Two models better than one.
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Barrett Esophagus↗
Biomedical subjects
G S Gazelle
Publications and source records attributed to G S Gazelle.
Comparison of excretory phase, helical computed tomography with intravenous urography in patients with painless haematuria.
AIM: To compare excretory phase, helical computed tomography (CT) with intravenous (IV) urography for evaluation of the urinary tract in patients with painless haematuria. MATERIALS AND METHODS: Ninety-one out-patients had IV urography followed by helical CT limited to the urinary tract. Both IV urograms and CT images were evaluated for abnormalities of the urinary tract in a blinded, prospective manner. The clinical significance of abnormalities was scored subjectively and receiver operator characteristic curve analysis was performed. RESULTS: In 69 of 91 patients (76%), no cause of haematuria was identified. In 22 of 91 patients (24%), the cause of haematuria was identified as follows: transitional cell cancer of the bladder (n=15), urinary tract stones (n=3), cystitis (n=2), haemorrhagic pyelitis (n=1) and benign ureteral stricture (n=1). With IV urography, there were 15 true-positive, seven false-negative and three false-positive interpretations. With CT, there were 18 true-positive, four false-negative and two false-positive interpretations. There was no significant difference between IV and CT urography for the significance of the positive interpretations (n=0.47). CONCLUSION: Excretory phase CT urography was comparable with IV urography for evaluation of the urinary tract in patients with painless haematuria. However, the study population did not include any upper tract cancers.
Adult↗
A cost--utility analysis of treatment options for inguinal hernia in 1,513,008 adult patients.
BACKGROUND: The controversial issue of the cost-effectiveness of laparoscopic inguinal hernia repair is examined, employing a decision analytic method. MATERIALS AND METHODS: The NSAS, NHDS (National Center for Health Statistics), HCUP-NIS (Agency for Healthcare Research and Quality) databases and 51 randomized controlled trials were analyzed. The study group constituted of a total of 1,513,008 hernia repairs. Projection of the clinical, economic, and quality-of-life outcomes expected from the different treatment options was done by using a Markov Monte Carlo decision model. Two logistic regression models were used to predict the probability of hospital admission after an ambulatory procedure and the probability of death after inguinal hernia repair. Four treatment strategies were modeled: (1) laparoscopic repair (LR), (2) open mesh (OM), (3) open non-mesh (ONM), and (4) expectant management. Costs were expressed in US dollars and effectiveness in quality-adjusted life years (QALYs). The main outcome measures were the average and the incremental cost-effectiveness (ICER) ratios. RESULTS: Compared to the expectant management, the incremental cost per QALY gained was 605 dollars (4086 dollars, 9.04 QALYs) for LR, 697 dollars (4290 dollars, 8.975 QALYs) for OM, and 1711 dollars (6200 dollars, 8.546 QALYs) for ONM. In sensitivity analysis the two major components that affect the cost-effectiveness ratio of the different types of repair were the ambulatory facility cost and the recurrence rate. At a LR ambulatory facility cost of 5526 dollars the ICER of LR compared to OM surpasses the threshold of 50,000 dollars/QALY. CONCLUSIONS: On the basis of our assumptions this mathematical model shows that from a societal perspective laparoscopic approach can be a cost-effective treatment option for inguinal hernia repair.
Adult↗
Injection of allogeneic bone marrow cells into the portal vein of swine in utero.
The ability to safely manipulate the immune system of the developing fetus carries the hope of effective treatment strategies for certain congenital disorders that can be diagnosed during gestation. One possible intervention is the induction of specific transplantation tolerance to an adult donor who could provide tissue after birth without the need for immunosuppression. Although the introduction of allogeneic stem cells to a developing immune system has been shown to result in hematopoietic chimerism, donor-specific transplantation tolerance has not been demonstrated in a large animal model. In previous reports of in utero stem-cell transplantation, the cells were injected into the fetus by an intraperitoneal route. We sought to improve upon this technique of cell transplantation by developing a method for the safe delivery of allogeneic stem cells directly into the hepatic circulation of fetal swine. In the second phase of our study, we determined if adult allogeneic bone marrow cells delivered to the fetus by this intravascular route could result in result in hematopoietic chimerism and donor-specific transplantation tolerance. A method of successful intravascular injection was designed in which a laparotomy was performed on a sow at midgestation (50-55 days) to administer 1 cc of inoculum into the portal vein of each fetus using transuterine ultrasound guidance and a 25-gauge spinal needle. In one sow, 10 piglets were injected with saline to test safety, and 8 piglets were born. For transplantation of stem cells to the fetuses, donor bone marrow was harvested from a genetically defined miniature swine. In one sow the marrow was injected without T-cell depletion resulting in abortion. In the third sow, the marrow was depleted of T-cells to less than 0.01% using magnetic beads conjugated to anti-CD3 monoclonal antibodies. No chimerism was detected in these offspring. Only in the fourth sow where the T-cell depletion was reduced to about 1% of the cells in the inoculum did one animal demonstrate chimerism. This piglet showed reproducible blood chimerism (0.95% donor cells) detected by flow cytometry measurement of monoclonal antibodies to the donor MHC. In addition, this animal demonstrated hyporesponsiveness to donor lymphocytes in an MLR assay while reacting strongly to third-party stimulator cells. A split-thickness skin graft from the donor was accepted, and a third-party graft was rapidly rejected.
