Evaluation of the barostat for recordings of gastrointestinal motility

BACKGROUND

The barostat has been used to investigate gastrointestinal motility. No detailed technical evaluation to characterize the properties of this device for motility recordings has been reported. We, therefore, aimed to test the barostat in vitro under standardized conditions.

METHODS

Barostat and manometry recordings were performed using a combined catheter in a pressure chamber. Some of the experiments were made in pig sigmoid colon in order to mimic recordings in a hollow organ. Data are mean +/- SD.

RESULTS

Baseline changes of the bag volume under constant conditions were 3.9 +/- 2.0%. The bag volume increased by 4.5 +/- 1.1% with a temperature increase from 22 to 37 degrees C (p < 0.05). At external pressures above the bag operating pressure, the barostat bag collapsed, while only minimal volume reductions occurred at external pressures below the bag pressure. Barostat recordings of pressure events were delayed when compared with manometry and not linearly related to the pressure increases.

CONCLUSION

The influence of temperature changes on barostat recordings is small. The volume decrease in the barostat bag is not linearly related to the external pressure increase and influenced by the operating pressure in the bag. This experimental study provides insight and caveats for those planning to use the barostat device for motility recordings of the gastrointestinal tract.

Neurotransmitter coding of enteric neurones in the submucous plexus is changed in non-inflamed rectum of patients with Crohn's disease

Knowledge of the neurochemical coding of submucosal neurones in the human gut is important to assess neuronal changes under pathological conditions. We therefore investigated transmitter colocalization patterns in rectal submucosal neurones in normal tissue (n=11) and in noninflamed tissue of Crohn's disease (CD) patients (n=17). Neurone-specific enolase (NSE), choline acetyltransferase (ChAT), vasoactive intestinal polypeptide (VIP), substance P (SP), nitric oxide synthase (NOS) and calcitonin gene-related peptide (CGRP) were detected immunohistochemically in whole-mount preparations from rectal biopsies. The neuronal marker NSE revealed no differences in the number of cells per ganglion (controls 5.0; CD 5.1). Four cell populations with distinct neurochemical codes were identified. The sizes of the populations ChAT/VIP (58% vs. 55%), ChAT/SP (8% vs. 8%), and ChAT/- (22% vs. 22%) were similar in control and CD. The population VIP/- was significantly increased in CD (12% vs. 2% in controls). Unlike in controls, all NOS neurones colocalized ChAT in CD. Thickened CGRP-fibres occurred in CD. We identified neurochemically distinct populations in the human submucous plexus. The increase in the VIP/- population, extensive colocalization of ChAT and NOS and hypertrophied CGRP fibres indicated adaptive changes in the enteric nervous system in noninflamed rectum of CD patients.

Postoperative colonic motility and tone in patients after colorectal surgery

PURPOSE

Colonic motility is crucial for the resolution of postoperative ileus. However, few data are available on postoperative colonic motility and no data on postoperative colonic tone. We aimed to characterize postoperative colonic tone and motility in patients.

METHODS

Nineteen patients were investigated with combined barostat and manometry recordings after left colonic surgery. During surgery a combined recording catheter was placed in the colon with two barostat bags and four manometry channels cephalad to the anastomosis. Recordings were performed twice daily from Day 1 to Day 3 after surgery.

RESULTS

Manometry showed an increasing colonic motility index, which was a mean (+/- standard error of the mean) of 37 +/- 5 mmHg/minute on Day 1, 87 +/- 19 mmHg/minute on Day 2, and 102 +/- 13 mmHg/minute on Day 3 (P < 0.05 for Day 1 vs. Day 2 and Day 2 vs. Day 3). Low barostat bag volumes indicating a high colonic tone were observed on Day 1 after surgery and increased subsequently (barostat bag I was 19 +/- 4, 32 +/- 6, and 32 +/- 6 ml; barostat bag II was 13 +/- 1, 19 +/- 3, and 22 +/- 5 ml on Days 1, 2, and 3, respectively; for both barostat bags P < 0.05 for Day 1 vs. Day 2 but not Day 2 vs. Day 3).

CONCLUSIONS

Colonic motility increased during the postoperative course. The low barostat bag volumes indicated a high colonic tone postoperatively which would correspond to a contracted rather than to a distended colon. High colonic tone postoperatively may be relevant for pharmacologic treatment of postoperative ileus.

Functional results after transanal rectal advancement flap repair of trans-sphincteric fistula

BACKGROUND

Transanal rectal advancement flap repair is an operation to treat trans-sphincteric fistula which leaves the external sphincter muscle essentially untouched. Anal sphincter function was evaluated prospectively before and after this procedure.

