Reproducibility of noninvasive baroreceptor sensitivity measurement.
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Female↗
Biomedical subjects
S L Dawson
Publications and source records attributed to S L Dawson.
The reproducibility of cardiac baroreceptor activity assessed non-invasively by spectral sequence techniques.
Baroreceptor sensitivity (BRS) is increasingly used as a prognostic indicator in cardiovascular disease. Traditionally it has been measured using invasive techniques with pharmacological manipulation of blood pressure (BP). With the advent of newer methods to measure pulse interval and beat-to-beat changes in BP it is now possible, using sophisticated mathematical modelling techniques, to calculate cardiac BRS non-invasively. However, there are virtually no data on the reproducibility of these newer techniques and what factors may affect the repeatability of these measurements. We studied 39 subjects, aged 22-82 years, with a supine systolic BP range 97-160 mmHg and a diastolic BP range 57-94 mmHg on two occasions between 1 week and 6 months apart. Cardiac BRS was measured by power spectral analysis using Fast Fourier Transformation (FFT), sequence analysis (using up, down and combined sequences) and from phase IV of the Valsalva manoeuvre. There was no significant difference between visits for any of the methods for measuring cardiac BRS. Mean BRS values were similar for FFT (16.7 +/- 11.2 ms/mmHg) and sequence analysis (15.8 +/- 11.4 ms/mmHg); however, results using phase IV of the Valsalva manoeuvre were significantly lower (8.1 +/- 2.9 ms/mmHg, p < 0.0001). The coefficient of variation for the five measures of cardiac BRS varied from 16.8% for Valsalva-derived values to 26.1% for 'down' sequence analysis. However, in ten subjects BRS could not be calculated from the Valsalva manoeuvre. None of the independent variables tested (including age, BP levels and time between testing) significantly influenced the degree of repeatability. In summary, there appears to be little difference between these non-invasive methods in their degree of reproducibility. These techniques would seem suitable for longitudinal studies of changes in cardiac BRS and overcome many of the problems associated with the invasive pharmacological methods.
Adult↗
Attenuation effects of biliary endoprostheses on therapeutic radiation.
Seven commercially available biliary stents were tested to determine if they caused any clinically important attenuation of therapeutic radiation. Attenuation effects were evaluated in models of brachytherapy (iridium-192 source) and external beam radiation therapy (cobalt-60 source), with use of parameters that mimicked those used in patient treatment for biliary neoplasms. No stent demonstrated clinically important attenuation or scatter of therapeutic radiation, so local dosimetry was not affected.
Bile Duct Neoplasms↗
Evaluation of the abdomen in sepsis of unknown origin.
The radiologic evaluation of sepsis of unknown origin has changed dramatically since the introduction of cross-sectional imaging. Interventional procedures such as abscess drainage, cholecystostomy, biliary drainage, nephrostomy, and fluid aspiration have reduced the morbidity and mortality associated with occult sources of sepsis. This article examines some of the common etiologies and treatments of sepsis in the hospitalized patient.
Abdominal Abscess↗
Tissue ablation with radiofrequency: effect of probe size, gauge, duration, and temperature on lesion volume.
RATIONALE AND OBJECTIVES: We evaluated the parameters affecting the size and distribution of thermal tissue damage produced by radiofrequency electrodes. METHODS: Thermal lesions were produced by electrodes connected to a radiofrequency generator in specimens of liver (n = 143) and muscle (n = 20). Various combinations of probe tip exposure (0.5-8 cm), gauge (12-24 gauge), duration of treatment (0.5-12 min), and temperature (80-90 degrees C) were studied. The resulting volumes of tissue coagulation were measured and compared. RESULTS: Lesions equal to or less than 1.6 cm in diameter were symmetrically distributed around the electrode. Lesion diameter (but not length) increased with probe gauge and duration of treatment to a maximum of 6 min. However, lesions with mean diameters larger than 1.6 cm could not be produced using a single probe with any technique. Lesion length correlated with probe tip exposure from 1 to 8 cm (r2 = .996). Over the limited range investigated, increased temperature had minimal effects, except for tip exposures greater than 5 cm, in which larger and more uniform lesions resulted. Lesions varied equal to or less than 3 mm in diameter and equal to or less than 5 mm in length for each combination of variables. CONCLUSION: Radiofrequency ablation can accurately and reproducibly cause coagulative tissue necrosis. Necrosed tissue volume increases with length of exposed probe tip, larger probes, and sessions lasting at least 6 min.
Animals↗
Percutaneous ethanol injection for the treatment of hepatic tumors: indications, mechanism of action, technique, and efficacy.
