Biomedical subjects

J A Ventura

Publications and source records attributed to J A Ventura.

8 recordsLinked to original sources

PubMed1998

Cost analysis of hospital material management systems.

Integrated healthcare material management begins with manufactures of medical/surgical supplies, uses distributors and ends at the point of use at hospitals. Recent material management philosophies in the healthcare industry, such as just-in-time and stockless systems, are yet to be fully evaluated. In order to evaluate the cost effectiveness of each type of material management technique, a cost model for hospital materials management has been designed. Several case scenarios are analyzed and results are reported.

Cost Savings↗

PubMed1990

Ioxilan, a third generation low osmolality nonionic contrast medium. Systemic and renal hemodynamic effects.

The choice between high cost, low toxicity nonionic contrast media (CM) and low cost ionic CM poses a dilemma for radiologists. Ioxilan, a third generation nonionic CM, is obtained by simple conversion from an ionic CM. To examine how this economically promising, low osmolality CM (570 mOsm at 300 mgI/ml) affects canine systemic and renal hemodynamics, IV bolus injections of 350 mgI/ml at 2 ml/kg of Iohexol and Ioxilan were compared. Satisfactory nephrograms and pyelograms were produced by both agents, without significant differences. The effects on systemic and renal hemodynamics were minimal and statistically equal for both CM. The acute systemic and renal responses and radiographic image quality of Ioxilan and Iohexol confirm that the two compounds are biologically equivalent, and that the novel molecular design employed in Ioxilan to achieve very low osmolality also provides good biological tolerance.

Animals↗

PubMed1988

Role of angiotensin II in renal hemodynamic functions during the initial stages of acute ureteral obstruction.

This investigation examines the role of Angiotensin II in renal hemodynamic functions during acute unilateral ureteral obstruction (UUO) in a dog model. An electro magnetic flow probe was utilized to assess renal blood flow while the arteriovenous extraction technique of technetium 99m DTPA was utilized for the assessment of changes in filtration fraction and glomerular filtration rate. The effects of Angiotensin II receptor blockade on renal hemodynamic functions during acute UUO was evaluated in six dogs and compared to acute ureteral obstruction without receptor blockade in seven dogs. Angiotensin II blockade with (Sar1, Thr8)-Angiotensin II during UUO led to a striking increase in renal blood flow that was significantly different in comparison to normalized values from UUO alone (+delta 63 +/- 17 vs. +delta 22 +/- 6% at 30 min; p less than 0.05). There were, however, no significant differences in the magnitude of the decrease in filtration fraction and glomerular filtration rate in comparison to UUO alone. This investigation demonstrates that Angiotensin II has an inhibitory effect on the initial increase in renal blood flow with acute UUO. The possibility of successful pharmacologic intervention in the setting of UUO can be examined using animal models similar to the one described here. Pharmacologic treatment in the setting of acute UUO in patients might permit better preservation of renal function.

Angiotensin II↗

PubMed1988

Effects of the magnetic resonance contrast medium ferrioxamine methanesulfonate on systemic and renal hemodynamics in the anesthetized dog.

Ferrioxamine methanesulfonate (S-FDF) is a new magnetic resonance (MR) contrast agent developed to improve magnetic resonance imaging of the abdomen and pelvis. This stable complex of deferoxamine methanesulfonate and iron is excreted in the urine by glomerular filtration modified by active renal tubular resorption. This study examines the acute systemic and renal hemodynamic responses to this agent after intravenous administration either as an infusion of 25 mg/kg over 5 minutes or as a rapid bolus at a dose of 50 mg/kg. In eight anesthetized dogs, renal plasma flow (RPF) was measured with an electromagnetic flowmeter, and GFR was determined by the renal extraction of technetium-99m-DTPA. Mean arterial pressure (MAP), pulse rate, and a lead II ECG were assessed. At a dose of 25 mg/kg over 5 minutes, MAP decreased significantly (control 146.0 +/- 6.5 mm Hg vs. 107 +/- 18 mm Hg at 2 minutes; P less than .05). In two of the eight animals, the MAP dropped below 60 mm Hg. Significant decreases in GFR and RPF also were noted. All four of the animals receiving the rapid injection of S-FDF experienced profound hypotension (MAP less than 50 mm Hg). The drop in heart rate from 152 +/- 11.6 bpm to 121 +/- 4.9 bpm was associated with a marked depression of the ST wave in the lead II ECG. Further animal studies are needed to assess the mechanism of toxicity and a potential synergism of action with pentobarbital anesthesia.

Animals↗

PubMed1986

Effects of contrast media on renal function and subcellular morphology in the dog.

The effects of intravenous contrast media (CM) on renal excretory function and subcellular morphology are examined in this animal investigation. A decrease in GFR (12.0 +/- 1.6 vs. control 30.2 +/- 2.5 ml/min) was observed when renal function was evaluated by means of the artero-venous extraction method with Tc99m DTPA and the anticipated inverse relationship to urinary flow (Vml/min) noted. An artifactual increase in GFR (43.5 +/- 10.0 vs. control 39.1 +/- 3.8 ml/min) was observed using the timed urinary clearance of inulin. V(ml/min) increased four-fold (0.6 +/- 0.16 control vs. 2.7 +/- 0.7 ml/min; P less than .05) over the first five minutes after injection of CM. Urine osmolality initially approached isotonicity and then returned toward preinjection values. Osmolal clearance (Cosm) rose 2.5 times (1.4 +/- 0.3 control vs. 3.7 +/- 1.0 ml/min; P less than .05). The fractional excretion of both Na+ (FENa+) and K+ (FEK+) increased. A comparison of urinary osmolality vs. time after injection of CM confirms a nonspecific osmotic effect on tubular (and hence total urine) flow. The hemodynamic effects of CM on the kidney via the i.v. route reflect a predominant and nonspecific osmotically mediated vasodilation. No significant light or electron microscopic changes were observed. These findings suggest that the major renal physiologic actions of hypertonic CM are a nonspecific response to agent osmolality.

