Minimal Distending Pressure Research Articles

Proximal gastric motility functions are normal in severe obesity.

The role of altered gastric motor functions for the development of obesity is still unclear. In this study, we investigated whether severe obesity is related to gastric dysfunctions or to abnormal perception in response to distension. 31 obese patients and 20 healthy volunteers were studied using an electronic barostat. Basal gastric tone, gastric accommodation, and perception in response to distension were not altered in obese patients. The median minimal distending pressure, reflecting the intra-abdominal pressure, was significantly elevated in obese patients, being 12 versus 7 mm Hg, respectively (p < 0.0001). We conclude that the proximal gastric motility, including perception and accommodation in response to intragastric distension, is not impaired in severe obesity. Whether disturbances of gastric reflex relaxation in response to a meal are involved in the pathogenesis of obesity remains to be established.

Function of the proximal stomach after Nissen fundoplication

Background After Nissen fundoplication patients frequently report upper abdominal (dyspeptic) symptoms. Theoretically, these symptoms may be the result of changes in function of the proximal stomach as induced by fundoplication. Methods In this case–control study the response of the proximal stomach to both distension by an air-filled bag and a liquid meal were evaluated with the use of a barostat. In 12 patients after fundoplication and 12 healthy volunteers (age- and sex-matched) perception of symptoms was evaluated during both bag distension and liquid meal stimulus. Results The minimal distending pressure required to overcome the intra-abdominal pressure was significantly different between patients and controls (mean(s.e.m.) 9·34(0·26) versus 6·73(0·43) mmHg; P < 0·001). There was no difference between groups in either the fasted state, volume–pressure curve (compliance) or total symptom score. After ingestion of the liquid meal the adaptive relaxation in the fundoplication group was significantly less than that in controls (mean(s.e.m.) 150(29·2) versus 244(34·8) ml; P = 0·04). Conclusion This study showed that after Nissen fundoplication compliance of the proximal stomach is no different from that in healthy volunteers. Postprandial relaxation of the proximal stomach is decreased and this abnormality may be involved in the pathogenesis of reported dyspeptic symptoms. © 1998 British Journal of Surgery Society Ltd

Mechanics of porcine coronary arteries ex vivo employing impedance planimetry: a new intravascular technique.

Our objective was to evaluate methodological aspects of impedance planimetry, a new balloon catheter-based technique, for the investigation of coronary artery mechanical wall properties. We used a four ring-electrode electrical impedance measuring system that was located inside a balloon. Two of the electrodes were used for excitation and connected to a generator producing a constant alternating current of 250 mA at 5 kHz. The other two electrodes for detection were placed midway between the excitation electrodes. The balloon was distended with electrically conducting fluid through an infusion channel. The vessel cross-sectional area (CSA) was measured according to the field gradient principle by measuring the impedance of the fluid inside the balloon. Impedance planimetry was applied in the three major branches of the coronary arteries of seven extracted porcine hearts to assess luminal CSAs in response to internal pressurization. The biomechanical wall properties were evaluated by computing the strain [(r - r0) x r0(-1), where r is the vessels inner radius computed as (CSA x pi-1)1/2 and r0 is the radius of the vessel at a minimal distension pressure], the tension [(r x dP), where dP is the transmural pressure difference], and the pressure elastic modulus (delta P x r x delta r-1). We found that in vitro testing demonstrated that impedance planimetry was accurate and reproducible. The technique has controllable sources of error. Measurements were performed with consecutively increasing pressures in the range 1-25 kPa (8-188 mmHg, 0.01-0.25 atm). The CSAs increased nonlinearly and were significantly larger in the left anterior descendent coronary artery (LAD) (1 kPa, mean 5.0 mm2; 25 kPa, mean 21.8 mm2) than in both the left circumflex (Cx) (4.5-16.0 mm2) and the right coronary artery (RCA) (2.8-15.6 mm2) (analysis of variance, P < 0.001 for both). The circumferential wall tension-strain relation showed exponential behavior. For a given strain, tension values for LAD were significantly lower than those of Cx (P < 0.01). The pressure elastic modulus-strain relation also was exponential, and values for Cx were significantly lower than values for LAD (P < 0.001) and RCA (P < 0.05). Impedance planimetry was applied to the study of coronary artery biomechanics ex vivo. The LAD had the largest CSA, and the Cx was the least compliant. Methodological aspects of an in vivo introduction of the method require additional evaluation.

