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Biomedical subjects

P F Sheedy

Publications and source records attributed to P F Sheedy.

At least 73 records · Page 4Linked to original sources
PubMed1992

The effects of transcutaneous electrical stimulation during wakefulness and sleep in patients with obstructive sleep apnea.

Upper airway (UA) collapse in obstructive sleep apnea (OSA) is considered in part to result from the decrease in UA dilator muscle tone that occurs during sleep. We hypothesized that augmentation of UA muscle function by transcutaneous electrical stimulation (TES) might function to enlarge UA size during wakefulness and/or prevent UA collapse during sleep in patients with OSA. Eight male patients with OSA were studied both awake and asleep, with TES administered to the submental region in two patients and to both the submental and subhyoid regions in six patients. Fast-CT scans obtained at FRC and end-inspiration (VTei) demonstrated increased UA size with tidal breathing, p less than or equal to 0.05. The active generation of -10 cm H2O pressure at FRC substantially decreased UA size, p less than or equal to 0.001. However, no changes in UA size were detected at either FRC or VTei with TES applied at 50 and 100% of the maximal tolerated intensity. The collapsibility of the UA in response to the generation of -10 cm H2O pressure was also unchanged by TES. In contrast to the lack of effect of TES on UA size, voluntary protrusion of the tongue increased cross-sectional area (CSA) of the orohypopharyngeal (OHP) segment of the UA, p less than 0.05, and to a lesser extent the CSA of the distal velopharyngeal segment, p = 0.06. When applied during sleep, TES failed to prevent or improve either sleep-disordered breathing or sleep architecture.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1991

The effect of a low-osmolar radiographic contrast medium on in vivo and postmortem renal size.

High osmolar radiographic contrast media (CM) are known to cause an increase in renal size. To examine the effect of low-osmolar CM on renal size, 14 anesthetized dogs received 12 intravenous bolus injections of 0.5 mL/kg iohexol (541 mOsm/L). The postmortem renal, cortical, and medullary volumes were determined by fluid displacement. Renal volumes of 18 control dogs were determined similarly. The mean (+/- SEM) postmortem renal volumes were 66.1 +/- 2.2 mL for the CM group and 52.3 +/- 3.3 mL for the control group (P = 0.003), whereas the cortical and medullary volumes were similar. Six dogs were also scanned by fast computerized tomography before and after iohexol administration. The in vivo whole renal and medullary volumes enlarged from 67.4 +/- 3.0 to 77.1 +/- 2.8 mL (P = 0.006), and from 28.5 +/- 2.0 to 35.1 +/- 1.1 mL (P = 0.026), respectively, while the cortical volume remained unaltered. These results suggest that even low osmolar CM may significantly increase renal volume, probably by causing tubular expansion.

Animals↗
PubMed1991

Incidentally discovered adrenal tumors: an institutional perspective.

With the aim of developing guidelines for investigation and management of adrenal incidentalomas, 2066 patients with adrenal masses were analyzed from a total of 61,054 computerized tomographic (CT) scans done from 1985 through 1989. Excluding patients with previous or concurrent malignancies, adrenal tumors localized after biochemical documentation of disease, and adrenal nodules less than 1 cm, 259 patients (0.4%) remained for analysis. Added to these were 83 patients (total 342) in whom the adrenal tumor had been found elsewhere before referral. There were 136 men and 206 women with a mean age of 62 years. Tumor diameter ranged from 1 to 11 cm (average 2.5 cm). Studies to evaluate biochemical hyperfunction were performed in 172 patients (50%), 2 of whom were found to have cortisol-producing tumors and 5 pheochromocytomas. Histologic proof of diagnosis was obtained in 55 patients at the time of adrenalectomy. Malignancy was discovered in five patients (four primary and one metastatic), the smallest malignant tumor measuring 5 cm. In the 287 patients without histologic diagnoses, a minimum of 1 year of clinical follow-up was obtained in 251 (88%), including repeat CT scan in 156 (54%). None of these patients had clinical or biochemical adrenal abnormalities. We suggest (1) biochemical screening in patients with incidentalomas larger than 1 cm, (2) surgical excision of tumors 4 cm or greater, and (3) a comparison CT scan approximately 3 months after diagnosis in patients with tumors less than 4 cm in whom observation has been chosen.

Adolescent↗
PubMed1990

Adrenal insufficiency from bilateral adrenal hemorrhage.

