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Study Title and Description

Evaluation of electrocardiographic and hemodynamic effects of caffeine with acute dosing in healthy volunteers.



Key Questions Addressed
1 For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on cardiovascular outcomes?
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Primary Publication Information
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TitleData
Title Evaluation of electrocardiographic and hemodynamic effects of caffeine with acute dosing in healthy volunteers.
Author R Ammar,JC Song,J Kluger,CM White,
Country
Year 2001
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Cardiovascular Design
Design Details
Question... Follow Up Answer Follow-up Answer
What outcome is being evaluated in this paper? Cardiovascular
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What is the objective of the study (as reported by the authors)? Our study used a validated electrocardiographic variable determination method14 to determine whether a moderate, single dose of caffeine lengthened the PR, QRS, QT, QTc, and RR intervals, and the QT/QTc interval dispersion. The effect of caffeine on blood pressure and heart rate also was evaluated to determine the duration of hemodynamic effects after moderate caffeine ingestion.
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Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods) Methods In this randomized, double-blind, placebo-controlled, crossover trial, Full- or part-time students over age 17 years at the University of Connecticut were eligible to participate. Students were excluded if they had a history of ventricular or supraventricular arrhythmias, hepatic or renal dysfunction, insomnia, lactose intolerance (due to the diluent of the placebo), or caffeine allergy, or were without QT intervals evaluable in at least eight ECG leads. Ten healthy volunteers (five men, five women), aged 22–29 years (mean ± SD age 24 ± 2 yrs), met inclusion criteria. Investigational Procedure Appointments for an individual were scheduled for the same time of day (within 2 hrs) to minimize any circadian variation in electrocardiographic variables. Participants abstained from caffeinated products for at least 2 days before study initiation. Participants were randomly selected to receive placebo (lactose monohydrate; Humco, Texarkana, TX) or caffeine 400 mg (NoDoz; Bristol-Myers Products, New York, NY), the equivalent of four cups of coffee, during phase 1. A baseline 12-lead ECG was performed during each study phase, and a subsequent 12-lead ECG was done 3 hours after ingesting the study drug. A washout period of at least 2 days was employed between study phases. Electrocardiographic Variable Determination Each patient’s 12-lead ECG recordings were grouped together and read by a blinded investigator. Lead II was selected in all ECG recordings for general comparisons of PR, QRS, QT, and RR intervals. A precision ruler (0.5-mm scale; Schlaedler Quinzel, Inc., Parsippany, NJ) was used to measure all intervals. The onset of the P wave is defined as the junction between the isoelectric line and the beginning of the P-wave deflection. The beginning and end of the QRS complex were determined by visual inspection, whereas the end of the T wave was determined by extrapolating the descending slope of the T wave to the isoelectric baseline. If a U wave was present, the descending slope of the visible portion of the T wave was used for extrapolation. The QT interval was corrected for heart rate using the following formula: QTc = QT/(RR)^0.5. QT Interval Dispersion Determination QT and RR intervals were measured in every evaluable lead, and the maximum and minimum QT, RR, and QTc intervals on the 12-lead ECG were determined. The QT and QTc interval dispersions were calculated by subtracting the shortest interval from the longest. Blood Pressure and Heart Rate Determination The same investigator performed baseline and 3-hour post-ingestion blood pressure determinations for all subjects during both study phases. Subjects were instructed to avoid the use of stimulants (e.g., catecholamine nasal sprays, Ma Huang, and nicotine) for 12 hours before each phase. Blood pressure was measured with a mercury sphygmomanometer using standard methodology. Heart rate was calculated by dividing 60 seconds by the lead II RR interval (in seconds). Statistical Analysis Baseline intervals, dispersions, and SBP and DBP readings from each phase were compared with their respective 3-hour post-ingestion variables using a paired t test. Intervals, dispersions, and blood pressure readings taken after ingestion also were compared with those of the placebo group using a Student’s unpaired t test. If a variable was not normally distributed, intragroup comparisons were made with a Wilcoxon signed rank test whereas intergroup comparisons were made with a Mann-Whitney test. All data are mean ± SD. A p value less than 0.05 is statistically significant.
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How many outcome-specific endpoints are evaluated? 3
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Blood pressure (SBP and DBP)
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List additional health endpoints (separately). 2 Heart rate
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List additional health endpoints (separately).3 Heart rhythm (PR, QRS, QT, QTc and RR intervals; QT and QTc interval dispersion)
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List additional health endpoints (separately).4
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List additional health endpoints (separately).5
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List additional health endpoints (separately).6
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Clinical, physiological, other Physiological
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What is the study design? Controlled Trial
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Randomized or Non-Randomized? RCT
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What were the diagnostics or methods used to measure the outcome? Objective
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Optional: Name of Method or short description 12-lead ECG recordings; blood pressure was measured with a mercury sphygmomanometer using standard methodology; heart rate was calculated by dividing 60 seconds by the lead II RR interval (in seconds).
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Caffeine (general) Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other?
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Measured or self reported? Measured
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Children, adolescents, adults, or pregnant included? Adults
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What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) Each subject received the same treatment (caffeine or placebo). Comparisons made within treatment "groups" and control "groups"
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What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models.  Copy from methods) None
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What conflicts of interest were reported? No information provided
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Refid 11310517
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What were the sources of funding? No information provided
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Results & Comparisons

No Results found.