Biomedical subjects

P H Davids

Publications and source records attributed to P H Davids.

14 recordsLinked to original sources

PubMed2003

Lesion progression with time and the effect of vascular occlusion following radiofrequency ablation of the liver.

BACKGROUND: The effectiveness of radiofrequency ablation (RFA) under selective vascular occlusion and its effects on architecture and viability of normal liver parenchyma was studied in a porcine model. METHODS: RFA was applied in the liver under general anaesthesia in 18 pigs. Six animals were killed immediately after the procedure and 12 at 24 h. RFA was performed sequentially under four conditions: (1) without vascular occlusion, (2) during occlusion of the hepatic artery, (3) during occlusion of the portal vein and (4) during occlusion of the hepatic artery and portal vein. Liver biopsies from the treated area were stained for conventional histological examination, reduced nicotinamide adenine dinucleotide diaphorase and 5'-nucleotidase activity. RESULTS: Vascular occlusion significantly increased the size of the coagulation centre after RFA. Combined portal venous and arterial occlusion had no additional effect on lesion size compared with venous or arterial occlusion alone. After 24 h, deterioration of viability was observed in the parenchyma up to 3 cm from the coagulated area. CONCLUSION: The efficacy of RFA in liver increases with occlusion of the portal vein or hepatic artery. The extent of secondary heat-induced necrosis in liver parenchyma should be considered for determination of the final size of the ablated area.

Animals↗

PubMed2001

[Consequences of caustic damage of the esophagus].

Following ingestion of a highly concentrated acetic acid solution, three women aged 29, 23 and 25 years old, suffered damage to the oesophagus and the stomach, respiratory and renal insufficiency and haemolysis. After intensive treatment, gastric tube reconstruction was carried out in 2 of these patients, and the third woman required repeated dilatations of the oesophageal stricture from 6 weeks after ingestion onwards. This resulted in a normal passage of solid food in all women. A 58-year-old man who had ingested caustic soda at 4 years of age, presented with increasing problems associated with swallowing food. A squamous cell carcinoma was diagnosed and treated with chemotherapy, oesophagus-cardia resection and gastric tube reconstruction. After 2 years the tumour has not recurred. Ingestion of corrosive substances can lead to serious damage of the gastrointestinal tract. Early endoscopy is important in establishing the extent of the injury. During the acute phase, intensive care admittance is often necessary and resection of the oesophagus is also necessary in some cases. Subsequent treatment can vary from endoscopic dilations to gastric tube reconstruction following resection of the oesophagus.

Acetic Acid↗

PubMed2001

Analysis of the quality and efficiency in learning laparoscopic skills.

OBJECTIVES: This study demonstrates the application of time-action analysis to the evaluation of task performance of diagnostic laparoscopy with laparoscopic ultrasonography. METHODS: The first 25 diagnostic laparoscopies with laparoscopic ultrasonography performed by a surgical resident were analyzed and compared with the outcomes of these procedures performed by an experienced surgeon. The time, actions, and correctness of task performance were evaluated. Furthermore, outcome correctness and postoperative complications were assessed. RESULTS: No postoperative complications occurred. The resident made one wrong diagnosis, for which the cause was detected by peroperative analysis. Additionally, 1% of the subtasks were performed only partially, 4% not at all, and 2% using the wrong technique. The efficiency for most diagnostic tasks remained significantly lower than that of the experienced surgeon (p < 0.001). CONCLUSIONS: Time-action analysis can be used to provide detailed insight into the quality and efficiency of learning surgical skills. It enables objective measurement of correctness in task performance as well as time and action efficiency.

Ampulla of Vater↗

PubMed2001

[Mix-up of patient specimen: DNA-microsatellite analysis as a fast identification method].