Animals↗
Potential influence of acute CT on inpatient costs in patients with ischemic stroke.
RATIONALE AND OBJECTIVES: Patients presenting with ischemic brain symptoms have widely variable outcomes dependent to some degree on the pathologic basis of their stroke syndrome. The purpose of this study was to determine the cost implications of the emergency use of a computed tomographic (CT) protocol comprising unenhanced CT, head and neck CT angiography, and whole-brain CT perfusion. MATERIALS AND METHODS: By using a retrospective patient database from a tertiary care facility and publicly available cost data, the authors derived the potential savings from the use of CT angiography. CT perfusion, or both at hospital arrival by means of a cost model. The cost of the CT angiography-CT perfusion protocol was determined from Medicare reimbursement rates and compared with that of traditional imaging protocols. Cost savings were estimated as a decrease in the length of stay for most stroke patients, whereas the most benign (lacunar) strokes were assumed to be managed in a non-acute setting. Misdiagnosis cost (erroneously not admitting a patient with nonlacunar stroke) was calculated as the cost of a severe complication. Sensitivity testing included varying the percentage of misdiagnosed patients and admitting patients with lacunar stroke. RESULTS: The nationwide net savings that would result from the adoption of the CT angiography-CT perfusion protocol are in the $1.2 billion range (-$154 million to $2.1 billion) when patients with lacunar strokes are treated nonacutely and $1.8 billion when those patients are admitted for acute care. CONCLUSION: The results demonstrate the potential effect of implementing a CT angiography-CT perfusion protocol. In particular, prompt CT angiography-CT perfusion imaging could have an effect on the cost of acute care in the treatment of stroke.
Cerebral Angiography↗
Inpatient costs of routine endovascular repair of abdominal aortic aneurysm.
RATIONALE AND OBJECTIVES: The purpose of this study was to determine the inpatient cost of routine (ie, without emergent conversion to open repair during the hospital stay) endovascular stent-graft placement in a consecutive series of patients undergoing elective endovascular repair of abdominal aortic aneurysm (AAA) at a single institution. MATERIALS AND METHODS: Inpatient hospital costs of 91 patients who underwent initial elective endovascular repair of AAA were analyzed retrospectively. All patients had participated in clinical trials at the authors' institution during the previous 6 years. Financial data were derived from the hospital's cost-accounting system; additional procedural data were collected from a departmental database and with chart review. Stent-graft and professional costs were excluded. RESULTS: The mean total cost for endovascular repair was $11,842 (standard deviation [SD], $5,127), mean procedure time was 149 minutes (SD, 79 minutes), and mean length of stay was 3.5 days (SD, 2.3 days). Total cost depended on stent-graft type (means, $12,428 [bifurcated] vs $9,622 [tube]; P = .0002) and strongly correlated with procedure time and length of hospital stay (r = 0.78 and 0.66, respectively; P < .0001). Ninety-six percent of total costs for all patients were attributable to the following departments: operating theater (31%), radiology (31%), nursing (22%), and anesthesia (12%). CONCLUSION: Overall costs are greater with bifurcated than with tube stent-grafts. Total procedure-related costs are divided relatively equally between the operating theater, the radiology department, and the combination of the nursing and anesthesia departments.
Aged↗
Endovascular versus open surgical elective repair of infrarenal abdominal aortic aneurysm: predictors of patient discharge destination.
