Biomedical subjects
Publications and source records attributed to H S Ong.
Castleman's disease is a rare lymphoproliferative disorder of uncertain origin. We report an unusual presentation of Castleman's disease in the transverse mesocolon that mimicked a vascular gastrointestinal stromal tumour and review the literature surrounding this peculiar entity.
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Peritoneal encapsulation (PE) is a rare condition that has been described interchangeably with sclerosing encapsulated peritonitis as well as abdominal cocoon. We report an otherwise well 38-year-old man who presented with two episodes of intestinal obstruction about two months apart. Computed tomography (CT) of the abdomen showed characteristic features of the PE syndrome. Exploratory laparotomy was performed and small bowel was freed of adhesions and the encapsulation. Post-operative recovery was uneventful. PE is an extremely rare congenital condition in which there is abnormal return of the midgut loop to the abdominal cavity in the early stages of development. The small intestine is thus covered by the original dorsal mesentery, forming the characteristic accessory peritoneal sac. Management of cases is difficult as CT findings may not be characteristic and may only be diagnosed at laparotomy.
BACKGROUND: The aim was to determine symptomatic and functional outcome after reoperative antireflux surgery for recurrent reflux, persistent dysphagia and severe gas bloat, using a primarily laparoscopic surgical approach. METHODS: This was a retrospective analysis of prospectively collected data from 118 patients, of whom 70 had reoperative surgery for recurrent reflux, 35 for dysphagia and 13 for gas bloat. DeMeester scores before and 1 year after surgery, functional symptoms after surgery and overall patient satisfaction were analysed. RESULTS: Reoperation was completed laparoscopically in 101 patients (85.6 per cent), in 28 after previous open hiatal surgery. The operation was converted from an initial laparoscopic approach to open surgery in 17 patients. One-year follow-up data were available for 104 patients (88.1 per cent). After reoperation for recurrent reflux, 84 per cent had a DeMeester heartburn score of zero or one, and 87 per cent had a regurgitation score of zero or one. After reoperation for dysphagia, 21 of 32 patients had a dysphagia score of zero or one, with improvement observed in 25. All patients undergoing reoperation for severe gas bloat were satisfied with the outcome 1 year after operation. CONCLUSION: Revisional surgery for recurrent reflux using a laparoscopic approach offered high rates of success and patient satisfaction. Swallowing returned to normal in two-thirds of patients after reoperation.
The use of self-expanding metallic stents (SEMS) as esophageal endoprosthesis represents an advancement in the palliation of dysphagia from unresectable esophageal carcinoma. However, the problem of stent migration persists. Although most migrated stents have a benign outcome, complications do occur. Rare reports of intestinal obstruction have been confined to the stiff plastic and stainless-steel stents. We report the first case of intestinal obstruction secondary to the pliable Nitinol SEMS (Ultraflex) migration.
Transabdominal duplex Doppler ultrasonography (TDDU) is commonly used for measuring hepatic blood flow (HBF) in clinical practice. Flow velocity and the cross-sectional area (CSA) of vessels are obtained separately and used to compute blood flow. Respiration and changes in portal pressure are known to cause variations in the CSA of the portal vein, but the impact of these parameters on TDDU measurement of portal blood flow is unclear. Eight Yorkshire pigs (20.7-25.1 kg) were used for the study. TDDU determination of portal blood flow was carried out using CSA of the portal vein obtained at inspiration (maximal) and at expiration (minimal) for computation, and the differences obtained were compared. Determination of HBF was carried out simultaneously on the same animals using diisopropyliminodiacetic acid (DISIDA) clearance. A physiological increase in portal pressure was then created by 50% hepatectomy and TDDU measurement similarly carried out on the second postoperative day. Computing portal blood flow in the intact liver using maximal and minimal CSA gave rise to a mean difference of 7.0 ml kg(-1) min(-1) (P < 0.001). A significant correlation was obtained between HBF and portal flow computed from maximal CSA (Pearson's correlation = 0.85, P < 0.033). The respiratory index of the portal vein (maximal CSA/minimal CSA) decreased from 1.5 to 1.2 after hepatectomy, which also caused a 90% increase in portal pressure. Respiration and portal pressure thus significantly impact on TDDU determination of HBF, and in this porcine model, computation using maximal CS more accurately reflects HBF.
