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Biomedical subjects

R S Chung

Publications and source records attributed to R S Chung.

At least 55 records · Page 3Linked to original sources
PubMed1992

Gastric perforation after endoscopic treatment of a Dieulafoy's lesion.

Dieulafoy's vascular malformation is an underdiagnosed cause of massive, often recurrent upper gastrointestinal hemorrhage. Attempted endoscopic treatment of Dieulafoy's lesion has been recommended prior to surgery in many instances, but may occasionally be employed as primary therapy in patients that are not considered good "operative risks." Although generally considered safe and effective therapy for nonvariceal hemorrhage, combination therapy by injection and thermocoagulation techniques may result in perforation. We present a patient with a Dieulafoy's lesion of the stomach that illustrates both the efficacy and risks of combination endoscopic therapy for nonvariceal gastrointestinal hemorrhage.

Arteriovenous Malformations↗
PubMed1991

Retrograde dilation of esophageal strictures with balloon dilators.

Balloon dilators may be safely applied for retrograde dilation of esophageal strictures without the use of fluoroscopy or a pressure-gauge attachment. The turgidity of the dilating balloon is preferred to that of other materials such as polyvinyl, rubber, or metal. The technique enables endoscopic monitoring and can be adapted for strictures elsewhere in the gastrointestinal tract.

Aged↗
PubMed1991

Giant cerebral aneurysm repair. Incorporating cardiopulmonary bypass and neurosurgery.

Since our initial experience on April 28, 1989, a total of nine patients have received treatment for giant cerebral aneurysm using cardiopulmonary bypass with deep hypothermia and circulatory arrest. The following data summarize our findings associated with these patients. The average patient's age was 46 years (range: 16 to 59 years of age). Seven patients were female, two were male. The procedure required approximately eight hours to complete with an average cardiopulmonary bypass time of 104 minutes (range: 60 to 140 minutes). Circulatory arrest time averaged 26 minutes (range, 12 to 45 minutes) with an average of 30 minutes (range: 10 to 62 minutes) required to cool the patient to below 18 degrees C (64 degrees F). An average of 54 minutes (range: 28 to 81 minutes) was required to warm the patient to a bladder temperature of 36 degrees C (96.8 degrees F). During the cooling period, five patients went into asystole spontaneously, four patients required bolus of 20 mEq of potassium chloride, and upon rewarming, spontaneous defibrillation occurred in six patients. Three patients were defibrillated without difficulty with external shock. The average number of blood products administered in each of the nine patients was 3.6 units of packed red blood cells, 3 units of fresh frozen plasma, and 6.5 units of platelets. Six patients recovered postoperatively without complication, and the recovery of three patients was affected by the complex anatomical location of the giant aneurysm. Cardiopulmonary bypass with deep hypothermia and circulatory arrest offers an alternative approach to the treatment of giant cerebral aneurysms considered inoperable by conventional techniques. The effectiveness of each procedure depends on the collaborative efforts of every member of the perioperative nursing team, the neurosurgical team, the cardiac surgical team, the neuroanesthesiology team, and the perfusionists. Careful planning and anticipation at every stage of the surgery can reduce surgical time, cardiopulmonary bypass time, and most importantly, circulatory arrest time.

Angiography↗
PubMed1990

Riboflavin intakes and status of morbidly obese females during the first postoperative year following gastroplasty.

Eighteen women participated in a prospective study to assess the need for supplemental riboflavin after gastroplasty. Three groups of five patients received either a placebo or 0.6 or 1.2 mg riboflavin daily for up to 12 months, except during months 4 and 7 when all participants were given a "one-a-day" supplement containing 1.7 mg riboflavin. Dietary intakes of riboflavin decreased from 1.43 +/- 0.17 mg before the operation to 0.70 +/- 0.07 mg at 3 months, and then increased to 1.02 +/- 0.17 mg by 6 months. Even at 12 months, only 33% of the subjects had dietary intakes greater than or equal to 1.2 mg. All those with total intakes less than or equal to 1.7 mg at 3 months had impaired riboflavin status, as indicated by an erythrocyte gluthatione reductase activity coefficient greater than 1.40 and an erythrocyte riboflavin concentration less than 372 nmol/L. In contrast, 62% of the same subjects had urinary riboflavin excretion in the acceptable range. Supplemental intake of 1.7 mg riboflavin appeared to prevent tissue depletion in all subjects.

