Estimation of radionuclide content in contaminated laundry.

Radioactively contaminated laundry is normally sent off site for processing. Laundry is defined as radiologically contaminated anti-cs and respirators. This laundry is shipped as "limited quantity," in accordance with 49CFR173.421. This requires that 95% of the radionuclides shipped are characterized and quantified. In addition, the total quantity must be 10(-3) below the A2 limits specified in 49CFR173. In any facility evaluated, the most conservative (highest activity) waste stream was used as the source term. If a new waste stream is established for a facility, its normalized activity should be compared to the evaluated waste stream to ensure the limits are not exceeded. This article documents a method used for estimating the radionuclide content in contaminated laundry. The maximum values were compared to 49CFR173. Itwas determined that if the contaminated laundry/respirators are shipped in an Interstate Nuclear Services (INS), L-59, limited quantity shipping container and the highest contact radiation level on any side, as measured with an ion chamber, does not exceed 0.5 mR h(-1), the container complies with the requirements of 49CFR173 and could be shipped "limited quantity" from any of the facilities evaluated.

Serum nifedipine concentrations and response of patients with pulmonary hypertension.

In patients with primary pulmonary hypertension who respond to nifedipine during acute drug testing, there is a significant linear correlation of serum nifedipine concentration with pulmonary artery pressure and resistance. Although most demonstrate an initial response at readily attainable nifedipine concentrations with conventional dosages, a subset of patients seem to display delayed or incomplete oral absorption; these results may facilitate the clinical use of nifedipine in patients with primary pulmonary hypertension.

Effects of adenosine in combination with calcium channel blockers in patients with primary pulmonary hypertension.

OBJECTIVES: The purpose of this study was to evaluate the effects of vasodilator combination therapy in patients with primary pulmonary hypertension. BACKGROUND: Calcium channel blockers and adenosine have each been shown to be effective in reducing pulmonary artery pressure and pulmonary vascular resistance in patients with primary pulmonary hypertension. However, the effects of combining these vasodilators have not been studied. METHODS: To test the combination, 12 patients were placed on oral nifedipine and 3 on diltiazem therapy, using a dose titrated to maximal effect (mean nifedipine dose 103 +/- 24 mg, mean diltiazem dose 300 +/- 49 mg). Patients were then given maintenance doses of the calcium channel blocker at half the cumulative loading dose at 6-h intervals. One hour after the maintenance dose of calcium blocker, all patients received an infusion of adenosine, starting with 50 micrograms/kg per min and increasing by 50 micrograms/kg per min at 2-min intervals to a maximally tolerated dose (180 +/- 63 micrograms/kg per min). RESULTS: Ten patients responded to calcium channel blockers (defined as a > or = 20% decrease in pulmonary vascular resistance), with a 16% decrease in mean pulmonary artery pressure (p = 0.057), a 39% decrease in pulmonary vascular resistance (p = 0.002) and a 24% increase in stroke volume (p = 0.007). Five patients were nonresponders, with no significant changes in pulmonary artery pressure, pulmonary vascular resistance, cardiac index or stroke volume. In the calcium channel blocker responders, the combination of adenosine and calcium blocker reduced pulmonary vascular resistance by 49%, increased stroke volume by 33% and decreased mean pulmonary artery pressure by 14% compared with drug-free baseline values. In nonresponders, combination therapy resulted in nonsignificant changes in pulmonary artery pressure and pulmonary vascular resistance. CONCLUSIONS: Adenosine has the ability to further decrease pulmonary artery pressure and pulmonary vascular resistance in patients with primary pulmonary hypertension who respond to calcium channel blockers. Those who fail to respond to these agents have little added effect from adenosine.

Comparison of the effects of adenosine and nifedipine in pulmonary hypertension.