BACKGROUND: The changes in digestive function of patients with pancreaticoduodenectomy (PD) and pancreaticogastrostomy reconstruction have not been well-documented. The present study sought to assess the nutritional status, quality of life and pancreatic exocrine function in this group of patients. METHODS: The study group consisted of 11 PD with pancreaticogastrostomy patients. The control group consisted of 11 consecutive patients who had subtotal gastrectomy (SG) for distal stomach tumours. RESULTS: The median ages for the PD and SG groups were 57 and 59 years, respectively. The median intervals between surgery to assessment were 68 and 60 weeks, respectively. The PD group attained a mean of 92.7% of their pre-surgery weight compared to 91.3% in the SG group. Both groups had a comparable gastrointestinal quality of life index and Visick scale scores. Exocrine insufficiency using the faecal chymotrypsin test was present in 36% of patients with PD. None of the patients in the SG group had exocrine insufficiency. CONCLUSION: Pancreaticoduodenectomy patients had a significant occurrence of pancreatic exocrine insufficiency compared to the SG group. But patients with PD and pancreaticogastrostomy reconstruction maintained a nutritional status and quality of life similar to those with curative SG for stomach malignancy. Apart from exocrine insufficiency, the concomitant gastrectomy in the PD group is an important factor responsible for their inability to gain weight.
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Fulminant hepatic failure is a serious condition with very high mortality. Development of new therapies designed to bridge the patient through the acute period of their disease has been hampered by the lack of a large animal model that closely reproduces the changes in humans. We have established an improved model of fulminant hepatic failure in the pig by administration of an aminosugar d-galactosamine hydrochloride. Galactosamine in a dose of 1.0 g/kg was dissolved in 5% dextrose in water (D5W) and given intravenously to seven young pigs weighing 8 to 15 kg. Seven control pigs received an equal volume of D5W alone. Two days prior to injection, a baseline ultrasound-guided liver biopsy was done in each pig under general anesthesia using isofluorane. Clinical data were recorded and blood for laboratory determinations was drawn at 0 h (baseline), 24 h, 48 h, and 72 h after infusion of galactosamine or D5W alone, under general anesthesia. Neurological data were recorded at the same intervals before inducing anesthesia. Galactosamine-treated animals showed 100% mortality. All of them died by 86 h after injection of galactosamine, with death resulting from fulminant hepatic failure characterized by marked increases in total bilirubin, liver enzymes, ammonia, and lactate; associated coagulopathy; hypoglycemia; and coma. Liver histology showed massive hepatocellular necrosis in all seven galactosamine-treated animals. This large and highly reproducible animal model appears promising for future evaluation of bioartificial liver support systems designed to treat fulminant hepatic failure in humans.
Maximum duration of warm ischaemia within which the liver graft is viable for transplantation remains undefined. Published data on porcine allogeneic liver transplantation (LTx) using non heart beating donors (NHBDs) are conflicting because technical details like the hepatic artery status, systemic heparinisation of donor animals and duration of rewarming were not addressed. We described a novel porcine model which simulate conditions of transplantation from NHBDs. The pigs were divided into three groups of 6 each. Groups I, II and III were subjected to 60, 90 and 120 minutes of warm ischaemia, respectively. Liver viability was assessed using four parameters: serum liver function tests (serum bilirubin and transaminase), dynamic liver function test i.e. the monoethylglycinexylidide (MEGX) formation test, morphological assessment and animal survival. All animals in groups I and II (90 minutes of warm ischaemia or less) survived but 50% of animals in group III died of massive liver failure. Given that rewarming period required in actual allogeneic LTx is about 60 minutes, the safe period for intervention in NHBDs is determined to be about 30 minutes. Allogeneic porcine LTx using NHBDs with 30 minutes of cardiac arrest were performed in 5 animals. All of them survived.