PURPOSE: To evaluate patient discharge destination after elective endovascular or open surgical repair of infrarenal abdominal aortic aneurysm and to determine predictors for discharge to home or to a rehabilitation center. MATERIALS AND METHODS: All patients electively treated for infrarenal abdominal aortic aneurysm with endovascular repair (n = 182) or open surgery (n = 274) between January 1997 and September 1999 were included. From the hospital database, information on discharge destination, patient characteristics, complications, and length of stay was retrieved. Multiple logistic regression analysis was performed to determine predictors for discharge to home or to a rehabilitation center. RESULTS: Patient characteristics did not differ significantly between the treatment groups, with the exception of age (mean age, 75.1 vs 72.9 years in the endovascular and open surgical group, respectively; P =.005). Patient discharge destinations differed significantly between the treatment groups (P =.001). After endovascular procedures, 156 (85.7%) of 182 patients went home and 19 (10.4%) of 182 patients went to a rehabilitation center. After open surgery, 187 (68.2%) of 274 patients went home and 64 (23.4%) of 274 patients went to a rehabilitation center. The odds ratio of discharge to a rehabilitation center, instead of home, following endovascular procedures versus open surgery was 0.23 (95% CI: 0.13, 0.43). CONCLUSION: Following elective repair of infrarenal abdominal aortic aneurysm, significantly more patients went home after an endovascular procedure than after open surgery. Procedure type was a significant predictor of discharge destination.
Aged↗
Percutaneous radio-frequency ablation of hepatic metastases from colorectal cancer: long-term results in 117 patients.
PURPOSE: To describe the results of an ongoing radio-frequency (RF) ablation study in patients with hepatic metastases from colorectal carcinoma. MATERIALS AND METHODS: In 117 patients, 179 metachronous colorectal carcinoma hepatic metastases (0.9-9.6 cm in diameter) were treated with RF ablation by using 17-gauge internally cooled electrodes. Computed tomographic follow-up was performed every 4-6 months. Recurrent tumors were retreated when feasible. Time to new metastases and death for each patient and time to local recurrence for individual lesions were modeled with Kaplan-Meier analysis. Modeling determined the effect of number of metastases on the time to new metastases and death and effect of tumor size on local recurrence. RESULTS: Estimated median survival was 36 months (95% CI; 28, 52 months). Estimated 1, 2, and 3-year survival rates were 93%, 69%, and 46%, respectively. Survival was not significantly related to number of metastases treated. In 77 (66%) of 117 patients, new metastases were observed at follow-up. Estimated median time until new metastases was 12 months (95% CI; 10, 18 months). Percentages of patients with no new metastases after initial treatment at 1 and 2 years were 49% and 35%, respectively. Time to new metastases was not significantly related to number of metastases. Seventy (39%) of 179 lesions developed local recurrence after treatment. Of these, 54 were observed by 6 months and 67 by 1 year. No local recurrence was observed after 18 months. Frequency and time to local recurrence were related to lesion size (P < or =.001). CONCLUSION: RF ablation is an effective method to treat hepatic metastases from colorectal carcinoma.
Adult↗
Pancreatic cancer: cost-effectiveness of imaging technologies for assessing resectability.
PURPOSE: To evaluate the cost-effectiveness of imaging strategies for the assessment of resectability in patients with pancreatic cancer. MATERIALS AND METHODS: A decision model was developed to calculate costs and benefits (survival) accruing to hypothetical cohorts of patients with known or suspected pancreatic cancer. Results are presented as cost per life-year gained under various scenarios and assumptions of diagnostic test characteristics, surgical mortality, disease characteristics, and costs. RESULTS: With best estimates for all data inputs, the strategy of computed tomography (CT) followed by laparoscopy and laparoscopic ultrasonography (US) had an incremental cost-effectiveness ratio of $87,502 per life-year gained, compared with best supportive care. This strategy was significantly more cost-effective than CT followed by magnetic resonance (MR) imaging and was significantly less expensive than other imaging strategies while providing a statistically and clinically insignificant difference in life-year gains. A strategy involving no imaging (immediate surgery) was more expensive but less effective than all imaging strategies. A hypothetical perfect test with cost equal to that of CT followed by MR had an incremental cost-effectiveness ratio of $64,401 per life-year gained, compared to best supportive care. CONCLUSION: Most available imaging tests for assessing resectability of pancreatic cancer do not differ in effectiveness, but a strategy of CT, laparoscopy, and laparoscopic US would consistently result in significantly lower costs than other imaging tests under a wide range of scenarios.