Percutaneous injection of ethanol for treatment of hepatic tumors was first described by Sugiura et al. [1] in 1983. To date, reported experience with the procedure has focused mainly on therapy of hepatocellular carcinoma (HCC) [2-15], with little information available regarding its use in treating metastatic liver lesions [16]. Interest in this technique has grown recently as a possible means of treating patients with metastatic liver disease. The purpose of this perspective is to review the indications, mechanism of action, technique, complications, and efficacy of percutaneous ethanol injection for liver tumor treatment.
Carcinoma, Hepatocellular↗
Percutaneous drainage of subphrenic fluid collections that occur after splenectomy: efficacy and safety of transpleural versus extrapleural approach.
OBJECTIVE: The purpose of this study was to compare the safety and efficacy of transpleural and extrapleural approaches for draining left subphrenic abscesses in patients who have had splenectomy. MATERIALS AND METHODS: Twenty-five patients who had percutaneous catheter drainage (28 drainages) of postsplenectomy fluid collections were studied. Twenty drainages were transpleural and eight were extrapleural. In eight of the 20 transpleural drainages, it was elected to place the catheter transpleurally. In the remaining 12 patients, catheter drainage was judged to be transpleural on review, despite efforts to use an extrapleural approach. RESULTS: Sixteen of 18 patients who had transpleural percutaneous drainage and six of seven patients who had true extrapleural (subcostal) percutaneous drainage were cured by catheter drainage requiring no further intervention. The mean number of days of drainage was not significantly different (p > .05) for the group drained transpleurally (mean, 18 days; range, 1-90 days) versus the group drained extrapleurally (mean, 20 days; range, 6-43 days). Complications (pneumothorax) requiring treatment were seen in two patients in whom a transpleural approach was used and in none of the patients in whom an extrapleural approach was used. Complications that did not require treatment were seen in four further patients drained transpleurally. These were inadvertent placement of catheter into pleural space (two patients) and pneumothorax not requiring treatment (two patients). No patient had an empyema. CONCLUSION: Transpleural drainage of left subphrenic collections occurring after splenectomy is associated with a slightly increased complication rate but has a success rate similar to that of extrapleural drainage.
Adult↗
Tissue ablation with radiofrequency using multiprobe arrays.
RATIONALE AND OBJECTIVES: We studied the feasibility of increasing the volume of tissue destroyed by radiofrequency tissue coagulation using multiprobe arrays and defined parameters that determine lesion size and shape. METHODS: Radiofrequency was applied to ex vivo calf liver using arrays of two to five 18-gauge probes for 6 min at 70-90 degrees C. Probe spacing (1-3 cm) and arrangement, as well as the method of radiofrequency application (simultaneous or sequential), were varied. The resulting areas of tissue coagulation were measured and compared. RESULTS: Uniform tissue necrosis was observed with simultaneous radiofrequency application for probes 1.5 cm or less apart. At 1.5 cm, arrays of three equidistant probes produced spheroid lesions approximately 3.0 +/- 0.2 cm in diameter. Arrays of four equidistant probes produced cuboid lesions of 3.2 +/- 0.1 cm per side. However, probes placed 2 cm or more apart produced independent lesions 1.4 cm in diameter, with incomplete necrosis between probes. In the trials using five-probe arrays, a central region 4mm in diameter showed no visible evidence of tissue necrosis. With each array, lesion size varied less than 3 mm in any direction. Greater necrosis was accomplished when radiofrequency was applied simultaneously rather than sequentially. CONCLUSION: Multiprobe radiofrequency arrays permit the destruction of more tissue in a single treatment session than is possible with multiple individual probes operating alone. Probes spaced 1.5 cm or less apart act synergistically, producing a total volume of coagulated tissue that is greater than when the individual probes are operated sequentially.
Animals↗
Failed metallic biliary stents: causes and management of delayed complications.
OBJECTIVE: To describe the incidence, management and long-term outcome of metal stent failure in patients with malignant biliary obstruction. SUBJECTS AND METHODS: Sixty-nine patients received a total of 93 metallic biliary stents for relief of malignant biliary obstruction. Twenty-nine patients had hilar tumours; 40 had common bile duct tumours. RESULTS: Ten of 69 patients (14%) presented with stent occlusion at a mean interval of 4 months after stent insertion. Five of 29 patients (17%) with hilar lesions and five of 40 patients (12%) with common bile duct lesions had stent occlusion. Occlusion was due to tumour overgrowth in eight patients and to occlusion by debris in two. The eight patients with tumour overgrowth were treated with internal/external catheters (5 patients), no therapy (2 patients), and further metal stents (1 patient). These eight patients with tumour overgrowth had a limited lifespan after tumour overgrowth occurred with a mean survival of 2.6 months. The two patients with occlusion due to debris were treated by sweeping the stent with a balloon catheter and these patients survived 26 and 27 months, respectively. CONCLUSION: Adequate peripheral purchase in the biliary tree and overstenting are necessary to prevent tumour overgrowth when stenting hilar lesions. The development of stent occlusion due to tumour overgrowth heralds a limited survival and internal/external catheters are preferred over further metal stents for palliation.
