Multipair Esophageal Electrode Research Articles

Effect and mechanical mechanism of spontaneous breathing on oxygenation and lung injury in mild or moderate animal ARDS

ObjectiveThe present study aimed to determine the effect and mechanical mechanism of spontaneous breathing during mechanical ventilation on oxygenation and lung injury using Beagles dogs mild or moderate acute respiratory distress syndrome (ARDS) model.MethodsAfter inducing mild or moderate ARDS by infusion of oleic acid, Eighteen Beagles dogs were randomly split into Spontaneous breathing group (BIPAPSB, n = 6), and Complete muscle paralysis group (BIPAPPC, n = 6),Six Beagles without ventilator support comprised the control group. Both groups were ventilated for 8 h under BIPAP mode. High-pressure was titrated TV to 6 ml/kg. A multi-pair esophageal balloon electrode catheter was used to measure respiratory mechanics and electromyogram. End-expiratory lung volume (EELV), gas exchange and respiratory variables were recorded in the process of mechanical ventilation. The contents of Interleukin (IL)-6 and IL-8 in lung tissue were measure using qRT-PCR. Besides, lung injury score was calculated in the end of mechanical ventilation.ResultsBased on the comparable setting of ventilator, BIPAPSB group exhibited higher safety peak transpulmonary pressure, abdominal pressure, EELV and P/F(PaO2/FiO2) than BIPAPPC group, whereas mean transpulmonary pressure, the mRNA levels of the IL-6 and IL-8 in the lung tissues and lung injury score in BIPAPSB group were lower than those in BIPAPPC group.ConclusionIn mild to moderate ARDS animal models, during mechanical ventilation, SB may improve respiratory function and reduce ventilator-induced lung injury. The mechanism may be that spontaneous inspiration up-regulates peak transpulmonary pressure and EELV; Spontaneous expiration decreases mean transpulmonary pressure by up-regulating intra-abdominal pressure, thereby reducing stress and strain.

Effects of the Elevation Training Mask® 2.0 on dyspnea and respiratory muscle mechanics, electromyography, and fatigue during exhaustive cycling in healthy humans

ObjectivesExamine the effects of the Elevation Training Mask® 2.0 (ETM) on dyspnea, and respiratory muscle function and fatigue during exercise. DesignRandomized crossover. Methods10 healthy participants completed 2 time-to-exhaustion (TTE) cycling tests while wearing the ETM or under a sham control condition. During the sham, participants were told they were breathing air equivalent to “9000 ft” (matched to the selected resistance valves on the ETM according to the manufacturer), but they were breathing room air. Dyspnea and leg discomfort were assessed using the modified 0–10 category-ratio Borg scale. Qualitative dyspnea descriptors at peak exercise were selected from a list of 15. Crural diaphragmatic electromyography (EMGdi) and transdiaphragmatic pressure (Pdi) were measured via a multipair esophageal electrode balloon catheter. Participants performed maximal respiratory maneuvers before and after exercise to estimate the degree of respiratory muscle fatigue. ResultsExercise with the ETM resulted in a significant decrease in TTE (p = 0.015), as well as increased dyspnea at baseline (p = 0.032) and during the highest equivalent submaximal exercise time (p = 0.0001). The increase in dyspnea with the ETM was significantly correlated with the decrease in exercise time (r = 0.73, p = 0.020). EMGdi and Pdi were significantly increased with the ETM at all time points (all p < 0.05). There was a significant increase in the selection frequency of “my breath does not go in all the way” at peak exercise with the ETM (p = 0.02). The ETM did not induce respiratory muscle fatigue. ConclusionsExercising with the ETM appears to decrease exercise performance, in part, by increasing the sensation of dyspnea.

The control of respiratory pressures and neuromuscular activation to increase force production in trained martial arts practitioners.