Cost-Benefit Analysis↗
Radio-frequency thermal ablation with NaCl solution injection: effect of electrical conductivity on tissue heating and coagulation-phantom and porcine liver study.
PURPOSE: To characterize the effects of NaCl concentration on tissue electrical conductivity, radio-frequency (RF) deposition, and heating in phantoms and optimize adjunctive NaCl solution injection for RF ablation in an in vivo model. MATERIALS AND METHODS: RF was applied for 12-15 minutes with internally cooled electrodes. For phantom experiments (n = 51), the NaCl concentration in standardized 5% agar was varied (0%-25.0%). A nonlinear simplex optimization strategy was then used in normal porcine liver (n = 44) to determine optimal pre-RF NaCl solution injection parameters (concentration, 0%-38.5%; volume, 0-25 mL). NaCl concentration and tissue conductivity were correlated with RF energy deposition, tissue heating, and induced coagulation. RESULTS: NaCl concentration had significant but nonlinear effects on electrical conductivity, RF deposition, and heating of agar phantoms (P<.01). Progressively greater heating was observed to 5.0% NaCl, with reduced temperatures at higher concentrations. For in vivo liver, NaCl solution volume and concentration significantly influenced both tissue heating and coagulation (P<.001). Maximum heating 20 mm from the electrode (102.9 degrees C +/- 4.3 [SD]) and coagulation (7.1 cm +/- 1.1) occurred with injection of 6 mL of 38.5% (saturated) NaCl solution. CONCLUSION: Injection of NaCl solution before RF ablation can increase energy deposition, tissue heating, and induced coagulation, which will likely benefit clinical RF ablation. In normal well-perfused liver, maximum coagulation (7.0 cm) occurs with injection of small volumes of saturated NaCl solution.
Animals↗
Cost-effectiveness of colorectal cancer screening.
PURPOSE: To determine the most cost-effective colorectal cancer screening strategy costing less than $100,000 per life-year saved and to determine how available strategies compare with each other. MATERIALS AND METHODS: Standardized methods were used to calculate incremental cost-effectiveness ratios (ICERs) from published estimates of cost and effectiveness of colorectal cancer screening strategies, and the direction and magnitude of any effect on the ratio from parameter estimate adjustments based on literature values were estimated. RESULTS: Strategies in which double-contrast barium enema examination was performed emerged as optimal from all studies included. In average-risk individuals, screening with double-contrast barium enema examination every 3 years, or every 5 years with annual fecal occult blood testing, had an ICER of less than $55,600 per life-year saved. However, double-contrast barium enema examination screening every 3 years plus annual fecal occult blood testing had an ICER of more than $100,000 per life-year saved. Colonoscopic screening had an ICER of more than $100,000 per life-year saved, was dominated by other screening strategies, and offered less benefit than did double-contrast barium enema examination screening. CONCLUSION: Double-contrast barium enema examination can be a cost-effective component of colorectal cancer screening, but further modeling efforts are necessary.
Barium Sulfate↗
Percutaneous radio-frequency ablation of liver metastases from breast cancer: initial experience in 24 patients.
PURPOSE: To evaluate the authors' initial experience in a consecutive series of 24 patients with breast cancer liver metastases treated with radio-frequency (RF) ablation. MATERIALS AND METHODS: Twenty-four consecutive patients with 64 metastases measuring 1.0--6.6 cm in diameter (mean, 1.9 cm) underwent ultrasonography-guided percutaneous RF ablation with 18-gauge, internally cooled electrodes. Treatment was performed with the patient under conscious sedation and analgesia or general anesthesia. A single lesion was treated in 16 patients, and multiple lesions were treated in eight patients. Follow-up with serial computed tomography ranged from 4 to 44 months (mean, 10 months; median, 19 months). RESULTS: Complete necrosis was achieved in 59 (92%) of 64 lesions. Among the 59 lesions, complete necrosis required a single treatment session in 58 lesions (92%) and two treatment sessions in one lesion (2%). In 14 (58%) of 24 patients, new metastases developed during follow-up. Ten (71%) of these 14 patients developed new liver metastases. Currently, 10 (63%) of 16 patients whose lesions were initially confined to the liver are free of disease. One patient died of progressive brain metastases. No major complications occurred. Two minor complications were observed. CONCLUSION: On the basis of preliminary study results, percutaneous RF ablation appears to be a simple, safe, and effective treatment for focal liver metastases in selected patients with breast cancer.
Adult↗
Hospital costs for elective endovascular and surgical repairs of infrarenal abdominal aortic aneurysms.
