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Day to day variability and the effect of repeated distensions of symptom thresholds during rectal distension
A610
AGA ABSTRACTS
EFFECT OF PROLONGED PRESERVATION ON T H E I N T E S T I N A L N E U R O - M U S C U L A R S Y S T E M IN C A N I N E S M A L L B O W E L A U T O T R A N S P L A N T A T I O N N. Hamada W.R. Hutson, K. Nakada, A. Ikoma, T. Suzuki, Y. Zhu, J.C. Reynolds, S. Todo, T.E. Starzl. Dept. of surgery and Internal Medicine, University of Pittsburgh, School of Medicine, Pittsburgh, PA. Dysmotility of the transplanted intestinal graft has been explained, in part, by denervation of extrinsic nerve or ischemic and reperfusion injury to the muscular and/or nervous system in t h e intestinal wall. Little information, however, is available Concerning motility following prolonged preservation of the autotransplanted small intestine. Aim: To in'~estigate the effect of prolonged preservation on the neuro-muscular system involved in intestinal motility. Methods: The entire small intestine of adult hound dogs was procured and flushed with cold lactated Ringer's solution. The small intestine was autotransplanted either immediately or after 24 hours of cold preservation in the same solution. Fasted motility pattern and the response of the intestinal smooth muscle and enteric nerve tO bethanecbol (100 gg/kg/0.5hr, DIV) and cisapride (0.5mg/kg, IV), respectively, were determined using multiple strain gauge transducers On post-operative days (PODs) 2, 4, 7, 14, 21, 28, comparing transplanted jejunoileum (n=6 for each group) and control (n=4). Fasted small intestinal transit time (SITT) was measured on PODs 2, 7, 14, 21,281'25 mg !ndocyanine green (ICG) reagent dissolved with 10ml distilled water was administered through the catheter duodenostomy, and the transit t i m e was determined by initial detection of the ICG in the intestinal contents taken from the catheter ileostomy. Results' Migrating myoelectric contractions (MMC) were observed in control and immediate groups even from POD 2; however, in the preservation group the appearance of phase 3 Contractions were delayed until a minimum of 2 weeks, and even until 4 weeks in 50 % of this group, showing almost no motor activity until POD 2 and very active motor activity as frequent clustered contractions thereafter. There was no particular difference between the groups in their mean amplitude and frequency of the bursts after muscle stimulation by bethanechol or excitatory enteric nervous stimulation by cisapride during the study period. Although SITT in the preservation group was remarkably slower than the other groups at POD 2, it was accelerated and faster after POD 7. Conclusion: These results suggest that the integrity of the canine intestinal smooth muscle and excitatory enteric nervous system was rather well preserved even after 24 hours preservation in lactated-Ringer's solution; however, the inhibitory enteric nervous system appeared to be impaired and did not recover until at least 2 weeks after transplantation.
DAY TO DAY VARIABILITY AND THE EFFECT OF REPEATED DISTENSIONS ON RECTAL TONE AND ELASTANCE. HF Hammer, SF Phillips, M CamiUeri, A Zinsmeister, RB Hanson. Mayo CliniC, GI Unit, Rochester, MN. BACKGROUND Tone and elastance may be importam for normal rectal function and for symptoms in rectal disease. AIM: To assess day to day variability, and the effect of repeated distensions on rectal tone and elastance. METHODS: 5 healthy subjects (23-41yrs, 3m/2f) were studied 5 times, separated by 3 to 6 days. Subjects were in left lateral decubitus with the feet elevated by 20°. A cylindrical 10 cm polyurethane bag was inserted 5 cm from the anal verge. On 4 days basal rectal tone was measured immediately before and 25 minutes after a ramp distension (10 ml/min) using the Distender II (G+J Electronics). Differences in rectal tone before and after distensions were expressed as percent changes of the volume of air in the rectal