Rate Of Distention Research Articles

LONG-TERM EFFECT OF ANTIHYPERTENSIVE AGENTS ON THE NEURAL BAROREFLEX SENSITIVITY-A SUBSTUDY OF THE PARIS PROSPECTIVE STUDY III

Objective: The baroreflex is a crucial mechanism regulating moment-to-moment blood pressure (BP) to ensure appropriate flow and pressure to the brain and other organs. All antihypertensive treatments, because of their BP lowering effect, interact with the autonomic nervous system by stimulating the sympathetic response. In addition, specific drugs may further interact with the BRS because of their specific mode of action. Whether antihypertensive agents have remnant effect is still unknown. Design and method: In the Paris Prospective Study III, spontaneous baroreflex, carotid stiffness and pharmacological drugs intake were available in 7967 adults (mean age of 60 ± 6 years, 62% men). The neural component of the baroreflex sensitivity (nBRS) was obtained with a cross-spectral analysis of variations in carotid distention rate and R-R intervals. Individuals with a BP lowering medication (BP-treated) were paired to non-BP treated individuals (controls) with similar cardiovascular comorbidities using a propensity score matching procedure (n = 1182 pairs). Results: Sympathetic activity was higher in the BP-treated group compared to their matched-controls, as shown by the increased spectral power of distention rate in the low frequency band (log LF distrate: 4.106 ± 0.530 vs 4.055 ± 0.514, p = 0.018). Amongst pharmacological classes of BP lowering agents, only agents acting on the angiotensin system (ACEi-ARB) were associated with nBRS. Compared to their matched controls (n = 331 pairs), ACEi-ARB users had lower nBRS (2.79 ± 0.66 (ln) vs. 2.90 ± 0.62 (ln), p = 0.03). After adjustment for carotid stiffness (stdbeta = 0.25, p < 0.001) and systolic pressure (stdbeta = -0.20, p < 0.001), ACEi-ARB remained significantly associated with nBRS (stdbeta = -0.09, p = 0.025). Conclusions: In this community-based population study, antihypertensive treatments induced activation of the autonomic nervous system independently of cardiovascular comorbidities. Taken as a whole, BP treatments did not have any effect on the neural component of the baroreflex loop, with the exception of ACEi-ARB which were negatively associated with nBRS. This effect was independent of BP and stiffness, which may suggest an inhibition of sympathetic activity by ACEi-ARB.

Effect of early bile regurgitation via gastric tube on gastrointestinal function in patients undergoing laparoscopic choledochotomy

Objective To investigate the effect of early bile regurgitation via gastric tube on gastrointestinal function in patients undergoing laparoscopic choledochotomy. Methods A total of 98 patients who underwent laparoscopic biliary tract surgery were selected treated in our hospital from August 2015 to August 2017, according to random number table method, all of the patients were randomly divided into two groups, the control group and the test group. The two groups of patients were given routine nursing intervention, the experimental group received early bile regurgitation via gastric tube. The incidence rate of postoperative abdominal distension and gastrointestinal function recovery were compared between two groups. Results After treatment, there were 10 cases of abdominal distention in the test group and 21 cases in the control group. The abdominal distention rate in the test group was 20.41%(10/49), which was significantly lower than that in the control group 42.86%(21/49) (χ2=5.934, P < 0.05). After treatment, the anal exhaust time and bowel sound recovery time in the test group were (33.01±8.29) h and (17.53±3.92) h, respectively, which were significantly lower than those in the control group (43.22±11.02) h and (23.94±7.02) h, respectively. The difference between the two groups was statistically significant. (t = 4.859, 5.823, P < 0.05). Conclusions Early bile regurgitation through gastric tube can effectively reduce the incidence of postoperative abdominal distension and promote the recovery of gastrointestinal function in patients with laparoscopic choledochotomy. It is worthy of being popularized in clinical practice. Key words: Choledocholithiasis; Bile; Nursing care; Gastric dysfunction; Laparoscopic operation

Rectal sensorimotor dysfunction in women with fecal incontinence

The rate and pattern of rectal distension affect rectal distensibility, perception, and anal relaxation in health. Because rectal urgency is a prominent symptom in fecal incontinence (FI), we assessed rectal distensibility, contractions, perception, and anal pressures during rectal distention in 21 healthy, asymptomatic women (age 61 +/- 2 yr, mean +/- SE) and 51 women with FI (60 +/- 2 yr). Rectal staircases (0-32 mmHg, 4-mm steps) and ramp distensions [0-200 ml at 25, 50, and 100 ml/min with a phase of sustained distension (SD), lasting 1 min, between inflation and deflation]. The rectum was stiffer during rapid than slow ramp distention. This effect was more prominent at a lower volume (50 ml) and was also more pronounced in older subjects and in FI. A rectal contractile response was observed not only during inflation but also during SD and during deflation. During inflation, this contractile response was rate dependent in controls but not in FI. During staircase but not ramp distentions, the threshold for the desire to defecate was lower in FI. During ramp distentions, the duration of perception was significantly longer in FI. The rate of distention did not affect rectal perception (i.e., sensory thresholds or duration of perception) during ramp distentions. Baseline anal pressures and the magnitude of anal relaxation during rectal distention were also reduced in FI. In addition to reduced rectal capacity and compliance, women with FI had an exaggerated rate-dependent reduction in rectal distensibility, lower sensory thresholds, and more prolonged perception, indicative of rectoanal dysfunctions.

