Management of adrenal lesions.

PURPOSE OF REVIEW: Adrenal lesions are commonly seen on modern imaging modalities, and although the majority are benign, potentially lethal entities necessitate exclusion. This group of both functional lesions and malignancies can produce an extensive variety of symptoms. The purpose of this review is to summarize recent advances in diagnosis and therapies for adrenal lesions. RECENT FINDINGS: New tumor markers and genetic risk factors continue to be discovered, and improved diagnostic techniques have made adrenal incidentalomas more common than ever before. Laparoscopic approaches for adrenal lesions continue to evolve for functional lesions, and also for lesions 12 cm and larger. Open adrenalectomy continues to be the most appropriate for adrenocortical cancer. SUMMARY: All adrenal lesions should prompt a functional hormonal assessment and additional imaging to determine malignancy employed.

Developing a small animal model of extracorporeal circulation.

To identify nonthrombogenic devices to be used in extracorporeal circulation (ECC), an efficient, small animal model is required. Initially, a venovenous (VV) model in rabbits was designed for this purpose and was a good representation of ECC. Technical difficulties in the VV model led to the development of a more simplistic arteriovenous (AV) model. Anesthetized, tracheotomized, 3-kg rabbits were used for both models. Circuits were constructed of PVC tubing. The VV model used 8-Fr umbilical artery catheters for both drainage and reinfusion, and the AV model used a 14-GA angiocatheter for carotid artery access and a 10-Fr thoracic catheter for venous access. The AV model included a chamber to mimic oxygenator or filter modeling. Hourly measurements included blood gases, platelet counts, and fibrinogen levels for the 4-hour studies. The VV ECC groups demonstrated platelet consumption like that seen in the clinical arena. The AV model demonstrated the same with or without additional surface area within the chamber. The AV model was deemed to be superior due to its simplicity, ability for filter modeling, and decrease in intensive monitoring. However, both models are excellent designs for nonthrombogenic surface testing.

Ultrasonography for the endocrine surgeon: a valuable clinical tool that enhances diagnostic and therapeutic outcomes.

BACKGROUND: Surgeon-performed ultrasonography (U/S) has revolutionized many subspecialties by broadening the diagnostic and interventional scope of practice. We report our experience on the impact of surgeon-performed U/S in an endocrine surgery practice. METHODS: Prospectively maintained records of patients from November 1999 to November 2004 were reviewed to establish patterns and outcomes of U/S practice. Surgeon-performed neck U/S was done routinely at the initial clinic visit and incorporated into resident/fellow education. RESULTS: A total of 5703 U/S were performed on endocrine patients with thyroid 42%, parathyroid 57%, and adrenal 1% disorders. Diagnostic fine-needle aspiration biopsy (FNA) was achieved with low sampling errors (<7%). When U/S identified thyroid nodules coexisting with hyperparathyroidism, preoperative FNA correctly established benign thyroid diagnosis and minimized need for thyroidectomy. U/S successfully imaged abnormal parathyroid glands when (99)Tc-sestamibi scans were negative. U/S data significantly changed treatment plans in nearly two thirds of thyroid cancer patients. Surgical residents readily mastered essential U/S skills. CONCLUSIONS: Surgeon-performed U/S is a highly specific tool for identification of endocrine disease in the neck. It is learned readily and performed accurately, and functions as an informative extension of physical examination. Because it substantially benefits patient care and impacts surgical decision making, neck U/S is recommended highly as a valuable adjunct to endocrine surgical practice.

Nitric oxide releasing silicone rubbers with improved blood compatibility: preparation, characterization, and in vivo evaluation.

Nitric oxide (NO) releasing silicone rubbers (SR) are prepared via a three-step reaction scheme. A diamino triaminoalkyltrimethoxysilane crosslinker is used to vulcanize hydroxyl terminated polydimethylsiloxane (PDMS) in the presence of ambient moisture and a dibutyltin dilaurate catalyst so that the respective diamine triamine groups are covalently linked to the cured SR structure. These amine sites are then diazeniumdiolated, in situ, when the cured SR is reacted with NO at elevated pressure (80 psi). Although nitrite species are also formed during the NO addition reaction, in most cases the diazeniumdiolated polymer is the major product within the final SR matrix. Temperature appears to be the major driving force for the dissociation of the attached diazeniumdiolate moieties, whereas the presence of bulk water bathing the SR materials has only minimal effect on the observed NO release rate owing to the low water uptake of the SR matrices. The resulting SR films/coatings release NO at ambient or physiological temperature for up to 20 d with average fluxes of at least 4 x 10(10) mol x cm(-2) x min(-1) (coating thickness > or = 600 microm) over first 4 h, comparable to the NO fluxes observed from stimulated human endothelial cells. The NO loading and concomitant NO release flux of the SR material are readily adjustable by altering the diamine triamine loading and film/coating thickness. The new NO releasing SR materials are shown to exhibit improved thromboresistance in vivo, as demonstrated via reduced platelet activation on the surface of these polymers when used to coat the inner walls of SR tubings employed for extracorporeal circulation in a rabbit model.