PURPOSE: To determine and compare the average in-hospital costs of elective open surgical and endovascular repairs of infrarenal abdominal aortic aneurysms. MATERIALS AND METHODS: Total actual cost data for patients undergoing elective endovascular (n = 181) or open surgical (n = 273) repair of abdominal aortic aneurysms between 1997 and 1999 were retrieved. The mean total hospital cost (including stent-graft costs and excluding attending physician fees) and mean postoperative length of stay were calculated for each treatment group. Costs were expressed in 1999 U.S. dollars. RESULTS: Endovascular repair yielded a shorter postoperative length of stay than did open surgery (mean stay, 3.4 vs 8.0 days; P <.001) and a lower proportion of patients who were admitted to the intensive care unit for 1 full day or longer (2.8% vs 36.3%; P <.001). The mean total hospital cost was significantly higher for endovascular repair than for open surgery ($20,716 vs $18,484; P <.001). CONCLUSION: Hospital costs were higher for endovascular repair than for open surgical repair. However, endovascular repair was associated with a decreased length of stay and fewer intensive care unit admissions. The increased mean hospital cost for endovascular repair was smaller than one would expect, considering the higher costs of endovascular grafts, as compared with those for surgical grafts (approximately $6,400 according to literature data).
Aortic Aneurysm, Abdominal↗
CT colonography with teleradiology: effect of lossy wavelet compression on polyp detection--initial observations.
PURPOSE: To assess the consequences of lossy compression on the diagnostic accuracy of CT colonography for detecting colonic polyps. MATERIALS AND METHODS: Helical CT images of cleansed colonic segments were evaluated. Source images were compressed to 1:1, 10:1, and 20:1 ratios with lossy wavelet compression. Two independent readers blinded to corresponding colonoscopic results analyzed 144 randomly ordered colonic segments in multiplanar and volume-rendered endoscopic views. Sensitivity, specificity, and receiver operating characteristic curves were generated for each compression ratio on the basis of expressed confidence in lesion presence. Similar analyses were performed to assess distention and bowel preparation adequacy and evaluation time required. RESULTS: Results based on video colonoscopy-confirmed lesions revealed 100% (four of four) sensitivity for lesions larger than 10 mm for compression ratios 1:1, 10:1, and 20:1 for both readers; sensitivities for all lesions smaller than 10 mm were 50%-78%, 38%-67%, and 38%-67% for respective ratios for both readers. Differences in diagnostic performance for each reader across ratios were not significant (P =.30-.99, McNemar test). The time required to evaluate and assess bowel preparation and distention adequacy did not change significantly across ratios. CONCLUSION: On the basis of the patient sample, lossy compression of transverse source images to at least a 20:1 ratio did not adversely affect diagnostic performance or evaluation time for CT colonography.
Aged↗
Percutaneous tumor ablation: increased necrosis with combined radio-frequency ablation and intratumoral doxorubicin injection in a rat breast tumor model.
PURPOSE: To determine whether a combination of intratumoral doxorubicin injection and radio-frequency (RF) ablation increases tumor destruction compared with RF ablation alone in an animal tumor model. MATERIALS AND METHODS: R3230 mammary adenocarcinoma 1.2-1.5-cm- diameter nodules (n = 110) were implanted subcutaneously in 84 female Fischer rats. For initial experiments (n = 46), tumors were treated with (a) conventional, monopolar RF (250 mA +/- 25 [SD] at 70 degrees C +/- 1 for 5 minutes) ablation alone; (b) direct intratumoral doxorubicin injection (volume, 250 microL; total dose, 0.5 mg) alone; (c) combined therapy (doxorubicin injection immediately followed by RF ablation); (d) RF ablation and injection of 250 microL of distilled water; or (e) no treatment. In subsequent experiments, amount of doxorubicin (0.02-2.50 mg; n = 40 additional tumors) and timing of doxorubicin administration (2 days before to 2 days after RF ablation; n = 24 more tumors) were varied. Pathologic examination, including staining for mitochondrial enzyme activity and perfusion, was performed, and the resultant tumor destruction from each treatment was evaluated. RESULTS: Coagulation diameter was 6.7 mm +/- 0.6 for tumors treated with RF ablation alone and 6.9 mm +/- 0.7 for those treated with RF ablation and water (P =.52), while intratumoral doxorubicin injection alone produced only 2.0-3.0 mm of coagulation (P <.001). Increased coagulation was observed only with combined doxorubicin injection and RF therapy (P <.001). Coagulation was dependent on concentration and timing of doxorubicin administration, with greatest coagulation (11.5 mm +/- 1.1) observed for doxorubicin administered within 30 minutes of RF ablation. CONCLUSION: Adjuvant intratumoral doxorubicin injection increases coagulation in solid tumors compared with RF ablation alone. Increased tumor destruction is also seen when doxorubicin is administered after RF ablation, which suggests that RF ablation may sensitize tumors to chemotherapy. Such combination therapies may, therefore, offer improved methods for ablating solid tumors.
