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N R Dunnick

Publications and source records attributed to N R Dunnick.

At least 55 records · Page 3Linked to original sources
PubMed1991

Captopril renography in the diagnosis of renovascular disease.

Several investigators have reported methods for the use of renal scintigraphy in the diagnosis of renal artery stenosis. We report the experience of Duke University Medical Center, and offer some suggestions for standardizing and optimizing the use of this potential screening tool. We evaluated 140 clinically selected hypertensive adults with postcaptopril renal scintigraphy (renography), pre- and postcaptopril peripheral renin activity, and conventional renal arteriography. Postcaptopril renography (using 99mTc-diethylenetriaminepentaacetic acid (DTPA) to measure glomerular filtration and [131I]iodohippurate to measure renal plasma flow) was considered abnormal if one kidney contributed 47% or less of total activity. Postcaptopril renin was considered elevated if it was at least 4 ng/mL/h. Renovascular disease was defined as 50% or greater main renal artery stenosis. Of 140 subjects, 31 (22%) had significant renovascular disease. Captopril-stimulated DTPA renography suggested asymmetric function in 24 (74%) of these, but was also abnormal in 61 of 109 (56%) with normal renal arteries. Captopril-stimulated hippuran renography performed in a similar manner. Captopril-stimulated renin activity was elevated in only 58% of subjects with renal artery stenosis, and had a false positive rate of 24%. These data differ from reports from other centers, perhaps due to differences in renography methods, criteria for interpretation of renography, and/or patient selection criteria.

Adult↗
PubMed1991

Selective use of low-osmolar contrast media.

Two thousand thirty-four consecutive patients presented for excretory urography within a 22-month period. Of 57 observed adverse reactions (incidence 2.8%), 54 occurred in 1219 low-risk patients injected with conventional ionic contrast media (HOCM) (incidence 4.4%) while three reactions were noted in the 815 high-risk patients receiving low-osmolar contrast media (LOCM) (incidence 0.4%). Despite strict enforcement of an unchanging list of high-risk criteria by the same pool of radiologists, LOCM use was not constant, increasing in use over time from 26.5% to 55.3% of urograms. In addition, frequency of LOCM selection increased transiently (from 33% to 52%) following a single life-threatening reaction to HOCM. Our results suggest that strict guidelines for use of LOCM are subject to loose individual physician interpretation. Physicians' perceptions of safety made it increasingly difficult to withhold LOCM and progressively more patients were included in high-risk groups.

Adolescent↗
PubMed1991

Extravascular toxicity of two magnetic resonance contrast agents. Preliminary experience in the rat.

We compared the relative toxicities of standard concentrations of two magnetic resonance imaging (MRI) contrast agents, ionic gadolinium diethylenetriaminepentacetic acid (DTPA) and low-osmolar gadolinium-1, 4, 7 tris (carboxymethyl)-10-(2'-hydroxypropyl)-1, 4, 7, 10 tetra-azacyclododecane (HP-DO3A) with that of the conventional radiographic contrast medium meglumine diatrizoate, when extravasated into the deep dermal tissues of laboratory rats. Gadolinium-DTPA caused moderate necrosis, hemorrhage, and edema which was not statistically different than meglumine diatrizoate. In contrast, gadolinium HP-DO3A was significantly less toxic than meglumine diatrizoate. Additional experience will be needed in order to determine whether these laboratory results will be clinically relevant in humans.

Animals↗
PubMed1991

Renal vein renins: inability to predict response to revascularization in patients with hypertension.

To determine whether the captopril-stimulated renal vein renin ratio (CSRVRR) could enable identification of patients with hemodynamically significant renovascular lesions who would respond to revascularization, the authors measured CSRVRRs in 143 consecutive patients with hypertension who had been selected because of clinical features suggestive of renovascular hypertension. All patients underwent conventional renal arteriography. Renovascular hypertension was the final diagnosis if revascularization resulted in cure or improvement in blood pressure. Complete data were available for 133 patients. Twenty patients had renovascular hypertension; CSRVRR was greater than 1.5 in 13 of these 20 patients (sensitivity, 65%). However, it was also greater than 1.5 in 54 of the 113 patients without renovascular hypertension (false-positive rate, 47.8%). The positive predictive value of CSRVRR was 18.6%; the negative predictive value, 89.3%. It is concluded that CSRVRR is not sufficiently sensitive to enable prediction of which patients will respond to revascularization and is not specific enough to exclude patients who do not have renovascular hypertension.

