Perception Of Distension Research Articles

Acupuncture transcutaneous electrical nerve stimulation reduces discomfort associated with barostat-induced rectal distension: A randomized-controlled study

To explore the effectiveness of acupuncture transcutaneous electrical nerve stimulation (Acu-TENS), a non-invasive modality in reduction of rectal discomfort during barostat-induced rectal distension. Forty healthy subjects were randomized to receive 45 min of either Acu-TENS or placebo-TENS (no electrical output) over acupuncture points Hegu (large-intestine 4), Neiguan (pericardium 6) and Zusanli (stomach 36). A balloon catheter attached to a dual-drive barostat machine was then inserted into the subjects' rectum. A step-wise (4 mmHg) increase in balloon pressure was induced until maximal tolerable or 48 mmHg. Visual analogue scale and a 5-point subjective discomfort scale (no perception, first perception of distension, urge to defecate, discomfort/pain and extreme pain) were used to assess rectal discomfort at each distension pressure. Blood beta-endorphin levels were measured before, immediately after intervention, at 24 mmHg and at maximal tolerable distension pressure. There was no difference in the demographic data and baseline plasma beta-endorphin levels between the two groups. Perception threshold levels were higher in the Acu-TENS group when compared to the placebo group, but the difference reached statistical significance only at the sensations "urge to defecate" and "pain". The distension pressures recorded at the "urge to defecate" sensation for the Acu-TENS and placebo-TENS groups were 28.0 ± 4.5 mmHg and 24.6 ± 5.7 mmHg, respectively (P = 0.043); and the pressures recorded for the "pain" sensation for these two groups were 36.0 ± 4.2 mmHg and 30.5 ± 4.3 mmHg respectively (P = 0.002). Compared to the placebo group, a higher number of participants in the Acu-TENS group tolerated higher distension pressures (> 40 mmHg) (65% in Acu-TENS vs 25% in placebo, P = 0.02). The plasma beta-endorphin levels of the Acu-TENS group were significantly higher than that of the placebo group at barostat inflation pressure of 24 mmHg (1.31 ± 0.40 ng/mL vs 1.04 ± 0.43 ng/mL, P = 0.044) and at maximal inflation pressure (1.46 ± 0.53 ng/mL vs 0.95 ± 0.38 ng/mL, P = 0.003). Acu-TENS reduced rectal discomfort during barostat-induced rectal distension and concurrently associated with a rise in beta-endorphin level.

Identification of the biomechanical factors associated with the perception of distension in the human esophagus.

Current techniques used to investigate the mechanisms responsible for the sensory responses to distension of the human esophagus provide limited information because the degree of circumferential stretch required to determine tension can only be inferred. We used impedance planimetry to measure the cross-sectional area during esophageal distension to ascertain the degree of stretch and tension that initiated motor and sensory responses. Hyoscine-N-butyl bromide (HBB), a cholinergic muscarinic receptor blocker, was also used to alter esophageal tension during distension. Motor activity was initiated at a lower degree of stretch and tension than that which initiated sensory awareness; both increased directly with increasing distension. HBB reduced both esophageal motility and tension during distension without altering the relationship between sensation intensity and cross-sectional area. Esophageal stretch, rather than tension, thus appears to be the major factor influencing sensory responses to esophageal distension.

Intrarectal injection of glycerol induces hypersensitivity to rectal distension in healthy subjects without modifying rectal compliance.