The mechanisms that explain the ability of trained martial arts practitioners to produce and resist greater forces than untrained individuals to aid combat performance are not fully understood. We investigated whether the greater ability of trained martial arts practitioners to produce and resist forces was associated with an enhanced control of respiratory pressures and neuromuscular activation of the respiratory, abdominal, and pelvic floor musculature. Nine trained martial arts practitioners and nine untrained controls were instrumented with skin-surface electromyography (EMG) on the sternocleidomastoid, rectus abdominis, and the group formed by the transverse abdominal and internal oblique muscles (EMGtra/io). A multipair oesophageal EMG electrode catheter measured gastric (Pg), transdiaphragmatic (Pdi), and oesophageal (Pe) pressures and EMG of the crural diaphragm (EMGdi). Participants performed Standing Isometric Unilateral Chest Press (1) and Standing Posture Control (2) tasks. The trained group produced higher forces normalised to body mass2/3 (0.033 ± 0.01 vs. 0.025 ± 0.007N/kg2/3 mean force in Task 1), lower Pe, and higher Pdiin both tasks. Additionally, they produced higher Pg (73 ± 42 vs. 49 ± 19 cmH2O mean Pg) and EMGtra/ioin Task 1 and higher EMGdiin Task 2. The onset of Pgwith respect to the onset of force production was earlier, and the relative contributions of Pg/Pe and Pdi/Pe were higher in the trained group in both tasks. Our findings demonstrate that trained martial arts practitioners utilised a greater contribution of abdominal and diaphragm musculature to chest wall recruitment and higher Pdi to produce and resist higher forces.

The effect of diaphragm fatigue on the multidimensional components of dyspnoea and diaphragm electromyography during exercise in healthy males

Diaphragm fatigue may increase the intensity (sensory dimension) and unpleasantness (affective dimension) of dyspnoea, which may partially explain why diaphragm fatigue negatively affects exercise performance. We hypothesized that diaphragm fatigue would negatively affect exercise performance via increases in both the intensity and unpleasantness of dyspnoea, and that the increase in dyspnoea would be mechanistically linked to an increase in diaphragmatic EMG (EMGdi ), a surrogate measure of neural respiratory drive. Fatiguing the diaphragm prior to exercise reduced cycling performance and increased both the intensity and unpleasantness of dyspnoea. The change in submaximal dyspnoea unpleasantness was significantly correlated with the change in cycling performance. Pre-fatigue of the diaphragm did not increase EMGdi during exercise and is therefore unrelated to the increase in either the sensory or affective dimension of exertional dyspnoea. The purpose of this study was to examine the effect of diaphragm fatigue on the multidimensional components of dyspnoea and diaphragm electromyography (EMGdi ) during cycling. Sixteen healthy males (age=27±5yr, =45.8±9.8mlkg-1 min-1 ) completed two high-intensity, time-to-exhaustion cycling tests in randomized order: (i) inspiratory pressure threshold loading (PTL) prior to exercise to induce diaphragm fatigue (pre-DF) and (ii) no PTL (control). Diaphragm fatigue after PTL was confirmed via cervical magnetic stimulation of the phrenic nerves. Dyspnoea intensity and unpleasantness were measured throughout exercise with the 0-10 category-ratio Borg scale and following exercise using the Multidimensional Dyspnoea Profile (MDP). EMGdi was continuously recorded via a multipair oesophageal electrode catheter. Time-to-exhaustion decreased with pre-DF vs. control (9.0±5.5 vs. 10.7±7.5min, P=0.023). Pre-DF increased dyspnoea intensity ratings by 0.6±1.0 Borg 0-10 units at the highest equivalent submaximal exercise time (HESET) a participant could achieve in both conditions (P=0.020). Dyspnoea unpleasantness ratings increased with pre-DF by 0.5±1.0, 0.7±1.2 and 0.9±1.4 (all P<0.05) Borg 0-10 units during the 2nd, 3rd and 4th minutes of exercise, respectively. There was a significant correlation between the change in breathing unpleasantness ratings at HESET and the change in time-to-exhaustion (r=0.66, P=0.006). The immediate perception domain, a combination of peak unpleasantness and specific dyspnoea descriptor intensity ratings, was the only component of the MDP that was significantly increased with pre-DF (4.3±1.9 vs. 3.6±1.8, P=0.04). There were no significant differences in EMGdi . In conclusion, diaphragm fatigue has negative effects on multiple domains of dyspnoea, which may partially explain why exercise performance decreases with it.

