Nonopioid analgesics shorten the duration of postoperative ileus

Morphine inhibits propagating and stimulates nonpropagating colon contractions in monkeys and humans. The use of morphine or other opioids that inhibit propulsive contractions prolongs postoperative ileus. In contrast, ketorolac tromethamine, a nonsteroidal analgesic, has no effect on colon contractions in monkeys. In 14 patients having elective abdominal operations, bipolar electrodes were implanted on the right (n = 13) and left (n = 10) colon. Group A (n = 8) received ketorolac, 30 mg IM q6h, for pain relief. Group B (n = 6) needed supplemental morphine, 2-10 mg IV or IM, plus ketorolac to control their pain. Myoelectric activity was recorded from each subject on postop Days 1-5 and analyzed by computer for electrical control activity (ECA), short and long electrical response activity (ERA), and propagation of long ERA. There was a difference between the two groups in return of propagated long ERA bursts that correlated with clinical recovery from postoperative ileus. Postoperative analgesia with ketorolac resulted in faster resolution of ileus compared to morphine plus ketorolac because opioid-induced motor abnormalities in the colon were avoided.     

Possibilities of the non-invasive electrogastrography

A non-invasive method for recording the electrical activity of the gastric muscle wall is presented. Electrogastrograms (EGG) with cutaneous electrodes on the abdominal wall were recorded using an original electrogastrograph. High-quality records without cardiac artifacts allowed for identification of waves belonging to the quiescent or activity period of the migrating myoelectric complex (MMC). The amplitude of the waves of the activity period of MMC were almost twice higher than that of the waves of the quiescent period. The wave amplitude immediately after feeding increased two times and a half compared to that during fasting. The high-amplitude waves in the activity periods of MMC and after feeding in the electrogastromyograms (EGMG) of dogs corresponded to bursts of spike potentials with slow potentials, i.e. to intense gastric muscle wall contractions. The method could contribute to the diagnosis of gastric motility disturbances in clinical practice.     

Gastric myoelectric and motor activity in dogs after isoflurane anesthesia

To characterize the effects of isoflurane on gastric motility, gastric electrical and contractile activities were assessed in six healthy adult dogs before and after recovery from anesthesia. Baseline recordings (fasting and fed state) were obtained in unanesthestized dogs 8 days after implantation of serosal electrodes and strain-gauge force transducers. After an overnight fast, dogs were anesthetized with 1.3 minimum alveolar concentration (MAC) isoflurane for 4.5 hours (approximately 6 MAC hours). No other anesthetic or sedative drugs were administered. During anesthesia, ventilation was mechanically controlled to maintain arterial carbon dioxide tension at 36 +/- 4 mm Hg. Gastric electrical and contractile activities (fasting and fed state) were recorded again 18 hours after recovery from isoflurane anesthesia. Recordings were analyzed to determine gastric slow-wave frequency, presence of slow-wave dysrhythmias, slow-wave propagation velocity, coupling of contractions to slow waves, a motility index based on relative contractile amplitudes, and onset and duration of contractions after a standardized meal. The only variable that was significantly decreased 18 hours after 6 MAC hours of isoflurane anesthesia was the gastric motility index during fasting-state phase III. This decrease was not apparent in the fed-state test periods. Our results suggest that, with the exception of gastric motility index during fasting-state phase III, variables for gastric electrical and contractile activities in dogs are unaffected by isoflurane 18 hours after anesthesia.     

Effects of L-NG-nitro arginine on cholinergic transmission in the gastric muscle of the rabbit

In the circular muscle of the rabbit gastric corpus, the nitric oxide-synthesis inhibitor L-NG-nitro arginine (L-NOARG), enhanced the neurally-induced cholinergic responses evoked by electrical field stimulation (EFS) and ganglionic stimulating agents (nicotine, dimethylphenyl piperazinium iodide). The muscular contractions caused by acetylcholine (Ach) and methacholine were not influenced by the nitric oxide-synthesis inhibitor. The nitric oxide-releasing compound sodium nitroprusside (SNP) did not affect the Ach-induced muscular responses. Our results suggest that L-NOARG enhances gastric cholinergic responses by removing an inhibitory influence exerted at the prejunctional level in the nerve-muscle pathway.     

