Percentage Change In Blood Pressure Research Articles

Blood Pressure Response to Patterns of Weather Fluctuations and Effect on Mortality

Very few studies have looked at longitudinal intraindividual blood pressure responses to weather conditions. There are no data to suggest that specific response to changes in weather will have an impact on survival. We analyzed >169 000 clinic visits of 16 010 Glasgow Blood Pressure Clinic patients with hypertension. Each clinic visit was mapped to the mean West of Scotland monthly weather (temperature, sunshine, rainfall) data. Percentage change in blood pressure was calculated between pairs of consecutive clinic visits, where the weather alternated between 2 extreme quartiles (Q(1)-Q(4) or Q(4)-Q(1)) or remained in the same quartile (Q(n)-Q(n)) of each weather parameter. Subjects were also categorized into 2 groups depending on whether their blood pressure response in Q(1)-Q(4) or Q(4)-Q(1) were concordant or discordant to Q(n)-Q(n). Generalized estimating equations and Cox proportional hazards model were used to model the effect on longitudinal blood pressure and mortality, respectively. Q(n)-Q(n) showed a mean 2% drop in blood pressure consistently, whereas Q(4)-Q(1) showed a mean 2.1% and 1.6% rise in systolic and diastolic blood pressure, respectively. However, Q(1)-Q(4) did not show significant changes in blood pressure. Temperature-sensitive subjects had significantly higher mortality (1.35 [95% confidence interval, 1.06-1.71]; P=0.01) and higher follow-up systolic blood pressure (1.85 [95% confidence interval, 0.24-3.46]; P=0.02) compared with temperature-nonsensitive subjects. Blood pressure response to temperature may be one of the underlying mechanisms that determine long-term blood pressure variability. Knowing a patient's blood pressure response to weather can help reduce unnecessary antihypertensive treatment modification, which may in turn increase blood pressure variability and, thus, risk.

Landiolol attenuates cardiovascular response at induction of general anesthesia for cesarean delivery

General anesthesia for cesarean delivery is frequently associated with hypertension and tachycardia caused by tracheal intubation, which may lead to cardiac ischemia in susceptible patients or may cause harm due to increased intracranial pressure. To prevent these adverse events, we investigated the efficacy and safety of single-dose intravenous administration of landiolol, a short-acting selective β(1) receptor blocker, just prior to intubation. Patients scheduled for cesarean delivery under general anesthesia were randomized into two groups: landiolol (group L, n=32); and nontreated (group N, n=32) patients. After patients entered the operating room, blood pressure (BP), heart rate (HR), and fetal heart beats were monitored to ensure no problems were present, then thiopental 5mg/kg and rocuronium 0.9mg/kg were given. In addition, group L received a single dose of landiolol 0.2mg/kg. After tracheal intubation, anesthesia was maintained in both groups using sevoflurane. From before starting anesthesia to the time of delivery, BP, HR, need for additional treatment with uterotonic or vasopressor agents, and neonatal Apgar scores were recorded. Data were compared between groups. Group L showed significantly lower percentage changes in BP and HR than group N (p<0.05 each). Intraoperative blood loss, frequency of decreased uterine contraction, and fetal Apgar scores did not differ significantly between groups. In our study, landiolol reduced BP and HR changes during anesthesia induction, whereas no adverse effects on uterine contraction or the fetus were seen. These findings suggest landiolol provides adequate hemodynamic regulation during general anesthesia induction in patients undergoing cesarean delivery.

Prokinetic therapy with erythromycin has no significant impact on blood pressure and heart rate in critically ill patients

Prokinetic therapy with erythromycin has no significant impact on blood pressure and heart rate in critically ill patients

Assessing dynamic cerebral autoregulation after stroke using a novel technique of combining transcranial Doppler ultrasonography and rhythmic handgrip.

Dynamic cerebral autoregulation (CA) is impaired after stroke. Methods employed to assess this phenomenon usually involve deliberate alterations in blood pressure (BP) by physical means. We performed a pilot study to assess dynamic CA in acute stroke patients using a novel technique of combining transcranial Doppler (TCD) ultrasonography with rhythmic handgrip. Ten patients with ischaemic stroke in the middle cerebral artery (MCA) territory were studied. We performed continuous recordings of bilateral MCA velocities and used rhythmic handgrip to induce BP oscillations. Changes in autoregulation were indicated by changes in phase shift and gain of MCA velocity in relation to BP. Patients were examined at <7 days, 6 weeks, and 3 months after stroke. There were no significant differences in phase shift or gain between the affected and unaffected cerebral hemispheres. Combining the results from both hemispheres, there was a trend of increasing phase shift (P=0.04) and decreasing gain (P=0.24) over the first three months after stroke, indicating improving CA. Rhythmic handgrip produced an average percentage change in BP (peak-to-trough) of 10% around the mean, and the frequency of the induced BP oscillations was very similar to that of the rhythmic handgrip. Combining TCD with rhythmic handgrip appeared to be a useful technique for assessing dynamic CA and it deserves further studies. In this pilot study, there was some evidence that CA might improve up to 3 months after ischaemic stroke.