Correlation of surface respiratory electromyography with esophageal diaphragm electromyography

ObjectivesTo assess the correlation between surface respiratory electromyography(sEMG) and esophageal diaphragm electromyography(EMGdi) at different levels of neural respiratory drive (NRD). DesignRandomised parallel design controlled trial. SettingThe First Affiliated Hospital of Guangzhou Medical University. Participants15 healthy subjects and 1 severe to very severe stable COPD patients were studied. Interventions15 healthy subjects performed incremental inspiratory threshold loading (ILT) and 15 stable COPD patients underwent noninvasive positive pressure ventilation (NPPV).The correlation between EMGdi and sEMG at different NRD levels was analyzed. EMGdi was performed with a multi-pair esophageal electrode catheter; sEMG were was performed by surface diaphragm EMG(located in right anterior axillary line and left anterior axillary line respectively expressed as sEMGdi(r) andsEMGdi(l))、surface parasternal EMG(sEMGpara),and surface sternocleidomastoid EMG(sEMGsc).Signals were normalized using the peak EMG expressed as EMG%max. Primary and secondary outcome measuresThe mean ± standard deviation resting EMGdi%max was higher in patients with COPD than in healthy subjects (57.26%±15.45% vs13.64% ±4.96%, respectively; p < 0.001).During ILT and NPPV, EMGdi was correlated with sEMGdi (r), sEMGdi (1), sEMGpara and sEMGsc (r = 0.90, 0.87, 0.90, 0.90 and r = 0.92, 0.83, 0.92 and 0.71, respectively; all P < 0.001). ConclusionA strong relationship is present between NRD measured by EMGdi%max and NRD measured by sEMG%max. sEMG%max serves as a non-invasive marker of NRD.

Diaphragm Recruitment Increases during a Bout of Targeted Inspiratory Muscle Training

The extent to which the diaphragm is targeted during a bout of inspiratory muscle training (IMT) is unknown. The purpose of this study was to characterize the relative activation patterns of the diaphragm and extradiaphragmatic inspiratory muscles during a bout of IMT and to determine whether diaphragmatic recruitment can be increased by giving subjects specific diaphragmatic breathing instructions (IMTdi). Ten healthy men were instrumented with surface EMG electrodes on the sternocleidomastoid (EMGscm), scalenes (EMGsca), parasternal intercostals (EMGpic), and seventh intercostal space (EMG7ic). A multipair esophageal electrode catheter measured crural diaphragmatic EMG (EMGdi) and transdiaphragmatic pressure (Pdi). Trial 1 of IMT involved 25 dynamic inspiratory maneuvers at 40% of maximal inspiratory mouth pressure using a variable flow resistive loading device where subjects were free to choose their own inspiratory muscle recruitment strategy. Trial 2 involved the same procedures, but subjects were given specific instructions to actively recruit their diaphragm. Cervical magnetic stimulation of the phrenic nerves verified the absence of diaphragmatic fatigue before commencing the second trial. Compared with IMT, IMTdi resulted in a significant increase in EMGdi (56 ± 12 vs 73 ± 10%max, P = 0.002) and Pdi swings (39 ± 14 vs 64 ± 17 cm H2O, P < 0.0001) and a decrease in EMGsca (52 ± 21 vs 36 ± 22%max, P = 0.04). There was no difference in EMG7ic (26 ± 19 vs 33 ± 21%max, P = 0.36), EMGpic (31 ± 24 vs 25 ± 15%max, P = 0.22), and EMGscm (58 ± 21 vs 45 ± 24%max, P = 0.08) when comparing IMT versus IMTdi, respectively. Simple diaphragmatic breathing instructions can significantly increase the recruitment of the diaphragm during IMT compared with a bout of IMT where individuals are free to choose their own inspiratory muscle recruitment strategy.

