Family history of hypertension and pain during blood donation

Impact of antihypertensive treatment on resiliency to clinical pain

OBJECTIVES

Although progress has been made in the regulation of hypertension over the past decades, the USA and some other countries have faced a significant rise in incidence of chronic pain management cases during the same period. Studies of the relationship between pain and blood pressure (BP) regulations propose that these two processes may be interconnected. Studies of effects of antihypertensive treatment on pain in general and its chronification have never been reviewed.

METHODS

A narrative review of respective studies with analysis of credibility of the findings was conducted.

RESULTS

Some studies have suggested that aggressive reduction of high BP may contribute to a return in pain symptoms and may require more aggressive, long-term pain management. Other studies propose that long-term antihypertensive medication could also increase the risk for new cases of chronic pain. Pain initiates a central neuroplastic resetting of the baroreceptor activation accounting for sustained increase of BP with an adaptive 'pain-killing' or maladaptive 'pain-complication' effect associated with pain chronification, and these mechanisms may be moderated by antihypertensive medications. However, different antihypertensive drugs and nondrug treatments may diversely affect pain mechanisms at different stages of treatments.

CONCLUSION

Uncontrollable reduction of high BP in some patients with hypertension could increase the risk for chronic pain incidence and its severity. Practical recommendations in BP control should be reconsidered to take into account patients' chronic pain. Further research is needed of moderation effects of different antihypertensive manipulations on pain to improve pain management in these patients.

Enhanced pain perception prior to smoking cessation is associated with early relapse

Accumulated evidence suggests that nicotine induces analgesia, and endogenous pain regulatory mechanisms may be altered by chronic smoking. The extent to which individual differences in pain perception are related to smokers' ability to abstain from smoking has not been directly examined. Seventy-one smokers who were interested in quitting completed a pre-cessation laboratory session which included the cold pressor test (CPT). Pain ratings were collected during and after CPT. Also, mood changes, cardiovascular measures, and salivary cortisol samples were evaluated prior to, during, and after CPT. Participants attended 4 weekly follow-up assessment sessions after their quit day. Cox regression analysis revealed that higher pain ratings during and after CPT predicted greater risk for smoking relapse. These results remained significant after affective and physiological responses to CPT were controlled, suggesting that pain ratings prior to smoking cessation are potentially useful in identifying smokers who are at greater risk of early smoking relapse and may reflect underlying putative risk for nicotine dependence and relapse.

Ultrasound-enabled topical anesthesia for pain reduction of phlebotomy for whole blood donation

BACKGROUND

Ultrasound-facilitated delivery of topical anesthetics has been used to achieve effective anesthesia within 5 minutes for venipuncture and the insertion of intravenous access devices, but has never been studied for blood donation.

STUDY DESIGN AND METHODS

This study was a single-center, prospective, randomized, sham treatment-controlled, single-blinded clinical evaluation. Repeat donors were randomly assigned to undergo treatment with ultrasound and topical anesthetic or sham ultrasound and placebo anesthetic before phlebotomy for whole blood donation. The primary outcome measures were pain assessments using the Verbal Categorical Scale (VCS) and the Visual Analogue Scale and the assessment of skin irritation at the target site.

RESULTS

One-hundred subjects were enrolled and all completed the study. Compared to the sham/placebo control group, donors receiving ultrasound/anesthetic had lower pain scores on the VCS (1.81 +/- 0.67 vs. 2.17 +/- 0.68; p = 0.01) and Visual Analog Scale (17.2 +/- 15.5 vs. 27.6 +/- 19.5; p = 0.006). The proportion of subjects in the treatment group who experienced skin irritation (8%) was similar to that in the control group (2%; p = 0.20).

CONCLUSION

Ultrasound-enhanced delivery of topical anesthetic was demonstrated to be a safe means of quickly achieving clinically meaningful reduction in the pain of phlebotomy for whole blood donation compared to sham/placebo treatment.

Pain perception, blood pressure levels, and peripheral benzodiazepine receptors in patients followed for differentiated thyroid carcinoma: a longitudinal study in hypothyroidism and during hormone treatment

BACKGROUND

Elevated blood pressure levels that are associated with hypalgesia and hypothyroidism have major influences on the cardiovascular system. The potential modulation of pain sensitivity by thyroid hormones is largely undetermined. Moreover, a few experimental studies show that peripheral benzodiazepine receptors (PBRs), which may be altered in hypothyroidism, seem to be related with pain perception.

