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Biomedical subjects

Thomas G Pickering

Publications and source records attributed to Thomas G Pickering.

At least 91 records · Page 5Linked to original sources
PubMed2002

What is the white-coat effect and how should it be measured?

The white coat effect is conceived as a measure of the blood pressure response to a clinic visit, but there is no agreement as to exactly how it should be defined. The most widely used definition is the difference between the average clinic and daytime ambulatory blood pressures, but other methods that have been used include the difference between clinic and home pressures, measurements using ambulatory blood pressures only, clinic measurements only, and laboratory (reactivity) testing. Few studies have compared the different methods, but the reactivity method has reported bigger changes of blood pressure and heart rate than the others. The effect tends to be greater in older than younger patients, in women than in men, but is present to a greater or lesser degree in almost all hypertensive patients. It is diminished but not obliterated by drug treatment. It is not closely related to overall blood pressure variability, and does not predict cardiovascular risk. The white coat effect appears to be idiosyncratic to the clinic setting.

Antihypertensive Agents↗
PubMed2002

Limitations of current validation protocols for home blood pressure monitors for individual patients.

BACKGROUND: Automatic blood pressure monitoring conducted at home is increasingly used in the diagnosis and management of hypertension. We assessed the adequacy of existing British Hypertension Society (BHS) and Association for the Advancement of Medical Instrumentation (AAMI) validation standards for automatic blood pressure monitoring devices. SUBJECT AND METHODS: A theoretical study and an empirical test are presented to estimate the proportion of persons for whom a blood pressure monitor validated according to existing BHS and AAMI standards would be inaccurate. RESULTS: The results suggest that a major limitation of both protocols is the lack of attention given to the number of individual patients for whom a monitor may be inaccurate. A blood pressure monitor that meets the AAMI and BHS validation criteria may report blood pressures in error by more than 5 mmHg for more than half of the people. CONCLUSIONS: A validation standard that does not take account of the person-effects on error will lead to a substantial proportion of persons using self-monitors that are systematically inaccurate for that person.

Blood Pressure Determination↗
PubMed2002

The influence of work- and home-related stress on the levels and diurnal variation of ambulatory blood pressure and neurohumoral factors in employed women.

The purpose of this study was to examine the effects of self-reported perceived stress at work and home on the levels, variation and co-variation of ambulatory blood pressure (BP), pulse rate (PR) and urinary catecholamine, cortisol, and aldosterone excretion measured at work, home and during sleep in women employed outside the home. The subjects of the study were 134 women (mean age 34.4 +/- 9.6 years, range 18 to 64 years) who were employed in managerial, technical or clerical positions at the same work place. Perceived stress at work and home was self-reported on a scale from 0 (low) to 10 (high). BP, PR and the urinary rates of excretion of epinephrine, norepinephrine, cortisol and aldosterone were averaged in the daily work environment from 11 AM to 3 PM, in the daily home environment from approximately 6 PM to 10 PM, and during sleep from approximately 10 PM to 6 AM the following morning. The results showed that systolic and diastolic BP (SBP and DBP) and the rates of urinary catecholamine, cortisol, and aldosterone excretion measured in the work environment were significantly higher than corresponding measurements taken in the home environment. SBP measured at work was also positively correlated with the difference in perceived stress between work and home (p < 0.05). PR (p < 0.001) and the rate of urinary norepinephrine excretion (p < 0.05) measured in the home environment were positively correlated with stress at home. When the subjects were divided into groups based on whether the work or home environment was perceived to be most stressful, women reporting greater stress at work (n=85) had higher work SBP (p < 0.005), work DBP (p < 0.05), and sleep SBP (p < 0.005) than women who perceived the home environment to be more stressful (n=34). There were no differences in the urinary hormonal excretion rates between these perceived-stress groups. Among women with greater perceived stress at home, the home-stress score was positively correlated with sleep SBP level (r = 0.310, p < 0.05), its variation (SD of sleep SBP: r = 0.402, p < 0.01) and home pulse rate ( r= 0.414, p < 0.01). These findings suggest that among employed women, work stress may increase ambulatory BP levels throughout the day, while home stress may induce additional sympathetic activation at home. In addition, they also show that among employed women who perceive greater stress at home than at work, higher home stress levels may also elevate sleep BP levels.

Adult↗
PubMed2002

Psychological and physical stress-induced cardiovascular reactivity and diurnal blood pressure variation in women with different work shifts.

There is increasing evidence that diurnal blood pressure (BP) variation, in addition to high BP per se, is related to target organ damage and the incidence of cardiovascular events. However, the determinants of diurnal BP variation are not adequately understood. This paper tests the hypothesis that cardiovascular reactivity to acute stress and/or delayed recovery predicts greater diurnal BP variation (i.e., a lower sleep/awake BP ratio). We studied the relationship of diurnal BP variation (assessed by ambulatory BP monitoring) to mental stress (mental arithmetic and anger recall tasks) and physical stress (treadmill)-induced cardiovascular reactivity and recovery in 87 female nurses who worked different shifts. The sleep/awake systolic BP (SBP) ratio was negatively correlated with relative SBP reactivity (maximum SBP increase/baseline SBP: r = -0.21, p = 0.06) and relative stress response (average of SBP during stress/baseline SBP:r = -0.23, p = 0.04) induced by anger recall, while the correlations of the sleep/awake SBP ratio with other parameters of reactivity or recovery in the anger recall or mental arithmetic task were not significant. When subjects were divided into day-shift workers (n=54) and night-shift workers (n = 33), the sleep/awake SBP ratio was negatively correlated with relative SBP reactivity (r = -0.41, p = 0.02) and relative stress response of SBP (r = -0.48, p = 0.006) induced by anger recall, and positively correlated with recovery rate (r = 0.34, p = 0.06) in the latter group, while these correlations were not significant in the former group. The sleep/awake SBP ratio was inversely correlated with the exercise-induced SBP increase in the day-shift workers (r = -0.30, p = 0.03), while this association was not found in the night-shift workers. In conclusion, cardiovascular reactivity triggered by psychological and physical stress in the laboratory may be a weak, but significant, determinant of diurnal BP variation; in addition, work shift (day or night) appears to moderate the relationship between these two pressor mechanisms.