Adult↗
PubMed1990

Pathogenesis of complications of percutaneous endoscopic gastrostomy. A lesson in surgical principles.

In two comparable series of percutaneous endoscopic gastrostomy differing in only one technical detail, complications were significantly reduced by omitting traction on the gastrostomy tube to approximate the gastric to the abdominal wall. Radiologic studies show that traction shortened the tract (4.9 +/- 1.1 cm with traction, 11.6 +/- 2.3 cm without traction). In two patients with fasciitis, gross pericatheter leak of contrast into a short and patulous tract was observed. Tube extrusion and gastrointestinal bleeding from gastric ersion ulcers were eliminated when traction was not used. No peritonitis occurred as a result of not attempting to approximate the stomach to the abdominal wall. The data suggest that traction on the gastrostomy tube is not only unnecessary, but is the cause of many of the complications reported.

Aged↗
PubMed1989

Prediction of post-cardiopulmonary bypass cardiac output.

The ability to predict cardiac output (CO) before termination of cardiopulmonary bypass (CPB) allows identification of potential complications once the patient is off bypass. We have previously demonstrated that CO early after CPB can be reliably predicted by a plot of venous oxygen saturation at various flow rates on CPB, based on in-line monitoring of venous oxygen saturation. In this study, we evaluated a simplified technique for predicting CO with a series of 50 patients on CPB. When CPB weaning began, patients were normothermic, anesthetized, and paralyzed. Venous oxygen saturation and arterial blood flow were recorded. At low pump flow just before termination of CPB, the final venous oxygen saturation was recorded. Assuming a proportional relationship between venous oxygen saturation and arterial blood flow, CO early after CPB was predicted. The simplified CO prediction was compared with the thermodilution CO immediately after CPB. The simplified technique reliably predicted CO early after CPB compared with the thermodilution technique. The simplicity and reliability increase the clinical value of the CO prediction.

Adult↗
PubMed1989

Videoendoscopy for difficult anastomoses.

To determine whether intra-operative videoendoscopy provides useful information on the integrity of gastrointestinal anastomoses, laboratory and clinical studies were undertaken. In the dog model, the videoendoscope was inserted per orum to visualize side-to-side (gastrojejunostomy) and end-to-end (jejunojejunostomy) anastomoses and to establish endoscopic criteria of normal anastomosis, verified by examination of the specimen. Technically faulty anastomoses were then constructed and inspected endoscopically to determine the signs of poor technique. In clinical application, the videoendoscope was used to inspect the anastomoses after low anterior resection, revision of gastric bypass, and choledochoduodenostomy. The laboratory results indicate that direct visualization of a defect in suture-line with the end-viewing endoscope is difficult, although indirect signs of trouble are helpful. Conversely, the appearance of a perfect anastomosis without any indirect signs of poor technique is accurate in the assurance of a trouble-free anastomosis. The best clinical use is in low anterior resection of the rectum and the worst is in choledochoduodenostomy. It is concluded that videoendoscopic inspection of anastomosis is only of limited help in determining the integrity of a difficult anastomosis, and much work is required to perfect both the instrument and technique before general use is recommended.

Anastomosis, Surgical↗
PubMed1988

Endoscopic measurement of gastric mucosal blood flow by laser Doppler velocimetry: effect of chronic esophageal variceal sclerosis.

A technique of endoscopic measurement of gastric mucosal blood flow using laser Doppler velocimetry was described. The technique was validated in the laboratory by performing endoscopic measurement of gastric mucosal blood flow in the dog simultaneously with application of a second probe at open operation, utilizing the same laser Doppler flowmeter. Probe pressure causing minor dimpling (less than 20 gm/cm2) was found to cause insignificant alteration of mucosal blood flow. Criteria were developed to aid separation of artifacts introduced by probe motion. A conversion factor was established for converting the readout of the instrument (Hertz x 10(2] into ml/100g/min by synchronously measuring mucosal blood flow by hydrogen gas clearance technique and laser Doppler velocimetry in the gastric and duodenal mucosa. In patients with portal hypertension gastric mucosal blood flow was determined before and after sclerotherapy, and compared to the gastric mucosal blood flow in subjects without portal hypertension. Gastric mucosal blood flow was elevated in portal hypertensives, but sclerotherapy did not appear to cause changes in blood flow. Endoscopic mucosal blood flow measurement is non-invasive, practical and of potential value in clinical investigation of gastrointestinal pathophysiology.