Gastric pacing improves emptying and symptoms in patients with gastroparesis

BACKGROUND & AIMS: No effective treatment is available for patients with gastroparesis refractory to standard medical therapy. The aim of this study was to investigate the effects of gastric pacing on gastric electrical activity, gastric emptying, and symptoms in patients with gastroparesis. METHODS: Nine patients with gastroparesis participated in this study. Four pairs of cardiac pacing wires were implanted on the serosa of the stomach. The protocol consisted of two portions: a temporary inpatient study period and an outpatient study for a period of 1 month or more. RESULTS: Gastric pacing entrained the gastric slow wave in all subjects and converted tachygastria in 2 patients into regular 3-cpm slow waves. Gastric emptying was significantly improved after the outpatient treatment with gastric pacing. The gastric retention at 2 hours was reduced from 77.0% +/- 3.3% to 56.6% +/- 8.6% (P < 0.05). Symptoms of gastroparesis were substantially reduced at the end of the outpatient treatment (1.51 +/- 0.46 vs. 2.84 +/- 0.61; P < 0.04). Eight of 9 patients no longer relied on jejunostomy tube feeding, and no adverse events were noted related to the pacing unit. CONCLUSIONS: Gastric pacing seems to be able to improve symptoms of gastroparesis and to accelerate gastric emptying in patients with gastroparesis. More controlled studies are necessary to further investigate the role of gastric pacing in clinical practice.     

Stomach movement following selective gastric vagotomy: correlation of roentgen contrast studies and electromyography in the conscious dog

Electrical gastric activity in the alert dog was continuously registered by bipolar steel electrodes simultaneously with contrast x-ray studies. Delayed gastric emptying in the postoperative period following selective gastric vagotomy and pyloroplasty can be attributed to specific changes of electrical activity: 1. Electrical potential units become irregular in amplitude and frequency; 2. electrical activity of antrum is no longer synchronized with the corpus; 3. appearance of high frequency, atypical electrical activity in the antrum is associated with gastric motor inactivity; 4. peristalsis and emptying are linked to the de novo appearance of action-potential bursts.     

Fine structure of the acinar and duct cell components in the parotid and submandibular salivary glands of the rat: a TEM, SEM, and HRSEM study

We have developed a process for producing fine, very flexible microwires suitable for use as small signal leadwires or nerve electrodes. The process incorporates metallization of high-performance monofilament polymer fibers to yield electrically conductive fibers with greatly improved flexibility over solid metal wires of similar strength. The metallization layers are produced by serial vacuum deposition of a 0.3 micron thick coating of three metals, titanium-tungsten (Ti/W), gold (Au), and platinum (Pt), onto monofilament, poly-p-phenyl-terephthalate aramid fibers (Kevlar). The metallized fibers are then insulated with an approx. 1 micron thick layer of silicone elastomer. The result is a microlead with high electrical conductivity (linear resistance = 30 omega/cm), desirable interfacial properties, excellent mechanical stability and extremely high flexibility. These physical characteristics are appropriate for application as signal leadwires or recording/stimulating electrodes where small size and high flexibility are paramount. In this paper we report on the electrical and mechanical properties of these metallized fibers and demonstrate their use as intrafascicular electrodes for recording multi-unit neural activity in feline peripheral nerves.     

Evaluation of direct bladder stimulation with stainless steel woven eye electrodes

