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PubMed1994

A general purpose neural network simulator system for medical data processing.

We developed a general purpose neural network simulator system for medical data processing. This system has a flexible network definition language. Users can define arbitrary hierarchical neural networks using the definition language to analyze medical data that contains some complex patterns. The learning algorithm used in this system is back propagation. Learning curves are displayed on multiple windows. This is a general purpose system, so it can be used for various kinds of medical data processing such as one dimensional signal processing or two dimensional image processing. The system can run on a standard UNIX workstation, which is faster and more powerful than most personal computers. The system needs an X window system/Motif and C compiler. These are standard system programs already available on most UNIX workstations. The source code of the system can be retrieved from our anonymous ftp site via Internet.

Algorithms↗

PubMedDate not supplied

Follow-up of anal dynamic graciloplasty for fecal continence.

The feasibility of anal dynamic graciloplasty (transposition of the gracilis muscle and subsequent implantation of a stimulation device) to restore continence, was assessed in a case-control study of 26 patients with severe fecal incontinence. It was shown that anal dynamic graciloplasty is capable of achieving the sphincter tone of healthy persons, as stimulated graciloplasty increased anal pressure from 46 mmHg without stimulation to 65 mmHg with stimulation (mean increase 19 mmHg; 95% confidence interval 13, 25; n = 25; p < 0.01). Time to retain a 250-ml phosphate enema increased from 52 seconds before to 204 seconds after 8 weeks of electrical stimulation (mean increase 151 seconds; 95% confidence interval 61, 241; n = 25; p < 0.01). Complete fecal continence was achieved in 17 patients (65%); two of these patients developed a wound infection, but one of the two realized continence without stimulation and the other patient became continent after reimplantation. Three other patients improved after anal dynamic graciloplasty, but infection necessitated removal of the stimulation device. One patient developed a fistula. Failures were encountered in five patients. Although our long-term follow-up results suggest a learning curve, it is concluded that electrical stimulation improves the results of conventional graciloplasty and avoids construction of a colostomy.

Adult↗

PubMedDate not supplied

Operative ultrasonography during hepatobiliary and pancreatic surgery.

On the basis of our experience with operative ultrasonography during hepatobiliary and pancreatic surgery, its indications, benefits, and disadvantages are summarized. High-resolution operative ultrasound scanning of the liver, biliary tract, and pancreas was performed during 357, 735, and 242 operations, respectively. The benefits of operative ultrasonography were categorized as acquisition of diagnostic information otherwise not available, replacement for or complement to operative radiography, and guidance of surgical procedures. Operative ultrasonography provided beneficial information during 73 of 82 hepatic operations (89.0%), 57 of 69 noncalculous biliary operations (82.6%), and 177 of 242 pancreatic operations (73.1%). Operative ultrasonography was significantly superior (sensitivity 93.3%) to other screening tests for diagnosing liver metastasis from colorectal carcinoma evaluated in 189 patients, and it detected previously unrecognized metastatic tumors in 18 patients (9.5%). For screening common bile duct calculi during 666 operations, operative ultrasonography and operative cholangiography were comparable in all indices of accuracy except for a higher predictability of a positive test of operative ultrasonography (94.8% versus 71.7%). For diagnosing portal vein invasion of pancreatic carcinoma, operative ultrasonography provided better overall accuracy than preoperative studies (89.7% versus 64.1%). On the basis of operative ultrasound findings, previously planned surgical procedures were altered in 32 of 82 hepatic operations (39.0%) and 24 of 145 pancreatic operations for chronic pancreatitis (16.6%). Operative ultrasound guidance of various surgical procedures was performed during 88 hepatic and 84 pancreatic operations, including 40 ultrasound-guided hepatectomies and 42 pancreatotomies. Operative ultrasonography has a number of advantages, such as safety and speed in performance, wide application, high diagnostic accuracy, and ability of guiding procedures. Its disadvantages are the limitation of the fields of view in certain applications, the need for special equipment, and a slow learning curve.

Biliary Tract↗

PubMedDate not supplied

Complications associated with ileal pouch-anal anastomosis.

