Diaphragm electromyography using an oesophageal catheter: current concepts

Abstract

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.

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

“…Improvements in amplifier design and signal processing have made it possible to distinguish the EMG signals from different respiratory muscles during spontaneous breathing [22,23]. In contrast, the diaphragm CMAP recorded using an oesophageal electrode is not affected by obesity and less influenced by line artefact and contamination by other muscles [11,19,20] leading to its increasing use as a clinical and research technique [12]. Disadvantages remain however, including discomfort and the risks of regurgitation and aspiration, as well as vagally mediated bradycardia during placement.…”

“…Multipair oesophageal electrode catheters have been developed [11] that provide potentially clearer, less contaminated signals than those from surface electrodes [11,12] and the technique is less invasive than needle electrodes. In addition, the phrenic nerve latency (PNL) and compound muscle action potential (CMAP) amplitude are reproducible as the catheter can be positioned accurately at the electrically active centre of the diaphragm [13].…”

Desafios Na Captação Do Sinal De Eletromiográfico Do Músculo Diafragma

“…A SENIAM não possui recomendações para o uso do EMG nos músculos respiratórios [9]. A eletromiografia pode ser um exame com muitas vantagens, mas para avaliação diafragmática pode haver abrangência de mais de uma unidade motora, por ser um musculo profundo a proximidade de músculos na inserção do diafragma podem comprometer o sinal adquirido por contaminação, a gordura abdominal subcutânea pode dificultar a captação de sinal, alterações posturais também dificultam a fixação dos eletrodos [9,10].…”

Hot Topics in Noninvasive Ventilation: Report of a Working Group at the International Symposium on Sleep-Disordered Breathing in Leuven, Belgium

“…The operator must be experienced in placing the catheter in a conscious subject to acquire a diaphragm EMG signal, and there are also concerns that the signal may be affected by a cardiac artifact, changes in body position, and lung volume. 178,179 The second intercostal space parasternal intercostal muscles are obligate inspiratory muscles that contract in concert with diaphragm muscles during inspiration to stabilize the upper chest wall. [180][181][182] Adjacent to the sternum, second intercostal space parasternal intercostal muscles have inspiratory mechanical advantage with little postural artifact, and mapping the neural respiratory drive of the chestwall muscles has confirmed this to be the point of maximum inspiratory neural respiratory drive.…”