Encouraged by recent clinical reports of micturition induced in patients by direct bladder stimulation, we conducted a study of optimum methods of direct bladder stimulation. During surgery six male cats received eight large surface-area woven eye electrodes sutured to the bladder wall serosa, four on the bladder dome and four adjacent to the trigone area. Two additional small surface-area single knot electrodes were sutured in the trigone area. Suprapubic and intraperitoneal tubes were placed for pressure recording and bladder filling. Leg and pelvic floor EMG electrodes were also used for tethered recordings. One to eight weeks after surgery, optimum stimulation methods were evaluated as the animal freely moved about a urodynamic recording cage. Electrodes in the trigone region were more effective than electrodes on the dome and induced bladder contractions and voiding similar to spontaneously induced voiding with bladder filing. Large surface area, woven eye electrodes, composed of multistranded 316LVM stainless steel wire, were more effective than smaller surface area single knot electrodes. High stimulating frequencies (40 Hz) were better than lower frequencies (10 to 20 Hz), and a 1 millisecond pulse duration was optimal. Pulsing with stimulating currents from 10 to 25 mA induced effective bladder contractions with voiding when applied for 3 seconds. However, lower currents using longer stimulation periods were also effective. Bipolar electrodes with both electrodes on the bladder wall were superior to monopolar arrangements with the positive ground electrode along the animal's back. We concluded that in the able-bodied cat model, bladder contractile activity for micturition can be induced with direct bladder stimulation and with little discomfort. An effective stimulation protocol consists of capacitor-coupled monophasic pulses with large surface area bipolar electrodes in the trigone region. Stimulating parameters of 40 Hz, 1 msec., 10 to 25 mA applied for 3 seconds were optimal. In addition, based on corrosion resistance observations, the electrodes are quite suitable for long-term studies.     

Alloimmune neonatal neutropenia: flow cytometry study of the 1st patient described in Spain with identification of an anti-NA1

We developed a Micro-neurostimulator that is suitable for intracranial electrical stimulation of the facial nerve in excision of acoustic neurinomas. The tips of our Micro-neurostimulator were thinner and finer than those of commercially-available bipolar forceps and therefore it was possible to stimulate tumor tissue and the facial nerve selectively. This facilitated precise excision of tumor tissue from the facial nerve without residual tumor tissue around it. It was emphasized that the shape of the tips of stimulating electrodes and the stimulus intensity were the most important factors in obtaining reliable responses in preserving the facial nerve using intracranial electrical stimulation and evoked electromyographic responses.     

Gastrointestinal myoelectrical activity during the postoperative period in man

Myoelectrical activity of the gastrointestinal tract has been studied in the postoperative period of 13 patients who underwent cholecystectomy. The recordings have been performed by means of extracellular electrodes which were implanted at the levels of stomach, jejunum, ileum and colon during the surgical procedure. The records showed that fast activity is always persistent while the basic electrical rhythm is greatly disorganized during the immediate postoperative period. Such a characteristic pattern of the electrical activity suggested that the lack of peristaltic and propulsive movements, always noted during this period, is not correlated with a disappearance of gastrointestinal contractions, but only with a disturbance in their coordination.     

A gastroesophageal electrode for atrial and ventricular pacing

Temporary transvenous cardiac pacing requires technical expertise and access to fluoroscopy. We have developed a gastroesophageal electrode capable of atrial and ventricular pacing. The flexible polythene gastroesophageal electrode is passed into the stomach under light sedation. Five ring electrodes, now positioned in the lower esophagus, are used for atrial pacing. A point source (cathode) on the distal tip of the electrode, now positioned in the gastric fundus, is used for ventricular pacing. Two configurations of atrial and ventricular pacing were compared: unipolar and bipolar. During unipolar ventricular pacing the indifferent electrode (anode) was a high impedance chest pad. For bipolar ventricular pacing the indifferent electrode was a ring electrodes placed 2 cm proximal to the tip. Unipolar atrial pacing was performed with 1 of 5 proximal ring electrodes acting as cathode ("cathodic") or as anode ("anodic") in conjunction with a chest pad. Bipolar atrial pacing was performed using combinations of 2 of 5 ring electrodes. Atrial capture was obtained in all 55 subjects attempted. When all electrode combinations were compared, atrial capture was significantly more frequent using the bipolar approach (153/210 bipolar, 65/210 unipolar; t = 7.37, P < 0.001). For unipolar atrial pacing, cathodic stimulation (from esophagus) was more successful than anodic stimulation (cathodic 62/105, anodic 20/105; t = 5.81, P < 0.001). In 43 subjects attempted unipolar ventricular pacing resulted in a higher frequency of capture than the bipolar approach (unipolar 41/43 (95.3%), bipolar 19/43 (44.2%); P < 0.001). In conclusion, atrial pacing was optimal using pairs of ring electrodes ("bipolar") while ventricular pacing was optimal using the distal electrode tip (cathode) in conjunction with a chest pad electrode ("unipolar"). This gastroesophageal electrode may be useful in the emergency management of acute bradyarrhythmias and for elective electrophysiological studies.     