METHODS

Dental pain threshold and tolerance were evaluated in 19 patients followed for differentiated thyroid carcinoma (1) in severe short-term hypothyroidism (phase 1) and (2) during thyroid stimulating hormone-suppressive LT4 treatment (phase 2). PBR expression (cytofluorimetric evaluation) on peripheral blood mononuclear cells was also investigated in the 2 phases.

RESULTS

Pain perception differed throughout the study, the dental pain threshold was higher in phase 1 (P<0.05) whereas pain tolerance was higher but not significantly (P=0.07). Although the systolic blood pressure was higher during hypothyroidism (P<0.01), no relationship was found between blood pressure changes and pain sensitivity variations. Moreover, the multiple regression analysis showed an independent association of the clinical phase with pain sensitivity (r=-2.61, P=0.029), while accounting for systolic blood pressure. The intensity of PBRs was significantly higher in the first phase of the study (P=0.047) whereas the ratio did not significantly differ. However, no relationship was observed between pain sensitivity and PBRs.

DISCUSSION

In conclusion, in athyreotic patients, the pain sensitivity is related to the thyroid status and is independent of the increase in blood pressure induced by thyroid hormone deprivation. The PBRs do not seem to have major influence on pain sensitivity changes in hypothyroidism.

Effects of opioid blockade on the modulation of pain and mood by sweet taste and blood pressure in young adults

Increased blood pressure and sweet taste are often associated with decreased pain sensitivity. Animal research suggests that endogenous opioids are involved in both these relationships. Fifty-eight healthy young adults (36 male, 22 female) participated in two sessions receiving a placebo tablet or 50mg of naltrexone on counterbalanced days. On each day, three cold-pressor tests were administered while the participant held a sweet solution, water, or nothing in their mouth when their hand was in the water. 2 Drug x 3 Solution x 2 Gender x Pre-Drug Resting Blood Pressure general linear models (GLM) were conducted separately for systolic (SBP) and diastolic (DBP) pressure. Consistent with previous research, significant main effects of SBP were observed in GLMs of pain tolerance and pain unpleasantness ratings. A main effect of solution on tolerance was seen in the GLM with DBP, which was qualified by an interaction of solution by blood pressure. Sweet taste increased pain tolerance among those with lower DBP across drug conditions. This suggests some overlap between mechanisms of sweet taste and blood pressure analgesia, without implicating opioid activity in sweet taste analgesia. However, the GLM of tolerance also produced a significant drug by DBP interaction suggesting that blood pressure-related analgesia is at least partially opioid-mediated. Also participants with higher DBP showed dampened mood reactivity to the experiment, which was partially reversible by naltrexone. These results are consistent with findings suggesting that endogenous opioid activity may contribute to generally reduced pain sensitivity, and perhaps mood reactivity, in those with higher BP.

Fear of needles and vasovagal reactions among phlebotomy patients

Anxiety associated with blood and injections is a common problem in medical settings and, in severe cases, affects sufferers' ability to receive medically essential treatment. The present study was conducted to examine incidence of adverse reactions to venipunctures among phlebotomy patients, as well as to understand the demographic and psychological characteristics associated with such reactions. A large sample of participants undergoing venipuncture (N=3315) was recruited from hospital-based phlebotomy laboratories. Participants completed a brief questionnaire assessing psychological and physiological reactions to having their blood drawn. Results indicated that a small minority of patients experienced significant anxiety symptoms during venipuncture. Vasovagal reactions and vasovagal syncope were extremely infrequent. A tendency to experience pain, disgust, and fear of fainting during injections was associated with anxious responding to the venipuncture and a probable diagnosis of needle phobia. Theoretical and practical implications are discussed.

Assessment of opiate modulation of pain and nociceptive responding in young adults with a parental history of hypertension

This double blind, placebo-controlled study examined the effects of an opiate antagonist, naltrexone, on nociceptive flexion reflex (NFR) thresholds and subjective pain in individuals with and without a parental history of hypertension. Using a repeated measures design, NFR threshold was repeatedly assessed on two testing days after administration of either placebo or naltrexone. Immediately after NFR threshold was determined, participants rated the level of pain experienced during the preceding NFR assessment, and at the end of each session participants' electrocutaneous pain threshold was assessed. Two primary findings were obtained. First, individuals with a parental history of hypertension exhibited attenuated pain sensitivity. Second, endogenous opioid blockade was associated with increased pain ratings in women but with increased pain threshold in men. In sum, the present study did not support a direct involvement of the endogenous opioid system in the attenuated pain sensitivity observed in individuals at increased risk for hypertension.

