Robert M. Stern

Spectral analysis of tachygastria recorded during motion sickness

The purpose of the present experiment was to study frequency changes in gastric myoelectric activity of healthy human subjects and the development of symptoms of motion sickness as brought about by vection or illusory self-motion. Fifteen fasted healthy human subjects were seated inside a circular vection drum, the rotation of which produces visual signals of self-motion that are in conflict with vestibular signals (i.e., mismatched sensory input). An electrogastrogram was obtained for three 15-min. periods: baseline, rotation, and after drum rotation stopped. Respiration, symptoms volunteered by subjects, and a continuous measure of intensity of symptoms were recorded. Five subjects showed a continuation of normal 3-cycles/min. activity during drum rotation and reported no symptoms of motion sickness. Ten subjects showed a shift of their dominant gastric frequency from 3 cycles/min. to 4-9 cycles/min. during drum rotation and reported symptoms of motion sickness. Running spectral analysis revealed a close correspondence over time between tachygastria and reports of symptoms of motion sickness.

Gastric dysrhythmias and nausea of pregnancy.

Gastric dysrhythmias have been recorded from patients with a variety of nausea syndromes. The aim of this study was to measure gastric myoelectric activity in women with and without nausea during the first trimester of pregnancy. In 32 pregnant women gastric myoelectric activity was recorded for 30–45 min with cutaneous electrodes that yielded electrogastrograms (EGGs). Frequencies of the EGG waves were analyzed visually and by computer. Subjects rated their nausea at the time of EGG recording on a visual analog scale with 0 representing no nausea and 300 mm severe nausea. Gastric dysrhythmias were found in 26 pregnant subjects: Seventeen had tachygastrias (EGG frequencies of 4–9 cpm),five had 1- to 2-cpm EGG waves, and four had flat-line patterns. Mean nausea scores of the subjects with tachygastrias, 1- to 2-cpm, and flat-line patterns were 64.8±13, 93.4±23, and 77.2±36, respectively. Six pregnant subjects had normal 3-cpm EGG patterns, and their nausea scores averaged 2.8±1.1 (P<0.05 compared with nausea scores in subjects with tachygastrias, 1- to 2-cpm, and flat-line rhythms). Six subjects with gastric dysrhythmias during pregnancy were restudied after delivery; each of these subjects had normal 3-cpm EGG patterns and none had nausea. Thus, gastric dysrhythmias are objective pathophysiologic events associated with symptoms of nausea reported during the first trimester of pregnancy.

Nausea and Vomiting Remain a Significant Clinical Problem: Trends Over Time in Controlling Chemotherapy-Induced Nausea and Vomiting in 1413 Patients Treated in Community Clinical Practices

Data from 1413 outpatients in community-based clinical practices were collected in order to characterize the use and effectiveness of 5-HT(3) receptor antagonists for control of chemotherapy-induced nausea and vomiting (NV). Patients were divided by treatment starting date into six cohorts for trend analysis. In addition, NV symptoms were compared in 252 patients treated prior to the commercial introduction of the 5-HT(3) receptor antagonist antiemetics, and an equal number of patients treated after their introduction. A comparison of cohorts revealed a significant (P = 0. 027) downward trend over time for the frequency of post-treatment vomiting episodes, but not for frequency of post-treatment nausea (P = 0.69). The average duration of nausea following treatment increased significantly over time (P = 0.003). Although the introduction of 5-HT(3) receptor antagonist antiemetics has apparently led to a significant reduction in the frequency of post-treatment vomiting, there has been an accompanying increase in the duration of post-treatment nausea.

