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Study Title and Description

Acute caffeine intake influences central more than peripheral blood pressure in young adults.



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 Acute caffeine intake influences central more than peripheral blood pressure in young adults.
Author WS Waring,J Goudsmit,J Marwick,DJ Webb,SR Maxwell,
Country
Year 2003
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 purpose of this study was to examine the effects of acute caffeine intake on central BP and large artery stiffness using PWA [pulse wave analysis] in a randomized, placebo-controlled, double-blind study. The effects on sympathetic cardiac influence were also studied, using power spectral analysis of pulse interval during rest and sustained isometric handgrip exercise.
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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) Subjects were identified from a community database, held at the Clinical Research Centre of the University of Edinburgh. Men and women aged 18 to 45 years were included. Each subject regularly consumed 350 to 700 mL of coffee per day, containing approximately 180 to 360 mg caffeine. Exclusion criteria were elevated BP (> 160/100 mm Hg), a clinical history of diabetes or cardiovascular disease, regular use of any prescribed medication, or use of any over-the-counter medication in the week before examination. Hemodynamic Measurements Peripheral BP was recorded in duplicate in the brachial artery of the dominant arm using the validated Omron HEM-705CP oscillometric device (Omron Corp, Tokyo, Japan). Cardiac index was assessed using the noninvasive NCCOM3-R7 transthoracic bioimpedance technique (BioMed, Cheshire, UK). Mean arterial pressure (MAP) was calculated by integration of the arterial pressure waveform using SphygmoCor PWA software (PWV Medical, Sydney, Australia), and systemic vascular resistance index was calculated as MAP divided by CI. Peripheral pressure waveforms were recorded noninvasively from the radial artery at the wrist of the dominant hand using an applanation tonometer (SPC-301 micromanometer, Millar Instruments, Houston, TX), linked to SphygomoCor PWA apparatus. Integral software calculated MAP, based on peripheral systolic and diastolic BP pressure measurements, and the radial artery pressure waveform. Peripheral and central pressure waveforms are calibrated against MAP by harmonizing areas under both pressure–time curves. After 20 sequential waveforms have been acquired, the system software generates averaged peripheral and central aortic pressure waveforms, and calculates augmentation index (AIx) as the difference between the first and second central systolic BP peaks expressed as a percentage of pulse pressure. Pressure amplification was calculated as the ratio of peripheral to central pulse pressure. Heart Rate Variability Signals from an electrocardiograph, recorded continuously over 5 min, were delivered to a dedicated computer for offline analysis using Chart software (ADInstruments, Hastings, UK). Artifacts were removed automatically and HRV was determined by fast Fourier transformation of the pulse interval. Variability was expressed as very low frequency (< 0.04 Hz), LF (0.04 to 0.149 Hz), and HF (0.15 to 0.4 Hz) domains; the LF:HF ratio was used to represent relative sympatho-vagal cardiac influence.
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How many outcome-specific endpoints are evaluated? 6
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Blood pressure (central [aortic] and peripheral [brachial] SBP, DBP, MAP, pulse pressure amplification)
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List additional health endpoints (separately). 2 Heart rate
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List additional health endpoints (separately).3 Aortic stiffness (augmentation index [AIx])
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List additional health endpoints (separately).4 Cardiac index
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List additional health endpoints (separately).5 Systemic vascular resistance index
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List additional health endpoints (separately).6 Heart rate variability (very low, low, and high frequency; LF:HF ratio)
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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 Method for measuring heart rate not explicitly stated
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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.) Subjects served as their own controls
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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 14573329
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What were the sources of funding? No information provided
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Results & Comparisons

No Results found.