The hemodynamic effects of intravenously administered adenosine, a potent vasodilator, were examined in 15 patients with pulmonary hypertension. All patients were given adenosine, 50 micrograms/kg per min, increased by 50 micrograms/kg per min at 2 min intervals to a maximum of 500 micrograms/kg per min or until the development of untoward side effects. The patients were then given oral nifedipine, 20 mg every hour, until a greater than or equal to 20% decrease in pulmonary vascular resistance or systemic hypotension occurred. The administration of maximal doses of adenosine, 256 +/- 46 micrograms/kg per min, produced a 2.4% reduction in pulmonary artery pressure (p = NS), a 37% decrease in pulmonary vascular resistance (p less than 0.001) and a 57% increase in cardiac index (p less than 0.001). The administration of maximally effective doses of nifedipine (91 +/- 36 mg) produced a 15% reduction in the mean pulmonary artery pressure (p less than 0.05), a 24% decrease in pulmonary vascular resistance (p less than 0.01) and an 8% increase in cardiac index (p = NS). There was a significant correlation (r = 0.714, p = 0.01) between the reduction in pulmonary vascular resistance that resulted from adenosine administration and that achieved with the administration of nifedipine. Six patients had substantial reductions in pulmonary vascular resistance with adenosine but not with nifedipine. Thus, adenosine is an effective vasodilator in patients with pulmonary hypertension and can be used for safe and rapid assessment of vasodilator reserve in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Digoxin-like immunoreactive substance in renal transplant patients.

Digoxin-like immunoreactive substance (DLIS) has been detected in several patient populations that were not receiving digoxin, including those patients with end-stage renal disease. The structure and physiologic significance of this compound are unknown, and the fate of DLIS after renal transplantation has not been studied. The authors prospectively evaluated 163 patients (not receiving digoxin) before and after transplantation for the presence of DLIS. Three different assays were used: radioimmunoassay (RIA), affinity mediated immunoassay (ACA), and fluorescence polarization immunoassay (TDX I). Depending on the assay method used, 11% (RIA), 6% (ACA), and 9% (TDX) of patients had detectable DLIS pretransplant. Using all 3 assays, a total of 34 patients (21%) were found to have DLIS. The mean serum digoxin concentration was 0.41 +/- 0.13 ng/mL (range: 0.2-1.2 ng/mL) and DLIS was detectable by greater than 1 assay method in seven patients. DLIS persisted longer in patients who had delayed allograft function (13.7 +/- 7 days) than in those who did not (3 +/- 1.9 days), P less than .05. In summary, detection of DLIS in renal transplant recipients appears to be an infrequent occurrence when using a single digoxin assay method. When detected, the concentration of DLIS is often below the usual therapeutic range for digoxin and disappears once allograft function is established. The authors conclude that the presence of DLIS is unlikely to be clinically significant in the renal transplant population.

Evaluation of drug therapy for treatment of hypertensive urgencies in the emergency department.

Oral nifedipine (N) and clonidine (C) are often used in the treatment of hypertensive urgencies; however, until recently, there were no comparative studies using the same patient population. The authors reviewed the records of hypertensive patients treated in the emergency department between October 1, 1987 and September 30, 1988. Selected patients had a diastolic blood pressure (DBP) of greater than 115 mm Hg without evidence of acute end organ damage. Patients were stratified into three treatment groups: N, C, and group 3 (G3). G3 received a variety of drug therapies but not exclusively N or C. Systolic blood pressure (SBP), DBP, mean arterial pressure (MAP), percent decrease in MAP (%MAP), time to lower blood pressure, admissions, and discharges were evaluated. Efficacy and safety were defined as reaching a DBP less than 110 mm Hg but %MAP of no greater than either 25% or 40%, respectively. Thirty-five N, 32 C, and 27 G3 patients were identified with no statistical difference between groups in race, gender, pretreatment SBP, DBP, or MAP. N, C, and G3 significantly reduced SBP, DBP, and MAP (P less than .01). Comparing N, C, and G3, no differences were observed in %MAP, admissions, discharges, efficacy, or safety. Time required to decrease blood pressure differed between all three groups (44 +/- 32 N v 77 +/- 57 C v 152 +/- 94 min G3) (p less than .05). These results indicate that N, C, and a variety of drug therapies are equally effective and safe in the treatment of hypertensive urgencies.