Nociception and baroreceptor stimulation in hypertension-prone men and women

We examined the effects of baroreceptor stimulation on nociceptive responding in men and women with a positive or negative parental history of hypertension. The effects of three baroreceptor conditions (stimulation, inhibition, and control) on subjective pain and nociceptive responding were evaluated during electrocutaneous sural nerve stimulation. Pain ratings were lower in men with positive parental history relative to men with negative parental history, but this difference was not found in women. Both stimulatory and inhibitory baroreceptor conditions were associated with reduced pain reports compared to the control condition. There were no significant differences in nociceptive responding as a function of parental history of hypertension. Although this study confirms a link between hypoalgesia and risk for hypertension in men, it does not support the hypothesis that this attenuated pain perception is due to enhanced baroreceptor activity.

Muscle pain during exercise in normotensive african american women: effect of parental hypertension history

The purpose of the present investigation was to determine the influence of parental hypertension history on leg muscle pain ratings during cycling exercise in African American women. Eighteen women (age, 19 +/- 2 years) with a positive family history (+PH) of hypertension and 16 (age, 19 +/- 1 years) with a negative family history (-PH) underwent maximal exercise and cold pressor testing. Maximal exercise was conducted on a cycle ergometer. Quadriceps muscle pain intensity ratings were obtained each minute during the maximal exercise test by using a category-ratio scale. The hand cold pressor test was used to determine cardiovascular reactivity. Repeated measures analysis of variance showed significantly lower pain ratings during exercise for the +PH group compared to the -PH group. Psychophysical power functions indicated that the +PH participants had significantly lower exponents for pain throughout exercise. Systolic blood pressure reactivity did not significantly predict pain ratings during exercise. Normotensive African American women with +PH of hypertension experienced less muscle pain during exercise compared to normotensive African American women with a -PH of hypertension. The results are consistent with data demonstrating reduced sensitivity to experimental pain stimuli in individuals at risk for developing hypertension and extend them to naturally occurring muscle pain produced by exercise.

PERSPECTIVE

African American women, a sedentary group with an elevated risk for developing hypertension and chronic pain, show the same negative relationship between +PH and pain perception as men, suggesting that central nervous system mechanisms of pain modulation are more related to family history than gender. Acute exercise provides an experimental model for manipulating naturally occurring pain in studies concerned with the association between pain and hypertension.

Adolescent pain sensitivity is associated with cardiac autonomic function and blood pressure over 8 years

Low pain sensitivity has been reported in hypertensive subjects as well in groups deemed to be at increased risk of development of the disorder. However, it is uncertain whether individual differences in pain sensitivity are associated prospectively with increases in blood pressure. In the current study, 24-hour blood pressure and heart rate variability were recorded in 110, 22-year-old men previously assessed at age 14 years for casual blood pressure and pain sensitivity (mechanical finger pressure). Significant correlations were observed between pain tolerance in 14-year-olds and current 24-hour systolic blood pressure (r=0.37, P<0.01) and diastolic blood pressure (r=0.36, P<0.01). Hierarchical multiple regression analyses indicated that information regarding pain tolerance improved prediction of systolic and diastolic blood pressure at age 22 years beyond that afforded by differences in blood pressure, parental history of hypertension, and body mass index at age 14 years. Similar analyses revealed that average pain sensitivity at age 14 was also associated with 24-hour high-frequency heart rate variability (r=0.28, P<0.01) and low-frequency/high-frequency heart rate variability at age 22 (r=-0.35, P<0.01), suggesting increased sympathetic and reduced parasympathetic tone among individuals less sensitive to pain. These results provide further evidence that blood pressure related hypoalgesia might be related to processes involved in blood pressure regulation as well as in the development of sustained high blood pressure.

A longitudinal study of pain sensitivity and blood pressure in adolescent boys: results from a 5-year follow-up

A growing literature has observed a significant reduction in pain sensitivity among hypertensive animals and humans. It is uncertain whether a reduced sensitivity to pain can be observed in nonnotensive individuals who go on to develop high blood pressure. Blood pressure (BP) was reassessed in one hundred fifteen 19-year-old boys initially tested at age 14, when they were also presented with a pain stimulus (mechanical finger pressure). Hierarchical regression analyses indicated that information regarding pain tolerance improved prediction of changes in systolic and diastolic blood pressure beyond that afforded by differences in BP at age 14, parental history of hypertension, and body mass index. These analyses suggest that pain sensitivity may be associated with physiological processes involved in the development of sustained high blood pressure.

Hypertension and appraisal of physical and psychological stressors

OBJECTIVE

In the operant conditioning of hypertension hypothesis, it is assumed that the frequently found diminished sensitivity to painful stimuli in hypertensives can be generalized to sensitivity to other stressors, including psychological stressors. The validity of this assumption is examined in the present study.

