Responses of feline gastroesophageal junction to changes in abdominal pressure

1987 ◽  
Vol 253 (3) ◽  
pp. G315-G322 ◽  
Author(s):  
J. T. Boyle ◽  
S. M. Altschuler ◽  
T. E. Nixon ◽  
A. I. Pack ◽  
S. Cohen
Keyword(s):  
Gastroesophageal Junction ◽  
Gastric Distension ◽  
Abdominal Pressure ◽  
Electromyographic Activity ◽  
Abdominal Compression ◽  
Balloon Distension ◽  
Gastric Pressure ◽  
High Pressure Zone ◽  
Antireflux Barrier ◽  
Sustained Inhibition

The responses of the lower esophageal sphincter (LES), stomach, and diaphragm and their contribution to changes in the high-pressure zone (HPZ) at the gastroesophageal junction were determined during extrinsic abdominal compression or intragastric balloon distension in anesthetized cats. Abdominal compression consistently induced an increase in intraluminal end-expiratory LES and gastric pressure (P less than 0.01). Changes in LES pressure significantly exceeded the changes in gastric pressure (P less than 0.01). In contrast, the LES response during gastric distension was variable in the group of animals despite a consistent volume-dependent increase in gastric pressure. Mean LES pressure for the group was unchanged, although 33% of individual animals exhibited a decrease in LES pressure during gastric distension. Both abdominal stimuli induced sustained inhibition of crural (P less than 0.01), but not costal, diaphragmatic electromyographic activity. Vagotomy affected the LES but not the gastric or diaphragmatic responses to both stimuli. In the group of animals, the combined effect of the changes in the three measured variables on the HPZ resulted in maintenance of the antireflux barrier during abdominal compression but a significant decrease in the barrier during gastric distension.

scholarly journals Reflex Increase in the Gastroesophageal Junction High Pressure Zone Pressure During Sedated Endoscopy With Gastric Distension in Normal Volunteers

2011 ◽  
Vol 140 (5) ◽  
pp. S-626
Author(s):  
Anil K. Vegesna ◽  
Prabhu H. Yogeesh ◽  
Pallavi Murari ◽  
Shital P. Prabhu ◽  
Aiswerya Madanam Sampath ◽  
...  
Keyword(s):  
High Pressure ◽  
Gastroesophageal Junction ◽  
Gastric Distension ◽  
Normal Volunteers ◽  
Pressure Zone ◽  
High Pressure Zone

Human lower esophageal sphincter pressure response to increased intra-abdominal pressure

1990 ◽  
Vol 258 (4) ◽  
pp. G624-G630 ◽  
Author(s):  
R. K. Mittal ◽  
M. Fisher ◽  
R. W. McCallum ◽  
D. F. Rochester ◽  
J. Dent ◽  
...  
Keyword(s):  
Lower Esophageal Sphincter ◽  
Esophagogastric Junction ◽  
Tonic Contraction ◽  
Pressure Response ◽  
Abdominal Pressure ◽  
Abdominal Compression ◽  
Gastric Pressure ◽  
Straight Leg Raising ◽  
Esophageal Sphincter ◽  
Crural Diaphragm

We studied the effects of increased intra-abdominal pressure on the lower esophageal sphincter (LES) pressure in 15 healthy subjects. The role of the diaphragm in the genesis of LES pressure during increased intra-abdominal pressure was determined by measuring diaphragm electromyogram (EMG). The latter was recorded using bipolar intraesophageal platinum electrodes that were placed on the nonpressure sensing surface of the sleeve device. We also measured the LES pressure response to increased intra-abdominal pressure during inhibition of the smooth muscles of the LES by intravenous atropine (12 micrograms/kg). Straight-leg raising and abdominal compression were used to increase intra-abdominal pressure. Our results show that the increase in LES pressure during straight-leg raising is greater than the increase in gastric pressure. During abdominal compression, the rate of LES pressure increase is faster than that of the gastric pressure, suggesting an active contraction at the esophagogastric junction. The increase in LES pressure during periods of increased intra-abdominal pressure is associated with a tonic contraction of the crural diaphragm as demonstrated by EMG recording. Atropine inhibited the resting LES pressure by 50-70% in each subject but had no effect either on the peak LES pressure attained during increased intra-abdominal pressure or tonic crural diaphragm EMG. We conclude that 1) there is an active contraction at the esophagogastric junction during periods of increased intra-abdominal pressure and 2) tonic contraction of the crural diaphragm is a mechanism for this LES pressure response.