balloon which was held at a constant pressure. Elastance was expressed as the intercept and the linear slope of the P/V curve. On day 1, two further distensions were performed; rectal tone was measured for 15 minutes between and after distensions. Distensions were stopped when subjects had Urgency for 30 seconds. Day to day variability was expressed as the coefficient of variation (CV) which was calculated for each subject from the results Of the 5 study days. Paired t-tests with Bonferroni correction were used. RESULTS: 1) Rectal tone: The first distension decreased rectal tone by 52-t-16% (p<0.001). The second and third distensions did not significantly change rectal tone (+ 12+9% and + 16+4%). CVs of rectal tone before and after distension were not significantly different (18+6% and 28+12%, respectively)~ 2) Elastance: Slopes and intercepts are shown in the table. Intercept Slope [[ p < 0 02 vs dist. 1; 2p < 0.05 vs (ram Hg) (ram Hg/ml) dist. 1 and not significantly distension 1 2.3 ±0.8 1.05 ±0.24 different from dist. 2; 3p<0.001 distension 2 4.5±0.51 0.65±0.23 ns vs dist; I; nSnot significantly distension 3 4.3±0.62 0.36±0.203 different from dist. 1 and 3]. CV(5) 311±177 16±2 The CV for the intercept ranged between 1 6 a n d 797%, and for the slope between 9 and 21%. CONCLUSIONS: 1) Basal rectal tone and the slope of the rectal elastance curve have good day to day reproducibility, but there is a large variability in the intercept of the elastance curve, suggesting that hysteresis may be important. 2) In studies of rectal tone and elastance, an initial conditioning distension is needed to eliminate an order effect between the first and the following distensions.
GASTROENTEROLOGY, Vol. 108, No. 4
OMODULATION OF HUMAN CORTICAL SWALLOWING PATHWAYS BY MAGNETIC STIMULATION OF TRIGEMINAL AND VAGAL AFFERENT NERVES. S. Hamdy; Q. Aziz, A. Hobson, J. Barlow, D. G. Thompson. Department of Medicine, Hope Hospital, Unlversity of Manchester, UK
Background: We have previously reported the physiological characteristics of corticofugal pathways to the esophagus in healthy volunteers following magnetic stimulation of the motor cortex (Am. J. Physiol 1994. 267:30:G827-835). Swallowing responses in animals have also been elicited by Trigeminal (T) Or Vagal (V) afferent stimulation. In humans, however, the interactions between cortical and brainstem pathways to swallowing musculature are unexplored. Aims: To determine i). whetfier magnetic stimulation of T and V afferents excite brainstem swallowing pathways, ii). whether activation of these afferents modifies cortical swallowing pathways. Methods: 8 healthy volunteers were studied. Surface electrodes were placed on each mylohyoid muscle (M), and bipolar ring electrodes were positioned in the pharynx (P) and esophagus (E)via an intraluminal catheter. Magnetic stimulation was then applied at suprathreshold (1 tesla) intensities to motor cortex, supraorbital nerve IT) and extracranial vagus nerve at the angle of the jaw (V), and the EMG responses from each of the three muscle groups recorded. Study I; Stimulation Of either T or V afferents alone. Study 2;, Cortical stimulation alone or following T or V stimulation at intervals varying from 5-500ms between the two stimuli: Results: Study I; Two distinct responses were recorded in each of the three muscle groups: an early response, ranging in latencies from 21.7-28.1ms: and a late response, ranging in latencies from; 50.0-58.9ms. Study 2; Cortical stimulation alone evoked EMG responses in the M, P, and E muscles, mean latencies 8.9, 9.1, and 10.2ms respectively. After either T or V afferent stimulation, the latencies of the cortically evoked responses shortened, the effect being maximal at an interval of 50ms, to 6.2, 7.2, and 8.3ms. ~<,0.05) respectively. Conclusions! Stimulation of cranial nerve afferents initiates both early and late brainstem mediated pathways to the oropharynx and oesophagus and facilitates the corticofugal swallowing pathways.