Antiplatelet agents in coronary artery disease.

Coronary artery disease pathophysiology and platelet physiology are summarized, and the use of antiplatelet drugs in coronary artery disease is reviewed. Aspirin, sulfinpyrazone, and most other nonsteroidal anti-inflammatory agents alter platelet function by inhibiting the activity of cyclooxygenase, an enzyme necessary for the production of prostaglandins. Drugs that inhibit thromboxane synthetase or antagonize thromboxane A2 at the receptor level are under investigation. Prostacyclin and dipyridamole inhibit platelet function by elevating the concentration of cyclic AMP in platelets, but proof of their efficacy is limited. Most clinical trials of antiplatelet drugs in coronary artery disease have been small and of short duration; many have demonstrated short-term benefits, but long-term benefits are less obvious. Retrospective studies of patients before initial myocardial infarction suggest that regular aspirin ingestion may reduce the occurrence of cardiovascular complications. In prospective trials, the benefit of aspirin therapy for primary prevention of coronary artery disease was balanced by an increased likelihood of stroke. For secondary--after initial infarction--prevention of cardiovascular complications, the administration of aspirin and other antiplatelet agents has consistently decreased the rate of nonfatal myocardial infarction, overall mortality, or both. In the Second International Study of Infarct Survival, patients treated with streptokinase plus aspirin showed the greatest reduction in mortality, while each drug alone was associated with significantly lower mortality than placebo. Aspirin may improve clinical outcome in patients with or without previous myocardial infarction or with unstable angina pectoris. The daily dose should not exceed 325 mg. Antiplatelet therapy should not be used in patients at high risk for bleeding.

Mexiletine: a new type I antiarrhythmic agent.

Mexiletine is a type I antiarrhythmic drug that is structurally similar to lidocaine. Mexiletine has considerable potential for causing neurologic, cardiac, or gastrointestinal side effects. However, mexiletine does not undergo clinically significant first-pass metabolism and, thus, has good oral bioavailability. Mexiletine has a large and variable volume of distribution and an elimination half-life ranging from 6 to 12 hours. Mexiletine disposition is probably altered in patients with heart failure, liver disease, and severe renal dysfunction. Efficacy and toxicity are not well correlated with mexiletine serum concentrations. Mexiletine is as effective as traditional antiarrhythmics in the treatment of premature ventricular contractions. However, in patients with drug-refractory inducible ventricular tachycardia, mexiletine is usually ineffective when used alone. When mexiletine is combined with other antiarrhythmic agents, a significantly higher percentage of patients with this difficult arrhythmia have a good response. Mexiletine is a potentially important addition to the existing antiarrhythmic drugs currently available, but its place in the clinical setting and in therapeutic drug monitoring is not well defined at this time.

Acceptance of transcutaneous nitroglycerin patches by patients with angina pectoris.

The acceptance, preference, and side effects of the 3 commercially available nitroglycerin patches were examined in 30 patients with chronic, stable angina pectoris. Patients were serially interviewed after each treatment period regarding patch comfort, aesthetics, discomfort upon removal, adhesiveness, efficacy, and side effects. They were also interviewed and examined for adverse skin reactions. There were significant differences among the 3 patches with respect to comfort, aesthetics, discomfort, and adhesiveness. Skin reactions (mostly mild) occurred in 83% of patients: patch A, 70%; patch B, 43%; and patch C, 57%. Intolerable reactions, which would have caused patch discontinuation, were noted in 40% of patients: patch A, 30%; patch B, 7%; and patch C, 10%. Most patients had an intolerable reaction to only 1 patch. Significant differences were present only between patches A and B with respect to total and intolerable skin reactions. Thus the systems differed in terms of patient preference and skin reactions. Skin reactions are probably more prevalent than previously reported but usually occur with just one of the patches. Physicians and hospitals should probably individualize nitrate patch therapy within formulary and budgetary constraints.