Seventy-three patients underwent total colectomy, rectal mucosectomy, creation of J or S ileal reservoir, and ileal pouch-anal anastomosis from 1982 to 1989. Mean follow-up was 38 months, with a minimum of 3 months in 15 patients being followed long-term at another institution. Forty-eight (66%) patients had histologically proven ulcerative colitis and 25 (34%) patients had familial polyposis. Thirty-eight J reservoirs and 35 S reservoirs were constructed. There were no perioperative deaths. The failure rate (loss of pouch) was 3%. Thirty-six complications in 34 (47%) patients were reported, 14 (19%) patients required surgery. Bowel obstruction was the most common postoperative complication (16%), followed by pouchitis (15%), and cuff infection (5%). Seventy-eight percent of the complications were associated with the J pouch. Average stool frequency at 1 year was 4 per 24-hour period. Other complications included postoperative pneumonia (1), peroneal nerve palsy (1), and temporary sexual dysfunction (1). Seven of 15 complications requiring surgical intervention occurred in the first 2 years of the study period, illustrating the learning curve associated with the procedure. Blood loss, transfusion requirements, and length of operation were not associated with higher complication rates. Use of the J pouch and experience of the individual surgeon affected morbidity.

Adenomatous Polyposis Coli↗

PubMed1991

Paediatric liver transplantation: review of current experience.

During the 1980s the results of liver replacement in children improved dramatically, with 12-month survival rates rising from around 20% to over 85% at the most experienced centres. This improvement has been due to several factors, including better patient selection and timing of transplantation, advances in immunosuppressive therapy, and developments in liver preservation. Moreover, the learning curve effect has contributed with advances both in surgical technique and in the rapid diagnosis and treatment of complications, including the need to retransplant patients in whom the first graft has been irreversibly damaged. One major development is the refinement of the anatomically reduced grafts where a larger, usually adult, graft is cut down to fit a child. This has allowed a greater number of children to be grafted, including emergency cases such as fulminant hepatic failure in whom there is insufficient time to wait for a size-matched donor.

Child, Preschool↗

PubMed1998

Transurethral collagen injection for female stress incontinence.

Periurethral collagen injections have been used to treat female urinary incontinence secondary to intrinsic sphincteric deficiency (ISD). As an alternative, a transurethral submucosal collagen injection was used in 33 consecutive women suffering from stress incontinence secondary to ISD at Tulane University Medical Center. Prior to the procedure, careful clinical examination with a videofluorourodynamic study was performed for each case. The procedure was carried out under local anesthesia assisted with monitored anesthesia care (MAC). The collagen was injected transurethrally by the long collagen needle (C. R. Bard). In the first 11 cases the average cumulative collagen injected per patient was 6.1 ml, whereas in the last 22 cases the average was 3.5 ml. As a result of the injection 16 patients were dry (48.5%) and 11 were improved (33.3%), with an overall success rate of 81.8%. The injection failed in 6 patients (18.1%). The mean follow-up was 18.8 months, with a range of 2-33 months. In the successful group there was a significant decrease in pretreatment frequency, from an average of 8 to 4.9 (P = 0.005) and in nocturia from an average of 2.14 to 0.76 (P = 0.001). Also, there was a significant decrease in the number of pads, from an average of 3.7 to 1.1 (P = 0.001). The stress leak-point pressure showed a significant increase, from an average of 68.1 to 93.5 cm H2O (P = 0.03). There was no relation between grade of incontinence and the success of the injection. Two cases suffered from temporary urinary retention. This study revealed that the transurethral submucosal collagen injection is an effective method for treating cases of intrinsic sphincteric deficiency. The volume of collagen required to produce the seal effect is small and it may decrease the reinjection rate. As experience is gained, the procedure time is typically 15 minutes. This makes it a reliable, cost-effective and well-controlled method. However, it has a learning curve and the cystoscope instruments require minor adaptation for its use.

Adult↗

PubMed1994

Changing practice patterns in peripheral arterial disease.