DAY TO DAY VARIABILITY AND THE EFFECT OF REPEATED DISTENSIONS ON SYMPTOM THRESHOLDS DURING RECTAL DISTENSION. HF Hammer. SF Phillips, M Camilleri, RB Hanson, AR Zinsmcister. Mayo CLinic, GI Unit, Rochester, MN. BACKGROUND: Altered perception to intestinal distension may play a role in the symptoms of gastrointestinal dysfunction, but appropriate methods for testing are unclear. AIM: To assess intraindividual variabili[y of sensory thresholds to rectal distensign. METHODS: 5 healthy volunteers (23-41 yrs, 3m/2f) were studied 5 times, separated by 3 to 6 days. Subjects were in left lateral deeubitus with the feet elevated by 20°. A 10 cm polyurethane bag, inserted 5 cm from the anal verge, was inflated with air using a Distender II (GJ electronics). On 3 days, one distension was performed; on two days, 3 distensions, separated by 15 to 60 minutes, were performed. Subjects recorded a) the initial sensation of the rectal bag, b) a feeling akin to stool, and c) an the urgency to defecate. Thresholds were expressed as the volume (V), pressure (P), calculated circumference (C) of the bag, and wall tension (1") at the onset of sensations. Day to day variability of sensory thresholds was assessed by calculating the coefficient of variation (CV) for each subject from thresholds obtained during the first distensions on study days 2 to 5. CV for P, V, C and T thresholds were compared using paired t-tests, with Bonferroni correction. The effect of repeated distensions on sensory thresholds was assessed by calculating the difference between the first, second and third distensions. RESULTS: day to day Variability (CV) repeated distension (distension 1 minus distension 3) P V C T P V C T (%) (%) (%) (%) (mmng) (ml) (cm) (cm,mmHg) ±nit.sen. 32±8 30±6 16±3 ~ 45±10 7±3 32±28 2±2 21-7 stool 27±3 18±3 10±2123 34+31~ 10±24 60±254 2+1 33±9 argency 23±4 13±3 7±1123 28±412 11±4 i 59±32 2±1 38±14 Zp<0.01 vs V,2p<0.01 vs P,3p<0.01 vs T,4p<0.01 vs first distension. During the second distension, P and V thresholds were significantly higher than during the first, but not different from the third. CONCLUSIONS: 1) Sensory thresholds expressed as C were most reproducible. V thresholds tended towards being more reproducible than were P thresholds. 2) In studies of rectal sensation, an initial conditioning distension should eliminate an order effect, which is likely due to sensory adapation.
AGA ABSTRACTS
EFFECT OF PROLONGED PRESERVATION ON T H E I N T E S T I N A L N E U R O - M U S C U L A R S Y S T E M IN C A N I N E S M A L L B O W E L A U T O T R A N S P L A N T A T I O N N. Hamada W.R. Hutson, K. Nakada, A. Ikoma, T. Suzuki, Y. Zhu, J.C. Reynolds, S. Todo, T.E. Starzl. Dept. of surgery and Internal Medicine, University of Pittsburgh, School of Medicine, Pittsburgh, PA. Dysmotility of the transplanted intestinal graft has been explained, in part, by denervation of extrinsic nerve or ischemic and reperfusion injury to the muscular and/or nervous system in t h e intestinal wall. Little information, however, is available Concerning motility following prolonged preservation of the autotransplanted small intestine. Aim: To in'~estigate the effect of prolonged preservation on the neuro-muscular system involved in intestinal motility. Methods: The entire small intestine of adult hound dogs was procured and flushed with cold lactated Ringer's solution. The small intestine was autotransplanted either immediately or after 24 hours of cold preservation in the same solution. Fasted motility pattern and the response of the intestinal smooth muscle and enteric nerve tO bethanecbol (100 gg/kg/0.5hr, DIV) and cisapride (0.5mg/kg, IV), respectively, were determined using multiple strain gauge transducers On post-operative days (PODs) 2, 4, 7, 14, 21, 28, comparing transplanted jejunoileum (n=6 for each group) and control (n=4). Fasted small intestinal transit time (SITT) was measured on PODs 2, 7, 14, 21,281'25 mg !ndocyanine green (ICG) reagent dissolved with 10ml distilled water was administered through the catheter duodenostomy, and the transit t i m e was determined by initial detection of the ICG in the intestinal contents taken from the catheter ileostomy. Results' Migrating myoelectric contractions (MMC) were observed in control and immediate groups even from POD 2; however, in the preservation group the appearance of phase 3 Contractions were delayed until a minimum of 2 weeks, and even until 4 weeks in 50 % of this group, showing almost no motor activity until POD 2 and very active motor activity as frequent clustered contractions thereafter. There was no particular difference between the groups in their mean amplitude and frequency of the bursts after muscle stimulation by bethanechol or excitatory enteric nervous stimulation by cisapride during the study period. Although SITT in the preservation group was remarkably slower than the other groups at POD 2, it was accelerated and faster after POD 7. Conclusion: These results suggest that the integrity of the canine intestinal smooth muscle and excitatory enteric nervous system was rather well preserved even after 24 hours preservation in lactated-Ringer's solution; however, the inhibitory enteric nervous system appeared to be impaired and did not recover until at least 2 weeks after transplantation.