Glutathione S-transferase a major allergen of the house dust mite, Dermatophagoides pteronyssinus

Cutaneous electrogastrography (EGG) allows the measurement of gastric electrical activity. An association of EGG with gastrointestinal motility disorders has been shown. Abnormalities of electrical rate or rhythm are accepted as the most important parameters in EGG. However, the reliability of the magnitude of electrical amplitude in the assessment of motility is discussed controversially. Therefore in a prospective study we investigated the relation between amplitude and antral contractions by means of ultrasonography. 8 healthy volunteers (4 men, 4 women, 24-31 years) ingested 400 ml carbonated mineral water after an overnight fast at two separate study days. Over a period of 10 min preprandial and 10 min postprandial small and intense antral contractions were measured employing sagittal antral planimetry. Simultaneous amplitudes were determined during contractions and at 1 min intervals (average amplitude) by cutaneous electrogastrography. Data were analyzed by Wilcoxon's rank sum test and Spearman rank correlation test. The coefficient of variation of the postprandial/preprandial amplitude ratio was nearly two times greater between subjects than between recordings in the same subject, which reflects a moderate intraindividual reproducibility. We found a significant increase in the average amplitude postprandially (p < 0.05). Although postprandial contractions (n = 243) predominated preprandial contractions (n = 127) significantly (p = 0.02), no significant correlation between the number of contractions and the average amplitude existed (R = 0.1; p = 0.7). Moreover the average amplitude did not differ from amplitudes during intense and small contractions significantly (p = 0.7; p = 0.1). The magnitude of the amplitude measured by EGG does not correlate with the mechanical gastral activity significantly.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrical conduction between the right atrium and the left atrium via the musculature of the coronary sinus

BACKGROUND: The purpose of this study was to determine whether the coronary sinus (CS) musculature has electrical connections to the right atrium (RA) and left atrium (LA) and forms an RA-LA connection. METHODS AND RESULTS: Six excised dog hearts were perfused in a Langendorff preparation. A 20-electrode catheter (2-4-2-mm spacing center to center) was placed along the CS. Excision of the pulmonary veins provided access to the LA, and a second 20-electrode catheter was placed along the LA endocardium opposite the CS catheter. An incision opened the CS longitudinally, and microelectrodes were inserted into the CS musculature and adjacent LA myocardium. Continuous CS musculature was visible along a 35+/-9-mm length of the CS beginning at the ostium. During lateral LA pacing, CS electrodes recorded double potentials, a rounded, low-frequency potential followed by a sharp potential. The rounded initial potential propagated in the lateral-to-septal direction and represented "far-field" LA activation (timing coincided with adjacent LA potentials and with action potentials recorded from microelectrodes in adjacent LA cells). The sharp potential represented CS activation (timing coincided with action potentials recorded from CS musculature). A distal LA-CS connection (earliest sharp potential in the CS during lateral LA pacing) was located 26+/-7 mm from the ostium. During RA pacing posterior to the CS ostium, CS electrodes recorded septal-to-lateral activation of the high-frequency potential, with slightly later activation of the rounded potential (LA activation). Incisions surrounding the CS ostium isolating the ostium from the RA had no effect on the CS musculature and LA potentials during RA pacing within the isolated segment containing the CS ostium. RA pacing outside the isolated segment delayed activation of the CS musculature until after LA activation, confirming that the RA-CS connection was located in the region of the CS ostium as well as confirming the presence of the LA-CS connection. CONCLUSIONS: In canine hearts, the CS musculature is electrically connected to the RA and the LA and forms an RA-LA connection.     

