Processing transcutaneous electromyography measurements of respiratory muscles, a review of analysis techniques.

Transcutaneous electromyography (tc-EMG) has been used to measure the electrical activity of respiratory muscles during inspiration in various studies. Processing the raw tc-EMG signal of these inspiratory muscles has shown to be difficult as baseline noise, cardiac interference, cross-talk and motion artefacts can influence the signal quality. In this review we will discuss the most important sources of signal noise in tc-EMG of respiratory muscles and the various techniques described to suppress or reduce this signal noise. Furthermore, we will elaborate on the options available to develop or improve an algorithm that can be used to guide the approach for analysis of tc-EMG signals of inspiratory muscles in future research.

Effectiveness of Stabilization of Preterm Infants With Intact Umbilical Cord Using a Purpose-Built Resuscitation Table-Study Protocol for a Randomized Controlled Trial.

Background: Most preterm infants fail to aerate their immature lungs at birth and need respiratory support for cardiopulmonary stabilization. Cord clamping before lung aeration compromises cardiovascular function. Delaying cord clamping until the lung has aerated may be beneficial for preterm infants by optimizing hemodynamic transition and placental transfusion. A new purpose-built resuscitation table (the Concord) has been designed making it possible to keep the cord intact after preterm birth until the lung is aerated and the infant is respiratory stable and breathing [Physiological-Based Cord Clamping (PBCC)]. The aim of this study is to test the hypothesis whether stabilizing preterm infants by PBCC is at least as effective as the standard approach using time-based Delayed Cord Clamping (DCC). Study design: This is a randomized controlled non-inferiority study including 64 preterm infants born at <32 weeks of gestation. Infants will be randomized to either the PBCC approach or standard DCC. In case of PBCC, infants will be stabilized with an intact umbilical cord and the cord will only be clamped when the infant is considered respiratory stable, defined as the establishment of regular spontaneous breathing, a heart rate ≥100 bpm and oxygen saturation above 90% while using inspired fraction of oxygen (FiO2) < 0.40. The Concord will be used, which allows giving respiratory support with an intact umbilical cord. In the DCC group infants are clamped first before they are transferred to the standard resuscitation table for further treatment and stabilization. Cord clamping is time-based and delayed at 30-60 s. The primary outcome will be the time to respiratory stability of the infant, starting from birth. Secondary outcomes will include details of stabilization, important clinical outcomes of prematurity and maternal safety outcomes. Discussion: We expect that PBCC using the Concord may reduce major morbidities and mortality in preterm infants. The current study protocol will assess the effectivity of stabilization. Once effectivity of stabilization is confirmed, we will start a large multicenter randomized clinical trial to investigate whether PBCC reduces mortality and morbidity in preterm infants compared to the standard approach. Trial registration: Netherlands Trial Registry NTR7194, registered on April 20th, 2018.

Electrical activity of the diaphragm during nCPAP and high flow nasal cannula.

OBJECTIVE: To determine if the electrical activity of the diaphragm, as measure of neural respiratory drive and breathing effort, changes over time in preterm infants transitioned from nasal continuous positive airway pressure (nCPAP) to high flow nasal cannula (HFNC). DESIGN: Prospective observational study. SETTING: Neonatal intensive care unit. PATIENTS: Stable preterm infants transitioned from nCPAP to HFNC using a 1:1 pressure to flow ratio. INTERVENTIONS: The electrical activity of the diaphragm was measured by transcutaneous electromyography (dEMG) from 30 min before until 3 hours after the transition. MAIN OUTCOME MEASURES: At eight time points after the transition to HFNC, diaphragmatic activity was compared with the baseline on nCPAP. Percentage change in amplitudedEMG, peakdEMG and tonicdEMG were calculated. Furthermore, changes in respiratory rate, heart rate and fraction of inspired oxygen (FiO2) were analysed. RESULTS: Thirty-two preterm infants (mean gestational age: 28.1±2.2 weeks, mean birth weight: 1118±368 g) were included. Compared with nCPAP, the electrical activity of the diaphragm did not change during the first 3 hours on HFNC (median (IQR) change in amplitudedEMG at t=180 min: 2.81% (-21.51-14.10)). The respiratory rate, heart rate and FiO2 remained stable during the 3-hour measurement. CONCLUSIONS: Neural respiratory drive and breathing effort assessed by electrical activity of the diaphragm is similar in the first 3 hours after transitioning stable preterm infants from nCPAP to HFNC with a 1:1 pressure-to-flow ratio.

A literature review of the methodology of EMG recordings of the diaphragm.

INTRODUCTION: EMG measurements of the diaphragm (rEMG) provide insight in to ventilatory muscle activity. Applicability of these measurements has improved, but literature of the different rEMG measurement techniques is inconsistent. This makes it difficult to compare studies of rEMG technique. This study summarizes the current available literature on rEMG and focuses on the validation of the techniques. Furthermore, we propose to use validation criteria to improve the quality, for further research. METHODS: Pubmed, Ovid Medline and EMBASE were searched for studies describing rEMG experiments with transcutaneous (tc-rEMG) and/or transesophageal (te-rEMG) methods.Validation criteria included feasibility, repeatability, signal disturbance and ECG gating. RESULTS: 650 studies were eligible for reviewing; 211 were excluded, and 39 articles described the measurement technique and were analyzed according to the criteria. 194 studies referred to another paper with a description of the technique and 206 failed to describe the technique nor had references to it. CONCLUSIONS: Many studies showed neither a description of the technique used, nor a validation of this technique. Others referred to studies that described the measurement technique. We propose that future studies on rEMG measurements at least meet the above mentioned criteria, in order to be able to compare study results.

Optimized temperature and deadspace correction improve analysis of multiple breath washout measurements by ultrasonic flowmeter in infants.

BACKGROUND: Assessment of lung volume (FRC) and ventilation inhomogeneities with ultrasonic flowmeter and multiple breath washout (MBW) has been used to provide important information about lung disease in infants. Sub-optimal adjustment of the mainstream molar mass (MM) signal for temperature and external deadspace may lead to analysis errors in infants with critically small tidal volume changes during breathing. METHODS: We measured expiratory temperature in human infants at 5 weeks of age and examined the influence of temperature and deadspace changes on FRC results with computer simulation modeling. A new analysis method with optimized temperature and deadspace settings was then derived, tested for robustness to analysis errors and compared with the previously used analysis methods. RESULTS: Temperature in the facemask was higher and variations of deadspace volumes larger than previously assumed. Both showed considerable impact upon FRC and LCI results with high variability when obtained with the previously used analysis model. Using the measured temperature we optimized model parameters and tested a newly derived analysis method, which was found to be more robust to variations in deadspace. Comparison between both analysis methods showed systematic differences and a wide scatter. CONCLUSION: Corrected deadspace and more realistic temperature assumptions improved the stability of the analysis of MM measurements obtained by ultrasonic flowmeter in infants. This new analysis method using the only currently available commercial ultrasonic flowmeter in infants may help to improve stability of the analysis and further facilitate assessment of lung volume and ventilation inhomogeneities in infants.