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.

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.

Zinc protoporphyrin/heme ratio as parameter of iron status in moderately preterm infants: natural course and associations in the first 4 months.

OBJECTIVE: To determine the natural course of zinc protoporphyrin/heme ratio (ZnPP/H) and its role in the detection of iron deficiency (ID) and iron-deficiency anemia (IDA) in the first 4 months of life in moderately preterm infants. STUDY DESIGN: ZnPP/H was measured at 1 week, 6 weeks and 4 months postnatal age in a prospective cohort of 161 Dutch infants born at a gestational age of 32+0 to 36+6 weeks who did not receive an erythrocyte transfusion or iron supplementation. RESULTS: ZnPP/H levels decreased in the first 6 weeks and increased thereafter. At 4 months postnatal age, ZnPP/H was higher in the 11 (8.5%) infants with IDA (mean (s.d.): 260.8 (16.1)) but not in the 27 (21.3%) infants with ID (mean (s.d.): 177.0 (15.1)) compared with normal infants (mean (s.d.): 157.3 (12.5)). CONCLUSION: In moderately preterm infants, ZnPP/H can be of additional value to detect infants at risk for IDA due to iron-deficient erythropoiesis at 4 months of age.