Is preoperative iodine 123 meta-iodobenzylguanidine scintigraphy routinely necessary before initial adrenalectomy for pheochromocytoma?

BACKGROUND: Iodine 123 meta-iodobenzylguanidine (MIBG) scintigraphy has been used in patients with clinical suspicion of pheochromocytoma to confirm the nature of an adrenal or extraadrenal mass or to identify occult disease. Additionally, it may be used to identify unsuspected bilaterality or metastases in the setting of a known unilateral adrenal mass before operation. We sought to determine the role of (123)I MIBG scintigraphy in this apparently routine preoperative setting. Our hypothesis was that (123)I MIBG would provide additional preoperative information that could modify operative intervention. METHODS: All patients undergoing (123)I MIBG scintigraphy at our institution between 1992 and 2002 were identified. MIBG results, operative procedures and findings, and pathologic findings were retrospectively reviewed and compared. RESULTS: The (123)I MIBG scintigraphy was performed in a total of 315 patients. Of these, 48 were patients with an initial biochemical diagnosis of pheochromocytoma and a unilateral adrenal mass. 47 of the 48 (98%) primary scans were positive for a single focus of activity concordant with anatomic imaging data from computed tomography or magnetic resonance imaging and operative findings. The (123)I MIBG did not reveal unsuspected metastatic or bilateral disease in any patient. CONCLUSION: In this large series of patients undergoing (123)I MIBG scintigraphy, the test served only to confirm diagnostic impressions and corroborate anatomic imaging. The (123)I MIBG did not alter the operative management of any patient with a solitary adrenal lesion in the clinical context of biochemically-proven catecholamine excess.

Appearance of ectopic undescended inferior parathyroid adenomas on technetium Tc 99m sestamibi scintigraphy: a lesson from reoperative parathyroidectomy.

HYPOTHESIS: Critical postoperative review of technetium Tc 99m sestamibi scintigraphy can identify an undescended parathyroid adenoma on scans initially interpreted as nondiagnostic or negative. DESIGN: Case series. SETTING: A single, tertiary care academic medical center. PATIENTS: Three patients with persistent hyperparathyroidism. INTERVENTION: Technetium Tc 99m sestamibi scanning. OUTCOME MEASURE: Medical records, operative reports, selective venous sampling results, and sestamibi scans were reviewed to identify scintigraphic findings diagnostic of an undescended parathyroid adenoma. RESULTS: All patients were cured of their persistent or recurrent hyperparathyroidism during reoperation by resection of an undescended inferior parathyroid adenoma. Subsequent review of the preoperative sestamibi scans demonstrated scintigraphic evidence of the undescended adenoma. In each case there was asymmetry in the physiologic activity attributed to the ipsilateral submandibular gland that, in fact, corresponded to an ectopic parathyroid adenoma at the level of the carotid bifurcation. CONCLUSIONS: Careful attention to the contour of radioactivity in the region of the submandibular salivary gland may alert surgeons to the presence of an undescended inferior adenoma. After corroboration, this finding may facilitate a targeted operation.

Thrombogenicity is not reduced when heparin and phospholipid bonded circuits are used in a rabbit model of extracorporeal circulation.

In an effort to better mimic the thromboresistive nature of vascular endothelium, extracorporeal circuits bonded with heparin or phospholipids were developed. Using no systemic heparinization, these circuits were compared with standard poly(vinyl)chloride (PVC) (Tygon) in a rabbit model of extracorporeal circulation (ECC). Control circuits were run with and without systemic heparinization and used as comparison groups against the test circuits. Two New Zealand White rabbits were used per study: One was used as the platelet donor for 111Indium platelet labeling; the other animal was placed on bicaval ECC for 4 hours. Circuits (heparin coated n = 6, phospholipid coated n = 8, nonheparinized controls n = 14, heparinized controls n = 18) consisted of 1 m of tubing, two downsizing connectors, and two venous cannulae. ECC blood flow was at least 75 ml/min. Platelet and fibrinogen measurements were made hourly, and circuit dosimetry was performed at the end of the study or on circuit thrombosis. Thrombosis of the circuit occurred in one heparin coated, two phospholipid coated, and eight nonheparinized control circuits. None of the heparinized control circuits thrombosed. There was no significant difference between the groups with regard to platelet count or platelet adhesion. Test circuits exhibited preservation of fibrinogen levels. In this rabbit model of ECC, circuits coated with heparin or phospholipids appeared to preserve fibrinogen levels but did not reduce platelet adhesion or consumption.

Parathyroid adenomas versus four-gland hyperplasia as the cause of primary hyperparathyroidism in patients with prolonged lithium therapy.