ASSESSMENT OF THE MULTIPLE DIMENSIONS OF NAUSEA: THE NAUSEA PROFILE (NP)

Nausea, unlike emesis, is a subjective experience that is difficult to describe to others, be they clinicians or researchers. Previous research has been limited to examining the frequency, severity, and duration of nausea. The goal of this study was to design a questionnaire that would allow for the evaluation of the characteristics of nausea across individuals and situations. This study consisted of 4 stages: descriptors were generated, categorized into 3 dimensions, and reevaluated to verify their reliability; in the final stage, the developed checklist was compared to a visual-analogue-scale (VAS) report of nausea in subjects exposed to a rotating optokinetic drum to stimulate nausea. The overall nausea checklist score and the VAS score were highly correlated (r = 0.71, p < 0.01). The development and use of the nausea checklist are discussed.

Effect of Barium Meals on Gastric Electromechanical Activity in Man A Fluoroscopic-Electrogastrographic Study

The relationship between the cutaneously recorded electrogastrogram (EGG) and gastric contractions in man is unclear. We investigated: (1) the relationship between the electrogastrogram (EGG) signals and gastric contractions elicited by barium meals and (2) the effects of barium meals on frequency and amplitude of EGG signals. As documented by fluoroscopy in four healthy subjects, barium meals stimulated three per minute gastric peristalsis which corresponded with simultaneously recorded three cycle per minute (cpm) EGG waves. Eighteen other healthy volunteers ingested 45% (w/v) or 60% barium suspensions. As determined by Fourier analysis, the dominant EGG frequency before barium was 3 cpm in 16 subjects; two subjects had no distinct frequency peaks. After barium ingestion, the mean amplitude or power at 3 cpm and 1 cpm increased, but the increase was significant only after 45% barium. In conclusion: (1) individual EGG waves after barium reflect gastric peristaltic sequences, which are reflected in increases in amplitude or power of 3 cpm EGG activity; (2) density or viscosity of the barium meal affects the gastric myoelectric response; and (3) mechanical correlates of 1 cpm EEG activity are unknown.

Protein and Ginger for the Treatment of Chemotherapy-Induced Delayed Nausea

BACKGROUND Nausea that develops during the period that begins 24 hours after the administration of chemotherapy is called delayed nausea, and occurs in many patients with cancer. Meals high in protein decrease the nausea of motion sickness and pregnancy, possibly by reducing gastric dysrhythmias. Ginger also has antinausea properties. OBJECTIVES To explore the use of protein meals with ginger for the treatment of the delayed nausea of chemotherapy. DESIGN Twenty-eight (28) patients with cancer receiving chemotherapy for the first time were assigned to 1 of 3 groups. For 3 days beginning the day after their chemotherapy, Control Group patients continued with their normal diet, Protein Group patients consumed a protein drink and ginger twice daily, and High Protein Group patients consumed a protein drink with additional protein and ginger twice daily. OUTCOME MEASURES Patients recorded in a diary each day whether they had experienced nausea, whether their nausea had been frequent, whether their nausea had been bothersome, and whether they had needed any antiemetic medication. Gastric myoelectrical activity was assessed in 5 patients before and after ingestion of a high protein meal and ginger. RESULTS Reports of nausea, frequent nausea, and bothersome nausea were significantly less common among High Protein Group patients than among Control and Protein Group patients. Furthermore, significantly fewer patients in the High Protein Group used antiemetic medication. Differences between the Protein and Control groups were not statistically significant. In the 5 patients who had tests of gastric myoelectrical activity performed, a significant decrease in gastric dysrhythmia occurred after ingestion of the protein and ginger. CONCLUSIONS High protein meals with ginger reduced the delayed nausea of chemotherapy and reduced use of antiemetic medications. Protein with ginger holds the potential of representing a novel, nutritionally based treatment for the delayed nausea of chemotherapy.

Effects of worry and somatic anxiety induction on thoughts, emotion and physiological activity.

Thirty-six Ss received Velten (1968) emotion inductions designed to produce either worrisome, somatically anxious, or neutral states. A breathing-focus task assessed the frequency of negative thought intrusions before and after the emotion induction. Worry induction produced the greatest increase in negative intrusions, significantly greater than the neutral condition. Somatic anxiety induction produced some increase in intrusions, nonsignificantly between worry and neutral inductions. Both worry and somatic anxiety inductions generated significant increases in cardiovascular activity relative to the neutral condition, while no effect was observed on gastric myoelectric activity. Worry was characterized by emotions on the Multiple Affect Adjective Checklist that overlap with those of depression and somatic anxiety.