The development of interventional radiologic techniques during the past decade has changed our approach to the treatment of lower extremity peripheral arterial disease (LE-PAD). Balloon and laser-assisted angioplasty, atherectomy (rotary and directional devices), stent implantation, and thrombolysis as well as combinations of all of these approaches, at times with concomitant or secondary surgery, have been used in our institution. A review of our practice patterns during the past 5 years was performed to analyze changing attitudes and results with these newer techniques. All new patients seen in consultation for LE-PAD during three alternate years were reviewed with regard to demographics, initial complaints, initial treatment modality, initial outcome, indications for and results of secondary treatment, and ultimate outcome (at 1 year). The 603 patients were seen during the following three 12-month periods: 1987 to 1988, 1989 to 1990, and 1991 to 1992. An intention-to-treat analysis revealed (1) the number of patients seen for peripheral arterial disease has increased steadily; (2) in the last year more were initially treated with intervention as the primary modality; (3) the results of such catheter-based procedures improved only slightly over this 5-year period, despite our learning curve and the fact that we discarded several ineffective interventional approaches; (4) the fraction of patients primarily operated on and the excellent results of surgery have not changed; and (5) the number of operations for proximal (aortoiliac) disease has decreased markedly, with a corresponding increase in distal reconstructions. The evolution of our current approach to the treatment of LE-PAD is based on this continuing experience.

Angioplasty, Balloon↗

PubMed1996

Intraoperative laparoscopic complications. Are we getting better?

PURPOSE: The aim of this study was to assess various intraoperative and postoperative complications associated with laparoscopic colorectal surgery. Specifically, the impact of surgical experience and procedure type on complications was analyzed. METHODS: All patients who underwent laparoscopic surgery were analyzed by age, sex, surgical indications, procedure performed, procedure length, intraoperative and postoperative complications, incidence and causes for conversion, duration of postoperative ileus, and length of hospital stay. Patients were classified for type of procedure and chronologically into four consecutive groups. Procedures were also categorized into four different groups: GI, total abdominal colectomies; GII, segmental resections; GIII, diverting procedures; GIV, others (abdominoperineal resection, Hartmann's creation or closure, anterior resection, and rectopexy). RESULTS: Between August 1991 and October 1995, 167 patients of a mean age of 49.6 (15-88) years underwent laparoscopic colorectal procedures. All procedures were electively performed. Common indications for surgery included inflammatory disease in 70 (42 percent), neoplasia in 56 (33 percent), functional bowel disorders in 30 (18 percent), and other forms of colorectal disorders in 11 (7 percent) patients. The most significant variable affecting intraoperative laparoscopic complication rate was surgical experience measured as the time interval during which surgery was performed (P = 0.02). Total complication rate decreased from 29 percent during the first period to 11 percent by the second period (P < 0.04) and 7 percent during the third period (P < 0.005). Thus, the learning curve appeared to have required more than 50 cases to achieve. Moreover, even after performance of 94 (1991-1993) procedures in GI and GIV, these procedures were associated with higher complication rates than were those procedures in GII and GIII (P = 0.04). CONCLUSION: Surgical experience and case selection are the most critical variables by which the surgeon can decrease the intraoperative laparoscopic complication rate.

Adolescent↗

PubMed1997

Update of urethra-sparing approaches in cystectomy in women.

The emerging experience in urethra-sparing cystectomy in women undergoing subsequent orthotopic lower-urinary-tract reconstruction with regard to the anatomy of the remnant urethra, patient selection, refinements of the surgical technique, the patients' outcome with respect to the underlying disease, the risk for tumor recurrence, and postoperative urodynamics are the main focus of this report. In the present study, 30 carefully selected female patients underwent orthotopic reconstruction of the lower urinary tract. Surgical variations emerging from the first learning curve, including nerve-sparing anterior exenteration, vaginal reconstruction, omental support of the neobladder floor, and ureterointestinal anastomosis, were applied in 21 patients with lower-urinary-tract reconstruction. Of 24 patients followed for more than 6 months, 21 (87.5%) are continent at daytime, 19 (79%) have nocturnal continence, and only 1 (4%) requires self-catheterization; 3 patients with urinary retention were successfully treated for obstructed ileal valves. After a follow-up period of 2-41 (mean 15.4) months one patient each developed local recurrence (uterine adenosarcoma) after 13 months and distant metastasis transitional-cell cancer of the bladder after 3 months; all other patients are currently free of disease. Urethra-sparing surgery has established itself in selected women with bladder cancer. Refinements in the technique of radical cystectomy and orthotopic creation of a neobladder to the urethra may improve the continence, spontaneous micturition, and surgical oncological outcome of these patients.