DAY TO DAY VARIABILITY AND THE EFFECT OF REPEATED DISTENSIONS ON RECTAL TONE AND ELASTANCE. HF Hammer, SF Phillips, M CamiUeri, A Zinsmeister, RB Hanson. Mayo CliniC, GI Unit, Rochester, MN. BACKGROUND Tone and elastance may be importam for normal rectal function and for symptoms in rectal disease. AIM: To assess day to day variability, and the effect of repeated distensions on rectal tone and elastance. METHODS: 5 healthy subjects (23-41yrs, 3m/2f) were studied 5 times, separated by 3 to 6 days. Subjects were in left lateral decubitus with the feet elevated by 20°. A cylindrical 10 cm polyurethane bag was inserted 5 cm from the anal verge. On 4 days basal rectal tone was measured immediately before and 25 minutes after a ramp distension (10 ml/min) using the Distender II (G+J Electronics). Differences in rectal tone before and after distensions were expressed as percent changes of the volume of air in the rectal balloon which was held at a constant pressure. Elastance was expressed as the intercept and the linear slope of the P/V curve. On day 1, two further distensions were performed; rectal tone was measured for 15 minutes between and after distensions. Distensions were stopped when subjects had Urgency for 30 seconds. Day to day variability was expressed as the coefficient of variation (CV) which was calculated for each subject from the results Of the 5 study days. Paired t-tests with Bonferroni correction were used. RESULTS: 1) Rectal tone: The first distension decreased rectal tone by 52-t-16% (p<0.001). The second and third distensions did not significantly change rectal tone (+ 12+9% and + 16+4%). CVs of rectal tone before and after distension were not significantly different (18+6% and 28+12%, respectively)~ 2) Elastance: Slopes and intercepts are shown in the table. Intercept Slope [[ p < 0 02 vs dist. 1; 2p < 0.05 vs (ram Hg) (ram Hg/ml) dist. 1 and not significantly distension 1 2.3 ±0.8 1.05 ±0.24 different from dist. 2; 3p<0.001 distension 2 4.5±0.51 0.65±0.23 ns vs dist; I; nSnot significantly distension 3 4.3±0.62 0.36±0.203 different from dist. 1 and 3]. CV(5) 311±177 16±2 The CV for the intercept ranged between 1 6 a n d 797%, and for the slope between 9 and 21%. CONCLUSIONS: 1) Basal rectal tone and the slope of the rectal elastance curve have good day to day reproducibility, but there is a large variability in the intercept of the elastance curve, suggesting that hysteresis may be important. 2) In studies of rectal tone and elastance, an initial conditioning distension is needed to eliminate an order effect between the first and the following distensions.
