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Biomedical subjects

Mark E Baker

Publications and source records attributed to Mark E Baker.

12 recordsLinked to original sources
PubMed2006

The long-term efficacy of pneumatic dilatation and Heller myotomy for the treatment of achalasia.

BACKGROUND & AIMS: Studies comparing long-term success after pneumatic dilatation (PD) and laparoscopic Heller myotomy (HM) are lacking. This study compares long-term outcome of PD (single dilatation and graded approach) and laparoscopic HM and identifies risk factors for treatment failure. METHODS: A cross-sectional follow-up evaluation of an achalasia cohort treated between 1994 and 2002 was followed-up for a mean of 3.1 years. There was a total of 106 patients treated by graded PD (1-3 dilatations with progressively larger balloons) and 73 patients treated by HM (20 had failed graded PD and crossed over to HM). A symptom assessment (structured telephone interview or clinic visit) was performed and patients were given freedom from alternative therapies to determine treatment outcome. Endoscopy, manometry, and timed barium esophagram were performed to determine the cause of treatment failure. RESULTS: The success of single PD was defined as freedom from additional PDs: 62% at 6 months and 28% at 6 years (risk factors for failure: younger age, male sex, wider esophagus, and poor emptying on posttreatment timed barium esophagram). Freedom from subsequent PDs increased with each dilatation (graded PD). The success of graded PD and HM, defined as dysphagia/regurgitation less than 3 times/wk or freedom from alternative treatment, was similar: 90% vs 89% at 6 months and 44% vs 57% at 6 years (no risk factors for failure were identified). Causes of symptom recurrence were incompletely treated achalasia (96% after PD vs 64% after HM) and gastroesophageal reflux disease (4% after PD vs 36% after HM). CONCLUSIONS: No treatment cures achalasia. Short- and long-term success is similar for graded PD and laparoscopic HM. Therapeutic success decreases steadily over time. Achalasia patients need careful long-term follow-up evaluation.

Adult↗
PubMed2006

Colonic abnormalities on CT in adult hospitalized patients with Clostridium difficile colitis: prevalence and significance of findings.

OBJECTIVE: The purpose of this study was to determine the prevalence of an abnormal colon on CT in adult inpatients with Clostridium difficile colitis, compare the clinical presentation of these patients, and determine whether CT findings predicted the need for surgical treatment. MATERIALS AND METHODS: Over a 21-month period, 152 of 572 inpatients with C. difficile colitis were identified and had CT scans performed within 2 weeks of the diagnosis. These were independently and retrospectively reviewed by two reviewers. Those with colonic wall thickness greater than 4 mm were considered positive (CT-positive patients) and were further reviewed for specific findings in the colon. All 152 patients with CT scans were also retrospectively reviewed using the hospital information system for certain clinical parameters, admitting diagnoses, and reasons for scanning. The following were compared using several statistical tests: clinical parameters in CT-positive and CT-negative patients and surgical and nonsurgical groups to determine if positive scans or surgical treatment could be clinically predicted; specific CT findings in CT-positive patients to see if an association was found with clinical parameters or surgical treatment; and admitting diagnoses and reasons for scanning in scanned and unscanned populations to see which patients were more likely to undergo CT. RESULTS: Seventy-six (50%) of 152 scanned hospitalized patients with C. difficile colitis were CT-positive. These patients most often had segmental involvement (50 [66%] of 76 patients), with the rectum (60 [82%] of 73 patients) and sigmoid colon (61 [82%] of 74 patients) most often affected. Positive scans were associated with increased WBC, abdominal pain, and diarrhea. Patients with signs and symptoms of infection or abdominal complaints were more likely to be scanned. No statistical correlation was found between specific CT findings and clinical parameters or clinical parameters and patients requiring surgery. There was no predictive value of specific CT findings for surgical treatment. CONCLUSION: Half of the patients scanned had an abnormal CT, with segmental colonic disease more common than diffuse. Positive scans were more likely in patients with leukocytosis, abdominal pain, and fever. Specific CT findings did not correlate with clinical parameters and could not predict surgical treatment.

Adult↗
PubMed2005

A physiologic clinical study of achalasia: should Dor fundoplication be added to Heller myotomy?