Effect of abdominal compression on diaphragmatic tendon organ activity

1992 ◽  
Vol 72 (1) ◽  
pp. 288-292 ◽  
Author(s):  
R. Revelette ◽  
S. Reynolds ◽  
D. Brown ◽  
R. Taylor
Keyword(s):  
Phrenic Nerve ◽  
Muscle Activation ◽  
Muscle Spindles ◽  
Abdominal Pressure ◽  
Electromyographic Activity ◽  
Abdominal Compression ◽  
Level Of Activity ◽  
Tendon Organs ◽  
The Right ◽  
Tendon Organ

Previous studies suggest that afferents in the diaphragm participate in the reflex reduction in phrenic nerve efferent activation when the length of the diaphragm is increased by abdominal compression. The present study determined the response of tendon organ afferents in the diaphragm to increases in abdominal pressure. Five cats were anesthetized with thiopental sodium (60 mg/kg ip to induce, supplemented intravenously). Extracellular recordings from nine individual tendon organ afferents were made from right cervical dorsal root ganglia 5 and 6. Right crural electromyographic activity was recorded. The right extrathoracic phrenic nerve was isolated and stimulated to identify tendon organs on the basis of conduction velocity and response to twitch. The response to ramp-and-hold stretch of the diaphragm was used as an additional test to differentiate tendon organs from muscle spindles. The mean level of activity of the tendon organs during the 1st s of the inspiratory phase was 47 +/- 10 (SD) Hz. Abdominal compression was associated with a significant increase in the activity of these afferents to 61 +/- 11 Hz. Results indicate that increases in the activity of diaphragmatic tendon organs are associated with moderate increases in abdominal pressure and are likely the result of elevations in the active tension developed by the diaphragm. Combined with results from previous studies, it is possible that diaphragmatic tendon organs may play a role in the attenuation of respiratory muscle activation when abdominal pressure is increased.

Simultaneous reflex inhibition of lower esophageal sphincter and crural diaphragm in cats

1985 ◽  
Vol 249 (5) ◽  
pp. G586-G591 ◽  
Author(s):  
S. M. Altschuler ◽  
J. T. Boyle ◽  
T. E. Nixon ◽  
A. I. Pack ◽  
S. Cohen
Keyword(s):  
Lower Esophageal Sphincter ◽  
Gastroesophageal Junction ◽  
Pressure Profile ◽  
Gastric Fundus ◽  
Intraluminal Pressure ◽  
Neural Pathways ◽  
Balloon Distension ◽  
Esophageal Sphincter ◽  
Crural Diaphragm ◽  
High Pressure Zone

We have previously suggested that both the lower esophageal sphincter and diaphragm contribute to the high-pressure zone (HPZ) at the gastroesophageal junction. The purpose of this study in anesthetized cats was to compare changes in diaphragmatic electrical activity with changes in the intraluminal pressure profile in the HPZ following either balloon distension of the esophagus or swallowing evoked by pharyngeal stimulation. Intraluminal pressure was continuously recorded by a perfused manometric assembly anchored to the gastric fundus through an abdominal surgical approach. Integrated EMG was simultaneously measured in the costal and crural parts of the diaphragm. Our results indicate that simultaneous relaxation of the lower esophageal sphincter (LES) and crural diaphragm follows both swallowing and balloon distension of the esophagus; during swallowing both inhibitory reflexes depend on the initiation of esophageal peristalsis; crural relaxation abolishes respiratory-induced pressure oscillations in the HPZ during LES relaxation; ventilation is maintained during relaxation of the HPZ in part by continued contraction of the costal diaphragm; and different neural pathways control LES relaxation and crural relaxation. The data support the view that the crural diaphragm augments the intrinsic smooth muscle sphincter mechanism at the gastroesophageal junction and that crural relaxation may be an important factor in mouth-to-gastric transit.