Adult↗
PubMed2002

[Silent and clinically overt stroke in older Japanese subjects with white-coat and sustained hypertension].

BACKGROUND: Whether white-coat hypertension in older subjects is a benign condition or is associated with an increased risk for stroke remains uncertain. White-coat hypertension as a risk factor for stroke was investigated in relation to silent cerebral infarct in the older Japanese population. METHODS: The prognosis for stroke was studied in 958 older Japanese subjects [147 normotensives (NT), 236 white-coat hypertensives (WCHT), and 575 sustained hypertensives (SHT)] in whom ambulatory blood pressure monitoring was performed in the absence of antihypertensive treatment. Silent cerebral infarct was also assessed using brain magnetic resonance imaging in 585 subjects (61%). RESULTS: Silent cerebral infarcts were found in 36% of NT (n = 70), 42% of WCHT (n = 154), and 53% of SHT (n = 361), and multiple silent cerebral infarcts(presence of > or = 2 silent cerebral infarcts) were found in 24% of NT, 25% of WCHT, and 39% of SHT. During a mean 42-month-follow-up period, clinically overt strokes occurred in 62 subjects [NT 3(2.0%), WCHT 5(2.1%), SHT 54(9.4%)], with 14 fatal cases [NT 1(0.7%), WCHT 0(0%), SHT 13 (2.3%)]. Cox regression analysis showed that age (p = 0.0001) and SHT [RR(95% confidence interval): 4.3 (1.3-14.2), p = 0.018] were independent stroke predictors, whereas WCHT was not significant. Adding presence/absence of silent cerebral infarct at baseline into this model, the RR (95% confidence interval) for silent cerebral infarct was 4.6 (2.0-10.5) (p = 0.003), and that of SHT was 5.5 (1.8-18.9) vs WCHT (p = 0.004) and 3.8 (0.88-16.7) vs NT (p = 0.07). CONCLUSIONS: The incidence of stroke in WCHT is similar to that of NT, and one fourth the risk in SHT in older subjects. Although silent cerebral infarct is a strong predictor of stroke, the difference in stroke prognosis between SHT and WCHT was independent of silent cerebral infarct. It is clinically important to distinguish WCHT from SHT even after assessment of target organ damage in the elderly.

Aged↗
PubMedDate not supplied

Hot flashes are associated with increased ambulatory systolic blood pressure.

OBJECTIVE: To determine the association between ambulatory blood pressure (BP) and hot flash experience. DESIGN: The participants in the study were 154 women (mean age=46 years, range=18-65 years), who were evaluated as part of a cross-sectional study on ethnicity, socioeconomic status, and diurnal BP patterns. Participants could be either normotensive or mildly hypertensive. Participants wore an ambulatory BP monitor for 24 hours and recorded their awake and sleep times. Hot flashes were assessed using an everyday complaint questionnaire that embeds symptoms associated with menopause into a list of everyday complaints. RESULTS: Thirty-three percent of participants reported having had hot flashes during the 2 weeks before they completed the questionnaire. Compared with women who did not report hot flashes, mean awake and sleep systolic BP values were significantly higher (P<0.004 and P=0.007, respectively) in women who reported having had hot flashes. Hot flashes continued to independently predict average awake and sleep systolic BP (both P=0.03) after controlling for age, race/ethnicity, body mass index, and menopausal status. Hot flashes were not associated with diastolic BP or nocturnal dipping of BP. CONCLUSIONS: Hot flashes are associated with increased awake and sleep systolic BP independent of menopausal status. Further investigation is warranted to elucidate the mechanisms by which hot flashes are associated with BP.

Adolescent↗
PubMedDate not supplied

Toward a causal model of cardiovascular responses to stress and the development of cardiovascular disease.

OBJECTIVE: Cardiovascular reactivity is hypothesized to mediate the relationship between stress and cardiovascular disease. We describe three considerations that are crucial for a causal model of cardiovascular responses to stress: the need for laboratory-life generalizability, the role of interactions between environmental exposures and individual response predispositions, and the importance of the duration of both stressor exposure and cardiovascular responding. METHODS: We illustrate current understanding of stress-cardiovascular disease relationships with examples from the human and animal psychophysiology, epidemiology, and genetics literature. RESULTS: In a causal model of reactivity, the usefulness of laboratory assessment rests on the assumption that laboratory-based cardiovascular reactivity predicts responses in the natural environment. We find only limited generalizability and suggest that cardiovascular responses to stress can be better understood when examined in the natural environment. The interaction of individual response predispositions and stressor exposures contributes to the development and progression of cardiovascular disease; stress-disease relationships could therefore be better understood if predispositions and exposures were assessed simultaneously in interactive models. Cardiovascular responses to stress are likely to be most deleterious when responses are prolonged. Responses may vary in their magnitude, frequency, and duration; however, reactivity captures only response magnitude. The assessment of anticipatory and recovery measures, with response magnitude, may therefore lead to a more useful model of the stress-disease relationship. CONCLUSIONS: A causal model of cardiovascular responses to stress should generalize to the real world, assess interactions between individual predispositions and environmental exposures, and focus on sustained pathogenic exposures and responses.

Adolescent↗
PubMedDate not supplied

Orthostatic intolerance.

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Autonomic Nervous System↗