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Biomedical subjects

R H Falk

Publications and source records attributed to R H Falk.

120 records · Page 7Linked to original sources
PubMed1976

Rapid intravenous injection of tobramycin: suggested dosage schedule and concentrations in serum.

A single, rapid intravenous injection of tobramycin in doses of 1.5 mg/kg or 80 mg administered to subjects with normal renal function produced a wide range of concentrations in serum. Serum concentrations peaked at greater than 20mug/ml in one third of the subjects, but these peaks were transitory. At 6 hr the serum levels were less than 2 mug/ml in all but one subject and were less than 0.1 mug/ml in 50% of the subjects. A dosage interval of 6 hr with a total dosage of 6 mg/kg per day is recommended. The variation in individual dose responses emphasizes the need for monitoring of levels of tobramycin in serum during treatment. Serum concentrations of 4-6 mug/ml 1 hr after injection can be considered indicative of adequate therapy. Levels in serum 6 hr after administration should also be monitored, particularly in the elderly. No immediate or delayed toxic effects were observed after intravenous injection of tobramycin.

Adult↗
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Cost-effectiveness of therapies for patients with nonvalvular atrial fibrillation.

BACKGROUND: The most appropriate treatment(s) for patients with atrial fibrillation remains uncertain. OBJECTIVE: To examine the cost-effectiveness of anti-thrombotic and antiarrhythmic treatment strategies for atrial fibrillation. METHODS: We performed decision and cost-effectiveness analyses using a Markov state transition model. We gathered data from the English-language literature using MEDLINE searches and bibliographies from selected articles. We obtained financial data from nationwide physician-fee references, a medical center's cost accounting system, and one of New England's larger managed care organizations. We examined strategies that included combinations of cardioversion, antiarrhythmic therapy with quinidine, sotalol hydrochloride, or amiodarone, and anticoagulant or antiplatelet therapy. RESULTS: For a 65-year-old man with nonvalvular atrial fibrillation, any intervention results in a significant gain in quality-adjusted life years (QALYs) compared with no specific therapy. Use of aspirin results in the largest incremental gain (1.2 QALYs). Cardioversion followed by the use of amiodarone and warfarin together is the most effective strategy, yielding a gain of 2.3 QALYs compared with no specific therapy. The marginal cost-effectiveness ratios of cardioversion followed by aspirin, with or without amiodarone, are $33800 per QALY and $10800 per QALY, respectively. Cardioversion followed by amiodarone and warfarin has a marginal cost-effectiveness ratio of $92400 per QALY compared with amiodarone and aspirin. Strategies that include cardioversion followed by either quinidine or sotalol are both more expensive and less effective than competing strategies. CONCLUSIONS: Cardioversion of patients with nonvalvular atrial fibrillation followed by the use of aspirin alone or with amiodarone has a reasonable marginal cost-effectiveness ratio. While cardioversion followed by the use of amiodarone and warfarin results in the greatest gain in quality-adjusted life expectancy, it is expensive (ie, has a high marginal cost-effectiveness ratio) compared with aspirin and amiodarone. Finally, for patients who are bothered little by symptoms of atrial fibrillation, cardioversion followed by either aspirin or warfarin without subsequent antiarrhythmic therapy is the treatment of choice.

Aged↗
PubMedDate not supplied

Optimal number of beats for the Doppler measurement of cardiac output in atrial fibrillation.

This study was undertaken to determine the optimum number of Doppler velocity waveforms required to calculate cardiac output in atrial fibrillation with the same degree of accuracy as that for sinus rhythm. Twenty-one patients in atrial fibrillation underwent calculations of cardiac output derived from aortic Doppler waveform velocity time integrals and RR intervals. The variability in estimates of the cardiac output was calculated with the successive addition of sequential beats and compared with that determined in a control group of 12 subjects in sinus rhythm. For the group in atrial fibrillation, a mean of 13 beats (range 4 to 17 beats) was required to achieve an estimation of cardiac output with a variability of less than 2%, compared with a mean of four beats in sinus rhythm. In atrial fibrillation, the mean number of beats required to determine cardiac output was approximately three times that necessary in sinus rhythm.

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