METHODS

Unmedicated hypertensives (42) and normotensive controls (21) of both sexes were exposed to a physical stressor (electric current) and psychological active coping (mental arithmetic, free speech) and passive coping (unpleasant films) tasks, while indices of prestressor anxiety and task appraisal were measured.

RESULTS

Hypertensive women, but not men, showed diminished pain sensitivity, together with lower prestressor anxiety and a tendency to lower negative appraisal of the tasks, compared to their normotensive counterparts. In addition, positive correlations were obtained between pain sensitivity and negative appraisal of psychological stressors involving interpersonal threat (speech) and passive coping (films).

CONCLUSION

Preliminary support has been obtained for extrapolation of diminished pain appraisal to appraisal of some psychological stressors (although for a part only in women); an important assumption in the operant conditioning hypothesis of hypertension.

Cardiopulmonary baroreflex stimulation and blood pressure-related hypoalgesia

Results from both experimental animals and humans suggest that baroreflex stimulation may be involved in blood pressure-related hypoalgesia. However, most of this research, especially in the area of human experimentation, has focused on sinoaortic baroreceptors. Cardiopulmonary baroreflex stimulation may also be an important moderator of pain. Sixty-six healthy male undergraduates varying in risk for hypertension participated in an experimental protocol in which painful mechanical finger pressure was presented three times in a counterbalanced fashion. One pain stimulus was preceded by 6 min of supine rest, another by a period of rest interspersed with periodic Valsalva manoeuvres, and another by a period in which cardiopulmonary baroreceptors were stimulated by passive leg elevation. Significantly lower pain was reported by men with relatively elevated systolic blood pressure following leg elevation but not the other conditions. Cardiopulmonary baroreflex stimulation was documented by increased forearm blood flow and other data obtained via impedance cardiography. These results suggest that blood pressure related hypoalgesia may be at least partially related to cardiopulmonary baroreflex stimulation.

Relationship between dental pain perception and 24 hour ambulatory blood pressure: a study on 181 subjects

OBJECTIVE

To investigate dental pain perception in a large group of essential hypertensive subjects.

METHODS

A total of 130 hypertensive patients together with 51 normotensive subjects were submitted to tooth-electrical stimulation to determine the dental pain threshold (occurrence of pulp sensation) and tolerance (time when the subject asked for the test to be stopped). Blood pressure was measured at rest, before pain perception evaluation, and during a 24 h period by ambulatory monitoring.

RESULTS

The normotensive and hypertensive subjects differed with regard to pain threshold (P = 0.002) and tolerance (P = 0.01). Pain perception variables were significantly correlated with both resting blood pressure and 24 h, diurnal and nocturnal arterial pressures, the correlation between pain threshold and 24 h systolic blood pressure being the most significant (r = 0.31, P < 0.0001). By contrast, parameters indicating 24 h blood pressure variability (percentage of nocturnal blood pressure reduction and 24 h blood pressure variation coefficients) were not associated with pain perception. Moreover, among the hypertensives only, a significant relationship was observed between pain sensitivity and both baseline and 24 h pressures. No association was found when pain perception and blood pressure were correlated in the normotensive group.

CONCLUSIONS

The correlation between both baseline and 24 h blood pressure and pain perception has been confirmed in a large group study of normotensive and hypertensive subjects. Moreover, even among the hypertensive range of blood pressure, the higher the blood pressure is, the lower the sensitivity to pain is. These findings strengthen the hypothesis of a role of the degree of blood pressure elevation in modulating pain sensitivity.

Sex differences in pain perception and cardiovascular responses in persons with parental history for hypertension

We investigated gender differences in cardiovascular and pain responses to the cold pressor (CP) test in persons with positive (PH+) or negative parental history (PH-) for hypertension. Previous work has suggested an attenuated sensitivity to painful stimulation in hypertensive men and more recently in men with parental disposition for hypertension. It is not known whether this hypoalgesic effect is present in PH+ women. In this study, we evaluated differences in pain perception between men and women with PH+ or PH- using an assessment method to measure current as well as delayed pain. Participants rated their pain every 15 s during a 90-s hand CP (0-4 degrees C) and a 90-s post-CP rest period. Systolic and diastolic blood pressures (SBP, DBP) and heart rate (HR) were measured before, during, and after the CP. PH+ and PH- groups did not differ in age, height, weight, education, resting SBP, DBP, or HR. PH+ men showed greater DBP responses to the CP than PH- men, while female groups did not differ in cardiovascular responses to the CP. Although pain ratings during the CP did not differ between groups, post-CP reported pain receded faster in the PH+ men than in the PH- men. PH+ women, on the other hand, tended to report greater pain than PH- women. These findings question the generalizability of the hypoalgesic effects in hypertension-prone women.

