Skin Surface Electrodes Research Articles

Ventilation in the horse with stimuli applied to skin‐surface electrodes

Ventilation in the horse with stimuli applied to skin‐surface electrodes

In vivo response times for a heated skin surface CO2 electrode during rest and exercise.

The continuous, noninvasive estimation of arterial carbon dioxide tension (PaCO2) by heated skin surface electrodes has recently become available for pediatric patients. Skin surface (PsCO2) electrodes can enhance the safety of procedures such as intubation, bronchoscopy, ventilator changes, sleep studies, or measurement of the ventilatory response to CO2 or hypoxia. However, clinical situations that include rapid changes in PaCO2 demand knowledge of the in vivo response time. We compared the response of a heated PsCO2 electrode to end tidal CO2 (PetCO2) during abrupt changes in inspired CO2 from room air to 7% CO2 and back to room air. We obtained 54 curves on nine healthy subjects. There was an initial lag time with less than a 10% change in PsCO2. Then PsCO2 approached PetCO2 exponentially. For subjects at rest changing from breathing room air to 7% CO2, the initial lag time was 40 +/- 2 seconds and the 50% response time of the exponential portion was 46 +/- 3 seconds. Thus, it took 86 seconds for the electrode to record a 60% response to an abrupt increase in inspired CO2. The initial lag and 50% response time were considerably shorter during exercise (30 +/- 2 and 33 +/- 2 seconds) and even shorter when switched from breathing 7% CO2 to room air (23 +/- 2 and 21 +/- 2 seconds). Exercise did not further reduce the response time when CO2 was initially elevated, suggesting the faster response time was due to vasodilation of the skin due to elevated CO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Choice of the Optimum Pulse Duration for Precordial Cardiac Pacing: A Theoretical Study

In precordial pacing with skin-surface electrodes, the goal is to excite the ventricles with minimal stimulation of overlying tissues. A theoretical analysis is presented to identify the relevant factors; the two most important are electrode location and pulse duration. Using the basic law of stimulation, we developed a model which indicates that the optimum pulse duration for the closed-chest pacing pulse is one that is long with respect to the membrane time constant of cardiac muscle. Current-versus-duration curves are presented for pacing and pain, based on experimentally obtained data. For pacing with minimum pain, the optimum stimulus duration was found to be about 10 ms.

Human sympathetic electrical activity recorded with skin surface electrodes

Spontaneous electrical activity correlated to cardiac rhythm has been recorded with electrodes placed on the surface of the human arm or using the rabbit hindlimb. The signal-to-noise ratio has been improved using record averaging synchronized with the ECG. The recorded activity in man is a slow negative wave of sinusoid-like shape with a mean peak amplitude 0.08 ± 0.03 μV. The sympathetic origin of this activity is suggested by the facts that its time course and conduction velocity are similar to those of integrated spontaneous electrical activity, recorded directly from postganglionic sympathetic fibers in the rabbit, and that it can be recorded from skin surface as a response to direct electrical stimulation of sympathetic nerve fibers in the same animal.

Estimation of ventilatory response to carbon dioxide in newborn infants using skin surface blood gas electrodes

Using only skin surface blood gas measurements, we calculated the ventilatory response to inhaled carbon dioxide from changes in skin surface PCO2 (PSCO2). This new method is based on the fact that if CO2 elimination is nearly constant, the change in alveolar ventilation from one steady state level to another is inversely proportional to the change in PSCO2. From this we derived a ventilatory ratio (VR) for 0%, 2%, and 4% CO2 breathing. A ventilatory response slope is then calculated from the three VR values, and is similar to a standard CO2 response slope. We serially studied 20 infants (28 to 40 weeks gestation) 2 to 9 weeks of age. Ten infants had serious apnea, ten did not. The infants breathed each test gas for 8 to 10 minutes during quiet sleep with skin surface electrodes attached. Infants with apnea were studied before and after apneic spells resolved. We found that apneic infants had a significantly reduced VR slope compared with that in the nonapneic infants, regardless of age. When apnea disappeared, the ventilatory ratio slope always increased into the range measured in nonapneic infants. In nonapneic infants the ventilatory ratio slope significantly increased with postnatal age. We conclude that infants with serious apnea have a reduced ventilatory response to CO2 and that the resolution of apnea is associated with the development of a normal CO2 response.