Bilateral adrenal hemorrhage is a rare cause of adrenal insufficiency in adults. Because of the nonspecific manifestations of adrenal insufficiency, antemortem diagnosis is difficult. Serial computed tomographic scans of the abdomen are a valuable adjunct in confirming the diagnosis of bilateral adrenal hemorrhage, which manifests as round or oval adrenal masses of high density that subsequently decrease in both size and density. The diagnosis should be suspected in any complex highly stressful illness, in the postoperative period, or in the presence of a coagulopathy in conjunction with hypotension, fever, or electrolyte disturbances. Herein we describe five patients in whom the computed tomographic scans suggested or confirmed the presence of bilateral adrenal hemorrhage. In three of the five patients, the presence of a circulating lupus anticoagulant was demonstrated. Once the diagnosis of adrenal hemorrhage is suspected, steroid replacement therapy should be initiated promptly.

Adrenal Gland Diseases↗
PubMed1990

Radiologic evaluation of penetrating aortic atherosclerotic ulcer.

Patients with penetrating atherosclerotic ulcers of the aorta present with back or chest pain that mimics classic aortic dissection. The pathologic findings, however, are distinctly different from those of aortic dissection in that an atherosclerotic lesion with ulceration penetrates into the internal elastic lamina, allowing hematoma formation within the media of the aortic wall. This may lead to false aneurysm or, rarely, transmural rupture of the aorta. Imaging findings of penetrating aortic atherosclerotic ulcers are also different from those of classic aortic dissection. We have found computed tomography to be especially useful in differentiating between these entities and present several illustrative cases.

Aged↗
PubMed1990

Intravascular US of the distal aorta and iliac vessels: initial feasibility studies.

Intravascular ultrasound (US) imaging is a new, evolving technique in which a high-frequency transducer is placed on the tip of a catheter. With this device it is possible to obtain high-resolution images of vessel structure in real time. This may provide valuable information about the degree of stenosis, as well as the type and extent of atherosclerotic plaque, in relation to the underlying tunica media and adventitia. The intravascular US catheter was used in seven patients undergoing transfemoral angiography because of arteriosclerosis obliterans. High-resolution images were obtained in all seven patients, and no complications were noted. Various US findings were demonstrated and correlated with the angiographic findings.

Aged↗
PubMed1990

The assessment of major airway function in a ventilator-dependent patient with tracheomalacia.

A 60-pack-year smoker presented with cough, dyspnea and orthopnea of three months' duration. Spirometry revealed severe reduction in maximal expiratory flow; CT of the chest and bronchoscopy demonstrated expiratory collapse of a mid-tracheal segment, and a presumptive diagnosis of tracheomalacia was made. A right lateral thoracotomy was performed to resect the unstable segment and improve maximal expiratory flow. Diffuse major airway disease with absence of cartilaginous rings from the thoracic inlet to the mainstem bronchi was encountered. The trachea and mainstem bronchi were stented externally. A high resistance to airflow and absence of expiratory flow limitation were present, suggesting a fixed rather than variable intrathoracic obstruction of major airways. This case illustrates some potential pitfalls in preoperative assessment of patients with tracheomalacia. Recordings of airway pressure and flow during mechanical ventilation are useful in distinguishing between fixed and variable intrathoracic obstruction and may complement tests of airway anatomy.

Airway Resistance↗
PubMed1990

Fast-CT evaluation of the upper airway during wakefulness in patients with obstructive sleep apnea.

Fast-CT scanning was used to study the dynamic changes in the upper airway (UA) during quiet tidal ventilation (VT) in 25 patients with obstructive sleep apnea (OSA). Ten fast-CT scans were sequentially obtained over one respiratory cycle from the level of the hard palate to the hypopharynx with the patients awake in the supine position. The patients were 44 +/- 2 years old, weighed 104 +/- 5 kg, and had moderately severe OSA with an apnea plus hypopnea index (AHI) of 59 +/- 7 per hour. Maximum and minimum UA cross-sectional areas (Amax -Amin) were determined for each UA level and percent reductions in UA size or collapsibility index (CI) were computed as (Amax -Amin)*100/Amax. The lower velo-pharynx was the narrowest (Amin = 80 +/- 12 mm2) and most collapsible segment of the UA (Cl = 55 +/- 5%). Amin was less than 25, 50, or 75 mm2 in 64%, 76%, and 88% of the patients, respectively. Significant narrowing was confined to the proximal segment (levels 1 to 4) in the majority, with the remaining patients having narrowing in both the proximal and distal segments. None of the patients had major narrowing confined to the distal segment alone. Mean UA cross-sectional area (Amean) was generally largest at end-inspiration and smallest at end-expiration. In conclusion, fast-CT has documented substantial changes in UA cross-sectional area during quiet VT in awake supine patients with OSA. The velopharyngeal (retropalatal) segment was the narrowest and most collapsible region. Maximal narrowing was greatest at end-expiration, consistent with relaxation of UA dilator muscle activity.

Adult↗
PubMed1989

CT-guided biopsy: prospective analysis of 1,000 procedures.

