Biomedical subjects

T R Hartley

Publications and source records attributed to T R Hartley.

3 recordsLinked to original sources

PubMed2000

Hypertension risk status and effect of caffeine on blood pressure.

We compared the acute effects of caffeine on arterial blood pressure (BP) in 5 hypertension risk groups composed of a total of 182 men. We identified 73 men with optimal BP, 28 with normal BP, 36 with high-normal BP, and 27 with stage 1 hypertension on the basis of resting BP; in addition, we included 18 men with diagnosed hypertension from a hypertension clinic. During caffeine testing, BP was measured after 20 minutes of rest and again at 45 to 60 minutes after the oral administration of caffeine (3.3 mg/kg or a fixed dose of 250 mg for an average dose of 260 mg). Caffeine raised both systolic and diastolic BP (SBP and DBP, respectively; P<0.0001 for both) in all groups. However, an ANCOVA revealed that the strongest response to caffeine was observed among diagnosed men, followed by the stage 1 and high-normal groups and then by the normal and optimal groups (SBP F(4),(175)=5.06, P<0.0001; DBP F(4,175)=3.02, P<0.02). Indeed, diagnosed hypertensive men had a pre-to-postdrug change in BP that was >1.5 times greater than the optimal group. The potential clinical relevance of caffeine-induced BP changes is seen in the BPs that reached the hypertensive range (SBP >/=140 mm Hg or DBP >/=90 mm Hg) after caffeine. During the predrug baseline, 78% of diagnosed hypertensive men and 4% of stage 1 men were hypertensive, whereas no others were hypertensive. After caffeine ingestion, 19% of the high-normal, 15% of the stage 1, and 89% of the diagnosed hypertensive groups fell into the hypertensive range. All subjects from the optimal and normal groups remained normotensive. We conclude that hypertension risk status should take priority in future research regarding pressor effects of dietary intake of caffeine.

Adult↗

PubMed1999

Self presentation and cardiovascular reactivity.

This research was concerned with two issues: first, whether cardiovascular response patterns to a social stressor (i.e. self-presentation under evaluative circumstances) differ as a function of one's ability to control the impression one makes on others; second, whether cognitive appraisals are necessary or sufficient for the cardiovascular components of emotional arousal. Forty-two male subjects (Ss), monitored for cardiac impedance and blood pressure, were shown a previously recorded videotape of themselves in which each S verbally described personal aspects about himself. Ss in an Active condition were allowed to mark segments of the tape they wanted to re-shoot before the tape was evaluated by reviewers. Ss in a Passive condition viewed their tape but could not indicate whether to revise it. Control conditions allowed assessment of the activity entailed in tape marking and of evaluation per se. Self-reports of stress, threat, and coping ability regarding the upcoming task were taken. Blood pressure elevations occurred equally in both experimental conditions, but apparently through different underlying mechanisms. The Active condition produced myocardial responses (increased ejection fraction), while the Passive condition produced a vascular response (increased total peripheral resistance). However, while cardiovascular reactivity patterns did differ as a function of the opportunity to control the impression one could make on evaluative others, they did not differ as a function of having appraised the task as a challenge or as a threat. Consideration also is given to the conditions necessary for cognitive appraisal to occur and to influence reactivity.

Adolescent↗

PubMedDate not supplied

Caffeine and stress: implications for risk, assessment, and management of hypertension.

Caffeine use is widespread, and its consumption increases during periods of stress. Caffeine raises blood pressure by elevating vascular resistance, and this effect is larger and more prolonged in hypertensive patients than in normotensive. The pressor response to caffeine occurs equally in persons at rest and under stress. The elevated baseline pressures of the hypertensive patient are therefore increased by both caffeine and stress, potentially leading to undesirably high pressures. Such combined effects on blood pressure may potentially confound the evaluation of hypertension, and possibly reduce the effectiveness of antihypertensive therapy. These effects are not abolished by pharmacologic tolerance to caffeine, as tolerance may not be complete with daily intake. The contribution of caffeine's effects to the development of hypertension warrants continued study, and caffeine use by patients merits consideration in terms of assessment and management of this disorder.

Blood Pressure↗