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Biomedical subjects

W O Kirwan

Publications and source records attributed to W O Kirwan.

At least 19 recordsLinked to original sources

Rectoanal inhibitory reflex following low stapled anterior resection of the rectum.

The rectoanal inhibitory reflex plays an important role in the normal mechanisms of anorectal continence. Anterior resection abolishes the reflex, but whether it recovers, particularly after inverted stapled anastomosis, is not clear. Anal manometry was performed on patients undergoing low anterior resection for carcinoma. Maximum anal resting pressure and the rectoanal inhibitory reflex were assessed preoperatively and up to two years postoperatively. The reflex was present in 43 of 46 patients (93 percent) preoperatively, in 8 of 45 patients (18 percent) on the 10th postoperative day, and in 6 of 29 patients (21 percent) between six months and one year following surgery. Twenty patients were studied more than two years postoperatively, and in 17 (85 percent) the reflex was demonstrated. In the majority of low anterior resection patients, the rectoanal inhibitory reflex is abolished by surgery, remains absent throughout the first year, and has recovered by the end of the second postoperative year. This may be important in the recovery of anorectal function in these patients.

Adult

Mechanism of sphincter impairment following low anterior resection.

It has been postulated that reduction in anal resting pressure following low anterior resection is due to intraoperative injury to the internal anal sphincter during transanal passage of the stapling device or damage to its nerve supply in the course of rectal mobilization. The aim of this study was to assess the relative importance of either mechanism. Fourteen dogs had a standard segment of colon and distal rectum excised. Colorectal reconstruction was performed using either a low stapled EEA (U.S. Surgical Corporation, Norwalk, CT) colorectal anastomosis (n = 7) or a handsewn anastomosis (n = 7). Anorectal manometry was performed preoperatively and again on the 10th postoperative day. Resting anal pressure was significantly reduced after EEA anastomosis (mean +/- SEM: before, 49 +/- 3 mm Hg; after, 20 +/- 4 mm Hg; P less than 0.001) and handsewn anastomosis (mean +/- SEM: before, 46 +/- 4 mm Hg; after, 35 +/- 4 mm Hg; P less than 0.01). Postoperative resting pressures were also significantly reduced (P less than 0.05) following EEA anastomosis when compared with the handsewn group. This study suggests that damage to the innervation of the internal anal sphincter during rectal mobilization and further direct injury to the sphincter during transanal instrumentation both contribute to the fall in anal resting pressure observed following low anterior resection.

Anal Canal

Massive incisional hernia: abdominal wall replacement with Marlex mesh.

Marlex (polypropylene) mesh was used to replace the abdominal wall in massive incisional herniation in 50 patients. Seventeen unsuccessful attempts at primary repair had previously been made on nine patients. Patient follow-up ranged from 6 to 120 months (mean = 45 months). There was minor hernia recurrence in four (8 per cent) patients. In each instance it was due to partial detachment of the peripheral fixation of the patch. Complications were: wound infection, four (8 per cent); wound seroma, two (4 per cent); wound haematoma, one (2 per cent); and wound sinus, six (12 per cent). Complications did not necessitate removal of the patch in any case. Inadequate peripheral attachment of the patch has been the only cause of hernia recurrence and should be avoidable.

Adult

Hereditary sacral agenesis with presacral mass and anorectal stenosis: the Currarino triad.

A family with autosomal dominant inheritance of sacral agenesis is described. Ten members were affected; four had associated presacral teratomas and anterior sacral meningoceles, giving rise to serious complications in three, including bacterial meningitis, local recurrence of teratoma and perianal sepsis. Three of those with presacral masses presented initially with anorectal anomalies. Other associated abnormalities included tethering of the cord, hydrocephalus, duplex ureter, hydronephrosis, vesicoureteric reflux, neurogenic bladder, bicornuate uterus, rectovaginal fistula and hereditary spherocytosis. Early diagnosis and surgical excision of a presacral mass is advised to prevent future morbidity and mortality.

Adolescent

Starting laparoscopic cholecystectomy--the pig as a training model.

Laparoscopic cholecystectomy is a reality and units must convert from open to endoscopic technique. To this end we have used the pig, whose biliary anatomy resembles the human, as a laboratory in vivo training model. Laparoscopic cholecystectomy has been performed in 35 animals. Techniques of pneumoperitoneum, vision, manipulation, clipping, ligation, cutting, diathermy and gall bladder removal were quickly mastered. All surviving animals underwent postmortem examination after 4 weeks. Following this laboratory programme, laparoscopic cholecystectomy in the human was introduced and has been completed successfully in 70 cases.

Animals

Familial infantile oesophageal achalasia.

Oesophageal achalasia is uncommon in children and in its familial form it is a rarity. The presentation and management of two male siblings who presented with oesophageal achalasia as infants are reported. A high degree of consanguinity in the parents of the children existed, suggesting autosomal recessive transmission.