Cystectomy↗

PubMed2000

Should enteric fistulas from Crohn's disease or diverticulitis be treated laparoscopically or by open surgery? A matched cohort study.

PURPOSE: The aim of this study was to study a group of consecutive patients with enteric fistulas treated by laparoscopic surgery and to compare outcomes with a matched group of patients treated by open surgery. METHODS: The outcomes of 13 patients with Crohn's disease or sigmoid diverticulitis with enteric fistulas treated laparoscopically (Group I) were compared with 13 patients matched for age, weight, gender, diagnosis, and characteristics of fistulas and treated by conventional surgery (Group II) during the same period. RESULTS: No patient died postoperatively in either group. Mean operative time was 183 minutes in Group I vs. 154 minutes in Group II (P = 0.280). No significant difference was found between Groups I and II in the number of patients with major postoperative complications (3 vs. 5; P = 0.462), or postoperative stay (7.6 +/- 3.6 vs. 9.2 +/- 3 days; P = 0.239). Conversion to open laparotomy occurred in one (7.7 percent) patient from Group I. No patient required readmission for secondary surgery in Group I, and two patients were readmitted and underwent reoperation for complications in Group II (P = 0.462). CONCLUSIONS: The laparoscopic treatment of selected cases of enteric fistulas is safe. Although most good outcome trends favor the laparoscopic group, the study is inconclusive, because no statistical difference was demonstrated with regard to operative time, number of postoperative complications, readmission rate, and length of postoperative stay, most likely because of the small number of cases in each arm of the study. Study of a greater number of cases outside the learning curve of the laparoscopic surgeons would clarify this issue. Other outcomes, including cost, pain control, cosmesis, and return to activities of daily living, need to be included in the evaluation.

Adult↗

PubMed1998

Intestinal anastomosis by use of the biofragmentable anastomotic ring: is it safe and efficacious in emergency operations as well?

PURPOSE: Although sutureless anastomosis by use of the biofragmentable anastomotic ring is now accepted as an alternative to conventional manual sutured or stapled methods in elective enterocolic surgery, its applicability to emergency enterocolic surgery has not yet been established. The aim of this prospective study was to determine whether the biofragmentable anastomotic ring anastomosis in emergency enterocolic surgery could be performed as safely as in elective surgery or as emergency handsewn anastomosis. METHODS: To evaluate the safety and efficacy of sutureless bowel anastomosis by use of the biofragmentable anastomotic ring in emergency enterocolic surgery, a prospective, randomized study was undertaken to compare the biofragmentable anastomotic ring with conventional handsewn anastomotic technique. One hundred nineteen patients who required emergency laparotomy were randomly assigned to two groups: 56 patients (47 percent) underwent 58 biofragmentable anastomotic ring anastomoses, and 63 patients (53 percent) underwent 65 sutured anastomoses. In addition, the safety and efficacy of the biofragmentable anastomotic ring in emergency surgery were compared with those of the biofragmentable anastomotic ring in 86 elective biofragmentable anastomotic ring anastomoses performed in 84 patients during the same period of time. RESULTS: Specific intraoperative complications related to use of biofragmentable anastomotic rings occurred in six patients (10.7 percent), and another new biofragmentable anastomotic ring anastomosis was constructed in one patient. These reflected learning-curve errors, but they did not adversely affect the outcome. No statistical differences were observed among the groups with respect to wound complications, postoperative bleeding, intra-abdominal abscess, intestinal obstruction, or postoperative death. As for anastomotic leakage, six patients, two in each group, had complications of anastomotic failure, wherein four colonic fistulas required a diversion and two enteric fistulas closed spontaneously. Although there were no statistically significant differences in incidence of leaks among groups (P = 0.4522), two fistulas in colocolic anastomoses, one in the suture group and the other in the biofragmentable anastomotic ring group, manifested the risk of primary anastomosis in emergency colon resection. Seven patients, three in the elective biofragmentable anastomotic ring group and two each in the emergency suture and biofragmentable anastomotic ring groups, died after the operation, but no deaths were directly attributed to the anastomotic technique used. CONCLUSION: The data suggest that the biofragmentable anastomotic ring is a safe and reliable alternative to conventional handsewn anastomosis in emergency enterocolic surgery, where the rapidity and security of anastomosis may be critical. Consideration, however, should be given to emergency primary colocolic or colorectal anastomosis, because of a high risk of anastomotic failure, although there are too few cases for a definite conclusion.