Relationship between a genetic predisposition to hypertension, blood pressure levels and pain sensitivity

INTRODUCTION

The aim of this study was to determine whether the degree of blood pressure elevation and/or a genetic predisposition to hypertension have a major role in determining a reduced pain perception in hypertensives. The reasons underlying the relationship between blood pressure elevation and pain perception mechanisms are not completely understood.

METHODS

One hundred and four untreated hypertensive patients (65 subjects with and 39 without a positive parental history of hypertension) together with a control group of 42 subjects (20 normotensive offspring of normotensive parents, and 22 normotensive offspring of hypertensive parents) were submitted to standard blood pressure evaluation, 24-h blood pressure monitoring and dental pain perception evaluation.

RESULTS

Both pain threshold and tolerance were found to be higher in hypertensive than normotensive subjects (P < 0.0001 and P < 0.015, respectively). Positive significant correlations were found between both 24-h systolic and diastolic pressure and the pain perception variables. When a 2 x 2 ANOVA test was performed, factoring for the effects of both blood pressure status and family history of hypertension on pain sensitivity, a significant effect was revealed only for blood pressure status. Moreover, after controlling for blood pressure by a covariate analysis, no significant difference was found between the subjects with or without hypertensive parents as regards pain perception variables.

CONCLUSIONS

Pain sensitivity is correlated to blood pressure levels whereas the parental history of hypertension per se does not affect the pain perception pattern. Thus, the degree of blood pressure elevation, more than a genetic predisposition to hypertension may influence the mechanisms leading to hypalgesia in hypertension.

Hypertension and pain sensitivity: effects of gender and cardiovascular reactivity

Repeatedly, hypertensives have been found to appraise physical stressors as less aversive than normotensives. The main aim of the present study was to examine the effects of gender and cardiovascular reactivity in the relationship between hypertension and appraisal of pain. Forty-two unmedicated hypertensives and 21 normotensive controls of both genders were exposed to an electric current stimulus, while various cardiovascular parameters and prestressor anxiety were measured. In general, hypertensive women, but not men, showed diminished pain sensitivity compared to their normotensive counterparts. When the analyses were repeated with controlling for cardiovascular reactivity, the between-group effects were no longer significant. The results indicate that (i) profound gender differences exist in hypertension-related pain sensitivity and (ii) these effects seem to be mediated, at least partly, by cardiovascular reactivity.

Risk for hypertension and diminished pain sensitivity in women: autonomic and daily correlates

Research suggests an association between risk for hypertension and decreased pain sensitivity. However, few studies have utilized non-behavioral indices of pain to corroborate subjective reports or sought to generalize these findings to women. Furthermore, it has not been established whether results obtained using well-controlled laboratory pain stimuli extend to naturalistic pain. In Study 1, 80 young adult women with (N = 40) and without (N = 40) a parental history of hypertension and with either normatively low or high resting systolic blood pressure (SBP) were exposed to two experimental pain stimuli, finger pressure and the cold pressor test. In addition to behavioral pain measures, respiratory sinus arrhythmia (RSA) reactions to pain were also assessed. Women with a parental history of hypertension and/or normatively high resting SBP experienced significantly less pain, as assessed by both behavioral and RSA measures. In Study 2, 37 of the participants from Study 1 monitored their behaviors, affect, and physical symptoms, three times a day for 32 days. Laboratory pain sensitivity was significantly correlated with daily reports of pain but not gastrointestinal symptoms. The present results confirm an association between risk for hypertension and hypoalgesia in women and suggest generalizability of this relationship to everyday life.

Resting blood pressure and thermal pain responses among females: effects on pain unpleasantness but not pain intensity

In order to investigate the influence of resting blood pressure on thermal pain responses among females, this experiment studied 21 pain-free, normotensive females (mean age 23) classified as having high (HBP) vs. low blood pressure (LBP) based on a median split of resting blood pressure collected prior to thermal testing. All subjects then underwent thermal pain testing, including determination of pain threshold and tolerance followed by verbal descriptor ratings of the intensity and unpleasantness of suprathreshold thermal stimuli, ranging from 45 to 49 degrees C. Thermal stimuli were delivered to the volar forearm and the ipsilateral face using a 1 cm2 contact thermode. Results indicated that the blood pressure groups did not differ in thermal pain threshold or tolerance or on ratings of the intensity of suprathreshold thermal stimuli. However, the HBP group provided significantly lower ratings of thermal pain unpleasantness than the LBP group (P < 0.01). These data indicate that resting blood pressure is inversely associated with pain sensitivity among females, but this relationship may be selective for the affective component of pain.