Animals↗
PubMed1988

The role of tissue ischemia in the pathogenesis of anastomotic stricture.

In a chronic dog model, colocolostomies with intact blood supplies were constructed with the circular stapler. By means of "tight" stapling, an ischemic suture line was induced (suture line blood flow reduced to less than 10% of baseline mucosal blood flow). Under these conditions, only one of 20 anastomoses resulted in stenosis at 1 month. Correctly stapled colocolostomies were then performed in bowels rendered ischemic by removal of all mesenteric arcades for 4 to 6 cm. Mucosal blood flow in such ischemic bowels was reduced to 30% and 16% of control, respectively, and suture line blood flow was as low as that of the tightly stapled anastomoses. Significant stenosis (more than 68% reduction of the lumen) was observed in the group with 6 cm of mesenteric clearance. In no dogs did peritonitis or colonic gangrene develop. Gross and histologic revascularization was evident when dogs were killed at 6 weeks. These findings suggest that it is ischemia of the bowel, rather than ischemia at the suture line itself, that leads to anastomotic stricture. In view of the known susceptibility of the human intestine to ischemia, the model may have overstated the degree of ischemia necessary to produce strictures in clinical practice. Since the induced acute ischemia did not persist in the chronic state, we conclude that it is the adequacy of collateral development that determines the outcome in this model.

Animals↗
PubMed1988

The sources of recurrent hemorrhage during long-term sclerotherapy.

The sources of recurrent hemorrhage during long-term sclerotherapy undertaken by a single surgeon were studied prospectively in a consecutive series of 53 patients for a period of 2 to 6 years. Recurrent hemorrhage, defined as upper gastrointestinal bleeding requiring transfusion or hospitalization or both, in the course of chronic sclerotherapy was investigated aggressively by means of endoscopy and the findings archived with videotape recording. In 24 patients 51 episodes of recurrent hemorrhage developed in the entire series. On the basis of endoscopic findings and serial comparison of videotape recordings, the most common source of recurrent hemorrhage was the original varices, which accounted for rebleeding in 18 patients. The risk of such bleeding was highest in the first month, diminishing thereafter until total variceal eradication. Rebleeding after eradication of varices was always from sources other than varices, as regenerated vessels were small and infrequent and never the source of bleeding. Continued sclerotherapy ultimately achieved total variceal eradication in 15 of 18 patients with variceal rebleeding. Sclerotherapy alone was successful in eradicating all varices in a total of 38 patients in this series, the mean time required being 13 +/- 4.1 months. Rebleeding from sources not amenable to sclerotherapy was treated with porto-azygos disconnection (6 patients) or distal splenorenal shunts (3 patients). There were 12 deaths: four attributed to hemorrhage (3 after surgery), five from liver failure, and three late deaths from causes not due to liver disease. Recurrent hemorrhage per se during the course of sclerotherapy may not be taken as a sign of treatment failure but must be vigorously investigated, since findings profoundly affect management and outcome.

Blood Transfusion↗
PubMed1987

Palliation of inoperable esophageal carcinoma. Therapeutic endoscopy as an adjunct to combined chemotherapy and radiotherapy.

The combined regimen of irradiation and chemotherapy has been successfully used as a preoperative measure to improve the cure rate for squamous cell carcinoma of the esophagus. In the nonresectable patient, we have seen response to this regimen in the form of conversion of the neoplastic stricture into a fibrous one. Dysphagia remained unchanged due to the persistence of a stricture. In this situation, therapeutic endoscopy can be highly effective for relief of dysphagia, as illustrated by a case report, and is proposed as the palliative procedure of choice when the patient has shown response to combined chemotherapy and radiotherapy.

Carcinoma, Squamous Cell↗
PubMed1987

Percutaneous endoscopic gastrostomy and jejunostomy by a single pass of the endoscope.