Distinguishing central from obstructive sleep apnea with chest wall surface electrodes

To determine whether or not diaphragm electromyography recorded from chest wall surface electrodes (EMGsur) can be used to distinguish central from obstructive sleep apnea. Ten patients (age (44 ± 10) years, body mass index (25.9 ± 1.8) kg/m²) with suspected obstructive sleep apnea referred from Guangzhou Institute of Respiratory Disease were studied between January and September 2009. EMGsur and diaphragm electromyography from esophageal electrode (EMGeso) were recorded during conventional overnight full polysomnography. And chest-abdominal movement was measured with chest and abdominal bands. High-quality EMGsur and EMGeso were recorded in all subjects except for one who could not tolerate a multipair esophageal electrode. Excellent correlation was found between EMGsur and EMGeso during sleep including apnea events (r = 0.81 ± 0.06, P < 0.05). The central sleep apnea events diagnosed by EMGeso were exactly the same as those diagnosed by EMGsur. However, the central sleep apnea events diagnosed by EMGsur were less than those diagnosed by conventional thoracic-abdominal bands (7 ± 11 vs 28 ± 31, P < 0.05). EMGsur may be used to distinguish central from obstructive sleep apnea events.

Neural respiratory drive, pulmonary mechanics and breathlessness in patients with cystic fibrosis

BackgroundNeural respiratory drive (NRD) measured from the diaphragm electromyogram (EMGdi) reflects the load/capacity balance of the respiratory muscle pump and is a marker of lung disease severity. EMGdi measurement is...

Efficiency of Neural Drive During Exercise in Patients With COPD and Healthy Subjects

It is unknown whether efficiency of neural drive as expressed by a ratio of ventilation to the diaphragm electromyogram (EMGdi) in patients with COPD differs from that of healthy subjects during exercise and whether maximal neural drive is exhibited at the point of exercise termination. We studied 12 male patients with COPD (mean ± SD age, 62.8 ± 10.3 years; FEV(1), 28.1 ± 10.2% predicted) and 12 age- and sex-matched healthy subjects (age, 61.1 ± 7.2 years, FEV(1), 101.5 ± 11.9% predicted). EMGdi was recorded from a multipair esophageal electrode during a constant work (80% of maximal oxygen consumption derived from a previous incremental exercise test) treadmill exercise. Minute ventilation and oxygen consumption were also measured. Root mean square (RMS) of the EMGdi increased initially and reached a plateau at submaximal drive during constant load exercise in both patients with COPD and healthy subjects. The ratio of ventilation to EMGdi remained stable during exercise in healthy subjects from beginning to the end (100% ± 70% at the beginning and 100% ± 39% at the end, P > .05), whereas the ratio decreased gradually during exercise in patients with COPD (from 85% ± 66% to 42% ± 13%, P < .05). Efficiency of neural drive decreases in patients with COPD during treadmill exercise. Neural respiratory drive reached a submaximal plateau during constant load exercise in both healthy subjects and patients with COPD, indicating that it may not be the only factor determining exercise capacity.

Diaphragm electromyogram in infants with abdominal wall defects and congenital diaphragmatic hernia