In a man aged 56 years with dysphagia, an oesophageal biopsy was found to contain an adenocarcinoma. In view of the discrepancy between the clinical and the histological pictures, the biopsy was repeated; in a second biopsy no carcinoma was demonstrable. DNA microsatellite analysis proved that the first biopsy originated from another person. The scheduled oesophageal resection was cancelled and the patient was reassured. A woman aged 77 years underwent gastrectomy because of biopsy samples with adenocarcinoma. However, no tumour was found in the resected stomach. DNA microsatellite analysis showed that the biopsy samples indeed originated from the patient. Unfortunately, mix-up of patient specimens occasionally occurs. Especially a discrepancy between the clinical picture and the histological diagnosis must raise the suspicion of a specimen mix-up. In such cases, DNA microsatellite analysis can give a rapid and reliable answer whether a mix-up has indeed taken place.

Adenocarcinoma↗

PubMed1996

Operative treatment for delayed union and nonunion of midshaft clavicular fractures: AO reconstruction plate fixation and early mobilization.

Fourteen patients were treated operatively for delayed union and nonunion of midshaft clavicular fractures from 1986 to 1994. Radiographically, nine nonunions were atrophic and five hypertrophic. The operative technique included opening the medullary canal, bone grafting, and fixation with an AO reconstruction plate. Postoperative mobilization started within one week. The mean follow-up was 60 months (range, 16 to 101 months). Consolidation was observed radiologically after 10 to 30 weeks. All patients were asymptomatic after 10 weeks and had a normal range of shoulder motion. One patient sustained a fractured clavicle following adequate trauma. Operative treatment for delayed union and nonunion of clavicular fractures with AO reconstruction plate fixation, bone grafting, and early postoperative mobilization yields excellent results.

Adult↗

PubMed1994

Bile viscosity in patients with biliary drainage. Effect of co-trimoxazole and N-acetylcysteine and role in stent clogging.

BACKGROUND: The main disadvantage of endoscopic insertion of an endoprosthesis is the tendency of the stent to clog after a few months. In this study we determined the role of bile viscosity in stent clogging. METHODS: Sixty patients were stented with 10 Fr 11-cm stents. The stents were electively removed after 2 months, and a bile sample was obtained simultaneously. Bile viscosity was measured with a coaxial rotation viscometer. The influence of treatment with antibiotics and a mucolytic agent on viscosity was assessed in a randomized trial. RESULTS: Bile viscosity correlated significantly with DNA and total protein concentration. After treatment with either N-acetylcysteine or co-trimoxazole a lower mean value of the viscosity was observed, but this was not statistically significant. There was no correlation between bile viscosity and the amount of sludge adhering to the stents. CONCLUSIONS: In most patients bile viscosity plays a limited role in stent clogging. Only in patients with excessively high viscosity do mucolytic agents or treatment with antibiotics seem to have a role.

Acetylcysteine↗

PubMed1994

Effects of biliary endoprostheses on the extrahepatic bile ducts in relation to subsequent operation of the biliary tract.

Despite the widespread use of transpapillary biliary endoprostheses, little is known about their effect on the extrahepatic bile ducts. In an experimental study in dogs, we induced inflammatory changes in the bile ducts by stent insertion and studied the reversibility of these changes after stent removal. In addition, the consequences of a period of preoperative stenting for subsequent operation of the biliary tract and the eventual detrimental effects of stenting on the histologic factors of the liver were studied. Twenty-six mongrel dogs were randomly divided into four groups: group 1, stenting during four weeks; group 2, after four weeks stenting, construction of a hepaticojejunostomy; group 3, four days of common bile duct (CBD) ligation, four weeks stenting and hepaticojejunostomy, and group 4, four days of CBD ligation and hepaticojejunostomy. All dogs were sacrificed two months after the last procedure. Hepatic biopsies were obtained during each procedure and bile duct biopsies during hepaticojejunostomy and upon sacrifice. Four weeks of stenting of a normal or obstructed CBD resulted in fibrosed bile ducts, showing severe chronic inflammation with papillary hyperplasia of the epithelium. All bile cultures grew fecal bacteria. Two months after stent removal, inflammation was still present, albeit less severe. Stenting and subsequent surgical treatment resulted in a higher incidence of postoperative complications (54 percent) compared with the control group (14 percent), although this did not reach statistical significance. Hepatic histologic factors were not markedly changed after transpapillary endoprosthesis placement, but after hepaticojejunostomy cholangiolitis was observed. Whenever transpapillary biliary endoprostheses are used, the local effects on the extrahepatic bile ducts and the subsequent bacterial contamination of the bile should be considered.

