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Study Title and Description

Coffee acutely increases sympathetic nerve activity and blood pressure independently of caffeine content: role of habitual versus nonhabitual drinking.



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 Coffee acutely increases sympathetic nerve activity and blood pressure independently of caffeine content: role of habitual versus nonhabitual drinking.
Author R Corti,C Binggeli,I Sudano,L Spieker,E Hänseler,F Ruschitzka,WF Chaplin,TF Lüscher,G Noll,
Country
Year 2002
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)? The aim of the present study was to assess the effects of caffeine, as well as regular and decaffeinated coffee, on sympathetic nerve activity and hemodynamics in humans in vivo.
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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) In 15 healthy volunteers (6 habitual and 9 nonhabitual coffee drinkers) arterial BP and heart rate were continuously recorded before and after different interventions (see below) in the same subjects. Smokers and offspring of hypertensive parents (common confounding factors that may affect SNS activity) were excluded. Habitual coffee drinkers and nonhabitual coffee drinkers (defined as drinking no coffee or any other beverages containing caffeine) were studied after [Note: Interventions 1 and 2 not relevant (IV administration of caffeine or a placebo)]: (3) coffee drinking (triple espresso; n=10, 5 habitual and 5 nonhabitual coffee drinkers); and (4) drinking of decaffeinated coffee (triple espresso; n=4, nonhabitual coffee drinkers). Subjects were blinded to the intervention (ie, coffee versus decaffeinated coffee). All subjects were studied in supine position after coffee abstinence for at least 16 hours under standardized conditions—ie, in the afternoon (2:00 PM) after a light meal. The leg was fixed with vacuum cushion, and ECG leads, BP cuff, and respiration strain gauge were attached. An indwelling catheter (DeltaFlo2, 20 gauge, DELTA-MED) was inserted into a cubital vein. After a running-in period and stable hemodynamics for 15 minutes, baseline recordings and blood samplings were obtained. Micorneuropathy Multifiber recordings of muscle sympathetic nerve activity (MSA) were obtained during the entire duration of the study from the peroneal nerve posterior to the fibular head with tungsten microelectrodes (200-um shaft diameter, 1 to 5 um uninsulated tip; Medical Instruments, University of Iowa). A reference electrode was inserted subcutaneously 1 to 2 cm from the recording electrode. Electrodes were connected to a preamplifier (gain, 1.000) and amplifier (variable gain, 10 to 50). Neural activity was fed through a band-pass filter (bandwidth, 700 to 2000 Hz) and a resistance-capacitance integrating network (time constant, 0.1 second) to obtain a mean voltage neurogram with the typical pulse-wave–triggered bursts. The signal was displayed on an oscilloscope, amplified, and connected to a loudspeaker to further identify the characteristic signal and exclude artifacts ECG and BP An ECG was recorded simultaneously throughout the experiment. BP was assessed noninvasively through oscillometric occlusion at the left upper arm (Dinamap, Critikon Inc). Signal Recording and Signal Processing MSA and 1-lead surface ECG were continuously recorded with a LabView application, a MIO 16L (National Instruments) A/D conversion board, and a Macintosh computer. The signals were sampled at 500 Hz and stored with 12-bit accuracy. Signal processing was done with MATLAB (The MathWorks, Inc). MSA was quantified in a computer-assisted evaluation of the frequency and the amplitude of the sympathetic bursts. The results are expressed as bursts per minute (bursts/min) and cumulative sum of the amplitude (ACS) in volts per minute (V/min) for absolute value, as a parameter of the total activity, whereas changes in the SNS activity are expressed as percent of baseline values. Coffee Preparation Coffee was prepared with an espresso machine (triple espresso). Decaffeinated coffee of the same brand was prepared with an espresso machine in the same way as the triple espresso Data and Statistical Analysis Data were entered and analyzed with SYSTAT version 10.0 (SPSS, Inc). For each subject, a 5-minute average of continuously registered data at baseline, 30 minutes, and 60 minutes was used in the statistical analysis. Results are reported as mean +/- SEM. The analyses began with an overall 3x2 repeated measures ANOVA followed by tests of the effect of time within each condition. Significant within-condition time effects were than followed up with tests of specific trends (eg, linear, quadratic). The effect of coffee on habitual drinkers was assessed by comparing the 60-minute change in the physiological parameter’s value to zero (baseline) with a 1-sample t test. Similar comparisons were made for nonhabitual drinkers. A value of P<0.05 was considered 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 Muscle sympathetic nerve activity (MSA) (cumulative sum of the amplitude [ACS] and bursts per minute)
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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? NCT
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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 Multifiber recordings of MSA were obtained during the entire duration of the study from the peroneal nerve posterior to the fibular head with tungsten microelectrodes (200-um shaft diameter, 1 to 5 um uninsulated tip; Medical Instruments, University of Iowa). An ECG was recorded simultaneously throughout the experiment. BP was assessed noninvasively through oscillometric occlusion at the left upper arm (Dinamap, Critikon Inc).
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Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other? Coffee
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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.) Subjects received the same treatment and served as their own controls (baseline prior to exposure)
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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 12460875
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What were the sources of funding? This study was supported by the Swiss National Research Foundation (grant No. 32-52690.97), the Swiss Heart Foundation, and the Stanley Thomas Johnston Foundation, Bern, Switzerland.
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Results & Comparisons

No Results found.