Adult↗
Pleural seeding from hepatocellular carcinoma: a complication of percutaneous alcohol ablation.
The authors present a case of proved seeding of the pleural space secondary to alcohol ablation of a primary hepatocellular carcinoma. The patient underwent alcohol ablation for a 6.5-cm-diameter tumor in the right lobe of the liver; approximately 20 needle punctures were required to ensure complete or almost complete destruction of the tumor. Six months after the original ablation, a hypervascular pleural metastasis was noted adjacent to the original lesion at computed tomography. Percutaneous biopsy of the pleural lesion showed hepatocellular carcinoma.
Carcinoma, Hepatocellular↗
Gallstones in critically ill patients with acute calculous cholecystitis treated by percutaneous cholecystostomy: nonsurgical therapeutic options.
OBJECTIVE: Patients with acute calculous cholecystitis require removal of gallstones (generally cholecystectomy), as acute cholecystitis is likely to recur if gallstones are left in situ. The purpose of this study was to assess the role of nonsurgical techniques for treating gallstones in critically ill patients with acute calculous cholecystitis managed by percutaneous cholecystostomy. MATERIALS AND METHODS: Twenty-six critically ill patients with complex medical and surgical problems who were in intensive care units underwent emergent percutaneous cholecystostomy for acute calculous cholecystitis. Seven of the 26 patients subsequently died of multiple organ failure. Curative gallstone therapies were tried in the surviving 19 patients, seven of whom underwent elective surgical cholecystectomy. Nonsurgical management was attempted in 12 of 19 patients, including six with terminal disease who were treated with long-term gallbladder drainage, three who were treated with methyl tert-butyl ether for stone dissolution, two who had percutaneous cholecystolithotomy, and one who had a gallbladder stone that had passed into the common bile duct and was retrieved endoscopically. RESULTS: Long-term gallbladder drainage was successful in all six patients with terminal disease in whom it was attempted; they experienced no further episodes of cholecystitis. In four of the other six patients treated with nonsurgical therapies (percutaneous cholecystolithotomy, stone dissolution with methyl tert-butyl ether, and endoscopic removal), gallstones were successfully removed and no further therapy was required. Percutaneous therapies failed in two patients, who then had cholecystectomy. CONCLUSION: Nonsurgical gallstone therapies should be attempted in high-risk patients with acute calculous cholecystitis. Some patients may benefit from long-term catheter drainage of the gallbladder.
Acute Disease↗
Interventional radiology in the management of bile duct injuries.
The advent of laparoscopic cholecystectomy has brought an increased number of bile duct injuries to the attention of surgeons and interventional radiologists. The spectrum of injury ranges from cystic duct stump leakage to partial obstruction to complete occlusion of the ducts and common hepatic or common bile duct ischemic strictures. The proper therapy for any given patient may be surgical or nonsurgical. Frequently, interventional radiologic techniques permit successful nonoperative drainage of postoperative fluid collections and percutaneous management of bile duct injury and stricture. In some patients in whom radiologic techniques are not successful or in whom the extent of injury requires surgical repair, interventional radiologic techniques can provide preoperative anatomic definition of the extent of injury as well as catheter localization of intrahepatic duct strictures before proximal hepaticojejunostomy.
Bile Ducts↗
Case report: combined conservative and percutaneous management of a perforated duodenal ulcer.
A case is presented of perforated duodenal ulcer with associated abscesses treated by percutaneous drainage in a patient with markedly impaired respiratory function. The potential role of conservative management in such patients is discussed.
Aged↗
Percutaneous management of hilar biliary malignancies with metallic endoprostheses: results, technical problems, and causes of failure.
Malignant obstruction at the biliary hilum is a challenging problem for percutaneous management because of the anatomy of the biliary hilum, which facilitates spread of tumor into multiple biliary radicles. Metallic self-expanding stents were used in 22 patients with hilar malignancies. Sixteen patients had focal common hepatic duct strictures, and six had multisegmental disease. Stents were placed in the biliary system with a single transhepatic approach in 16 patients with common hepatic duct strictures; stent placement in the right and left biliary ducts was performed with a bilateral transhepatic approach in five patients and with a single transhepatic approach in one patient. Metal stent occlusion occurred in six patients (27%) at a mean of 2.5 months after initial insertion. Stent occlusion was due to inspissated debris in two of these patients and to tumor overgrowth in four. The key to successful long-term treatment is to "overstent" to ensure adequate purchase above hilar tumors and insertion in a balanced position. Thus, the prevalence of tumor overgrowth is decreased.