Anastomosis, Surgical↗

PubMed1993

Benign biliary strictures. Surgery or endoscopy?

OBJECTIVE: This study compared the results of surgery and endoscopy for benign biliary strictures in one institution, over the same period of time and with the same outcome definitions. SUMMARY BACKGROUND DATA: Surgery is considered the treatment of choice, offering more than 80% long-term success. Endoscopic stenting has been reported to yield similar results and might be a useful alternative. METHODS: In this nonrandomized retrospective study, 101 patients with benign biliary strictures were included. Thirty-five patients were treated surgically and 66 by endoscopic stenting. Patient characteristics, initial trauma, previous repairs, and level of obstruction were comparable in both groups. Surgical therapy consisted of constructing a biliary-digestive anastomosis in normal ductal tissue. Endoscopic therapy consisted of placement of endoprostheses, with trimonthly elective exchange for a 1-year period. RESULTS: Mean length of follow-up was 50 +/- 3.8 and 42 +/- 4.2 months for surgery and endoscopy, respectively. Early complications occurred more frequently in the surgically treated group (p < 0.03). Late complications during therapy, occurred only in the endoscopically treated group. In 46 patients, the endoprostheses were eventually removed. Recurrent stricturing occurred in 17% in both surgical and endoscopic patients. CONCLUSIONS: Surgery and endoscopy for benign biliary strictures have similar long-term success rates. Indications for surgery are complete transections, failed previous repairs, and failures of endoscopic therapy. All other patients are candidates for endoscopic stenting as the initial treatment.

Adult↗

PubMed1993

Bile duct injury after laparoscopic cholecystectomy: the value of endoscopic retrograde cholangiopancreatography.

This study describes the value of endoscopic retrograde cholangiopancreatography (ERCP) in patients with bile duct injury after laparoscopic cholecystectomy. Twelve consecutive patients were studied over a one year period. In all patients the biliary tree was visualised during ERCP. Four patients had complete bile duct obstruction, seven patients had a stricture (two with concomitant leakage), and one patient had leakage from a hepatic branch. Three patients with complete obstruction, presented with a relatively prolonged symptom free, 'silent' period before diagnosis. In all four patients with complete transection, a proximal hepaticojejunostomy was performed. In one patient with a tough fibrous stricture, secondary to incorrect clip placement, passage of the guidewire was impossible, leaving surgical reconstruction as the only therapeutic option. All remaining seven patients with leakage or strictures, or both were successfully treated by endoscopic sphincterotomy only (n = 1) or sphincterotomy and subsequent stent placement (n = 6). When patients do not recover uneventfully after laparoscopic cholecystectomy even without cholestasis or jaundice, early ERCP is recommended as a safe and valuable method to detect bile duct injury and to suggest treatment. Subsequently, more than half of such patients can be treated endoscopically. Extended follow up is needed to evaluate the longterm results.

Adult↗

PubMed1992

Diagnosing scaphoid fractures: radiographs cannot be used as a gold standard!

To evaluate the reproducibility of the interpretation of radiographs for the diagnosis of scaphoid fractures, 134 radiographs (60 consecutive patients) were blindly observed by a resident radiologist, consultant radiologist, resident trauma surgeon and consultant trauma surgeon. The results of radiographs were analysed using kappa (kappa) statistics and stratified according to the results of the corresponding bone scan. In 23 patients the bone scan was positive for fracture of the scaphoid. Irrespective of training and experience, the kappa of the comparison of the scores of the radiographs between any two observers did not exceed 40 per cent. After stratification of the outcome of the bone scan, the kappa did not increase significantly. A panel of three experienced observers gave their opinion of all radiographs. The results were compared with the bone scan results. We conclude that radiographs in suspected scaphoid fracture cannot be used as a reliable diagnostic approach because of the low inter-observer agreement in the interpretation, irrespective of the experience and training of the observer.

Adult↗

PubMed1992

Early recurrence of obstructive jaundice after placement of a self-expanding metal endoprosthesis.