Adolescent↗

PubMed1992

An analytical short- and long-term memory model of presynaptic plasticity.

A mathematical model, called the Learning Gate Model (LGM), that describes phenomena responsible for biological synaptic plasticity, is presented. The functionality of the model are mainly based on the work of Kandel and colleagues on the most elementary forms of learning observed in the Aplysia Californica marine mollusc. In particular, emphasis is placed on the double temporal dynamics of synaptic plasticity and the temporal specificity of classical conditioning. By properly modeling the effect of the binding of Ca++ ions to the serotonin-sensitive adenylate cyclase enzyme, it is shown how a positively accelerated learning curve can be obtained for sensitization and classical conditioning. Phenomena of spontaneous recovery and second-order conditioning are reproduced through simulations. Mathematical analyses of the temporal trace of conditioned stimulus and of the Short-Term Memory steady state are also given.

Animals↗

PubMedDate not supplied

Immediate sealing of arterial puncture site following femoropopliteal angioplasty: a prospective randomized trial.

PURPOSE: A new hemostatic puncture closure device (HPCD) was evaluated following femoropopliteal angioplasty. Efficacy in hemostasis and complications were compared between manual compression and the new system. METHODS: One hundred patients undergoing percutaneous interventional procedures were randomly assigned to receive either manual compression or HPCD. The time to complete hemostasis (when a compression bandage was applied) was noted as well as complications such as hematoma or arterial stenosis at the puncture site. Follow-up was by clinical examination and color-coded duplex sonography (CCDS). RESULTS: With the HPCD, immediate hemostasis was achieved in 22 patients (44%). Discrete oozing without the necessity of external compression or further consequences was observed in 11 patients. Mean manual compression time was 25 (+/- 20) min including application of the pressure bandage. Eleven patients needed additional manual compression and technical failures were observed in 6 patients (12%). The compression time in these 17 cases was 27 (+/- 12) min. Subcutaneous hematomata with a diameter of more than 5 cm developed in 15 of 48 patients in the HPCD group and in 14 of 48 patients in the manual compression group. No surgical or percutaneous intervention was necessary. The complication rate was comparably low in the experimental and control groups. CONCLUSION: Compared with manual compression HPCD is faster and more accurate for sealing the arterial puncture defect following angioplasty. After an initial learning curve, it is easy to handle and time-saving as well as convenient for the patient. Furthermore, immediate and full anticoagulation is possible and arterial inflow is not compromised. A drawback is the necessity of an 8 Fr sheath. Nevertheless, the complication rate is comparably low for both methods.

Adult↗

PubMed2002

Sentinel lymph node mapping and biopsy for breast cancer at a rural-based university medical center: initial experience with intraparenchymal and intradermal injection routes.

BACKGROUND: Recent data suggests that intradermal (ID) injection for sentinel lymph node (SLN) mapping and biopsy in breast cancer is as effective and reproducible as intraparenchymal (IP) injection. The aim of this study was to review our initial experience with IP and ID injection for SLN mapping and biopsy at our rural-based university medical center. METHODS: From January 4, 1999 to January 5, 2001, 113 of 165 patients with breast cancer underwent attempted SLN mapping and biopsy by either IP (n=63) or ID (n=50) injection. Selection of the IP versus ID injection route was non-randomized and based on surgeon preference. Success of SLN localization was examined. RESULTS: SLN localization was successful in 82% of IP and 100% of ID for radioisotope (p=0.001), 69% of IP and 92% of ID for blue dye (p=0.002), and 90% of IP and 100% of ID (p=0.024) for radioisotope and blue dye. Identical comparisons made after excluding the first 10 cases, 20 cases, and 30 cases from each injection group showed that the percentage of cases in each group in which the SLN localized changed minimally; however, some of the resultant p values eventually lost statistical significance. CONCLUSIONS: SLN localization was more successful by ID injection than by IP injection, thus favoring utilization of the ID injection route. The eventual loss of statistical power in some of the comparisons with increasing numbers of initial cases excluded may reflect differential learning curves of the two injection techniques; however, this may simply be a reflection of decreasing sample size used in each subsequent analysis. A prospective randomized trial comparing the IP and ID injection route may be warranted.