Measurement of the diaphragm electromyogram (EMGdi) elicited by phrenic nerve stimulation could be useful to assess neonates suffering from respiratory distress due to diaphragm dysfunction, as observed in infants with abdominal wall defects (AWD) or congenital diaphragmatic hernia (CDH). The study aims were to assess the feasibility of recording EMGdi using a multipair oesophageal electrode catheter and examine whether diaphragm muscle and/or phrenic nerve function was compromised in AWD or CDH infants. Diaphragm compound muscle action potentials elicited by magnetic phrenic nerve stimulation were recorded from 18 infants with surgically repaired AWD (n = 13) or CDH (n = 5), median (range) gestational age 36.5 (34-40) weeks. Diaphragm strength was assessed as twitch transdiaphragmatic pressure (TwP(di)). One AWD patient had prolonged phrenic nerve latency (PNL) bilaterally (left 9.31 ms, right 9.49 ms) and two CDH patients had prolonged PNL on the affected side (10.1 ms and 10.08 ms). There was no difference in left and right TwP(di) in either group. PNL correlated significantly with TwP(di) in CDH (r = 0.8; p = 0.009). Oesophageal EMG and magnetic stimulation of the phrenic nerves can be useful to assess phrenic nerve function in infants. Reduced phrenic nerve conduction accompanies the reduced diaphragm force production observed in infants with CDH.

Distinguishing Obstructive From Central Sleep Apnea Events: Diaphragm Electromyogram and Esophageal Pressure Compared

Distinguishing central sleep apnea (CSA) from obstructive sleep apnea (OSA) can be clinically important because different types of apnea may require different treatment approaches. Academically, this distinction is important for investigating the pathological mechanism of different types of sleep apnea. Conventional polysomnography (PSG) with recording of chest and abdominal movement may overestimate the frequency of CSA, leading to inappropriate treatment of sleep-disordered breathing. We hypothesized that diaphragm electromyogram (EMGdi) could be a useful technique to assess neural respiratory drive and respiratory effort and, therefore, to distinguish accurately CSA from OSA. A multipair esophageal electrode catheter mounted with a balloon was used to record the EMGdi and esophageal pressure (Pes) during overnight PSG. Nineteen patients were included in the study, 12 of whom had previously been identified as having central apnea-hypopnea on a diagnostic PSG undertaken for symptoms that suggest OSA and 7 of whom were known to have heart failure. A good relationship was found between the swing of Pes and the root mean (+/- SD) square of the EMGdi during OSA events (0.89 +/- 0.10). About one third of CSA events diagnosed by uncalibrated respiratory inductance plethysmography could not be confirmed by Pes or EMGdi. No difference was found in the number of CSAs diagnosed by Pes (1,319) vs EMGdi (1,293; p > 0.01). We conclude that both Pes and EMGdi measurements are useful in accurately differentiating central from obstructive respiratory events. Conventional PSG with recording of chest and abdominal movement overestimates the frequency of CSA events.

Neural respiratory drive in healthy subjects and in COPD

The aim of the present study was to use the diaphragm electromyogram (EMG(di)) to compare levels of neural respiratory drive (NRD) in a cohort of healthy subjects and chronic obstructive pulmonary disease (COPD) patients, and to investigate the relationship between NRD and pulmonary function in COPD. EMG(di) was recorded at rest and normalised to peak EMG(di) recorded during maximum inspiratory manoeuvres (EMG(di) % max) in 100 healthy subjects and 30 patients with COPD, using a multipair oesophageal electrode. EMG(di) was normalised to the amplitude of the diaphragm compound muscle action potential (CMAP(di,MS)) in 64 healthy subjects. The mean+/-sd EMG(di) % max was 9.0+/-3.4% in healthy subjects and 27.9+/-9.9% in COPD patients, and correlated with percentage predicted forced expiratory volume in one second, vital capacity and inspiratory capacity in patients. EMG(di) % max was higher in healthy subjects aged 51-80 yrs than in those aged 18-50 yrs (11.4+/-3.4 versus 8.2+/-2.9%, respectively). Observations in the healthy group were similar when peak EMG(di) or CMAP(di,MS) were used to normalise EMG(di). Levels of neural respiratory drive were higher in chronic obstructive pulmonary disease patients than healthy subjects, and related to disease severity. Diaphragm compound muscle action potential could be used to normalise diaphragm electromyogram if volitional inspiratory manoeuvres could not be performed, allowing translation of the technique to critically ill and ventilated patients.