BACKGROUND/AIM OF STUDY: End-stage renal failure (ESRF) patients requiring long-term haemodialysis need a durable vascular access. The arterio-venous fistula (AVF) with its long patency rate and low complication profile is usually the first choice procedure for vascular access creation. However when superficial veins are not suitable for AVF creation or have all been exhausted as a result of repeated AVF procedures, arterio-venous grafts (AVG) using polytetraflouroethylene (PTFE) to bridge arteries and veins is an alternative for provision of continued vascular access for haemodialysis. This study is a review of our experience in using PTFE AVGs for vascular access in patients requiring chronic haemodialysis. METHODS AND MATERIALS: A retrospective review was done on 92 grafts in 77 patients placed by 3 vascular access surgeons at the Singapore General Hospital from January 1989 to December 1994. RESULTS: There were 58 female and 19 male patients with a median age of 43 years (range 15-76 years). Twelve patients (16%) were diabetic and 6 patients (8%) had systemic lupus erythematosis requiring long-term steroids. Seventy-three percent of patients had up to 2 previous AVF creations before placement of AVG over the forearm (64%), upper arm (23%) or thigh (6.5%). Complications include graft infection (19), pseudoaneurysm formation (10), graft thrombosis (24), steal syndrome (1), venous congestion (1) and venous end stenosis (1). Diabetic status and long-term steroid therapy did not significantly increase the incidence of graft infection. The patency rates at 24 months and 36 months were 77% and 58% respectively. However serviceability rates were 61% at 2 years and 38% at 3 years mainly due to infective complications. CONCLUSION: PTFE AVGs offer reasonable patency and serviceability rates as a vascular access modality but in view of their complication profile, the native vein arteriovenous fistula should continue to be the first choice procedure for vascular access in patients requiring chronic haemodialysis.
BACKGROUND: We report the retrospective review of 82 leg bypass grafts done in 79 patients who had critical leg ischaemia between May 1993 and November 1996. The mean age of the patients was 68 years (range 50 to 82). PATIENTS: There were 49 male and 35 female patients. Fifty-nine percent of the study population presented with gangrene, 33% had ischaemic ulceration and 58% had rest pain. Seventy-five percent of them were diabetics. Thirty-eight femoro-popliteal, 28 femoro-distal, 6 popliteal-distal, 5 pedal, 1 aorto-bifemoral, 3 axillo-bifemoral and 1 cross-over bypass grafts were done. RESULTS: The peri-operative mortality rate was 11.3% and 71% of patients were discharged with salvaged feet. Ninety percent of these legs were still viable 12 months after the operation.
BACKGROUND: The experience with genitoperineal gangrene at the Department of Colorectal Surgery, Singapore General Hospital is documented. METHODS: The results of 12 patients treated during the 5 year period between 1 January 1990 and 31 January 1995 were studied. There were 10 men and two women. The mean age of the patients was 55.2 (range 37-83) years. RESULTS: Perianal pain and swelling were the commonest presentation. However, three patients were admitted in a toxic state with mental confusion. The gangrene progressed from anorectal sepsis in six patients. Five of these patients had diabetes mellitus. Escherichia coli was the commonest organism cultured. Early diagnosis, immediate resuscitation, antibiotics and early aggressive surgery was our management policy. Applying these principles, all except two patients survived (mortality 17%). One had advanced malignancy and the other had extensive burn injuries. CONCLUSIONS: A high index of suspicion should be maintained in patients with diabetes and with anorectal sepsis. Should genitoperineal gangrene develop, aggressive surgery is often successful.