Impaired gastric relaxation in patients with achalasia.

Achalasia is considered a primary motility disorder confined to the oesophagus. The lower oesophageal sphincter (LOS) in achalasia is frequently hypertonic and manifests absent or incomplete relaxation in response to deglution. On the other hand, the LOS and the proximal stomach act physiologically as a functional unit whereby relaxation of the LOS during deglution is associated with receptive relaxation of the proximal stomach. Thus, this study investigated the hypothesis that impaired LOS relaxation in patients with achalasia might be associated with impaired relaxation of the proximal stomach. The study consisted of 20 patients with achalasia and 10 healthy controls. Gastric tone variations were quantified using an electronic barostat. Firstly, the study established the basal gastric tone (intragastric volume at the minimal distending pressure+1 mm Hg) and gastric compliance (volume/pressure relation) during isobaric distension (increasing stepwise the intragastric pressure from 0 to 20 mm Hg up to 600 ml). Secondly, the gastric tone response to cold stress (hand immersion into ice water for five minutes) or to control stimuli (water at 37 degrees) was determined. Basal gastric tone mean (SEM) was similar in achalasia and in healthy controls (125 (9) ml v 138 (9) ml, respectively). Compliance was linear and similar in both groups, which also showed similar gastric extension ratios (58 (7) ml/mm Hg v 57 (6) ml/mm Hg). Cold stress induced a gastric relaxatory response that, as a group, was significantly lower in achalasia than in healthy controls (volume: 43 (20) ml v 141 (42) ml; p < 0.05). The responses in each group were not uniform, five of the 20 patients with achalasia showed definite (volume > 100 ml) relaxatory responses whereas four of the 10 healthy controls did not. In conclusion, reflex gastric relaxation is impaired in most patients with achalasia showing that the proximal stomach, and not exclusively the oesophagus, may be effected by the disease.

広汎性子宮頸癌根治手術後の膀胱機能に関する研究

In the course after radical hysterectomy for carcinoma of the cervix, disturbance of the bladder function occures as a frequent and thence important complication, leading to a lasting dysuria. In our department I investigated this disturbance after the Okabayashi's operation, performing measurement before the operation, and on the 10th, 15th, 20th and 30th day after the operation. The results are as follows:1) In 60 cases there were measured minimal volume for distension feeling, maximal capacity of the bladder, reserve pressure of micturition and the length of the urethra. There was no difference as to age, parity and clinical stage of carcinoma. It was characteristic that the minimal volume of urine feeling was increased, the minimal distension pressure elevated, the maximal capacity of the bladder decreased and the urethra shortened. In comparison to the corresponding value before the operation, they showed significant change on any day after the operation. However, the reserve pressure of micturition had no remarkable postopeative change. These changes did not appear in parallel with the degree of dysuria.2) Intravesical pressure, before the operation the intravesical pressure had a slight increase by the filling of the contents, after the operation, a curve showing the intravesical pressure became steep in contrast to that of the preoperative day. However, the curve had no special relation to the degree of dysuria.3) Pressure of the posterior urethra: The pressure of the internal sphincter did not vary with the bladder contents. Its absolute value varied quite often. After the the operation this pressure was markedly lowered than the preoperative value and varied in parallel with the degree of dysuria.4) Vagostigmin, Spatym, Tropin, Buscopan, Alinamin-- these preparations were used to observe their effects on the dysuria.5) Treatment. There were in 53 cases mechanical dilatation of the urethra. 26 cases of Alinamin administration and 17 cases of chlorpromazine administration. The mechanical dilatation was effective 71.4% of the ishuria. Ailnamin or chlorpromazine had no effect, even if adminstered early, to mitigate the period of ishuria.