Method and apparatus for generating electrocutaneous stimulation patterns for the transmission of acoustic information

In an exemplary embodiment, the point of departure is that of a substitute signal system for deaf individuals which codes acoustical signals, in particular speech sound, into electrocutaneous stimulation patterns. Current pulse patterns serve as substitute signals which, via skin surface electrodes, e.g. on the forearm, bring about sensory patterns which can be interpreted as speech information. To this end, the sound signal is separated with band pass filters into e.g. twelve component signals characteristic for the recognition of speech, whose levels are converted into pulse durations, whereby the dependency of the sensation intensity upon the stimulation parameters is taken into account. The mean frequencies of the band pass filters are associated with a corresponding number of locations on the forearm (i.e. in the present example twelve). A simulation of lateral inhibition suppresses irrelevant spectral components and thus acts in a selectivity-increasing (or enhancing) fashion. It is thereby possible that, after only approximately fifteen hours of practice, ten monosyllabic words are correctly recognized with a reliability of approximately 95% by means of the sensor patterns which are to be transmitted in accordance with the disclosure. The disclosed method and apparatus for its realization are particularly suited for use in hearing prostheses for deaf individuals.

Impedance measurement of individual skin surface electrodes.

The methods for the individual determination of skin surface electrode impedances are briefly discussed. A measurement technique is described with which it is possible to measure two skin surface electrodes simultaneously, but individually, at the same frequency. The design of a small, portable, battery-operated meter using this principle is described with block diagrams. Results are presented from the study of bilateral g.s.r. waves, the site dependence of the skin impedance, the differences between 10Hz and 1000 Hz data, and tissue segment impedance.

Alae Nasi Activation (Nasal Flaring) Decreases Nasal Resistance in Preterm Infants

The effect of alae nasi activation on nasal resistance in a group of healthy preterm infants was measured. Alae nasi activity was determined via the alae nasi electromyogram obtained from skin surface electrodes during both active and quiet sleep. Nasal resistance was calculated from airflow measured with a mask pneumotachograph and transnasal pressure drop obtained by simultaneous measurement of nasal pressure via a catheter inserted in one nostril and mask pressure. The percentage of breaths accompanied by phasic alae nasi activity was higher during active sleep than during quiet sleep (43% +/- 10% v 14% +/- 6%; P less than .005), and hypercapnic stimulation (4% CO2 inhalation) significantly increased the incidence of phasic alae nasi activity to comparable levels in both sleep states (82% +/- 8% in active sleep and 82% +/- 9% in quiet sleep). Elevation of tonic alae nasi activity also occurred more frequently during active sleep (P less than .05). The presence of either phasic or elevated tonic alae nasi activity decreased nasal resistance by 23% +/- 4% during active sleep and 21% +/- 3% during quiet sleep. This reduction in nasal resistance resulted in either a lower transnasal pressure during inspiration, a higher peak inspiratory airflow, or a combination of the two. Alae nasi activity may be an important mechanism that facilitates ventilation by reducing nasal resistance, and it may help stabilize the upper airway by preventing the development of large negative pharyngeal pressure during inspiration.

Calibration of a heated transcutaneous carbon dioxide electrode to reflect arterial carbon dioxide.

The CO2 measured by a heated skin surface electrode is greater than arterial CO2. In this study we (1) determined the magnitude of this difference retrospectively, (2) adjusted the calibration of the heated transcutaneous CO2 electrode to reflect this difference, and (3) tested the validity of the calibration procedure prospectively. The retrospective study consisted of 252 simultaneous arterial and transcutaneous measurements on 38 infants and children (age range, 1 day to 6 yr). A linear regression analysis showed PtcCO2 = 1.61 X PaCO2 - 0.01 mmHg, r = 0.90 (p less than 0.0001). Because the intercept was virtually zero, we subsequently changed the calibration procedure by dividing the transcutaneous electrode reading by 1.61. The prospective study consisted of 269 more simultaneous arterial and transcutaneous measurements from 57 consecutive infants and children (age range, 1 day to 18 yr) using this calibration procedure. Regression analysis showed PtcCO2 = 1.02 X PaCO2 - 2.3 mmHg, r = 0.96 (p less than 0.0001). Thus, we found that the transcutaneous CO2 electrode, using this technique, reliably predicted the arterial CO2.

Continuous measurements of skin surface oxygen and carbon dioxide tensions in obstructive sleep apnea.