CCK enhances response to gastric distension by acting on capsaicin-insensitive vagal afferents

2005 ◽  
Vol 289 (3) ◽  
pp. R695-R703 ◽  
Author(s):  
E. H. E. M. van de Wall ◽  
P. Duffy ◽  
R. C. Ritter
Keyword(s):  
Vagal Afferents ◽  
Gastric Distension ◽  
Solitary Tract ◽  
C Fibers ◽  
Balloon Distension ◽  
Electrophysiological Responses ◽  
Vagal Afferent ◽  
Fos Expression ◽  
Afferent Response ◽  
And Control

Capsaicin treatment destroys vagal afferent C fibers and markedly attenuates reduction of food intake and induction of hindbrain Fos expression by CCK. However, both anatomical and electrophysiological data indicate that some gastric vagal afferents are not destroyed by capsaicin. Because CCK enhances behavioral and electrophysiological responses to gastric distension in rats and people, we hypothesized that CCK might enhance the vagal afferent response to gastric distension via an action on capsaicin-insensitive vagal afferents. To test this hypothesis, we quantified expression of Fos-like immunoreactivity (Fos) in the dorsal vagal complex (DVC) of capsaicin-treated (Cap) and control rats (Veh), following gastric balloon distension alone and in combination with CCK injection. In Veh rats, intraperitoneal CCK significantly increased DVC Fos, especially in nucleus of the solitary tract (NTS), whereas in Cap rats, CCK did not significantly increase DVC Fos. In contrast to CCK, gastric distension did significantly increase Fos expression in the NTS of both Veh and Cap rats, although distension-induced Fos was attenuated in Cap rats. When CCK was administered during gastric distension, it significantly enhanced NTS Fos expression in response to distension in Cap rats. Furthermore, CCK's enhancement of distension-induced Fos in Cap rats was reversed by the selective CCK-A receptor antagonist lorglumide. We conclude that CCK directly activates capsaicin-sensitive C-type vagal afferents. However, in capsaicin-resistant A-type afferents, CCK's principal action may be facilitation of responses to gastric distension.

scholarly journals Unusually High Intra-abdominal Opening Pressure Confirmed by Simultaneous Gastric Pressure Measurement during Laparoscopy

2012 ◽  
Vol 6 (1) ◽  
pp. 12-15
Author(s):  
Richard Matulewicz ◽  
Antonio R. Gargiulo ◽  
Stephen H. Loring ◽  
Massimo Ferrigno
Keyword(s):  
Respiratory Mechanics ◽  
Obese Woman ◽  
Veress Needle ◽  
Abdominal Pressure ◽  
Needle Placement ◽  
Opening Pressure ◽  
Robot Assisted ◽  
Gastric Pressure ◽  
High Degree ◽  
Viable Method

A 28 year-old obese woman was scheduled for robot-assisted bilateral tubal re-anastomosis under general anesthesia and neuromuscular blockade. As part of a respiratory mechanics study, gastric pressure (Pga) was measured. At the beginning of the operation, the surgeon repeatedly inserted a Veress needle consistently measuring an unusually high opening pressure of 15 mmHg, at a time when Pga was 12.5 mmHg. Based on the elevated Pga values, we inferred that the high opening pressure was a valid intra-peritoneal pressure, rather than a sign of incorrect needle placement; therefore, the surgeon proceeded with uneventful insufflation of the peritoneal cavity. This patient exhibited an unusually high opening intra-abdominal pressure that likely reflected her high degree of central obesity. Simultaneous Pga determination proved valuable in confirming intra-peritoneal location of the tip of Veress needle and may be a viable method of corroborating high opening pressures despite safe needle positions in laparoscopic cases.

Diaphragmatic contribution to gastroesophageal competence and reflux in dogs

1992 ◽  
Vol 263 (4) ◽  
pp. G551-G557 ◽  
Author(s):  
C. J. Martin ◽  
W. J. Dodds ◽  
H. H. Liem ◽  
R. O. Dantas ◽  
R. D. layman ◽  
...  
Keyword(s):  
Gastroesophageal Reflux ◽  
Lower Esophageal Sphincter ◽  
Short Duration ◽  
Gastroesophageal Junction ◽  
Selective Inhibition ◽  
High Amplitude ◽  
Gastric Distension ◽  
Esophageal Body ◽  
Esophageal Sphincter ◽  
Crural Diaphragm