Electrophysiological responses of cardiac muscle to isoproterenol covalently linked to glass beads

We investigated the effects of isoproterenol aryl glass beads on the electrical properties of cardiac muscle and related these to our previous results concerning biochemical and contractile effects (Ingebretsen et al., Circ, Rs., 40: 474-484, 1977). Beads (10-15) were placed near one end to guinea pig papillary muscles mounted horizontally in a bath perfused with Krebs-Henseleit solution at 30 degrees C and stimulated at 0.2 Hz. The beads produced increased tension and elevation and slight lengthening of the plateau potential when [k+]o = 3.8 mM. After depolarization to a resting potential of -49 mV with [K+]o = 22 mM, isoproterenol beads restored contraction to a comparable extent as occurred with 10(-8) M soluble drug. During field stimulation, action potentials were initiated at the site of bead application and spread decrementally. When beads were placed distal to the site of point stimulation, virtually no excitation could be obtained from cells in the vicinity of the beads. When they were placed close to the stimulating electrode, the beads increased excitability and typical slow action potentials spread to the other end of the muscle. These potentials had the characteristics associated with the slow inward Ca2+ current. The slow channel blocker, D-600, blocked responses to isoproterenol beads. Tetrodotoxin caused responses similar to those obtained with K+ depolarization. The beads probably act by stimulating only a small fraction of the papillary muscle catecholamine receptors. Spread of action potentials from these sites and propagated tension depend on Ca2+ influx, but the nature of an intermediate messenger involved in the propagation of contractions is unknown.     

Dipolar sources of the early scalp somatosensory evoked potentials to upper limb stimulation. Effect of increasing stimulus rates

Brain electrical source analysis (BESA) of the scalp electroencephalographic activity is well adapted to distinguish neighbouring cerebral generators precisely. Therefore, we performed dipolar source modelling in scalp medium nerve somatosensory evoked potentials (SEPs) recorded at 1.5-Hz stimulation rate, where all the early components should be identifiable. We built a four-dipole model, which was issued from the grand average, and applied it also to recordings from single individuals. Our model included a dipole at the base of the skull and three other perirolandic dipoles. The first of the latter dipoles was tangentially oriented and was active at the same latencies as the N20/P20 potential and, with opposite polarity, the P24/N24 response. The second perirolandic dipole showed an initial peak of activity slightly earlier than that of the N20/P20 dipolar source and, later, it was active at the same latency as the central P22 potential. Lastly, the third perirolandic dipole explaining the fronto-central N30 potential scalp distribution was constantly more posterior than the first one. In order to evaluate the effect of an increasing repetition frequency on the activity of SEP dipolar sources, we applied the model built from 1.5-Hz SEPs to traces recorded at 3-Hz and 10-Hz repetition rates. We found that the 10-Hz stimulus frequency reduced selectively the later of the two activity phases of the first perirolandic dipole. The decrement in strength of this dipolar source can be explained if we assume that: (a) the later activity of the first perirolandic dipole can represent the inhibitory phase of a "primary response"; (b) two different clusters of cells generate the opposite activities of the tangential perirolandic dipole. An additional finding in our model was that two different perirolandic dipoles contribute to the centro-parietal N20 potential generation.     

Restoration of the electrical activity and nervous apparatus following section of the stomach wall in dogs

In dogs, transection of the gastric wall at the level of incisura angularis, followed by end--to--end anastomosis, was made. The electrodes were implanted into the muscle wall of the two stomach segments. Electrical activity of the stomach wall on the 1st postoperative day showed dissociation in the spike activity between the two segments. 10 days later, first signs of sequence in the spike activity of the stomach above and below the anastomosis appeared. Microscopic examination revealed that regenerating nerve fibers formed a bridge over the scar. On the 16th day, groups of spike potentials from the gastric wall above the section propagated also in the stomach region below the anastomosis. Since the 14th day, the microscopic examination revealed newly formed synaptic endings on the ganglionic cells distal to the scar. After the 20th day, all signs of dissociation began to disappear.     