A modified Gauderer-Ponsky technique of percutaneous endoscopic gastrostomy has been described. The major advantage is elimination of a second insertion of the endoscope, as well as unnecessary traversing of the esophagus by snares and strings. The result achieved is equal to what has been achieved with the original technique, but the single-pass technique is more expeditious and less uncomfortable for the patient. In addition, it can easily be modified to insert both draining gastrostomy and feeding jejunostomy tubes at the same time, using only one pass of the endoscope.

Gastroscopy↗
PubMed1987

Gastric adaptive changes following experimental gastroplasty.

To study the adaptive response of the stomach secondary to partial obstruction imposed by gastroplasty, groups of rabbits with calibrated midgastric constrictions created as a stoma (unreinforced, Group II), as a short channel (Group III), or as a stoma reinforced with polypropylene mesh (Group IV), were compared to controls (Group I). It was found that the unreinforced stoma dilated rapidly while the pouch dilated moderately. In both the channel and reinforced stomas, the pouch dilated markedly. Increased fibrosis was found inside of the polypropylene banding, resulting in a significant incidence of luminal obstruction. The channel dilated in stages, affecting the proximal end first; but obstructive effect remained as long as part of the channel was undilated. We conclude that a narrow stoma is incompatible with a small pouch over time. Since anatomic specifications do not define function, both function (such as emptying) and adaptive changes should be studied in animal models before introduction of any new gastric limiting procedures into clinical practice.

Animals↗
PubMed1987

Blood flow in colonic anastomoses. Effect of stapling and suturing.

Sutureline blood flow was measured with laser Doppler velocimetry in colonic anastomoses created with the stapler, manual suturing, or a combination. Blood flow was always reduced in the sutureline compared with normal mucosa. Of all the anastomoses studied, tight stapling reduced sutureline blood flow the most, whereas the two-layered manual anastomosis or stapling reinforced with sutures were somewhat less ischemic. Stapling adjusted to bowel wall thickness impaired flow only moderately. It was possible with practice to outperform the stapler by single-layered manual anastomosis using fine sutures. In humans, stapled ileocolostomy had a higher sutureline blood flow than the two-layered manual anastomosis. In view of the existing clinical experience of safe stapling without adjustment for bowel wall thickness, a low sutureline blood flow is probably tolerated to a considerable degree in humans. However, this study clearly shows that tight stapling can reduce sutureline blood flow unduly, whereas superior blood supply can be attained by attention to staple closure height relative to bowel wall thickness.

Animals↗
PubMed1986

End colostomy and Brooke's ileostomy constructed by surgical stapler.

A technique for making an end colostomy and a Brooke's ileostomy using the surgical stapler is described. The resulting stoma is geometrically perfect. No complication or wound infection occurred in a series of 26 stomas observed for up to ten months. The cost of the cartridge may be considered recovered if this technique decreases the operating time by 13 minutes.

Colostomy↗
PubMed1985

Side-to-side and end-to-side anastomosis in partial gastrectomy and hemicolectomy using the EEA stapler.

We have described a new technique for side-to-side gastrojejunostomy as performed in Billroth II gastrectomy and for end-to-side ileocolostomy after right hemicolectomy utilizing the EEA stapler. By introducing the stapler through the area to be resected, we eliminated the need to close insertion enterostomies. This stapling technique also reduces the hazards and complications associated with multiple pursestring sutures normally required for end-to-end anastomosis with the EEA stapler, since, at most, one such suture is used. With minor modifications, the surgical technique can be applied to other operations in the alimentary tract, thus enhancing the utility of the EEA surgical stapler.

Colectomy↗
PubMed1985

The hemodynamic effects of the sclerosant sodium morrhuate in dogs.

The hemodynamic effects of systemic administration of 5 per cent sodium morrhuate was evaluated in normal dogs. Dogs in the control group were injected with 2 per cent benzyl alcohol with pH adjusted to 9.5. Animals injected with sodium morrhuate had a significant reduction in cardiac output, arterial blood pressure, portal vein and hepatic artery flows. These changes occurred primarily in the first 30 minutes of observation. In response to the reduction of the hepatic blood flow, there was an increase in portal vein pressure and resistance.

Animals↗