Academic Medical Centers↗

PubMed1991

Endoscopic management of common duct stones with laparoscopic cholecystectomy.

In the first year from October 1990 since starting the procedure 65 laparoscopic cholecystectomies were carried out on one surgical service. There were 4 planned open cholecystectomies and 8 laparoscopic procedures converted during the same period: 7 of these were in the first 3 months with only 1 of the last 53 being opened. Surgery was carried out during the same admission in 22 patients presenting as emergencies: acute cholecystitis (9), colic (6), pancreatitis (3), jaundice (4). Two patients had later laparotomies for complications; one patient bled from the umbilical stab and with ongoing peritonism had a pelvic haematoma drained on day 5 and a second was opened following a bile leak caused by a displaced cystic duct clip--both recovered uneventfully. Peroperative cholangiography was performed in 13 patients; 2 were positive (15%) and had ERCP papillotomy 3 days post op without complication. One patient who presented with pancreatitis had ERCP performed post-op without incident. Seven patients had laparoscopic cholecystectomy following papillotomy for common duct stones. The gallbladder was extracted per umbilicus in 45 (3 wound infections) and per right subcostal stab in 20 (no infections). Mean hospital stay was 48 hours (1-4 days) in uncomplicated cases. In conclusion, the learning curve is associated with higher conversion rates. Extraction through pliable hypochondrial muscles is easier and may be safer and less traumatic. Perioperative endoscopic papillotomy is safe and effective for choledochal stones.

Adult↗

PubMed2000

New facility picture archiving and communication system implementation strategy.

Strategies for deployment of picture archiving and communications systems (PACS) in new hospitals often involve the establishment of initial PACS operations. Such a strategy is flawed in the sense that the clinical and radiological users must adapt to PACS operations, while being faced with several other new facility learning curves. This increases the complexity and risk of the radiological services. A strategy of implementing PACS operations in the old facility and performing a zero-downtime transition into the new facility offers several advantages to this method. The successful undertaking of such a project will support not only the physical movement of the existing PACS, but the accomplishment of other re-engineering goals associated with the new hospital. This report will describe the strategy used in two successful transitions of PACS into newly constructed hospitals.

Hospital Design and Construction↗

PubMed2000

Laposcopic retroperitoneal lymph node dissection: evolution of a new technique.

Retroperitoneal lymph node dissection is the most accurate method of detecting occult lymph node metastases in the retroperitoneum. In clinical stage II disease, a residual tumor after primary chemotherapy has to be removed surgically. For these two indications we have replaced open surgery by laparoscopy, in order to reduce morbidity. Once the learning curve had been overcome, the operative time was in the range of that of open surgery, and from the very beginning morbidity and complication rates were lower. Oncologic long-term outcome was not compromised by the laparoscopic approach. Patient satisfaction was very high.

Humans↗

PubMed2000

Cages: outcome and complications.

The coincidental development of minimal intervention techniques for carrying out anterior lumbar spinal fusion and the introduction of cages to provide mechanical support of introduced bone graft led to the development of a type of cage suitable for both minimal intervention use (laparoscopic) and for the standard open procedure (the BAK cage). Reported results concentrated in the main on feasibility, safety and fusion rate achieved, rather than clinical outcome. Laparoscopic insertion at the lumbosacral level was as safe as if the procedure was an open one, although there was a slighter higher incidence of retrograde ejaculation. Immediate post-operative morbidity was less with the laparoscopic procedure and discharge home and return to work was earlier. There was no long-term benefit from the laparoscopic procedure. Laparoscopic insertion at the L4/5 level was attended by a greater incidence of complications, and had a longer learning curve.

Equipment Design↗