OBJECTIVE: Myotomy for achalasia disrupts the lower esophageal sphincter, improving emptying at the expense of reflux. We hypothesized that surgical palliation of achalasia requires balancing desirable improvement in esophageal emptying with undesirable production of gastroesophageal reflux. Therefore, we objectively studied the physiologic effects of adding Dor fundoplication to Heller myotomy. METHODS: From December 1996 to June 2004, 149 patients underwent Heller myotomy; 88 (59%) had additional Dor fundoplication. The adequacy of myotomy was assessed by premyotomy to postmyotomy change in lower esophageal sphincter pressures, esophageal emptying by change in timed barium esophagram, and gastroesophageal reflux by postoperative 24-hour pH monitoring. RESULTS: For adequacy of myotomy, postmyotomy resting lower esophageal sphincter pressure was higher with (median, 18 mm Hg) than without (median, 13 mm Hg) Dor fundoplication (P = .002), as was residual lower esophageal sphincter pressure (median, 4.6 vs 1.8 mm Hg; P = .01). For esophageal emptying, postmyotomy barium height and width were similar with or without Dor fundoplication (P > .1). For gastroesophageal reflux, percentage of upright time with a pH of less than 4 was lower with (median, 0.4%) than without (median, 2.9%) Dor fundoplication (P = .005), and percentage of supine time with a pH of less than 4 was lower with (median, 0%) than without (median, 5.8%) Dor fundoplication (P = .007). CONCLUSIONS: The addition of Dor fundoplication reduces the adequacy of myotomy without impairing emptying and reduces reflux. Heller myotomy and Dor fundoplication balance emptying and reflux and therefore should be the surgical treatment of choice for achalasia.

Digestive System Surgical Procedures↗
PubMed2005

Phenotypic identification of Candida albicans by growth on chocolate agar.

In this study, we describe a simple method for the identification of Candida albicans in clinical samples. A total of 383 clinical isolates of Candida species were streaked onto chocolate agar and incubated for 48 h at 37 degrees C in the presence of an atmosphere of 6% CO2. All 208 of the C. albicans isolates tested, developed an easy to identify filamentous colony morphology. Of 175 other Candida species tested, 172 (98.3%) were distinguishable from C. albicans by their smooth colony morphology. Three isolates (1.7%) exhibited weak filamentation after prolonged incubation. Although not a routine medium in medical mycology a significant advantage of using chocolate agar lies in its use in clinical bacteriology laboratories for the isolation of fastidious bacteria. Implementation of the proposed method is applicable across a range of specimen types, thus allowing the direct identification of C. albicans in clinical samples. This simple method may allow a quicker entry into directed treatment.

Candida albicans↗
PubMed2005

Recognizing and managing acute diverticulitis for the internist.

Colonic diverticulitis can present as mild abdominal discomfort or as life-threatening septic shock and can also mimic many inflammatory conditions. Most patients with acute diverticulitis can be managed with antibiotics and supportive care. Surgery is reserved for those with repeat attacks, disease unresponsive to medical therapy, certain complications, and the possibility of colon cancer that cannot otherwise be excluded.

Acute Disease↗
PubMed2004

Analysis of changes in attenuation of proven renal cysts on different scanning phases of triphasic MDCT.

OBJECTIVE: The purpose of this study is to document changes in attenuation values on triphasic MDCT of histologically or surgically proven cystic renal lesions. MATERIALS AND METHODS: A retrospective study of all renal lesions greater than 1 cm that underwent triphasic MDCT was performed in 90 patients before partial nephrectomy. Three reviewers independently measured the mean attenuation of all lesions in three phases (unenhanced, corticomedullary, and parenchymal) in a blinded retrospective fashion. Forty-three lesions identified at CT in 27 patients had pathologic or surgical confirmation as cysts (fluid-filled lesions). Mean change in attenuation between phases was calculated and correlated with size, unenhanced density, and percentage of the lesion exophytic from renal parenchyma. All scans were obtained after 150 mL of nonionic contrast material was injected at 3 mL/sec. Scanning delays were 30-40 sec (corticomedullary phase) and 120 sec (parenchymal phase). RESULTS: The mean change in attenuation coefficient of the cysts from the unenhanced to the parenchymal phase was -1.8 H (SD, +/- 4.4 H); from the unenhanced to the corticomedullary phase was -2.3 H (+/- 3.9 H); and from the corticomedullary to the parenchymal phase was 0.6 H (+/- 4.2 H). No cyst increased more than 10 H between the unenhanced and the parenchymal phases; more than 95% of cysts increased less than 8 H between any scanning phases. No significant difference was seen in enhancement related to lesion size (p > 0.054), unenhanced attenuation (p > 0.255), or percentage of the lesion that was exophytic (p > 0.124). CONCLUSION: The attenuation coefficient of a cystic renal lesion increased by no more than 10 H among the unenhanced, corticomedullary, and parenchymal phase scans.

