIN RESULTS

SNR degradation was generally proportional with CR. The mean degradation for 0 Hz-8 Hz (of interest for the target physiological variations) 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 associated with the corresponding down-sampled traces for CR  ⩾  25, corresponding to sub-Nyquist rate for breathing frequency. For instance, the mean error-rate associated with CR  =  50 was ~60% lower than that of the corresponding down-sampled traces.

SIGNIFICANCE

To the best of our knowledge, no other study has evaluated the applicability of compressive sensing techniques on raw 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.

Initial Observations on the Effect of Repeated Surfactant Dose on Lung Volume and Ventilation in Neonatal Respiratory Distress Syndrome

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.

Assessment of continuous pain in newborns admitted to NICUs in 18 European countries

AIM

Continuous pain occurs routinely, even after invasive procedures, or inflammation and surgery, but clinical practices associated with assessments of continuous pain remain unknown.

METHODS

A prospective cohort study in 243 neonatal intensive care units (NICUs) from 18 European countries recorded the frequency of pain assessments, use of mechanical ventilation, sedation, analgesia or neuromuscular blockade for each neonate for up to 28 days after NICU admission.

RESULTS

Only 2113 of 6648 (31.8%) of neonates received assessments of continuous pain, occurring variably among tracheal ventilation (TrV, 46.0%), noninvasive ventilation (NiV, 35.0%) and no ventilation (NoV, 20.1%) groups (p < 0.001). Daily assessments for continuous pain occurred in only 10.4% of all neonates (TrV: 14.0%, NiV: 10.7%, NoV: 7.6%; p < 0.001). More frequent assessments of continuous pain occurred in NICUs with pain guidelines, nursing champions and surgical admissions (all p < 0.01), and for newborns <32 weeks gestational age, those requiring ventilation, or opioids, sedatives-hypnotics, general anaesthetics (O-SH-GA) (all p < 0.001), or surgery (p = 0.028). Use of O-SH-GA drugs increased the odds for pain assessment in the TrV (OR:1.60, p < 0.001) and NiV groups (OR:1.40, p < 0.001).

CONCLUSION

Assessments of continuous pain occurred in less than one-third of NICU admissions and daily in only 10% of neonates. NICU clinical practices should consider including routine assessments of continuous pain in newborns.