METHODS

Anorectal manometry was performed in 24 patients before operation and 3 months after surgery. A detailed standardized questionnaire on faecal continence was answered before surgery, then at 3 and 48 months after surgery.

RESULTS

No significant differences were seen between mean(s.e.m.) preoperative and postoperative values for maximum squeeze pressure (100.0(9.7) versus 118.0(12.7) mmHg), maximum resting pressure (56.6(4.3) versus 52.8(4.1) mmHg), rectal compliance (4.4(0.6) versus 3.5(0.5) ml/mmHg) or any other parameter of anorectal manometry. The questionnaire revealed the occurrence of minor incontinence in two patients following surgery, which remained unchanged for 4 years. Three other patients had continence disturbances 4 years after surgery which were probably unrelated to the procedure.

CONCLUSION

In addition to high success rates, transanal rectal advancement flap repair also yields excellent functional results. This procedure should be performed for trans-sphincteric fistula in place of alternative treatments whenever feasible.

[Postoperative colon tonus after partial resection of the large intestine]

Only limited data are available on postoperative colonic motility in patients. We investigated colonic tone and motility after large bowel resection in 20 patients. A combined barostat/manometry catheter was placed intraoperatively. Postoperative colonic motility increased day by day. Barostat bag volumes were reduced on postoperative day 1 compared to postoperative day 2 and 3 indicating increased colonic tone on the 1st postoperative day. The use of morphine-like analgesics was highest right after surgery but might not explain increased colonic tone on postoperative day 1 since morphine has been shown to decrease colonic tone. Possibly, increased postoperative sympathetic activity which caused reduced splanchnic blood flow may be responsible for the apparent increase in postoperative colonic tone. The recording of colonic motility in the early postoperative period is feasible with a combined manometry/barostat catheter. These investigations may improve the understanding of the pathophysiology of postoperative colonic ileus.

The Favre system for anorectal manometry: comparison with other manometry systems in vitro and in healthy volunteers

BACKGROUND

The Favre system operates with airflow in a semi-closed circuit to transmit pressure. We aimed to evaluate the Favre system in comparison with other commonly used manometry systems.

METHODS

The Favre, Arndorfer, Arhan, and Synectics systems were evaluated in vitro and in 14 volunteers.

RESULTS

In vitro testing showed no relevant differences for latency, precision, or retest stability. In vivo, maximum resting pressure differed among all probes (P < 0.01) except for Arhan versus Arndorfer (NS). Maximum squeeze pressures differed among all probes (P < 0.01). Decrease of resting pressure during rectoanal inhibitory reflex was similar for Favre versus Arndorfer and Arhan versus Synectics (NS). Retest stability was higher with Favre than with Arndorfer (P < 0.05) and Synectics (P < 0.05) with regard to maximum resting pressure; it was higher with Favre than with Arhan (P < 0.01) and Arndorfer (P < 0.05) with regard to maximum squeeze pressure. Favre caused less discomfort than Synectics (P < 0.05) or Arndorfer (P < 0.05).

CONCLUSION

The Favre probe is an excellent and cost-efficient system for routine anorectal manometry.

Functional results after transanal endoscopic microsurgery

PURPOSE

Compared with traditional operations, superior results after transanal endoscopic microsurgery (TEM) for rectal tumors have been demonstrated in terms of morbidity and mortality. However, no data were available on functional outcome after TEM. We, therefore, studied 42 patients who were undergoing TEM.

METHODS

Patients were examined by anorectal manometry and participated in a standardized interview preoperatively and three months and one year after surgery.

RESULTS

Anorectal function as assessed by manometry was impaired three months after surgery but improved again during the first postoperative year. In parallel, some patients complained of impaired continence or defecation disorders in the interview three months postoperatively. These functions improved during the first year after surgery, too.

CONCLUSIONS

Correct comparison of our results with functional outcome after anterior rectal resection is impossible. We feel, however, that functional results after TEM are likely to be superior to those after anterior resection for rectal tumors.

Level of the anastomosis does not influence functional outcome after anterior rectal resection for rectal cancer

Anorectal function was studied in 55 patients undergoing low anterior resection for rectal adenocarcinoma. Patients were examined preoperatively and 3 months postoperatively by anorectal manometry and standardized interview. Postoperatively, the patients showed, in general, an impairment of anorectal functions. After 3 months, continence for flatus was defective, the ability to discriminate flatus from feces, and the ability to defer defecation were compromised. Stool frequency was elevated, and anal resting pressure, squeeze pressure, and rectal compliance were decreased. The rectoanal inhibitory reflex was abolished in all patients. However, the two groups with the level of the anastomosis less than or equal to 6 cm (n = 27, range 3 to 6) and more than 6 cm (n = 28, range 7 to 10) above the anal verge showed no differences in manometric values, stool frequency, or fecal continence assessed by the interview. No correlation was found between the level of the anastomosis and manometric values and between the level of the anastomosis and stool frequency (regression analysis = not significant). We concluded that anorectal function after anterior resection and low colorectal anastomosis are not influenced by the remaining length of the rectum but by the surgical trauma to the sphincter and its innervation.

