Waterproofing EMG Instrumentation

Abstract

While still experimental, measurement of external uterine electromyographic (EMG) activity is a more sensitive and noninvasive method for measuring uterine contractility in human labor than the methods currently used in clinical practice. Hydrotherapy is purported to improve contractility in labor, yet there have been no reports of abdominal uterine EMG activity measured during immersion. To test telemetric EMG equipment and different waterproofing techniques under dry and immersed conditions, the authors recorded surface EMG activity from the abdominal muscles of 11 healthy, nonpregnant women, 22 to 51 years of age. After attaching one pair of electrodes to the skin on either side of the umbilicus and applying the waterproofing material, the authors tested the signal by asking participants to perform a short series of leg lifts while seated in a chair to evoke abdominal muscle contractions. They were then immersed to the chest in a hydrotherapy tub while performing two to three leg lifts over 60 s every 5 min for 60 min with 20 lb of weight suspended from their ankles to counteract the buoyancy effect of water. EMG activity was continuously recorded. They then repeated the dry-measures sequence. While waterproofing remained intact, EMG signals were essentially unchanged between dry and wet conditions. Of the 11 waterproofing applications tested, 10 failed at some point. In the data from the successful application, EMG signals in both channels exhibited stable baselines throughout and an absence of low-frequency artifact. The development of this technique allows for the recording of external uterine EMG activity during hydrotherapy. The authors have begun using it to investigate the effects of hydrotherapy on uterine contractility during human labor.

Comparison and reproducibility of sEMG during manual muscle testing on land and in water

“…For example, Benfield et al (2007) noted distinct visual aberrations in sEMG baseline stability when surface electrodes were exposed to water. Consequently, prior to water immersion, each set of electrodes ( Fig.…”

“…Holes were cut in the center of the OpSite™ to access the electrode snaps. The covered electrodes and area around each electrode site were sprayed with a waterproof adhesive (Nexcare™ Spray Liquid Bandage, 3M, St. Paul, MN) as described by Benfield et al (2007). After attaching the electrode wires ( Fig.…”

“…An overlooked factor in underwater sEMG literature that may produce discrepancies, perhaps, is the integrity of sEMG recordings in water (Benfield et al, 2007;Masumoto and Mercer, 2008;Rainoldi et al, 2004;Veneziano et al, 2006). The use of indwelling needle electrodes obviates the need for waterproofing (Nuber et al, 1986;Perry, 1992), but surface electrodes require insulation from water contact between the electrode and skin interface and the electrode and lead connection.…”

“…The use of indwelling needle electrodes obviates the need for waterproofing (Nuber et al, 1986;Perry, 1992), but surface electrodes require insulation from water contact between the electrode and skin interface and the electrode and lead connection. Typical waterproofing procedures involve covering the electrodes with a water-resistant adhesive film, such as Tegaderm Ò or Opsite Ò (Benfield et al, 2007;Caty et al, 2007;Chevutschi et al, 2007;Rouard and Clarys, 1995), putty applied to electrodes and covered by an adhesive bandage (Kaneda et al, 2007) and also may include an additional layer using a foam pad (Masumoto and Mercer, 2008). Clarys et al (1983) and Rouard et al (1988) used two adhesive bandages covered by an adhesive disc and plastic varnish.…”

Respostas eletromiográficas induzidas pelo isolamento e pela imersão sobre os eletrodos de superfície

“…No entanto, recentemente, as pesquisas de Rainoldi et al (26) e Veneziano et al (30) mostraram que a amplitude do sinal EMG pode ser semelhante entre os meios aquático e terrestre, quando alguns fatores são controlados, tais como tipo de protocolo, temperatura da pele, que reflete a temperatura muscular e utilização de isolamento adequado sobre os eletrodos. De acordo com o estudo de Benfield et al (4) e Rainoldi et al (26) , a utilização de isolamento sobre os eletrodos de superfície para as coletas realizadas no meio líquido é de fundamental importância, uma vez que o movimento da água sobre os eletrodos pode introduzir artefatos de baixas freqüências no sinal EMG. Logo, a utilização de adesivos, que impedem a entrada e contato da água com os eletrodos, é a melhor solução para manter inalterada a freqüência e a amplitude do sinal EMG.…”