Contrast Media↗
PubMed2003

CT depiction of portal vein thrombi after creation of ileal pouch-anal anastomosis.

PURPOSE: To determine the presence and location of portal vein thrombi in patients who have undergone ileal pouch-anal anastomosis (IPAA) and who were scanned with computed tomography (CT). MATERIALS AND METHODS: During a 4-year period, 92 of 702 patients underwent contrast medium-enhanced CT after a total proctocolectomy with an IPAA. These CT scans were retrospectively reviewed for portal vein thrombus presence, location, and occlusive nature, as well as any accompanying enhancement abnormalities of the hepatic parenchyma. Only 13 patients who had initial CT scans that were positive for thrombi underwent follow-up examinations, and these were reviewed for resolution or progression of the original findings. RESULTS: Portal vein thrombi were present in 41 (45%) of the 92 patients; 24 (59%) of the 41 were isolated, often multiple, segmental right lobe thrombi. Five patients had both right and left segmental vein involvement. Eleven patients had various combinations of main portal vein, right and left portal vein, or segmental vein thrombi. One patient had an isolated superior mesenteric vein thrombus. Twenty-two of 25 superior mesenteric vein, main portal vein, and right and left portal vein thrombi were nonocclusive, while most (63 of 86) of the segmental vein thrombi were occlusive. Wedge-shaped, peripheral areas of hepatic parenchymal hyperenhancement that were distal to the thrombi were present in 30 (73%) of the 41 patients. Follow-up scans obtained in the 13 patients with portal vein thrombi showed thrombi resolved in five patients, progression to cavernous transformation occurred in one patient, and parenchymal enhancement changes persisted in seven patients. In the seven patients with persistent enhancement changes, four had complete resolution of thrombi. CONCLUSION: Portal vein thrombi appear to be relatively common after IPAA surgery and are most likely segmental, multiple, and occlusive. Peripheral wedge-shaped areas of hepatic parenchymal hyperenhancement commonly accompany these thrombi.

Adolescent↗
PubMed2002

Imaging of chronic pancreatitis.

This article reviews the recognized findings of chronic pancreatitis on CT and endoscopic retrograde cholangiopancreatography. It also discusses more recently developed techniques including gadolinium-enhanced MR imaging, MR cholangiopancreatography, and endoscopic ultrasound. Variants of chronic pancreatitis and difficulties in differentiating pancreatic neoplasms from inflammatory pancreatic masses are also discussed.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed2002

Prospective preoperative determination of mucinous pancreatic cystic neoplasms.

BACKGROUND: Optimal management of pancreatic cystic neoplasms includes identification and resection of mucinous neoplasms. This study was performed to assess the accuracy of preoperative variables in determining a mucinous lesion. METHODS: Patients referred for a cystic neoplasm were prospectively assessed by presenting symptoms, blinded radiologic review, and endoscopic ultrasound-guided cyst aspirate analysis. Patients who were symptomatic, or had aspirate findings of a mucinous neoplasm were resected. RESULTS: Eighty-seven patients were enrolled over a 22-month period ending in December 2001. There were 56 (64%) women and 31 (36%) men, with a mean age of 63 (27-86) years. Thirty-five (40%) patients were resected including 24 (69%) women and 11 (31%) men with a mean age of 58 years. Twenty-eight (80%) patients who had resection were symptomatic. Specimen histology included 18 (51%) mucinous neoplasms, 8 (23%) serous neoplasms, 4 (11%) ductal or neuroendocrine carcinomas, and 3 (9%) pseudocysts. The positive predictive value (PPV) for cyst-aspirate extracellular mucin (83%) was significant in predicting a mucinous neoplasm (P =.009). No other aspirate variables (amylase, carcinoembryonic antigen, CA15-3, viscosity), or patient characteristics were predictive of final histology. Diagnostic agreement between all 3 radiologists was 8% (P =.98). At a median follow-up of 12 months, no patients who were observed required resection. CONCLUSIONS: Patients with suspected pancreatic cystic neoplasms can be selectively treated on the basis of symptoms and cyst-aspirate mucin analysis. Symptomatic and mucin containing lesions should be resected.