Animals↗

PubMed1986

Acute systemic and renal hemodynamic effects of meglumine/sodium diatrizoate 76% and iopamidol in euvolemic and dehydrated dogs.

We examined the acute systemic and renal hemodynamic effects of intravenous meglumine/sodium diatrizoate-76% and iopamidol in euvolemic and dehydrated dogs. The physiologic responses were compared with acute changes in the level of an endogenous heparin-like material (EHM). One of eight dehydrated dogs receiving diatrizoate (2 ml/kg) had an immediate vomiting reflex associated with a very significant decline in all measured renal hemodynamic parameters; none of eight dehydrated dogs receiving iopamidol experienced a similar reaction. EHM levels did not correspond to the magnitude of the physiologic responses following either iopamidol or diatrizoate. Significant differences between iopamidol and diatrizoate were noted when comparing the magnitude of the decrease in systemic pressure (- delta 3.8 +/- 3.02, iopamidol, n = 8; vs. - delta 19.4 +/- 7.3 mm Hg, diatrizoate, n = 8; P less than .03), increased renal plasma flow (+ delta 6.2 +/- 4.9, iopamidol, n = 8; vs. + delta 33.7 +/- 8.0 ml/min, diatrizoate, n = 8; P less than .05), and decreased filtration fraction (- delta 0.09 +/- 0.01, iopamidol, n = 8; vs. - delta 0.14 +/- 0.02, diatrizoate, n = 8; P less than .03). There was no significant difference in the decrease in glomerular filtration rate (- delta 7.4 +/- 1.0, iopamidol, n = 8; vs. - delta 9.3 +/- 1.3, diatrizoate, n = 8; P greater than .05), since the marked drop in filtration fraction occurring with diatrizoate was counterbalanced by the marked increase in renal plasma flow. Acute systemic and renal hemodynamic effects are significantly lessened when comparing iopamidol with diatrizoate.

Animals↗

PubMed1986

A comparison of clearance and arteriovenous extraction techniques for measurements of renal hemodynamic functions.

No previous studies have directly compared timed urine collections (UV/P) vs. arteriovenous (A-V) extraction methods for determination of renal function in whole kidney preparations. We examined different markers and techniques for assessing renal plasma flow (RPF), filtration fraction (FF), and glomerular filtration rate (GFR) in both steady-state and rapidly changing conditions following 2 ml/kg bolus intravenous injections of either Renografin 76% (meglumine/sodium diatrizoate-76%) or hypertonic mannitol 25%. During steady-state conditions, excellent correlations were obtained when comparing markers and techniques. Thus, timed urinary clearances of inulin vs. 99m-technetium DTPA (Tc) had a correlation coefficient (R) of .96 (P less than .01; n = 16), and the A-V extraction technique of inulin vs. Tc as determinants of GFR showed a correlation of R = .98 (P less than .01; n = 15). The timed urinary clearance of inulin vs. the A-V extraction of inulin for glomerular filtration gave a correlation of R = .93 (P less than .01; n = 15). The clearance of para-aminohippurate (PAH) divided by the extraction of PAH vs. flow determinations using the electromagnetic flowmeter gave a correlation of R = .92 (P less than .01; n = 16). The anticipated decrease in GFR following contrast medium and hypertonic mannitol was observed using the A-V extraction technique, whereas an artifactual, exaggerated increase in GFR was observed using the timed urine collection technique. Similarly, we noted an exaggerated increase in RPF using CPAH/EPAH as the methodology. We conclude that rapid changes in renal hemodynamics may be measured accurately using the A-V extraction technique but not with clearance techniques requiring timed urine collections.

Animals↗

PubMed1985

Glomerular filtration response to acute ureteral obstruction in the dog.

In order to assess the glomerular filtration responses to acute ureteral obstruction in the dog we employed an established method that does not require timed urine collections. Our results show a 57 per cent increase in renal blood flow (baseline: 203.8 +/- 50.9 vs. 319 +/- 69.4 ml./min. at 105 minutes; no. = 7) that was associated with a monophasic decrease in filtration fraction to -70 per cent at 120 minutes (0.26 +/- 0.025 vs. 0.08 +/- 0.007) and an increase in ureteral pressure to 63.1 +/- 6.1 mm. Hg at 120 minutes. A biphasic GFR response was noted with an initial small increase (baseline: 32.5 +/- 7.5 vs. 36.3 +/- 11.0 ml./min. at 2 minutes) followed by a continual decline to -55 per cent at 120 minutes (to 14.5 +/- 2.6 ml./min.). This investigation has confirmed the results of micropuncture studies showing maintenance of GFR early after complete ureteral ligation.

Animals↗