Reliability of percent distribution of power of the electrogastrogram in recognizing gastric electrical uncoupling

The aim of this study was to examine the reliability of percent distribution of electrogastrographic (EGG) power in recognizing gastric electrical uncoupling. Sixteen anaesthetized dogs underwent laparotomy and implantation of six pairs of stainless-steel wire electrodes. Distal stomach was measured and three sections with approximately equal lengths were defined. Two pairs of electrodes were implanted in each section. Eight-channel EGG was also recorded. Three separate half-hour recordings were made: in the basal state; after a full circumferential separation of the distal antral section from the rest; after a second circumferential cut completely separating the middle from the proximal sections. EGG digital power spectra were split into three frequency ranges and dynamics of percent distribution of power was statistically examined. After the first cut, changes in the percent distribution of EGG power in the normal range were not significant (p = 0.2). Significant changes in the low range were noted (p < 0.05) and changes in the high range were borderline nonsignificant (p = 0.056). After the second cut, changes in percent distribution in the normal and the high range became significant (p < 0.01) while changes in the low range were insignificant (p = 0.075). Severe uncoupling was reflected in EGG by significant changes in the high-frequency range without internal tachygastria necessarily being present.     

Comparison of surface EMG signals between electrode types, interelectrode distances and electrode orientations in isometric exercise of the erector spinae muscle

The influence of electrode type, interelectrode distance (IED) and electrode orientation on EMG signals from the paraspinal muscles was investigated. Bipolar electrodes were placed at distances 2, 3, 4, 6 and 8 cm over the erector spinae in the cranio-caudal direction ("in series") as well as in the direction perpendicular to it ("in parallel"). Ten subjects performed 5 s isometric contractions of the erector spinae at 20, 40, 60, 80 and 100% MVC by pulling upward on a handlebar attached to the floor. RMS EMG signals were analyzed for mean average amplitude (AA). Mean total power (TP) and mean median frequency (MF) of the raw EMG signal were determined using fast Fourier transform. In addition to graded loading, sustained fatiguing contractions were performed from which TP and MF were obtained. With increasing IED the AA and TP increased while MF decreased. Although a trend towards higher AA, TP and MF was found for electrodes "in series", as compared to those "in parallel", the difference never reached significance. It is concluded that consistent information about muscle activity was obtained with Miniature Biopotential Skin Electrodes and 14445C Hewlett-Packard electrodes independently from IED or orientation. Orientation "in parallel" prevented the electrodes from sliding during muscle contraction. The third tested type, electrodes developed in the Neuromuscular Research Center, Boston, proved extremely sensitive to movement.     

Effect of glucagon on myoelectrical and mechnical activity of the isolated homologous perfused porcine stomach

Totally isolated whole porcine stomachs, perfused extracorporeally with homologous blood, were used for recording gastric electrical and mechanical activity. Hormones Hormones were administered into the arterial system of the isolated organ. Pentagastrin, methacholine and electrical stimulation of the vagus nerve induced premature control potentials with uncoupling of the normal, phase-locked, pattern of electrical control activity and also produced electrical response activity and mechanical reaction. When glucagon was infused a progressive decrease of frequency of the cycles of electrical control activity was observed. Glucagon also abolished electrical response activity and mechanical activity, if they were present prior to hormone infusion. When pentagastrin, methacholine or electrical stimulation were applied during the infusion of glucagon, the responses to these stimulants were decreased or absent. The inhibitory action of glucagon was dependent on the duration of infusion of this hormone and lasted for 30-45 min after the infusion was discontinued. During infusion of glucagon the mean gastric arterial perfusion pressure and gastric peripheral vascular resistance were reduced.     

Electrical and mechanical activity of isolated canine stomach perfused with fluorocarbon emulsion

Electrical and mechanical activities were recorded from the isolated canine stomach perfused with fluorocarbon emulsion and oxygenated in vitro. This preliminary experiment was undertaken to determine whether or not these activities can be preserved during extracorporeal bloodless perfusion using a perfusate containing only an oxygen carrier, fluorocarbon and a simulated physiologic salt solution of some electrolytes. We found that electrical control activity of stomachs so perfused was identical with that found under in vivo conditions. The electrical and mechanical response of these stomachs to intra-arterially injected methacholine and pentagastrin and to electrical stimulation of the vagus nerve suggested that the function of the muscular and intramural plexus layers of the gastric wall remained normal. It was also observed that the frequency of the cycles of electrical control activity and the amplitude of antral contractions were significantly increased, when pO2 of the circulating perfusate rose. Results of the biochemical studies of the perfusate suggested utilization of some of its components for the metabolic needs of the perfused organ. The gastric secretion was alkaline and contained particles of fluorocarbon emulsion.