Diaphragm electromyography using an oesophageal catheter: current concepts

The usefulness of diaphragm electromyography recorded from an oesophageal electrode depends on a reliable signal which is free of artefact. The diaphragm EMG (electromyogram) recorded from chest wall surface electrodes may be unreliable because of signal contamination from muscle activity other than the diaphragm. Initially, the oesophageal electrode catheter for human studies had only one electrode pair, which could be difficult to position accurately and was influenced by a change in lung volume. Recently, a multipair oesophageal electrode has been developed which allows a high-quality EMG to be recorded. In the present review, the progress of oesophageal electrode design is outlined. The effects of signal contamination, electrode movement and particularly the effect of change in lung volume on the diaphragm EMG are discussed. The diaphragm EMG, recorded from a multipair oesophageal electrode, is useful to assess neural respiratory drive and diaphragm function in different groups of patients with respiratory disease, including patients with neuromuscular disease and sleep-disordered breathing, and those in the intensive care unit. When combined with cervical and cranial magnetic stimulation, an oesophageal electrode can be used to partition the central respiratory response time and phrenic nerve conduction time.

Assessment of diaphragm paralysis with oesophageal electromyography and unilateral magnetic phrenic nerve stimulation.

The purpose of this study was to establish a sensitive and reliable method of diagnosing diaphragm paralysis by recording the diaphragm compound muscle action potential (CMAP) using a multipair oesophageal electrode and unilateral magnetic phrenic nerve stimulation. An oesophageal electrode catheter was designed containing six coils (1 cm wide and 3 cm apart), creating an array of four sequential electrode pairs. The oesophageal catheter was taped at the nose with the proximal electrode pair 40 cm from the nares. Eight patients with unilateral (n=5) or bilateral (n=3) diaphragm paralysis were studied. Five to seven phrenic nerve stimulations were performed at 80% of maximum magnetic stimulator output and the CMAPs were recorded simultaneously from the four pairs of electrodes. In the five patients with unilateral diaphragm paralysis, the CMAP amplitudes and latencies were 1.16+/-0.29 mV and 7.6+/-1.5 ms for functioning sides. No diaphragm CMAP could be detected when stimulating nonfunctioning phrenic nerves. This study shows that diaphragm paralysis can be reliably diagnosed by unilateral magnetic stimulation combined with a multipaired oesophageal electrode.

Nvestigation of force of leg muscles in fencing and judo sports

Examine the effects of the Elevation Training Mask® 2.0 (ETM) on dyspnea, and respiratory muscle function and fatigue during exercise.Randomized crossover.10 healthy participants completed 2 time-to-exhaustion (TTE) cycling tests while wearing the ETM or under a sham control condition. During the sham, participants were told they were breathing air equivalent to “9000 ft” (matched to the selected resistance valves on the ETM according to the manufacturer), but they were breathing room air. Dyspnea and leg discomfort were assessed using the modified 0–10 category-ratio Borg scale. Qualitative dyspnea descriptors at peak exercise were selected from a list of 15. Crural diaphragmatic electromyography (EMGdi) and transdiaphragmatic pressure (Pdi) were measured via a multipair esophageal electrode balloon catheter. Participants performed maximal respiratory maneuvers before and after exercise to estimate the degree of respiratory muscle fatigue.Exercise with the ETM resulted in a significant decrease in TTE (p = 0.015), as well as increased dyspnea at baseline (p = 0.032) and during the highest equivalent submaximal exercise time (p = 0.0001). The increase in dyspnea with the ETM was significantly correlated with the decrease in exercise time (r = 0.73, p = 0.020). EMGdi and Pdi were significantly increased with the ETM at all time points (all p < 0.05). There was a significant increase in the selection frequency of “my breath does not go in all the way” at peak exercise with the ETM (p = 0.02). The ETM did not induce respiratory muscle fatigue.Exercising with the ETM appears to decrease exercise performance, in part, by increasing the sensation of dyspnea.