Self-expanding metal endoprostheses have ben used in the treatment of malignant obstructive jaundice for a few years. We report on a patient with obstructive jaundice due to a metastasis of a squamous cell lung cancer into the pancreatic head who received an expandable metal endoprosthesis and suffered recurrent jaundice and cholangitis after 38 days. On repeat ERCP, a very narrow stenosis was seen in the stent lumen caused by tumor ingrowth through the mesh. Intraluminal biopsies showed squamous cell carcinoma. A 10 Fr plastic endoprosthesis was inserted through the self-expanding stent with good drainage. On the basis of this experience, we feel that when faced with a patient with obstructive jaundice due to metastatic disease from a rapidly progressive carcinoma, the use of the currently available self-expanding metal endoprosthesis should be discouraged until the results of prospective studies with large numbers of patients have proven its superiority over the plastic endoprostheses. Meanwhile, modifications to prevent tumor ingrowth through the mesh of the stent are under investigation.

Carcinoma, Squamous Cell↗

PubMed1992

Postoperative bile leakage: endoscopic management.

Bile leakage is an infrequent but serious complication after biliary tract surgery. This non-randomised single centre study evaluated the endoscopic management of this problem in 55 consecutive cases. Treatment consisted of standard sphincterotomy and, if needed, subsequent stone extraction with or without endoprosthesis placement. The aim of all treatments was to facilitate bile flow into the duodenum. The biliary tract and the site of the leakage were visualised during endoscopic retrograde cholangiopancreatography (ERCP) in 98%. There was distal obstruction in 33--caused by retained gall stones in 15 patients and concomitant strictures in 18. Overall, 48 of 55 patients were treated endoscopically. An excellent outcome (clinical and radiological resolution of the bile leak) was achieved in 43 patients (90%). Five patients (10%) had continuing sepsis from which they died. Postoperative bile leakage can be diagnosed safely and effectively by ERCP and subsequent endoscopic management is successful in most cases.

Adult↗

PubMedDate not supplied

Randomised trial of self-expanding metal stents versus polyethylene stents for distal malignant biliary obstruction.

Self-expanding metal stents are claimed to prolong biliary-stent patency, although no formal comparative trial between plastic and expandable stents has been done. In a prospective randomised trial, we assigned 105 patients with irresectable distal bile-duct malignancy to receive either a metal stent (49) or a straight polyethylene stent (56). Median patency of the first stent was significantly prolonged in patients with a metal stent compared with those with a polyethylene stent (273 vs 126 days; p = 0.006). The major cause of stent dysfunction was tumour ingrowth in the metal-stent group and sludge deposition in the polyethylene-stent group. Treatment after any occlusion included placement of a polyethylene stent. In the metal-stent group none of 14 second stents occluded, whereas 11 of 23 (48%) second stents clogged in the polyethylene-stent group (p = 0.002). Overall median survival was 149 days and did not differ significantly between treatment groups. Incremental cost-effectiveness analysis showed that initial placement of a metal stent results in a 28% decrease of endoscopic procedures. Self-expanding metal stents have a longer patency than polyethylene stents and offer adequate palliation in patients with irresectable malignant distal bile-duct obstruction.

Aged↗

PubMedDate not supplied

Endoscopic stenting for post-operative biliary strictures.

This study evaluates the efficacy of endoscopic stenting in 70 patients with noncomplete post-operative biliary strictures. The treatment consisted of placement of two 10 F gauge straight endoprostheses with elective exchange trimonthly, for a 1-year period. Successful endoprosthesis placement was accomplished in 66 of 70 patients (94%). In all 66 patients jaundice subsided. During the stenting period six patients had an operation and six died. In 46 patients the endoprostheses were removed. The mean period of follow-up was 42 months (range, 4 to 99 months). Excellent (asymptomatic, normal, or stable liver enzymes) and good (only one episode of cholangitis) responses were achieved in 83%; restricturing occurred after stent removal in 17%. Prolonged biliary stenting appears to be a safe and effective treatment modality for benign post-operative strictures and a valid alternative to surgery.

Adult↗