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The activity of the diaphragm during pulmonary transition in preterm infants : a feasibility and physiological study

Kho, Eline (2019) The activity of the diaphragm during pulmonary transition in preterm infants : a feasibility and physiological study.

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Abstract:Introduction: Cardio-pulmonary transition of (preterm) infants in the delivery room (DR) is monitored by heart rate (HR), respiratory rate (RR) and oxygenation using either chest impedance (CI) and/or pulse oximetry (PO). However, CI and PO do not provide information on the respiratory effort of the patient, an essential factor to titrate the level of respiratory support. Electromyography of the diaphragm (dEMG) measures the activity of the diaphragm and might be helpful to determine respiratory effort. In addition, it measures HR and RR, so dEMG might improve monitoring compared to CI. This study evaluates the use of dEMG for monitoring cardio-pulmonary transition. Methods: Inclusion criteria were gestational age (GA) > 26 weeks, and infants in need of cardio-respiratory support and monitoring without congenital anomalies. Measurements were performed during the cardio-respiratory stabilization, starting immediately after birth, using CI, PO, dEMG, and a flow sensor (measuring pressure and flow at the infants mask). First, the accuracy of dEMG in measuring HR was compared to techniques currently available in the DR. Time between device application on the infant and the first read out of the corresponding HR was calculated (∆t) for CI, PO and dEMG. HR was calculated, using the dEMG and the raw CI waveform, and acquired from the patient monitor, using CI and PO data. RR was calculated using the dEMG and compared to numerical flow and CI based RR-readings. All HR- and RR-readings during periods of noise-free recordings were compared using the intra-class correlation coefficient (ICC) and Bland-Altman analysis (mean difference and limits of agreement (LOA)). Second, an observational study was performed to describe the function of the diaphragm during cardio-pulmonary transition. dEMG parameters (amplitude and tonic activity) and the flow parameter (tidal inspiratory volume (VTi)) were assessed over time. The correlation between amplitude and VTi was assessed, as well as the time difference between the dEMG and flow signal in start inspiration (tRIA), and the expiration flow versus tonic activity (tPIA). Results: Fourteen preterm infants (GA 32.5 ± 3.0 weeks; birth weight 1743 ± 790 grams) were included. Due to technical issues, not all patients were measured with all techniques. Time between device application and the first HR read out was fastest for the dEMG and raw CI signal (both with median (interquartile range): 10.1 (10.1-10.3) seconds). dEMG and raw CI in monitoring heart rate showed the best agreement in Bland-Altman analysis (mean difference (LOA): -0.5 (6.8) beats/minutes) and a high ICC of 0.98 (p < 0.01, n = 8). RR analysis showed moderate correlations, with the highest ICC of 0.77 between dEMG and flow (mean difference (LOA): 0.1 (16.5) respirations/minute, n = 6). dEMG parameters and VTi decreased over time, and a poor correlation between the amplitude and VTi was found. Time parameters tRIA and tPIA were positive, so the diaphragmatic activity started prior to flow inspiration and ended after the start of flow expiration (n < 10). Conclusion: This study suggests that dEMG monitoring during cardio-pulmonary transition in the DR is feasible and provides fast and accurate data on HR, similar to CI and faster than PO. Preliminary observational outcomes based on the limited number of patients show a higher respiratory effort in the first minutes after birth. Future studies should focus on increasing the number of patients, to better assess the respiratory effort with diaphragmatic activity and investigate the effect of respiratory support on the diaphragmatic activity. This should eventually aid the physician in titrating respiratory support in the DR.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine, 50 technical science in general
Programme:Technical Medicine MSc (60033)
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