Adenocarcinoma↗
Treatment of intrahepatic malignancy with radiofrequency ablation: radiologic-pathologic correlation.
BACKGROUND: Radiofrequency (RF)-induced tissue coagulation represents a new approach for the thermal destruction of tumors within the liver. The purpose of the current study was to 1) assess technique safety; 2) determine the extent and evolution of induced cellular damage; and 3) correlate the observed pathologic effects with radiologic studies. METHODS: Twenty-three tumors measuring </= 8 cm (19 colorectal metastases and 4 hepatomas) in 22 patients were treated with RF (range, 500-1550 milliamperes) using internally cooled electrodes. All treated tumors were resected to allow pathologic analysis. Eleven tumors were treated intraoperatively under ultrasonographic guidance and excised immediately. Twelve tumors were treated percutaneously using ultrasound or computed tomography (CT) guidance and subsequently were excised 3-7 days after ablation. Contrast-enhanced CT (n = 12) and magnetic resonance imaging (MRI) (n = 2) were performed after ablation of all percutaneously treated patients. RESULTS: Tumors treated intraoperatively did not demonstrate definitive coagulative necrosis. However, pathologic abnormalities suggestive of tissue injury were observed with hematoxylin and eosin staining, and absent cytosolic and mitochondrial enzyme activity suggested irreversible cellular damage. In contrast, specimens removed > 3 days after ablation showed definite, contiguous coagulative necrosis without intervening areas of viable tumor. CT and MRI scans demonstrated circumscribed hypodense, nonenhancing regions surrounding the electrode tract as early as 15 minutes after ablation. These corresponded within 2 mm to measurements of coagulation at pathology. CONCLUSIONS: RF ablation is a minimally invasive and safe approach to the treatment of tumors in the liver. Tumors treated with RF energy do not immediately demonstrate coagulative necrosis, but do show evidence of irreversible cellular damage. The extent of tumor necrosis correlates closely with findings at contrast-enhanced imaging.
Aged↗
Variables affecting proper system grounding for radiofrequency ablation in an animal model.
PURPOSE: The authors sought to determine which factors contribute to excessive thermal deposition and burns at the grounding pad site after high-current percutaneous, image-guided radiofrequency (RF) ablation. MATERIALS AND METHODS: Radiofrequency (1,000-2,000 mA) was applied for 10 minutes with use of an internally-cooled electrode placed into in vivo pig livers (n = 88). In separate experiments, the number of pads (1, 2, or 4), orientation of pads (horizontal, vertical, or diagonal), and distance between the pads and the electrode (10-50 cm) of mesh or foil grounding pads (12.5 x 8 cm; 100 cm2) were varied. Thermistors measured skin surface temperatures during ablation. Pathologic analysis of skin changes was performed. RESULTS: Temperature elevations at the grounding pad were observed for every trial, with a temperature elevation > or =12 degrees C (as high as 45 degrees C) observed in 60 of 88 trials (68.2%). Temperatures at the grounding site pad were dependent on all variables studied, including the grounding pad surface area, the amount of current deposited in the liver, the orientation of the pad, and the pad's distance from the electrode. Second-degree burns were seen with temperatures exceeding 47 degrees C and third-degree burns were observed when a temperature > or = 52 degrees C was noted. For a given set of RF parameters, reduced heating was observed for trials in which foil grounding pads were used (P < .001). Grounding pad burns did not occur at 2,000 mA (maximum generator output) when four foil pads were placed horizontally > or = 25 cm from the electrode. CONCLUSIONS: High-current RF ablation can induce severe burns at the grounding pad site if inadequate precautions are taken. To minimize the risk of burns, multiple large-surface-area foil pads should be placed on well-prepared skin and oriented with the longest surface edge facing the RF electrode.
Analysis of Variance↗
The case for colorectal cancer screening.
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Colorectal Neoplasms↗