GASTROENTEROLOGY, Vol. 108, No. 4
OMODULATION OF HUMAN CORTICAL SWALLOWING PATHWAYS BY MAGNETIC STIMULATION OF TRIGEMINAL AND VAGAL AFFERENT NERVES. S. Hamdy; Q. Aziz, A. Hobson, J. Barlow, D. G. Thompson. Department of Medicine, Hope Hospital, Unlversity of Manchester, UK
Background: We have previously reported the physiological characteristics of corticofugal pathways to the esophagus in healthy volunteers following magnetic stimulation of the motor cortex (Am. J. Physiol 1994. 267:30:G827-835). Swallowing responses in animals have also been elicited by Trigeminal (T) Or Vagal (V) afferent stimulation. In humans, however, the interactions between cortical and brainstem pathways to swallowing musculature are unexplored. Aims: To determine i). whetfier magnetic stimulation of T and V afferents excite brainstem swallowing pathways, ii). whether activation of these afferents modifies cortical swallowing pathways. Methods: 8 healthy volunteers were studied. Surface electrodes were placed on each mylohyoid muscle (M), and bipolar ring electrodes were positioned in the pharynx (P) and esophagus (E)via an intraluminal catheter. Magnetic stimulation was then applied at suprathreshold (1 tesla) intensities to motor cortex, supraorbital nerve IT) and extracranial vagus nerve at the angle of the jaw (V), and the EMG responses from each of the three muscle groups recorded. Study I; Stimulation Of either T or V afferents alone. Study 2;, Cortical stimulation alone or following T or V stimulation at intervals varying from 5-500ms between the two stimuli: Results: Study I; Two distinct responses were recorded in each of the three muscle groups: an early response, ranging in latencies from 21.7-28.1ms: and a late response, ranging in latencies from; 50.0-58.9ms. Study 2; Cortical stimulation alone evoked EMG responses in the M, P, and E muscles, mean latencies 8.9, 9.1, and 10.2ms respectively. After either T or V afferent stimulation, the latencies of the cortically evoked responses shortened, the effect being maximal at an interval of 50ms, to 6.2, 7.2, and 8.3ms. ~<,0.05) respectively. Conclusions! Stimulation of cranial nerve afferents initiates both early and late brainstem mediated pathways to the oropharynx and oesophagus and facilitates the corticofugal swallowing pathways.
DAY TO DAY VARIABILITY AND THE EFFECT OF REPEATED DISTENSIONS ON SYMPTOM THRESHOLDS DURING RECTAL DISTENSION. HF Hammer. SF Phillips, M Camilleri, RB Hanson, AR Zinsmcister. Mayo CLinic, GI Unit, Rochester, MN. BACKGROUND: Altered perception to intestinal distension may play a role in the symptoms of gastrointestinal dysfunction, but appropriate methods for testing are unclear. AIM: To assess intraindividual variabili[y of sensory thresholds to rectal distensign. METHODS: 5 healthy volunteers (23-41 yrs, 3m/2f) were studied 5 times, separated by 3 to 6 days. Subjects were in left lateral deeubitus with the feet elevated by 20°. A 10 cm polyurethane bag, inserted 5 cm from the anal verge, was inflated with air using a Distender II (GJ electronics). On 3 days, one distension was performed; on two days, 3 distensions, separated by 15 to 60 minutes, were performed. Subjects recorded a) the initial sensation of the rectal bag, b) a feeling akin to stool, and c) an the urgency to defecate. Thresholds were expressed as the volume (V), pressure (P), calculated circumference (C) of the bag, and wall tension (1") at the onset of sensations. Day to day variability of sensory thresholds was assessed by calculating the coefficient of variation (CV) for each subject from thresholds obtained during the first distensions on study days 2 to 5. CV for P, V, C and T thresholds were compared using paired t-tests, with Bonferroni correction. The effect of repeated distensions on sensory thresholds was assessed by calculating the difference between the first, second and third distensions. RESULTS: day to day Variability (CV) repeated distension (distension 1 minus distension 3) P V C T P V C T (%) (%) (%) (%) (mmng) (ml) (cm) (cm,mmHg) ±nit.sen. 32±8 30±6 16±3 ~ 45±10 7±3 32±28 2±2 21-7 stool 27±3 18±3 10±2123 34+31~ 10±24 60±254 2+1 33±9 argency 23±4 13±3 7±1123 28±412 11±4 i 59±32 2±1 38±14 Zp<0.01 vs V,2p<0.01 vs P,3p<0.01 vs T,4p<0.01 vs first distension. During the second distension, P and V thresholds were significantly higher than during the first, but not different from the third. CONCLUSIONS: 1) Sensory thresholds expressed as C were most reproducible. V thresholds tended towards being more reproducible than were P thresholds. 2) In studies of rectal sensation, an initial conditioning distension should eliminate an order effect, which is likely due to sensory adapation.