The Role of the Hypothalamic-Pituitary-Adrenal (HPA) Axis in the Regulation of Blood Pressure

The role of the HPA axis in blood pressure regulation was examined in 6 normal male volunteers by comparing haemodynamic and hormonal effects of placebo, captopril, and dexamethasone given in random order for two days. The average 24-hour systolic and mean arterial pressures on placebo (135±6 and 93±2mmHg respectively) were significantly higher than on captopril (118±1 and 85±1mmHg respectively, p < 0.05) but there were no significant changes on dexamethasone compared with placebo (128±3 and 89±3mmHg respectively). There were no differences in the average 24-hour diastolic blood pressures or heart rates, nor the day-night differences, night:day ratios or percentage changes in blood pressure and heart rate between treatments. Captopril significantly increased active plasma renin concentration, whilst dexamethasone decreased cortisol concentration. These results confirm the role of the renin-angiotensin system in the regulation of blood pressure in normal subjects but suggest that the HPA axis does not play a major role in determining ambulatory blood pressure or day-night variability in the short term.

Abnormal reflex vasoconstriction to cold stimulation in forearm of patients with variant angina.

The responses of the blood vessels of the forearm to cold pressor test and mental stress were examined in patients with variant angina and in control subjects. In response to cold pressor test, blood pressure, heart rate and forearm vascular resistance increased with statistical significance in both groups. Percentage changes in blood pressure and heart rate were not significantly different in patients and control subjects. Percentage change in forearm vascular resistance in patients with variant angina (120 +/- 101%) was significantly greater (p less than 0.05) than that in control subjects (47 +/- 26%). In response to mental stress, percentage change in forearm vascular resistance was -20 +/- 19% in patients with variant angina and -24 +/- 18% in control subjects and there was no significant difference in the two groups. We conclude that, in some patients with variant angina, not only the coronary artery but the forearm vessels show the abnormal reflex vasoconstriction and it may be postulated that it represents the generalized abnormality of vascular smooth muscle or of their neural control which exists in some patients with variant angina.

Does the Renin—Angiotensin System Maintain Blood Pressure in Both Hypertensive and Normotensive Subjects? a Comparison of Propranolol, Saralasin and Captopril

1. Propranolol, saralasin and captopril changed blood pressure in normotensive as well as hypertensive subjects. 2. The percentage change in blood pressure with these three drugs for a given plasma renin activity was similar in normotensive and hypertensive subjects. 3. This suggests that when the renin-angiotensin system is maintaining blood pressure, it maintains the blood pressure to the same extent in percentage terms in normotensive and hypertensive subjects for a given plasma renin activity. 4. Saralasin has marked agonist activity, and probably underestimates the participation of the renin—angiotensin—aldosterone system in the maintenance of blood pressure. The fall in blood pressure that occurred with captopril in normal subjects on their normal sodium intake suggests that the renin—angiotensin—aldosterone system may have an important role in the control of blood pressure in normal subjects on their normal sodium intake. If it does, our results suggest that the renin—angiotensin—aldosterone system plays no greater role in maintaining blood pressure in patients with essential hypertension than normotensive subjects for a given plasma renin activity.

Blood pressure response to isometric and dynamic exercise in healthy black children.

One hundred seventy healthy black boys and girls (76 boys and 94 girls) had their systolic blood pressure (BP) determined at rest, during submaximum and maximum dynamic exercise, and in response to isometric exercise. Differences in BP between boys and girls were not significant. Blood pressure response to both dynamic and isometric exercise correlated with age and body surface area. Differences between resting BP and the BP during isometric exercise (BPiso), submaximum dynamic exercise (deltaBP170) and maximum dynamic exercise (deltaBPmax) for boys were: deltaBP150 18 +/- 9, deltaBP170 40 +/- 16 and deltaBPmax 55 +/- 17. Corresponding values for girls were: 16 +/- 8, 36 +/- 14 and 47 +/- 16. The higher the resting BP the less was the percentage change in BP to each stress.