Esophageal Achalasia

Effect of anterior resection on anal sphincter function.

Minor difficulties with continence may occur after low anterior resection. Intraoperative injury to the internal anal sphincter or its nerve supply may contribute to this. To study the effect of low anterior resection on the anal sphincter mechanism, anal manometry was performed on 20 patients before and 10 days after resection. Fifteen patients were studied again 6 months after operation. Resting, maximum squeeze and squeeze increment pressures were recorded. Intraoperative manometry (n = 11) and presacral nerve stimulation (n = 6) were performed to determine whether peroperative injury to the internal anal sphincter had occurred. Resting and maximum squeeze anal canal pressures were reduced by low anterior resection, and did not recover. The squeeze pressure increment did not change. Division of the inferior mesenteric artery, full mobilization of the rectum and mesorectum, and rectal transection did not affect resting anal pressure, which was reduced after EEA anastomosis (mean (s.e.m.) before, 40(5) mmHg; after, 27(4) mmHg; P less than 0.05, n = 5). Presacral nerve stimulation produced relaxation of the internal sphincter. Anal sphincter pressures are reduced after low anterior resection. The external anal sphincter and the nerve supply to the internal anal sphincter appear intact. A direct injury to the internal sphincter is postulated.

Adult

Declining indications for abdominoperineal resection.

In 126 consecutive patients operated on for carcinoma of the lower two-thirds of the rectum, a consistent policy of sphincter preservation resulted in 100 (79 per cent) having anterior resection and 22 (17 per cent) abdominoperineal resection. Perioperative complications in the anterior resection group were: death (two patients), clinical leakage (three patients), pulmonary embolism (five patients), pelvic haematoma (one patient), small bowel obstruction (one patient) and wound sepsis (six patients). Of 55 patients who had a potentially curative anterior resection with follow-up of at least 2 years, one developed local recurrence. Five per cent of patients had significant continence problems. Low anterior resection for carcinoma is associated with low perioperative morbidity, satisfactory functional results and acceptable local recurrence rates.

Aged

Pullthrough operation with delayed anastomosis for rectal cancer.

The technique of pullthrough resection with delayed anastomosis for carcinoma of the rectum as performed at the Cleveland Clinic is described. A series of 84 cases of rectal cancer treated in this way is reported. The average tumour diameter was 4.5 cm, the average margin of resection was 4.1 cm and the average distance of the tumour from the anus was 7.6 cm. The incidence of necrosis of the pullthrough was 1.2 per cent. The overall 5-year survival was 63 per cent with 100 per cent, 57 per cent and 53 per cent for Dukes' A, B and C tumours respectively. The quality of bowel function following surgery is described in detail. It is felt that this procedure has an important place in sphincter conservation in carcinoma of the middle third of the rectum.

Adult

Colonic propulsion in diverticular disease, idiopathic constipation, and the irritable colon syndrome.

Colonic intraluminal pressure and intestinal transit were examined in diverticular disease, idiopathic constipation, and the irritable colon syndrome. Small bowel transit was normal. Total gastrointestinal transit was prolonged. Colonic transit showed an equal delay in all segments, expedited by bran. In constipation, transit was the more prolonged, but in the irritable colon syndrome, pressure was more affected. Diverticular disease patients showed features resembling each of these two groups. Pressure and transit showed an inverse relationship maintained after bran.

Colon

Post prandial changes in colonic motility related to serum gastrin levels.

Colonic motor activity and serum gastrin levels were correlated during a basal period and after a meal in 16 subjects. Motor activity preceded the gastrin response. The motility index and the serum gastrin levels rose in parallel, but the motility fell before later showing a second rise. The frequency response showed the earliest change and since it preceded the gastrin rise may be neurogenic. This response was later "extinguished" and replaced by one of waves of increasing amplitude; the sustained nature of this response fitted more closely the gastrin response.

Colon

Bile acids and colonic motility in the rabbit and the human.

Colonic motor activity was initiated by infusions of bile salts into the caecum or rectum of the anaesthetized rabbit. Primary bile acids were examined proximally and distally in the colon and elicited marked motor responses. Sinc dihydroxy bile acids are known to be potent inhibitors of electrolyte and water absorption in the colon, the secondary bile acid deoxycholic acid, the dihydroxyl compound most related to cholic acid which is the main bile acid in the rabbit, was examined distally and was also active, but to a lesser extent than cholic acid conjugates in this species. In man, a relationship was found between the faecal bile acid excretion and colonic motility: the introduction of bile acids directly into the human sigmoid colon and rectum also stimulated colonic motility. In man, the dihydroxy compound chenodeoxycholic acid was slightly more active than conjugates of cholic acid.

Animals