An historical and critical review of the articles on blood pressure published in Psychosomatic Medicine between 1939 and 1997

Between 1939 and 1997, there have been 59 volumes of Psychosomatic Medicine. Over this period there were 200 articles dealing with blood pressure. About 90% of these were concerned with high blood pressure. This article reviews all of these papers both from an historical perspective and critically. Although there has been a significant growth in the rate of articles published since 1939, there has always been a strong interest in the nature of hypertension, particularly the roles of affects and emotions in the natural history of the disease. For example, volume 1, number 1 of the Journal includes a symposium on high blood pressure in which Franz Alexander stated his well-known hypothesis that the chronic inhibition of rage plays a causal role in the production of hypertension. In various forms, the notion that anger is an important mediator of hypertension has neither been proved nor abandoned. One major conclusion drawn from this review is that the current research on high blood pressure is drifting somewhat aimlessly. It has become preoccupied with demonstrations that various stimuli or situations (usually characterized as stresses) can acutely raise blood pressure. Despite this focus, neither the necessary nor the sufficient conditions for labeling a stimulus as stress has ever been agreed upon. Likewise, there have been many demonstrations of an iatrogenic effect on blood pressure, but neither the behavioral mechanisms underlying this effect nor the strategies for eliminating it have been explicated. Finally, this article identifies several areas where it would be useful to review and integrate current knowledge. Hopefully, such integrations could play a significant role in focusing and shaping future research and clinical practice.

Blood pressure-related hypoalgesia in bulimia nervosa

OBJECTIVE

This study examined pain sensitivity and its relationship to arterial blood pressure in bulimia nervosa (BN).

METHODS

Fourteen women who met Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, criteria for BN, purging subtype, and 14 controls were tested for ischemic pain sensitivity after an extended baseline period. Blood pressure, cardiac output, stroke volume, and total peripheral resistance were assessed during baseline, during ischemic pain testing, and at the point of voluntary tolerance.

RESULTS

Women with BN had significantly greater ischemic pain tolerance than controls. Additionally, only for BN women was blood pressure related to pain sensitivity. Systolic blood pressure during the pain procedure and at the point of tolerance was positively related to pain threshold and tolerance times and negatively related to rated unpleasantness of pain in BN, whereas no relationships involving blood pressure and pain sensitivity were observed in controls.

CONCLUSIONS

These results may have implications for maladaptive changes in central pain-cardiovascular regulatory systems for women with BN.

Blood pressure and metabolic factors in relation to chronic pain

Physical pain is a major trigger for changes in many homeostatic systems of the body physiology. Our aim was to study the relationship between blood pressure, metabolism and pain perception in subjects with chronic pain symptoms. This was undertaken in a population-based study in primary health care, including subjects with widespread pain (n = 16), or localized pain (n = 15), and pain-free controls (n = 14). The main outcome measures were office and ambulatory blood pressure, glucose, insulin, lipids, and beta-endorphin. Subjects with widespread pain were more obese and showed higher levels than controls (p < 0.05) of fasting glucose (4.9 vs 4.5 mmol/l), cholesterol (6.9 vs 5.8 mmol/l) and office systolic blood pressure (133 vs 120 mmHg), while the subjects reporting localized pain had values in-between. Ambulatory blood pressure, insulin and beta-endorphin levels did not differ between the groups. In conclusion, subjects with widespread and/or intense chronic pain have higher BMI, more pronounced metabolic disturbances and higher (office) systolic blood pressure, but not ambulatory blood pressure, than subjects without chronic pain. Future epidemiological studies are needed to test whether this is compatible with increased cardiovascular risk.

Empirical contributions

To evaluate the possible negative association between risk for hypertension and pain sensitivity by in women 24 healthy young adult women with a parental history of hypertension and 24 without a parental history of hypertension participated in 2 laboratory sessions in which electric shock and the cold-pressor test were administered To assess the possible role of stress-induced analgesia in blood pressure-related hypoalgesia, the sessions were identical with the exception of the fact that participants were exposed to a stressful 20-min videogame before the pain stimuli on one occasion and a nonstressful control task on the other. Women with a parental history of hypertension and high blood pressure reactivity to the videogame displayed a reduced sensitivity to electric shock on both days, suggesting that risk for hypertension is associated with reduced sensitivity to at least some pain stimuli in women. Blood pressure reactivity to stress-associated baroreceptor stimulation was not implicated as a mediator of decreased pain perception. However, other analyses revealed an effect of family history on shock pain only among women who report relatively high anxiety, suggesting that other aspects of the stress response may be involved in this phenomenon.