Adenocarcinoma, Mucinous↗
PubMed2002

Portal vein thrombi after restorative proctocolectomy.

BACKGROUND: Restorative proctocolectomy (RP) has been the surgical procedure of choice for surgical management of mucosal ulcerative colitis since 1978. This study was undertaken to investigate the clinical presentation and implications of portal vein thrombi (PVT). METHODS: We reviewed all patients undergoing RP in our institution in the 4 years from January 1997 to December 2000. As the diagnosis of PVT was made on computed tomography (CT) scan in all cases, we confined our incidence estimate to those patients having an abdominal CT scan postoperatively. All scans were reviewed by an experienced radiologist. Patient demographics, symptoms, and clinical course were recorded. RESULTS: A total of 702 patients underwent RP, of whom 94 had a CT scan within the postoperative period. PVT was diagnosed in 42 of the 94 patients (45%). PVT was diagnosed at initial reading of the scan in 11 patients, and on review in 31. The indications for CT scan included abdominal pain, fever, leukocytosis, and delayed bowel function. Septic complications of RP caused these symptoms and signs in 45 patients, 20 of whom had PVT. Twenty-two patients were found to have had PVT without evidence of any septic source. CONCLUSION: PVT can be found in a high proportion of patients undergoing abdominal CT scan after RP. It is often associated with pain, fever, nausea vomiting, tenderness, and leukocytosis. This study shows that PVT subtle enough to go undiagnosed has no serious consequences, even when not treated. Also, patients treated with anticoagulation recover completely.

Adult↗
PubMed2002

Enhancement characteristics of papillary renal neoplasms revealed on triphasic helical CT of the kidneys.

OBJECTIVE: The purpose of this study was to determine whether renal tumor enhancement or heterogeneity on triphasic helical CT scans is predictive of the papillary cell subtype or nuclear grade of renal cell carcinoma. MATERIALS AND METHODS: We reviewed the CT scans of 90 consecutive patients with renal masses who had undergone triphasic renal helical CT before a complete or partial nephrectomy (12 with papillary renal cell carcinomas, 66 with nonpapillary renal cell carcinomas, and 12 with benign lesions). Three radiologists who were unaware of the patients' diagnoses retrospectively and independently measured the attenuation of each patient's tumor, abdominal aorta, and normal renal parenchyma on the scans obtained during all three phases. Ratios of tumor-to-aorta enhancement and tumor-to-normal renal parenchyma enhancement were calculated for both of the phases performed after contrast material had been administered. Tumor heterogeneity was calculated as the difference between the highest and lowest attenuation values divided by the value of the enhancement of the aorta. Values were correlated with cell type and nuclear grade found at surgical pathology. RESULTS: Low tumor-to-aorta enhancement and low tumor-to-normal renal parenchyma enhancement ratios on the vascular phase scans significantly correlated (p < 0.001) with papillary renal cell type carcinoma. Homogeneity and tumor-to-parenchyma enhancement ratios on the parenchymal phase scans also significantly correlated (p < 0.001) with papillary renal cell type carcinoma. Heterogeneity and tumor enhancement ratios did not correlate with the nuclear grade of the carcinoma. CONCLUSION: Papillary renal cell carcinomas are typically hypovascular and homogeneous. A high tumor-to-parenchyma enhancement ratio (> or = 25%) essentially excludes the possibility of a tumor being papillary renal cell carcinoma. A low tumor-to-aorta enhancement ratio or tumor-to-normal renal parenchyma enhancement ratio is more likely to indicate papillary renal cell carcinoma.

Adult↗