The authors prospectively analyzed 1,000 biopsies guided with computed tomography (CT) and performed in 955 patients over a 30-month period. All patients were followed up from 3 months to 2 years. The biopsies were performed in an average of 22 minutes (range, 3-85 minutes) by 26 different radiologists; five radiologists performed 547 of the procedures. Of the 1,000 biopsies, 722 were performed in areas in the liver, retroperitoneum, pancreas, pelvis, and adrenal glands. Of 69 errors in diagnosis, 67 were falsely negative and two were falsely positive; 747 true-positive and 184 true-negative diagnoses were made. CT-directed biopsy for accurate diagnosis was 91.8% sensitive and 98.9% specific, with a positive predictive value of 99.7% and a negative predictive value of 73.3%. Of 11 patients with complications, seven had hematomas, three had pneumothorax, and one had hematuria. No deaths occurred, and only one patient required surgery.

Adrenal Glands↗
PubMed1988

Percutaneous placement of the Greenfield vena caval filter.

During the period from August 1986 to August 1987, 50 patients underwent percutaneous placement of a Greenfield vena caval filter from the right femoral vein, left femoral vein, or right internal jugular vein at our institution. All 50 patients had a contraindication to anticoagulation therapy or had complications of anticoagulation for deep venous thrombosis or pulmonary emboli. The percutaneous placement was accomplished in the angiographic suite with use of local anesthesia and was well tolerated by all patients. Only three complications related to the percutaneous approach occurred during the short-term follow-up (3 months to 1 year). These complications were deep venous thrombosis of the leg in two patients and misplacement of the filter in one patient. The three patients tolerated these complications well. We conclude that placement of Greenfield vena caval filters can be readily accomplished by means of percutaneous entry. Our experience demonstrated minimal associated morbidity and no mortality.

Aged↗
PubMed1988

Localization of pancreatic insulinoma: comparison of pre- and intraoperative US with CT and angiography.

Methods of preoperative radiologic localization of insulinoma were compared in 52 patients, 44 of whom had solitary tumors. Examinations performed in these 44 patients were preoperative ultrasonography (US) in 28, angiography in 26, and computed tomography in 23. Prospective sensitivities were 61%, 54%, and 30%, respectively. Imaging sensitivities were lower for the eight patients with multiple insulinomas. In 28 of the 44 patients, intraoperative US was performed without the examiner being aware of the surgical findings. The sensitivity was 84%. Four insulinomas were not palpable but were visualized sonographically. The combined sensitivity of intraoperative US and surgical palpation for detecting solitary insulinomas was 100%. High-frequency intraoperative US is valuable for detecting occult solitary insulinomas and considerably useful for determining the proximity of insulinomas to the pancreatic and bile ducts.

Adenoma, Islet Cell↗
PubMed1987

Percutaneous transluminal angioplasty in the lower extremities: a 5-year experience.

From January 1979 to March 1984, percutaneous transluminal angioplasty (PTA) was used to treat 148 limbs of 135 Mayo Clinic patients with occlusive arterial disease of the lower extremities. The procedure was technically successful in more than 95% of the attempts. The outcome was clinical improvement in 89 limbs and no improvement in 40 limbs; in 19 limbs, PTA was technically successful but the patient was dismissed from the hospital and lost to follow-up before the extent of improvement could be determined. Mean ankle/brachial pressure indices increased after PTA in those with clinical improvement but not in those without improvement. Clinical improvement was less likely to follow PTA in patients with advanced age, diabetes, severe initial symptoms, low ankle/brachial indices, or distal occlusive disease. In patients with improvement after PTA, the mean follow-up period was 33 months; during that time, failure (defined as recurrence of the original symptoms or the need for repeat PTA or operation) occurred at a rate of 6.4% per year. Serious complications occurred after three procedures (2.0%). We conclude that PTA is technically feasible and generally safe for many patients with occlusive arterial disease of the lower limbs.

Aged↗
PubMed1986

Treatment of pyogenic hepatic abscesses. Surgical vs percutaneous drainage.

A retrospective review of 39 patients with pyogenic hepatic abscess treated from 1977 through 1984 included 23 patients who were surgically treated and 16 who underwent percutaneous drainage. The average age in each group was similar (about 55 years). The most common cause of abscesses in each group was biliary tract disease. Abscesses caused by portal seeding and local extension were more common in the surgical group, 14 of whom required additional surgical procedures at the time of surgical drainage. Of the 16 patients in the percutaneously drained group, seven were seen during the immediate postoperative period. Most of the abscesses occurred in the right lobe of the liver, but single abscesses in the left lobe (30%) and multiple abscesses (57%) were more common in the surgical group. Klebsiella enterobacter and group D streptococcus were most common in the surgically and percutaneously drained groups, respectively. All patients received antibiotics, with a mean length of treatment of 14 days. Mean time to defervescence was about four days in both groups, with a longer hospital stay for the percutaneously drained group (26 vs 46 days). Morbidity was high in both groups (surgical, 48%; percutaneous, 69%). Three of the percutaneously treated patients required surgical drainage because of highly viscous abscess contents. Mortality was 17% in the surgical group and 13% in the percutaneously drained group. Percutaneous drainage with computed tomography probably should be the initial drainage procedure in patients with pyogenic hepatic abscesses in whom no concomitant surgical procedure is planned. Regardless of treatment, the morbidity and mortality remain high.