We have found that skin surface electrodes for continuously measuring oxygen (PSO2) and carbon dioxide (PSCO2) tensions provide reliable means of determining whether infants with apnea due to airway obstruction during sleep require treatment. Nine patients referred for evaluation of aqnea during sleep were studied. In 6 patients with PSO2 less than 50 torr during sleep, the hypoxic episodes were clearly associated with partial or total airway occlusion as judged by increasing respiratory effort without concomitant airflow. PSCO2 was found to increase during the episodes of obstruction in all 6 patients. These patients were treated with 1. tracheotomy, 2. tonsillectomy and adenoidectomy in 2 patients, 3. bilateral mandibular condylotomies, 4. pharyngeal flap release, and 5. discontinuing topical nasal decongestants. After treatment, all had decreased hypoxia, hypercarbia, or airway obstruction. Two of the remaining 3 patients had no alterations of PSO2 or PSCO2 associated with airway obstruction during sleep. The third exhibited hypoxia and hypercarbia secondary to central apnea. We conclude, therefore, that continuous monitoring of skin surface oxygen and carbon dioxide tensions is useful in evaluating children with obstructive sleep apnea.

Electrocochleographic study of Ménière's disease (author's transl)

Meniere's disease is a disorder of both the peripheral auditory and vestibular systems.Although a considerable amount of studies has been performed on the function of both systems in Meniere's disease, there is little informations on the function of the peripheral auditory system. Electrocochleography makes it possible to measure human cochlear potentials for the study of the function of the cochlea. The action potential (AP) of 8 th nerve, the cochlear microphonics (CM) and summating potential (SP) were used as indicators for the function of the peripheval auditory system. They were recorded through a meatal skin surface electrode. An average response computor was employed. Acoustic stimuli were clicks and pure tone bursts between 0.5 kHz and 8 kHz. They were delivered to the human ear in u free field.The electrocochleographic examinations were performed on 17 ears of involved site of Meniere's disease, 13 ears with normal hearing and 35 ears with sensorineural hearing loss without dizzines. It was physiologically proved that a clickevoked inner ear potential after cancellation of CM was consisted of AP and SP.AP, SP compound potential recorded from Meniere's disease group had characteristics of a broad wave form, a large negative SP and abrupt increasing of N1 amplitude in high click intensity.This distortion of wave form of AP, SP compound potential was evaluated by measuring its width on base line and its SP/AP ratio. It was stastically significant that values of these parameters in Meniere's disease group was larger than in other two groups. (p<0.01)These results made it possible to diagnose Meniere's disease by the cochlear examination without vestibular examination.Diagnostic criteria of Meniere's disease based on electrocochleographic examination were as follows1. subjective symptome; episodic vertigo, hard of hearing and tinnitus.2. objective findings; SP/AP ratio is more than 0.43 under click intensity more than 81 dB.3. no neurological disorders except 8th nerve.All these conditions must be satisfied in order to obtain diagnosis of Meniere's disease.

Comparative advantages of bipolar abraded skin surface electrodes over bipolar intramuscular electrodes for single motor unit recording in psychophysiological research.

ABSTRACTDual recordings of single motor unit (SMU) biopotentials were made utilizing abraded skin surface and intramuscular (IM) bipolar electrode placements. Time relationships and waveform isomorphy between the recorded potentials suggest that, within limits, surface electrode recording is a useful technique for registering certain muscle action potentials when intramuscular placements are not desirable. Pen records of good resolution were obtained, to supplement oscilloscope photographs, when the physiological signal was initially recorded on magnetic tape at high speed and then played back at low speed through a standard electroencephalograph‐electromyograph oscillograph.

Technical aspects of the magnetic transcutaneous coupling of EMG signals

For long time application of myoelectric signal read-out (e.g, for patients with controllable limb prothesis), a method, which avoids either the disadvantages of skin surface electrodes or the percutaneous galvanic conductors, is described. The myoelectric energy is inductively coupled out through the skin without amplification or any implanted energy source (or energy coupled or radiated into the body from an extracorporeal source). The electrodes are placed directly at or inside the muscle which generates the wanted signals and are connected by means of two ductile wires to the coil fixed subcutaneously. Achieved advantages are: good separation of signals originating from different muscles, improvement in the delivery of signals for a proportional control (to muscle activity) of, e.g., artificial limbs, and high probability of a good long time reliability because of the technical simplicity.

表面電極筋電図の周波数スペクトルに関する基礎的研究

表面電極筋電図の周波数スペクトルに関する基礎的研究