Rectal hyperreactivity to distention in patients with irritable bowel syndrome: role of distention rate

Background & Aims : Rectal motor hyperreactivity to distention may be involved in the pathophysiological course of defecatory symptoms in patients with irritable bowel syndrome (IBS), but results of patient studies are conflicting, possibly because of differences in the applied distention rate. Because a fast rate of distention increases the rectal motor response in healthy subjects, it also may show hyperreactivity in patients with IBS. The aim of this study is to compare the effects of 2 distention rates on rectal motor responses and sensations in 16 patients with IBS and 12 healthy subjects. Methods : Rectal distensibility and the frequency of rectal contractions and sensations were recorded during volume-controlled rectal distentions at 2 distention rates (10 and 100 mL/min). Results : Recta of patients with IBS were significantly less distensible than those of healthy subjects during fast distention ( P = 0.0006), but this difference was not statistically significant during slow distention ( P = 0.07). The frequency of rectal contractions and sensations, the majority of which were sensations of gas and a desire to defecate, were significantly greater in patients with IBS during both slow and fast distentions (both P < 0.025). Conclusions : Recta of patients with IBS are hyperreactive to distention, and fast distention magnifies this abnormal motor response. A greater frequency of sensations during a fixed-time distention period may help to characterize the patients.

Effect of distention rate on rectal accommodation and perception in irritable bowel syndrome (IBS)

Effect of distention rate on rectal accommodation and perception in irritable bowel syndrome (IBS)

Sensory and motor responses to rectal distention vary according to rate and pattern of balloon inflation

Anorectal motor activity and rectal sensation were recorded in 12 normal male subjects during ramp distention of the rectum with water and air at randomized rates of 10, 20, 50, and 100 mL/min and during intermittent rapid distention with air. There were no significant differences between the results of ramp inflation with water or with air, and the repeated infusion of the same medium yielded reproducible results. Ramp distention induced sigmoid pressure-volume profiles. Different sensations occurred at specific points on the pressure-volume curve and were maintained until succeeded by the next sensation. Initial perception of the distention occurred during the initial steep pressure increase, the sensation of wind occurred during the plateau phase, and the desire to defecate occurred at the onset of the final rapid ascent. Rectal sensations were induced at lower volumes at low infusion rates when the slope of the pressure-volume relationship was shallower than at high infusion rates. This suggests that the receptor triggering rectal sensation is not a simple volume or pressure receptor, but is more likely to be a slowly adapting mechanoreceptor lying parallel to the circular muscle of the rectal wall. During rapid intermittent distention, the rectal volumes required to elicit rectal sensations were lower than during ramp distention, although the pressure-volume curve was steeper. Moreover, sensations often only lasted a short period of time but recurred on deflation. These data suggest activation of an additional population of rapidly adapting or high threshold mechanoreceptors. Anal relaxation was always evoked by intermittent rectal distention and was almost always associated with a rectal sensation and an increase in external anal sphincter activity. In contrast, anal relaxation could be absent or delayed during ramp inflation, especially at lower infusion rates, suggesting that internal sphincter can maintain continence for a long period of time while the rectum is slowly filling. Rectal sensation and concomitant external anal sphincter activity was not associated with anal relaxation during ramp inflation; most subjects felt the sensation long after the pressure reached its lowest level. However, under all circumstances the onset of rectal sensation was associated with an increase of external anal sphincter electrical activity. In conclusion, the rectal sensory and anorectal motor responses to distention depend on the rate and pattern of distention, which may activate a different population of receptors. Results from different laboratories cannot be compared directly unless the pattern and rate of distention are the same.

Myocardial Rupture: III. Chamber Pressure, Rate of Distention, and Ventricular Disruption in Isolated Hearts

We have developed an in vitro technique for producing myocardial rupture in lamb hearts, which relates tensile strength to a variety of conditions which can prevail in normal and infarcted human hearts. Retrograde perfusion of saline solution and inflation of the left ventricle was used to apply progressive stress to the left ventricular wall. Three separate sites of myocardial rupture were observed and occurred with the frequency of 54% at the papillary muscle, 30% at the interventricular septum, and 16% at the free wall of the left ventricle. The distribution and configuration of the experimental ruptures were similar to those usually noted as complications of human myocardial infarction. The mean rupturing pressure was 526 mm Hg in normal lamb hearts. Application of these techniques should ultimately provide data relevant to the diagnosis, prevention, and treatment of myocardial rupture.

Water permeability of isolated protoplasts in relation to volume change

1. Unusual accuracy in the measurement of the permeability of protoplasm to water was obtained by taking time-lapse photomicrographs of isolated protoplasts during osmotic passage of water. 2. The permeability of free protoplasts is the same as that of protoplasts enclosed in their cell-walls. 3. When determined at different stages of deplasmolysis (or deplasmorrhysis) the rate of penetration of water showed a gradual and relatively steady rise to a little beyond the normal size of the cell, and then a sharp jump upward. 4. Per contra, at different stages of plasmorrhysis the rate of penetration remains nearly constant with only a slight falling off in high concentrations of plasmolytic (9 NaCl ∶ 1 CaCl2). 5. At normal to 3/4 normal volume of the cell, water permeability (averaged from our results) is about two and a half times as great when determined by deplasmorrhysis as by plasmorrhysis, but the value of the former varies with the rate of distention of the cell. Below 40 % of normal volume, plasmolysis and deplasmolysis give the same results. 6. The rise in permeability with degree of deplasmorrhysis is primarily a mechanical effect of the extension of the membrane, an effect which increases with both degree and rate of stretching. Increased hydration is not important, or else its effect would show in plasmorrhysis. 7. When allowance is made for change in thickness of the protoplasmic layer, the calculated permeability tends to show increase rather than decrease with the degree of plasmorrhysis. 8. The normal rate of penetration of water into cells of onion pulp is about 20μ per hour at 20° C., under a pressure difference of 1 atm.