Adult↗
PubMed1986

Preoperative staging of rectal carcinoma by computed tomography and 0.15T magnetic resonance imaging. Preliminary report.

A prospective study was done on 34 patients using magnetic resonance imaging (MRI) and computed tomography (CT) preoperatively to stage patients with known rectal carcinoma. The study was done to determine the accuracy and clinical usefulness of CT and MRI. The Thoeni staging method was used. Twenty-four of 30 cases were staged correctly by CT. Sixteen of 27 were staged correctly by MRI. CT detected lymph node metastases in six of 15 cases with one false-positive. MRI detected lymph node metastases in two of 15 patients with one false-positive. CT was the preferred examination, and was useful in some cases. These cases included patients with small tumors who were considered for local excision and patients with extensive disease who were candidates for preoperative or intraoperative radiation treatment. MRI demonstrated extensive disease, as did CT in our later cases.

Adult↗
PubMed1986

Computed tomography and ultrasonography of hepatoma.

Computed tomography (CT) scans and sonograms of 37 patients with hepatocellular carcinoma (hepatoma) were reviewed to determine the characteristics of the tumour and to compare the modalities in terms of accuracy in defining tumour morphology and ability to predict vascular invasion and extrahepatic spread. By CT, slightly over 50% of the tumours were multicentric, about 40% were solitary, and the rest were diffuse. About half of the hepatomas were heterogeneous in density before injection of contrast agent and most became enhanced in a non-uniform manner. In addition, about a quarter of the tumours either became visible or were better seen after injection of contrast agent. At sonography, approximately two-thirds of the neoplasms were thought to be solitary and one-third multicentric. The majority also had a mixed echo texture. Although the lesion was identified in all 13 patients who had both studies, sonography underestimated the extent of hepatic involvement in 38% of the cases. Sonography also failed to demonstrate lymphadenopathy that was detected by CT in two patients. In general, both techniques were effective in identifying vascular invasion. CT was very accurate in showing the extent of hepatic involvement but was unable to identify direct invasion of neighbouring structures. Because each technique has limitations in the evaluation of hepatoma, we believe that both should be performed if curative resection is being considered.

Adult↗
PubMed1986

Thromboembolic splenic infarction.

Splenic infarction occurs as a consequence of systemic thromboembolization in association with several cardiovascular disorders. We describe a case of splenic infarction in a patient who had paroxysmal atrial fibrillation after aortic valve replacement. In an autopsy series of 96 consecutive cases of splenic infarction, only 10% had been suspected clinically even though the splenic infarctions had contributed substantially to morbidity and mortality in 44% of the cases. Thromboembolic causes were responsible for the splenic infarcts in 67% of the cases, and concomitant infarcts in other organ systems were found in 62%. Embolization of atheromatous debris from the aorta, thrombotic elements from the left ventricle (in dilated cardiomyopathy and acute myocardial infarction), and vegetations from infected valves are the most common settings in which thromboembolic splenic infarcts are noted. The clinical picture associated with splenic infarction is typically nonspecific; manifestations may include fever, tachycardia, and left-upper-quadrant tenderness. Computed tomographic scanning and, to a lesser degree, ultrasonography are the imaging techniques of choice for diagnosing splenic infarction.

Aortic Valve Stenosis↗
PubMed1986

Penetrating atherosclerotic ulcers of the thoracic aorta: natural history and clinicopathologic correlations.

Clinically, penetrating atheromatous ulceration of the aortic wall may be confused with either symptomatic thoracic aneurysm or classic spontaneous aortic dissection. Aortography and computed tomographic (CT) scanning of the thoracic aorta provide specific diagnostic information which permits one to distinguish this lesion from atherosclerotic aneurysm and classic dissection. Hallmarks of findings on aortography and CT scan include the presence of the ulcer and an intramural hematoma. Since the findings may be disarmingly subtle, the potentially progressive and serious nature of this condition may remain unappreciated. Recognition of the penetrating atheromatous ulcer and distinguishing it from aortic dissection arising just distal to the origin of the left subclavian artery is mandatory. Resection of only a conservative segment of the proximal descending aorta suffices for classic dissection in the upper descending thoracic aorta, but the penetrating aortic ulcer requires graft replacement in the area of the ulcer and intramural hematoma.

Aged↗