Adult↗
PubMed1991

Similar prevalence of renovascular hypertension in selected blacks and whites.

Renovascular hypertension is a potentially curable form of high blood pressure that is thought to be extremely rare among blacks. We demonstrate, however, that in a clinically selected population, the prevalence of renovascular hypertension is similar in blacks and whites. We prospectively evaluated 167 hypertensive subjects who had one or more clinical features known to be associated with renovascular hypertension. All subjects had captopril-stimulated peripheral renin measurements and conventional renal arteriography. All significant renal artery stenoses (greater than 50% luminal narrowing) were treated with percutaneous transluminal angioplasty or surgery. Renovascular hypertension was diagnosed if there was a blood pressure response to interventional therapy, according to the criteria established by the Cooperative Study of Renovascular Hypertension. Of the total group evaluated, 24% (39 of 167) had renal artery stenosis and 14% (23 of 167) had renovascular hypertension. Renal artery stenosis or occlusion was found in 27% (26 of 97) of whites and 19% (13 of 67) of blacks (p = 0.27). Renovascular hypertension was diagnosed in 18% (17 of 97) of whites and 9% (6 of 67) of blacks evaluated (p = 0.25). Renovascular hypertension was associated with severe or refractory hypertension and with smoking, but there were no racial differences in these associations. Blacks with renovascular hypertension tended to have low captopril-stimulated peripheral renin activity. We conclude that blacks with clinical features suggestive of renovascular hypertension should be evaluated with angiography. Captopril-stimulated plasma renin may not be useful in detecting blacks with renovascular hypertension, but this and other potential screening tests require further evaluation.

Adolescent↗
PubMed1991

Screening for renovascular hypertension.

The most common curable cause of high blood pressure is renovascular hypertension. Although hypertension is common in the United States, only a minority, approximately 1%, of patients have a renovascular cause. Using clinical criteria, a subgroup of these patients can be selected in which the prevalence of renovascular hypertension will be approximately 15%. In these selected patients, it is appropriate to proceed to a radiographic screening modality to look for a significant renal artery stenosis. The choice of modality should reflect the strengths and expertise of each specific institution. Hypertensive urography is no longer recommended for screening. Excellent results have been reported with intravenous DSRA in institutions where a strong interest in this procedure exists. Furthermore, intravenous DSRA is easily coupled with the collection of renal vein samples for renin assay. Intravenous DSRA, however, has not maintained widespread use. Although the radionuclide renogram is no longer adequate as a radiographic screening tool, stimulation with an ACE inhibitor, such as captopril or enalaprilat, may produce excellent results. In many institutions, this is the most appropriate examination. Furthermore, it is relatively noninvasive. Merely detecting a significant renal artery stenosis does not, however, mean the patient has renovascular hypertension. Both hypertension and a renal artery stenosis may be present and not be causally related. Because renovascular hypertension is, at least initially, renin mediated, the demonstration of increased renin production by the ipsilateral kidney should confirm renovascular hypertension. Prospective application of these results to patients undergoing revascularization techniques, however, has been disappointing. This may be related to problems in patient preparation, sample collection, renin assay, or even the physiology of chronic hypertension, which is incompletely renin mediated. Thus, offering revascularization only to those patients with lateralizing renal vein renins is not appropriate. If radiographic screening is limited to those patient at greatest likelihood for a renovascular etiology, intra-arterial DSRA or conventional arteriography may be used. These techniques most reliably detect renal artery stenosis. Their main disadvantage lies in their relatively invasive nature, as an arterial puncture is required. The poor predictive value of selective RVRRs implies that revascularization may be attempted without awaiting those results. If percutaneous transluminal renal angioplasty can be performed with a satisfactorily low complication rate, both the diagnostic and the interventional procedure may be undertaken at the same setting. It is expected that further refinements in these diagnostic procedures, particularly with the use of stimulating drugs such as ACE inhibitors, will lead to further improvement in the diagnostic results.(ABSTRACT TRUNCATED AT 400 WORDS)

Angiography, Digital Subtraction↗
PubMed1991

The adrenal glands.

Explore the source record for details and available documents.

Adrenal Gland Neoplasms↗
PubMed1990

Percutaneous biopsy of the kidney and adrenal glands.

Percutaneous biopsy techniques play an important role in the diagnosis and management of patients with known or suspected malignancies. With refinements in biopsy techniques and the use of sophisticated guiding modalities, tissue can be reliably obtained for either cytologic or histologic evaluation. These procedures are safer and more cost effective than the surgical option of open biopsy.