Effect of autonomic nervous system manipulations on gastric myoelectrical activity and emotional responses in healthy human subjects.

OBJECTIVE The aim of this study was to determine the gastric myoelectrical and emotional responses provoked by two psychophysiological stimuli known to cause in one case increased sympathetic nervous system activity and in the other increased parasympathetic nervous system activity. METHODS Electrogastrograms (EGGs) were recorded, and interbeat intervals (IBIs) were obtained from electrocardiographic recordings from 20 subjects during baseline and in response to a shock avoidance task (shock stimulus) and forehead cooling (dive stimulus). After each experimental period, subjects reported their emotional experience by rating descriptors ranging from serenity to excitement. RESULTS During the shock stimulus, IBIs decreased significantly (p < .05), gastric tachyarrhythmias increased (p < .05), and emotional arousal increased, as indexed by reports of increased interest, excitement, and activation. In contrast, during the dive stimulus, IBIs increased (p < .05), but there were no associated changes in gastric myoelectrical activity or emotional arousal. CONCLUSIONS Acute stress can evoke arousal and dysrhythmic gastric myoelectrical activity, and these acute changes, which occur in healthy individuals, may provide insight into functional gastrointestinal disorders.

Significance of autonomic nervous system activity in functional dyspepsia

The purpose of this study was to examine if patients with functional dyspepsia could be separated into meaningful groups based on their autonomic function. Subjects were divided into two groups, and symptoms, gastric myoelectrical activity, gastric emptying, and psychological factors were compared. Group 1 had less autonomic variability but more cardiac reactivity than group 2. Symptom reports did not differ between groups. Group 1 had higher neuroticism scores than group 2, while group 2 showed greater tachyarrhythmia in response to drinking water than group 1. The relatively low autonomic variability in group 1 is consistent with higher sympathetic activity and may be associated with the groups greater neuroticism. The relative lack of cardiac reactivity in group 2 is consistent with lack of autonomic flexibility and may be related to the tachyarrhythmia observed in that group. The results of this study suggest that autonomic function may play a significant role in functional dyspepsia.

The effects of manipulating expectations through placebo and nocebo administration on gastric tachyarrhythmia and motion-induced nausea.

Background: Interest in the role of expectation in the development of nausea and other adverse conditions has existed for decades. The purpose of this study was to examine the effects of manipulating expectations through the administration of placebos and nocebos on nausea and gastric tachyarrhythmia provoked by a rotating optokinetic drum. Method: Seventy-five participants were assigned to one of three groups. Positive-expectancy group participants were given placebo pills that would allegedly protect them against the development of nausea and motion sickness. Negative-expectancy group participants were given the same pills as nocebos; they were led to believe there was a tendency for them to make nausea somewhat worse. Placebo-control group participants were told the pills were indeed placebos that would have no effect whatsoever. Results: Subjective symptoms of motion sickness were significantly lower among negative-expectancy group participants than positive-expectancy and placebo-control group participants (p< 0.05). Gastric tachyarrhythmia, the abnormal stomach activity that frequently accompanies nausea, was also significantly lower among negative-expectancy group participants than positive-expectancy and Placebo-Control Group participants during drum rotation (p<.05). Conclusions: Inducing negative expectations through nocebo administration reduced nausea and gastric dysrhythmia during exposure to provocative motion, whereas positive placebos were ineffective for preventing symptom development. That manipulation of expectation affected gastric physiological responses as well as reports of symptoms, suggests an unspecified psychophysiological mechanism was responsible for the observed group differences. These results also suggest that patients preparing for difficult medical procedures may benefit most from being provided with detailed information about how unpleasant their condition may become. SSMS = subjective symptoms of motion sickness; EGG = electrogastrogram; ANOVA = analysis of variance; FFT = fast-Fourier transform.