Blood pressure, gender, and parental hypertension are factors in baseline and poststress pain sensitivity in normotensive adults

We studied 38 men and 36 women to learn whether a brief speech stressor reduced normotensive humans' thermal pain sensitivity, whether baseline and poststress pain threshold and tolerance varied with blood pressure (BP) and hemodynamic measures, and whether these relations differed by gender and parental hypertension (PH). PH-women with low-resting BPs had lower baseline pain tolerance than did all the other groups (ps <.05), and this group alone exhibited stress-induced analgesia (p = .008). In women, pre- and poststress pain tolerance varied directly with rest and stress BP (ps <.05).

Resting systolic blood pressure, parental history of hypertension, and sensitivity to noxious stimuli

Increased nociceptive thresholds have been reported in hypertensive rats and humans, and also in normotensive humans at risk for developing hypertension by virtue of elevated resting blood pressure levels or a family history of hypertension. Because risk for hypertension may be more accurately predicted by a combination of risk factors, the present study examined the pain sensitivity of young adult males as a function of resting systolic blood pressure and family history of hypertension. Cold pressor and forearm ischemia tasks were administered in a counterbalanced order. Pain was assessed using numerical rating scales of intensity and unpleasantness during the tasks and the McGill Pain Questionnaire immediately following the tasks. Individuals with a parental history of hypertension obtained significantly lower Pain Rating Index scores on the McGill Pain Questionnaire for both tasks, and also reported significantly lower pain on both numerical rating scales during the ischemic task. No significant relationship was observed between resting systolic blood pressure and measures of pain sensitivity.

Pain perception and cardiovascular responses in men with positive parental history for hypertension

Evidence suggests a reduced pain sensitivity in hypertensive individuals. This study sought to extend this work to normotensive individuals with hypertensive parents. Men with a positive (PH+) or negative (PH-) parental history for hypertension rated their pain every 15 s during a 90-s hand cold pressor test and for 90 s after the cold pressor test. Systolic (SBP) and diastolic (DBP) blood pressures and heart rate were measured throughout. After the cold pressor test, the men recalled their pain using the McGill Pain Questionnaire. PH+ men showed greater SBP and DBP responses to the cold pressor test. Although pain ratings during the cold pressor test did not differ between groups, posttest reported pain receded faster in the PH+ than in the PH- men. The PH+ men also reported less total pain on the McGill. These findings support the hypothesis that risk for hypertension may be associated with attenuated pain responses to nociceptive stimuli.

Hypertension-associated hypalgesia. Evidence in experimental animals and humans, pathophysiological mechanisms, and potential clinical consequences

A behavioral hypalgesia (increased response threshold to noxious stimuli) has been consistently, although not invariably, reported in spontaneous and experimental acute and chronic hypertension in the rat. Studies in human hypertension have also demonstrated a diminished perception of pain, assessed as pain thresholds or ratings. The sensitivity to painful stimuli correlated inversely with blood pressure levels, and this relationship extended into the normotensive range. Evidence in humans and rats points to a role of the baroreflex system in modulating nociception. In the rat, blood pressure-related antinociception may be due to attenuated transmission of noxious stimuli at the spinal level secondary to descending inhibitory influences that are projected from brain stem sites involved in cardiovascular regulation and that may depend on baroreceptor activation and/ or on a central "drive." Both endorphinergic and noradrenergic central neurons (the latter acting through postsynaptic alpha 2-receptors) have been shown to be involved, and other mediators probably also play a role. Functionally, blood pressure-related antinociception may represent an aspect of a more-complex coordinated adaptive response of the body to "stressful" situations. It is still uncertain whether in human essential hypertension hypalgesia is secondary to elevated blood pressure or whether both depend on some common mechanism. Studies on the effect of hypotensive treatment are too few to allow conclusions. According to one hypothesis, the reduction in pain perception caused by baroreceptor activation secondary to blood pressure elevation may represent a rewarding mechanism that may be reinforced with repeated stress and may be involved in the development of hypertension in some individuals. Hypertension-associated hypalgesia may have clinically relevant consequences, especially in silent myocardial ischemia and unrecognized myocardial infarction, both of which are more prevalent in hypertensive individuals.

Exteroceptive suppression of temporalis and masseter muscle activity is enhanced in offspring of hypertensives

Exteroceptive suppression of temporalis and masseter muscle activity was examined in young men with and without a parental history of hypertension. Recent clinical studies suggest that the second exteroceptive suppression period is attenuated in several chronic pain disorders and that this brainstem reflex may serve as a noninvasive index of endogenous pain control. In the present study, offspring of hypertensives exhibited a significant protraction of the late exteroceptive suppression period for both muscle sites, suggesting that the decreased pain sensitivity previously observed in individuals at risk for hypertension may be related to enhanced central pain modulation.