Adrenal Glands↗
PubMed1990

Malpositioned peritoneal dialysis catheters: a critical reappraisal of correction by stiff-wire manipulation.

Tenckhoff peritoneal dialysis (PD) catheter malposition is one of the leading causes of catheter malfunction. Fluoroscopically directed stiff-wire manipulation of malpositioned PD catheters has been advocated as a method of catheter salvage. Two hundred eighty-nine single-cuff PD catheters were placed surgically into 203 patients during this 4-year study. Thirty-three patients developed catheter malfunction attributed to malposition. Forty-eight stiff-wire manipulations were performed on these patients. Thirty-eight (78%) of the manipulations were described as successful at the time of transfer from radiology. However, only 25 (51%) and 12 (25%) resulted in functioning catheters at 1 week and 1 month, respectively. Only 11 of 33 patients who underwent manipulation had functional prolongation of catheter life beyond 1 month. The PD catheter was replaced by a column-disk PD catheter without additional catheter dysfunction in six patients. A second single-cuff Tenckhoff PD catheter was inserted in another six patients. Three of these six catheters again malpositioned. We conclude that stiff-wire manipulation is a useful and safe technique worth using on a limited basis for the initial episode of catheter malposition. Catheters that repetitively malposition should be replaced with a catheter that is resistant to malpositioning.

Adult↗
PubMed1990

Extravascular extravasation of radiographic contrast media. Effects of conventional and low-osmolar agents in the rat thigh.

We compared the damage resulting from intradermal injection of four commonly used radiographic contrast media in laboratory rats. Sixty percent meglumine diatrizoate (Reno M 60) and ioxaglate (Hexabrix) produced significantly more ulceration and crusting on gross inspection and more necrosis, edema, and hemorrhage on histologic evaluation than iopamidol 300 (Isovue) or 0.9% (normal) saline. Thirty percent meglumine diatrizoate (Reno M Dip) had an intermediate toxicity, resulting in significantly more visible swelling and more microscopically detected hemorrhage than iopamidol or saline, but less ulceration/crusting and necrosis than Reno M 60 and ioxaglate. Since the three contrast agents of similar osmolality produced different degrees of tissue damage, our results suggest that factors other than high osmolality are partially responsible for determining the severity of injuries from extravasated contrast media.

Animals↗
PubMed1990

Clinical characteristics useful in screening for renovascular disease.

In an effort to detect renovascular hypertension, clinical characteristics are used to select patients likely to have renal artery stenosis. We prospectively evaluated the ability of commonly used clinical features to predict the presence of renal artery stenosis in 100 hypertensive adults. All subjects had conventional renal arteriography. Renal artery stenosis was diagnosed if there was 50% or more stenosis of a main renal artery. Eighteen of the 100 had renal artery stenosis. The presence of a bruit was strongly associated with renal artery stenosis (P less than .0005). In patients without a bruit, only refractory hypertension was associated with the presence of renal artery stenosis (P = .051). These data suggest that a bruit and refractory hypertension are associated with renal artery stenosis, but that other clinical features investigated may not be and that other means of screening for renovascular disease are needed.

Adult↗
PubMed1990

Extravasation of nonionic radiologic contrast media: efficacy of conservative treatment.

The authors report four large-volume (greater than 20-mL) extravasations in adults and one intermediate-volume (18-mL) extravasation in an infant of iopamidol, a nonionic contrast medium, that occurred during dynamic enhanced computed tomography. The largest volume that extravasated (in two patients) was 150 mL. Although all five patients initially had swelling, erythema, and/or pain after extravasation, all recovered uneventfully. The authors suggest that emergent surgical drainage of all large-volume extravasations, a procedure that was recently recommended, is unnecessary. Large extravascular collections of nonionic contrast media can be well tolerated and are often resorbed without adverse sequelae.

Aged↗
PubMed1990

Differential diagnosis and pathophysiology of Cushing's syndrome and primary affective disorder.

Most patients with major depression have increased 24-hour urinary free cortisol and cortisol nonsuppression after dexamethasone administration, which are cornerstones of a diagnosis of Cushing's syndrome. Similarly, Cushing's syndrome patients often suffer from major psychiatric syndromes, most often depression. These similarities between the two conditions sometimes make it difficult to differentiate them and have led some investigators to suggest they are two points on a spectrum of endocrinologic dysfunction. This article reviews the literature comparing Cushing's syndrome and primary affective disorder and presents two cases that illustrate just how closely these diseases may resemble one another.

Adrenocorticotropic Hormone↗