Bile Duct Neoplasms↗
Fine-needle biopsy: prospective comparison of aspiration versus nonaspiration techniques in the abdomen.
A prospective study was designed to compare the aspiration (suction method) and nonaspiration (nonsuction method) techniques of fine-needle biopsy (FNB) in 50 consecutive patients with abdominal pathologic conditions. Sites of biopsy included liver (n = 24), retroperitoneum (n = 9), adrenal gland (n = 5), pancreas (n = 4), omentum (n = 4), and miscellaneous sites (n = 4). Aspiration and nonaspiration FNBs were performed in each lesion with 22-gauge needles, and results were interpreted by a single cytopathologist. Cytologic specimens obtained with each technique were analyzed for diagnostic accuracy, total number of cell clusters per biopsy (graded 0-10, 10-20, 20-30, and > 30), presence of crush artifact, and amount of blood present (graded from 0 to +3). No significant differences were seen between the aspiration and nonaspiration techniques with regard to number of cell clusters per biopsy (44 of 50 specimens vs 42 of 50) (P < .0003), amount of blood present (grade 2.3 vs 2.2) (P < .0003), and amount of crush artifact. The positive predictive value for the aspiration technique was 91.5% versus 74% for the nonaspiration technique. The aspiration technique of FNB appears superior to the nonaspiration technique in the abdomen.
Abdomen↗
Gastrostomy conversion to transgastric jejunostomy: technical problems, causes of failure, and proposed solutions in 63 patients.
Sixty-three radiologically guided conversions of gastrostomy to transgastric jejunostomy performed over a 4-year period were reviewed. Conversions succeeded in 31 of 38 surgically placed gastrostomies (82%), in 14 of 18 endoscopically placed gastrostomies (78%), and in seven of seven radiologically placed gastrostomies, for an overall success rate of 83%. Almost all failures (10 of 11 gastrostomies) were primarily the result of unfavorable fundal angulation of the surgical or endoscopic tract; unfavorable angulation was also the most common technical problem encountered in the successful conversions. Of the 52 successful conversions, 23 (44%) necessitated tube replacement: eight for spontaneous proximal migration of the tube, 11 for accidental tube dislodgment, and four for tube blockage. While most gastrostomy to transgastric jejunostomy conversions are simple to perform, in many cases the unfavorable angle of the original transcutaneous tract precludes jejunal intubation and may be a cause for early recoil of a successfully placed jejunal catheter back into the stomach. With early recognition of an unfavorable tract, a fresh transgastric jejunostomy through a new, properly angled puncture may be the preferred approach.
Adolescent↗
Fine-needle biopsy of cervical lymph nodes in patients with thyroid cancer: a prospective comparison of cytopathologic and tissue marker analysis.
Tissue levels of thyroglobulin (Tg) or calcitonin were compared with specimens from neck lymph node biopsy in patients with suspected recurrent differentiated (papillary or follicular) or medullary thyroid cancer. Thirty-six neck lymph node biopsies were performed in 29 patients. Tissue Tg levels were obtained from 31 specimens from patients with differentiated thyroid cancers, and tissue calcitonin levels were obtained from five specimens from patients with medullary cancer. Thirteen nodes were diagnosed as negative for cancer at surgery (n = 3) or follow-up sonography (n = 10). Malignant disease was confirmed at surgery in 23 of the 36 lymph nodes. Cytopathologic examination had a sensitivity of 91% and a specificity of 100%. Tissue Tg levels ranged from 0 to 3.5 ng/mL (mean, 1.5 ng/mL; median, 1.2 ng/mL) in 12 of the 13 benign lymph nodes and from 21 to 247,500 ng/mL (mean, 30,600 ng/mL; median, 2,330 ng/mL) in the 23 malignant nodes. Tissue calcitonin levels were elevated (range, 850-703,125 pg/mL; mean, 184,762 pg/mL; median, 17,538 pg/mL) in four malignant nodes and were normal (3.0 pg/mL) in one benign node. Diagnostic sensitivity of tissue markers was 91%. Specificity was 91%. The combined diagnostic sensitivity and specificity of tissue marker analysis and cytopathologic examination was 100%.
Adenocarcinoma↗
Percutaneous cholecystostomy for acute acalculous cholecystitis in a critically ill patient.
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Acute Disease↗