Events associated with gastroesophageal reflux have been determined by concurrent diaphragmatic and esophageal body electromyography, video radiography, and manometry in four conscious dogs. Three characteristic phenomena occurred in parallel immediately before and during gastroesophageal reflux: 1) transient lower esophageal sphincter relaxation, 2) profound (99.5%) and selective inhibition of crural diaphragmatic activity, and 3) a previously unrecognized dorsal movement of the gastroesophageal junction (mean 1.3 cm) demonstrated by implanted radiological markers. The patterns associated with spontaneous acid and gas reflux were indistinguishable from those induced by gastric distension. Costolumbar diaphragmatic activity was stable up until the instant of sphincter opening, when there was a single costolumbar contraction of short duration and high amplitude. Esophageal shortening did not occur before reflux. Reflux that occurred after atropine-induced inhibition of lower esophageal sphincter tone to < 2 mmHg was intermittent and coincided with selective crural inhibition. These studies demonstrated that selective crural inhibition is a prerequisite for gastroesophageal reflux and suggest that the crural diaphragm is an important factor for the maintenance of gastroesophageal competence.

Regional differences in abdominal pressure swings in dogs

1984 ◽  
Vol 57 (6) ◽  
pp. 1682-1687 ◽  
Author(s):  
M. Decramer ◽  
A. De Troyer ◽  
S. Kelly ◽  
L. Zocchi ◽  
P. T. Macklem
Keyword(s):  
Regional Differences ◽  
Abdominal Muscle ◽  
Abdominal Pressure ◽  
Bilateral Stimulation ◽  
Quiet Breathing ◽  
Gastric Pressure ◽  
Anesthetized Dogs ◽  
Small Change ◽  
Crural Diaphragm ◽  
Stimulation Of

The pressure swings under the costal (Pcos) and crural diaphragms (Pcru) and between the intestinal loops (Pint) were compared with the swings in gastric pressure (Pga) in 13 supine anesthetized dogs. Pcos, Pcru, and Pint were measured with air-filled latex balloons in eight dogs and saline-filled catheters in five. Pga was measured with an air-filled balloon in all dogs. During quiet breathing differences were often present, the directions of which were variable from animal to animal. During mechanical ventilation, all pressures increased, but both Pcos and Pcru increased more than Pga, whereas only a small change was observed in Pint. During bilateral stimulation of the costal diaphragm, Pcos invariably increased more than Pga and Pint, whereas almost no change was observed in Pcru. During bilateral stimulation of the crural diaphragm, Pcru invariably increased more than Pga, Pint, and Pcos. During abdominal muscle stimulation as during external abdominal compression, Pint always increased more than Pcos and Pcru. During lower rib cage compression, Pga, Pcos, and Pcru increased more than Pint. During sternocleidomastoid stimulation, all pressure swings were negative, but the change in Pint was always smaller than in Pcos, Pcru, or Pga. Inhomogeneities observed with balloons and saline-filled catheters were similar. After the abdomen was filled with 2 liters of saline all pressure swings became much more homogeneous.

scholarly journals Spinal stiffness changes throughout the respiratory cycle

2003 ◽  
Vol 95 (4) ◽  
pp. 1467-1475 ◽  
Author(s):  
D Shirley ◽  
P. W. Hodges ◽  
A. E. M. Eriksson ◽  
S. C. Gandevia
Keyword(s):  
Muscle Activity ◽  
Spinous Process ◽  
Lumbar Vertebrae ◽  
Trunk Muscle ◽  
Erector Spinae ◽  
Abdominal Pressure ◽  
Abdominal Muscles ◽  
Electromyographic Activity ◽  
Spinal Stiffness ◽  
Wall Stiffness

Posteroanterior stiffness of the lumbar spine is influenced by factors, including trunk muscle activity and intra-abdominal pressure (IAP). Because these factors vary with breathing, this study investigated whether stiffness is modulated in a cyclical manner with respiration. A further aim was to investigate the relationship between stiffness and IAP or abdominal and paraspinal muscle activity. Stiffness was measured from force-displacement responses of a posteroanterior force applied over the spinous process of L2and L4. Recordings were made of IAP and electromyographic activity from L4/L2erector spinae, abdominal muscles, and chest wall. Stiffness was measured with the lung volume held at the extremes of tidal volume and at greater and lesser volumes. Stiffness at L4and L2increased above base-level values at functional residual capacity (L214.9 N/mm and L415.3 N/mm) with both inspiratory and expiratory efforts. The increase was related to the respiratory effort and was greatest during maximum expiration (L224.9 N/mm and L423.9 N/mm). The results indicate that changes in trunk muscle activity and IAP with respiratory efforts modulate spinal stiffness. In addition, the diaphragm may augment spinal stiffness via attachment of its crural fibers to the lumbar vertebrae.

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