The influence of resting blood pressure and gender on pain responses

Recent research suggests that resting blood pressure is inversely related to pain sensitivity, even among normotensives; however, most of these studies have included only male participants. To determine whether this hypoalgesic effect of blood pressure was also present in females, we investigated thermal and ischemic pain responses in a group of age-matched, normotensive females and males as a function of resting blood pressure. Thermal pain threshold and tolerance were determined, and a cross-modality thermal magnitude matching procedure was conducted, after which ischemic pain threshold and tolerance were determined using the submaximal effort tourniquet procedure. Systolic pressure, diastolic pressure, and heart rate were obtained using an automated blood pressure monitor with a pneumatic cuff positioned around the left ankle. Females provided higher normalized thermal magnitude estimates and a shorter time to ischemic pain tolerance, but no gender differences emerged on other pain measures. Systolic, diastolic, and mean arterial pressures were significantly correlated with thermal and ischemic pain responses among males but not females, with higher blood pressure being associated with lower pain sensitivity. After adjusting for resting blood pressure, the gender difference in normalized magnitude estimates was only marginally significant, and the gender difference in ischemic pain tolerance became nonsignificant. These findings are consistent with previous research indicating an inverse relationship between blood pressure and pain sensitivity. Additionally, the findings also suggest that blood pressure may partially moderate gender differences in pain sensitivity. Potential mechanisms and clinical implications of the current findings are discussed.

Predicting vasovagal reactions in volunteer blood donors

Measures of blood and injury sensitivity, pain sensitivity, and anxiety were examined as potential predictors of syncope and related reactions in 215 volunteer blood donors. The Blood and Injury Fears subscale of the Fear Survey Schedule was the best predictor for first-time donors (r[84] = 0.43, p < 0.001), whereas the Mutilation Questionnaire was the best predictor for experienced donors (r[127] = 0.31, p < 0.01). In contrast with previous studies, few significant predictions were observed for demographic variables (e.g., age, body mass index, or number of previous donations), suggesting that psychological measures may be better suited to the task of identifying high risk donors.

Parental history of hypertension and enhanced cardiovascular reactivity are associated with decreased pain ratings

Ischemic pain was examined in adult males with and without a parental history of hypertension. Blood pressure and heart rate were recorded during baseline, cold pressor, and ischemia. Repeated pain ratings were obtained during cold pressor and ischemia, and the McGill Pain Questionnaire was completed after each stressor. A median split was used to identify high and low mean arterial pressure and heart rate reactors to cold pressor. Parental history of hypertension, high heart rate reactivity, and high mean arterial pressure reactivity were each associated with significantly lower ischemic pain ratings on the McGill Pain Questionnaire, suggesting that risk for hypertension is associated with hypoalgesia in normotensives.

Baroreflex sensitivity during noxious stimulation in vasovagal reactors to blood donation

Baroreflex sensitivity was assessed at rest and during constrictive pain in healthy males with and without a history of vasovagal reactions to blood donation. Continuous recordings of cardiac inter-beat interval and finger arterial pressure were obtained at rest and during repeated presentations of constrictive thigh-cuff stimulation. Baroreflex sensitivity (in msec/mm Hg) was computed according to the spontaneous sequence analysis method. Results indicated that vasovagal reactors exhibited significantly lower descending baroreflex sensitivity across all periods, and significantly lower ascending baroreflex sensitivity at rest. Baseline differences in ascending baroreflex sensitivity were eliminated during thigh-cuff stimulation, as vasovagal reactors exhibited increases in ascending baroreflex sensitivity while non-reactors exhibited decreases. These findings suggest that susceptibility to vasovagal reactions may be associated with individual differences in baroreflex sensitivity.

Cardiovascular reactions to blood donation in offspring of hypertensives and normotensives

Blood pressure and heart rate reactions of 182 confirmed offspring of normotensive (110 female, 72 male) and 112 offspring of hypertensive (66 female, 46 male) individuals to the stressor of blood donation were examined. Subjects were tested at two sites, one in the United States and one in Canada. Although influenced by site, young normotensive offspring of hypertensives generally exhibited significantly greater blood pressure levels in anticipation of donating blood than offspring of normotensives. The higher reactivity of offspring of hypertensives observed in stressful laboratory settings may generalize to more ecologically valid settings, even those which, like blood donation, require passive coping efforts.