Chronic lithium therapy in patients with affective psychiatric disorders has been implicated as the cause of hypercalcemia and primary hyperparathyroidism. Our objective was to evaluate whether primary hyperparathyroidism was caused by an adenoma or four-gland hyperplasia. The medical records of 15 patients with affective psychiatric disorders who were treated with chronic lithium therapy from 1982 to 1997, all of whom were operated on for primary hyperparathyroidism, were reviewed. Data on age, symptoms, duration of lithium therapy, pre- and postoperative calcium levels, and parathyroid hormone levels were collected. Parathyroid histology for each patient was independently and blindly reviewed. The mean age was 58 +/- 10 years, the mean duration of lithium therapy 10.7 +/- 6 years, and the mean preoperative calcium level 11.7 +/- 0.5 mg/dl. All patients underwent bilateral neck exploration with selective resection of enlarged glands. Of the 15 patients, 14 (92%) had adenomas (11 single, 3 double), and 1 (8%) had four-gland hyperplasia. All patients were rendered eucalcemic, with a postoperative calcium level of 9.2 +/- 0.5 mg/dl ( p < 0.005). All patients resumed their lithium therapy, with 1 of 15 patients developing recurrent hyperparathyroidism 2 years following the first operation; this patient required reexploration, at which time an adenoma was resected. In our experience hyperparathyroidism in patients who have undergone prolonged therapy with lithium is associated with a high incidence of parathyroid adenomas versus four-gland hyperplasia. This suggests that lithium selectively stimulates growth of parathyroid adenomas in susceptible patients, who are best treated with adenoma excision rather than subtotal parathyroidectomy.

Nitric oxide-releasing fumed silica particles: synthesis, characterization, and biomedical application.

The preparation, characterization, and preliminary biomedical application of various nitric oxide (NO)-releasing fumed silica particles (0.2-0.3 microm) are reported. The tiny NO-releasing particles are synthesized by first tethering alkylamines onto the surface of the silica using amine-containing silylation reagents. These amine groups are then converted to corresponding N-diazeniumdiolate groups via reaction with NO(g) at high pressure in the presence of methoxide bases (e.g., NaOMe). N-Diazeniumdiolate groups were found to form more readily with secondary amino nitrogens than primary amino nitrogens tethered to the silica. Different alkali metal cations of the methoxide bases, however, have little effect on the degree of N-diazeniumdiolate formation. The N-diazeniumdiolate moieties attached on the silica surface undergo a primarily proton-driven dissociation to NO under physiological conditions, with an "apparent" reaction order somewhat greater than 1 owing to local increases in pH at the surface of the particles as free amine groups are generated. The rates of N-diazeniumdiolate dissociation are further related to the parent amine structures and the pH of the soaking buffer. The N-diazeniumdiolate groups also undergo slow thermal dissociation to NO, with zero-order dissociation observed at both -15 and 23 degrees C. It is further shown that the resulting NO-releasing fumed silica particles can be embedded into polymer films to create coatings that are thromboresistant, via the release of NO at fluxes that mimic healthy endothelial cells (EC). For example a polyurethane coating containing 20 wt % of NO-releasing particles prepared with pendant hexane diamine structure (i.e., Sil-2N[6]-N(2)O(2)Na) is shown to exhibit improved surface thromboresistivity (compared to controls) when used to coat the inner walls of extracorporeal circuits (ECC) employed in a rabbit model for extracorporeal blood circulation.

Extracorporeal life support for severe acute respiratory distress syndrome in adults.

OBJECTIVE: Severe acute respiratory distress syndrome (ARDS) is associated with a high level of mortality. Extracorporeal life support (ECLS) during severe ARDS maintains oxygen and carbon dioxide gas exchange while providing an optimal environment for recovery of pulmonary function. Since 1989, we have used a protocol-driven algorithm for treatment of severe ARDS, which includes the use of ECLS when standard therapy fails. The objective of this study was to evaluate our experience with ECLS in adult patients with severe ARDS with respect to mortality and morbidity. METHODS: We reviewed our complete experience with ELCS in adults from January 1, 1989, through December 31, 2003. Severe ARDS was defined as acute onset pulmonary failure, with bilateral infiltrates on chest x-ray, and PaO2/fraction of inspired oxygen (FiO2) ratio < or =100 or A-aDO2 >600 mm Hg despite maximal ventilator settings. The indication for ECLS was acute severe ARDS unresponsive to optimal conventional treatment. The technique of ECLS included veno-venous or veno-arterial vascular access, lung "rest" at low FiO2 and inspiratory pressure, minimal anticoagulation, and optimization of systemic oxygen delivery. RESULTS: During the study period, ECLS was used for 405 adult patients age 17 or older. Of these 405 patients, 255 were placed on ECLS for severe ARDS refractory to all other treatment. Sixty-seven percent were weaned off ECLS, and 52% survived to hospital discharge. Multivariate logistic regression analysis identified the following pre-ELCS variables as significant independent predictors of survival: (1) age (P = 0.01); (2) gender (P = 0.048); (3) pH < or =7.10 (P = 0.01); (4) PaO2/FiO2 ratio (P = 0.03); and (5) days of mechanical ventilation (P < 0.001). None of the patients who survived required permanent mechanical ventilation or supplemental oxygen therapy. CONCLUSION: Extracorporeal life support for severe ARDS in adults is a successful therapeutic option in those patients who do not respond to conventional mechanical ventilator strategies.