Rectal sensory thresholds are lowered in patients with irritable bowel syndrome (IBS), reflecting visceral hyperlagesia, which might be related to subclinical inflammation. To evaluate the effects of an intraluminal injection of glycerol, a mucosal irritant, on rectal tone and perception of distension in 12 healthy subjects. Rectal tone was evaluated with a barostat. First sensation, need to defecate and pain thresholds were evaluated during isobaric phasic distensions, before and 20 and 120 min after injection of 10 ml glycerol in the rectum. Baseline bag volume (97.9 +/- 56.2 ml) significantly decreased 20 min (49.7 +/- 42.2 ml; P= 0.026) and 120 min (66.5 +/- 38.3 ml; P= 0.050) after injection of glycerol, indicating its hypertonic effect. The pressure defining sensory thresholds was decreased significantly 20 min after glycerol injection: first sensation, 14.6 +/- 2.9 versus 18.3 +/- 7.2 mm Hg (P = 0.01); need to defecate, 19.6 +/- 3.7 versus 26.0 +/- 6.9 mm Hg; pain, 23.8 +/- 4.5 versus 35.6 +/- 9.5 mm Hg (P = 0.001). This effect was maintained for 120 min after injection of glycerol. Slopes of the compliance curves did not differ before and after injection of glycerol. Intraluminal injection of glycerol significantly increases rectal tone and sensitizes healthy volunteers to rectal distension, since they show significantly lower thresholds after glycerol. This could constitute a model of visceral hypersensitivity in healthy volunteers.

Proximal gastric compliance and perception of distension in type 1 diabetes mellitus: effects of hyperglycemia

OBJECTIVES: Upper GI symptoms and disordered gastric motor function occur frequently in patients with type 1 diabetes mellitus and may be influenced by the blood glucose concentration. The aims of this study were to evaluate proximal gastric compliance and perception of gastric distension during euglycemia and hyperglycemia in unselected patients with type 1 diabetes. METHODS: Ten randomly selected patients with type 1 diabetes were studied. On a single day, isovolumetric and isobaric distensions of the proximal stomach were performed during both euglycemia (blood glucose, 6 mmol/L) and hyperglycemia (15 mmol/L), in randomized order. Sensations of fullness, nausea, and bloating were scored using visual analog scales during each step. Results were compared with those obtained in 10 healthy subjects studied during euglycemia. RESULTS: During euglycemia, perceptions of fullness ( p < 0.01), nausea ( p < 0.01), and bloating ( p < 0.05) were greater during gastric distension in patients with diabetes when compared with healthy controls. In the patients, hyperglycemia increased gastric compliance ( p < 0.05) when compared to euglycemia. CONCLUSIONS: In unselected patients with type 1 diabetes 1) the perception of gastric distension during euglycemia is increased compared with healthy controls, and 2) hyperglycemia increases proximal gastric compliance.

Effects of GLP-1 on proximal gastric motor and sensory function in human

The hormonal incretin glucagon-like peptide-l(7-36)amide (GLP-1) retards gastric emptying and inhibits antroduodenal motility (Proc Am Assoc Phys 1997; 109:84-97). However, the effects of this peptide on the proximal stomach are unknown. This study was designed to assess fundus tone and compliance as well as perception of gastric distention in response to GLP-1. Methods: 10 healthy male volunteers were studied in random order on 3 separate days. On each day, fundus tone was recorded with an electronic barostat device (capacity of intragastric bag: 1100 ml). Minimal distending pressure (MDP) was determined as the pressure level that resulted in a bag volume of > 30 ml. Thereafter, gastric tone represented by balloon volume was recorded for 120 min with the pressure set at MDP+I mmHg. After a basal period of 60 rain, saline or GLP-I at 0.3 pmolokg4.min -1 or GLP-1 at 0,9 pmol°kg-l°min -1 were infused from 61 120 min. These loads were chosen to replicate physiological and supraphysiological plasma levels, respectively. Subsequently, with ongoing infusions of saline or GLP-1 graded isobaric and isovolumetric distentions (2 rain increments of 2 mmHg or 100 ml) were performed and volume and pressure responses recorded. Proximal gastric compliance was derived from isobaric distention. Perception of distention was scored by dialing a panel (score 1 5, 2: first perception, 5: discomfort). Blood glucose and plasma insulin were regularly determined. Results: Mean ± SEM, *:P<0.05 vs saline, #:P<0,05 vs. GLP-10.3 pmol.kg'l-min I