Parenteral aspirin and sodium salicylate are equally injurious to the rat gastric mucosa

The effects of parenteral aspirin (ASA) or sodium salicylate (SA) on the gastric mucosa were investigated in anesthetized pylorus-ligated rats 3 h after a bolus intravenous injection of ASA or SA, 150 mg/kg, or NaCl (control). Aspirin or SA produced similar extensive gross mucosal hemorrhagic lesions and similar microscopic damage in the presence of luminal acid (luminal pH 1.3 +/- 0.05). Neither ASA nor SA produced gastric mucosal injury with intragastric instillation of saline (luminal pH 3.7 +/- 0.5). Pretreatment for 1 h with luminal or subcutaneous 16,16-dimethyl prostaglandin E2 completely prevented the formation of red streaks in ASA-treated rats but not in SA-treated rats, although prostaglandin E2 pretreatment significantly reduced the gross lesion area in SA-treated rats (p less than 0.05). We conclude the following: (a) Intravenous SA is as damaging as intravenous ASA as long as luminal acid is present. (b) 16,16-Dimethyl prostaglandin E2 completely protected the gastric mucosa from injury by intravenous ASA, and to a lesser extent by intravenous SA. (c) In view of the damaging effects of SA on the gastric mucosa and the rapid conversion of ASA to SA, the mechanism of the gastric mucosal injury by intravenous ASA is much more complex than simple inhibition of endogenous prostaglandin synthesis.

Effect of simulated systemic administration of aspirin, salicylate, and indomethacin on amphibian gastric mucosa

The effects of 20 mM aspirin (ASA), 20 mM sodium salicylate (SA), or 10(-4) M indomethacin placed in the nutrient solution (N) to stimulate systemic administration were investigated at pHN 7.3 in Ussing-chambered amphibian gastric mucosae. In histamine-stimulated tissues, the initial rise and subsequent rapid fall in potential difference, rise in resistance, and inhibition of hydrogen ion (H+) secretion induced by SAN did not occur with ASAN unless hydrolysis of ASAN produced a SAN of greater than 3 mM. In metiamide-treated tissues, 20 mM SAN caused an immediate fall in potential difference and an increase in resistance; 2 mM SAN and 20 mM ASA produced similar qualitative electrical changes, but only those induced by ASA were reversible. IndomethacinN caused no significant changes in potential difference, resistance, or H+ secretion in histamine- or metiamide-treated tissues. Despite producing highly significant reductions in generation of prostaglandin E2, and prostaglanndin F2 alpha and 6-keto prostaglandin F1 alpha, ASAN and indomethacin caused no surface ulceration. Sodium salicylate placed in the nutrient solution caused only a small reduction in prostaglandin F2 alpha, without change in the other prostaglandins, and produced extensive edema in the lamina propria, histologically. We conclude the following: (a) The inhibition of H+ secretion and electrical changes caused by SAN in histamine-treated gastric fundus are not observed with ASAN unless there is hydrolysis to [SAN] greater than 3 mM. (b) Our data strongly implicate the SAN in ASAN-containing solutions as being responsible for the electrical effects and inhibition of H+ secretion. (c) There is no correlation in vitro between inhibition of prostaglandin synthesis and the electrical or morphologic changes produced by nutrient exposure to ASA, SA, or indomethacin.

Chloride transport of frog gastric fundus: effects of omeprazole

Omeprazole (10(-4) M) inhibited H+ secretion and increased potential difference (PD), resistance, and short-circuit current (Isc) in chambered bullfrog gastric mucosa, but the electrical changes developed only in tissues previously exposed to histamine. Net chloride transport (JnetCl) did not change after omeprazole under short-circuited conditions, and Isc increased to become equal to JnetCl. Under open-circuit conditions, JnetCl was reduced by 38%, the decrement attributable to the concomitant increase in PD, as evidenced by a linear relationship between JnetCl and PD in omeprazole-treated mucosae clamped to different PD (0-45 mV). The effect of omeprazole on PD and Isc could be blocked by metiamide and was absent in spontaneously resting tissues. HEPES nutrient solutions did not alter the electrical response or Cl- transport after omeprazole. In Na+-free solutions, omeprazole induced only a transient rise in PD and Isc. We conclude that omeprazole uncouples H+ and Cl- secretion. This Cl- secretion is electrogenic and dependent upon stimulation by histamine. Both Na+ and HCO3- seem to be involved in movement of Cl- across the basolateral membrane.