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Biomedical subjects

G J Stoddard

Publications and source records attributed to G J Stoddard.

7 recordsLinked to original sources
PubMed2000

Cardiopulmonary events during hemodialysis: effects of dialysis membranes and dialysate buffers.

Adverse cardiac and pulmonary events are frequently observed during hemodialysis and contribute to significant morbidity and mortality. The temporal relationship between these events during the intradialytic period has not been well defined. To examine the event rate and timing of silent ischemia, cardiac ectopy, and hypoxemia, we conducted a prospective, single-blind, randomized study of 10 subjects undergoing maintenance hemodialysis with four contiguous combinations of dialysis membranes (cuprammonium or polysulfone) and dialysates (acetate or bicarbonate). The frequency of oxygen desaturation events peaked during the first 2 hours, whereas silent myocardial ischemia and supraventricular ectopies occurred more often in the later hours. Ventricular ectopy occurred steadily throughout the intradialytic period. The combination of acetate dialysis and cuprammonium membrane is associated with the most frequent events. We conclude that cardiopulmonary events can occur frequently during hemodialysis, and the frequency is dependent on the type of dialysis membrane and dialysate buffer used.

Acetates↗
PubMed1997

ACE inhibitor effects on platelet function in stages I-II hypertension.

Angiotensin II enhances platelet aggregation through activation of the G protein-linked pathway present in platelets. Studies of several angiotensin-converting enzyme (ACE) inhibitors have demonstrated marked differences on platelets. Therefore this prospective, randomized, double-blind, crossover study compared the ex vivo effects of equivalent antihypertensive doses of captopril, enalapril, and fosinopril on platelet aggregation and thromboxane B2 (TxB2) formation in subjects with stage I-II essential hypertension. Nineteen male subjects with a baseline mean seated blood pressure of 141 +/- 3/100 +/- 1 mm Hg were enrolled. The decline in mean arterial pressure after 4 weeks of stable dosing was 10 +/- 1, 12 +/- 1, and 11 +/- 1 mm Hg for captopril, enalapril, and fosinopril, respectively (p = NS). There was no significant change in adenosine diphosphate (ADP)-, epinephrine-, or thrombin-stimulated platelet aggregation from baseline or between ACE inhibitors. Compared with baseline, fosinopril decreased TxB2 concentrations 27.5-67.6% with all stimuli after 1 and 5 min. Captopril also decreased TxB2 formation, but this effect was stimulus and time dependent. Enalapril consistently increased TxB2 concentrations, independent of stimuli or time. We conclude that different ACE inhibitors have distinct effects on platelet TxB2 formation without significant effects on platelet aggregation. Fosinopril may be a direct antagonist ofTxA2 synthase, suggesting benefit in syndromes of platelet activation or vascular occlusion.

Adult↗
PubMed1994

Subcutaneous, catheter-related inflammation in a rabbit model correlates with peripheral vein phlebitis in human volunteers.

In the development of a polyurethane vascular catheter with anti-infective properties, it became desirable to develop a measure of tissue inflammation. This was investigated in a rabbit model by implanting uncoated catheters and catheters coated with heparin (HEP), chlorhexidine (CH), or CH/HEP in the subcutaneous space with or without 10(4) Staphylococcus aureus. At intervals of 2, 4, and 7 days after implantation, animals were sacrificed; tissue blocks containing catheters were removed and preserved with formaldehyde; and sections were stained with hematoxylin and eosin. Using a histologic index, 240 sections (10 for each experimental condition) were evaluated by two investigators blinded to experimental conditions. Uncoated catheters or catheters coated with CH alone had a lower histologic index (less inflammation) than catheters coated with HEP alone or CH/HEP (P < .05). When catheters were inoculated with S. aureus, those coated with CH, with or without HEP, had a lower histologic index than uncoated catheters (P < .05). Next, 30 volunteers had a control catheter inserted in a vein in one forearm and a catheter coated with either CH alone or CH/HEP in a vein in the other forearm. After 96 h of observation there was a greater risk of phlebitis associated with CH/HEP catheters than control catheters (P < .05), and no difference in the risk of phlebitis between CH catheters and control catheters (P = 0.43). Thus, the amount of inflammation around the catheter in the subcutaneous space of rabbit correlated with the risk of peripheral vein phlebitis.

Adult↗
PubMedDate not supplied

The infusion nurse and patient complication rates of peripheral-short catheters. A prospective evaluation.

The objective of this study was to compare catheter-related complication rates in patients who had infusion devices placed by infusion nurses with complication rates in patients who had devices placed by generalist nurses. The data demonstrated that peripheral infusion devices placed by infusion nurses exhibited a statistically significant lower rate of leakage, phlebitis, and infiltration complications and remained in the vein significantly longer than those placed by generalist nurses. However, significance was not achieved with pain complication rates between the two groups. The implications of these outcomes for staff development and quality of patient care are discussed.

Adult↗
PubMedDate not supplied

Invasive pharmacodynamic characterization of combined ibopamine and calcium blocker therapy for heart failure.

STUDY OBJECTIVE: To determine the acute hemodynamic response of single-dose coadministration of ibopamine plus nifedipine or diltiazem in patients with New York Heart Association functional class (NYHA FC) II-III congestive heart failure. DESIGN: A single-blind, placebo-controlled, two-paired, crossover study. SETTING: Cardiology clinics at two large teaching hospitals. PATIENTS: Eight patients with NYHA FC II-III congestive heart failure who met the inclusion criteria were selected randomly. INTERVENTIONS: All patients underwent right heart catheterization. Day 1 consisted of concomitant calcium channel blocker plus placebo, with cardiac and peripheral hemodynamic recordings from 30 minutes-24 hours. The design was equivalent on day 2, with single-dose administration of ibopamine plus calcium channel blocker. MEASUREMENTS AND MAIN RESULTS: Single-dose nifedipine-diltiazem augmented cardiac output and stroke volume secondary to decreasing systemic vascular resistance. The nifedipine-ibopamine and diltiazem-ibopamine subgroups demonstrated relatively equal hemodynamics, augmenting cardiac index (nifedipine 43%, p < 0.05; diltiazem 40%, p < 0.05 vs baseline) while decreasing systemic vascular resistance (nifedipine 41%, p < 0.05; diltiazem 28%, p NS vs baseline) 30 minutes after the dose. In contrast to single-dose diltiazem, the diltiazem-ibopamine subgroup exhibited an increased left ventricular filling pressure (122%, p < 0.05 vs baseline) and mean pulmonary artery pressure (43%, p < 0.05 vs baseline) at 30 minutes after the dose. One patient experienced a transient episode of chest pain associated with increased heart rate and blood pressure with diltiazem-ibopamine. CONCLUSION: Diltiazem and ibopamine should be coadministered with caution in patients with coronary artery disease and left ventricular dysfunction.

Adult↗
PubMedDate not supplied

How to evaluate study methodology in published clinical research.

When reading a clinical research article, the clinician must judge if the reported findings and conclusions are valid before applying them to patient care. This concern is legitimate given the wide range of study validity in the clinical literature. In this article, the authors present many validity markers that signify the quality of the information reported from a study, such as authorship, bias, confounding, statistics, randomization, controls, blinding, and the logical framework of scientific investigations.

Bias↗