Magnitude Of Increase In Blood Pressure Research Articles

Are Statistics Misleading Sodium Reduction Benefits?

There is a global movement toward lowering the blood pressure (BP) to prevent cardiovascular disease. Researchers use statistical power test on dietary increased sodium and point to the resulting elevation in BP as proof that salt increases BP. However, while tests show that the increase in BP is not by chance and is the result of increased salt intake and it also shows that this increase is consistent across test subjects, the results do not show that the magnitude of increase in BP is significant enough to warrant concern. Similarly, it is questionable if the reduction in dietary salt culminates in meaningful BP reduction. Statistics mislead when misunderstood. We show that dietary salt changes do not represent significant variation in BP but reduction of salt significantly may increase triglycerides, which may be more harmful.

Intraoperative changes in blood pressure, heart rate, plasma vasopressin, and urinary noradrenalin during elective ovariohysterectomy in dogs: repeatability at removal of the 1st and 2nd ovary.

To investigate the physiologic reactions after removal of 1st ovary and whether this is repeated during removal of the 2nd ovary in elective ovariohysterectomy. Prospective study. Dogs (n = 10). Dogs were premedicated with acepromazine, carprofen, and methadone and anesthetized with propofol and isoflurane. Blood pressure, heart rate, and end-tidal isoflurane concentration were measured every minute. The effects of various events during surgery on physiologic variables were analyzed using mixed linear models. Blood and urine samples were collected before anesthesia, before incision, before and after removal of ovaries with a 15 minute pause between ovary removal, and after abdominal closure. Plasma vasopressin and urinary noradrenalin and creatinine concentrations were analyzed. The magnitude of blood pressure increase at removal of the 1st ovary was greater than for the 2nd ovary because of an elevation in baseline. Similarly, the heart rate increased at the removal of the 1st ovary but not at removal of the 2nd ovary. Plasma vasopressin concentration increased at removal of both ovaries. Urinary noradrenalin/creatinine ratio increased at anesthesia, removal of both ovaries, and was elevated at closure of the abdomen. End-tidal isoflurane concentration did not change. Blood pressure and vasopressin concentrations changed in parallel using z-scores for comparison. Peak values for blood pressure, heart rate, plasma vasopressin concentration, and urinary noradrenalin/creatinine ratio did not differ between removals of the ovaries. Relative changes differed between repeated noxious stimuli, which should be considered in evaluation of methods at ovary removal.

Type D personality and hemodynamic reactivity to laboratory stress in women

The Type D personality (identified by high levels of both negative affectivity and social inhibition) has been associated with negative health consequences in cardiac patients. However, few studies have explored whether the Type D personality is associated with particular patterns of cardiovascular responses to stress. In the present study, cardiovascular reactivity to psychological stress (CVR) was examined as a possible mediating mechanism by which Type D personality may affect cardiovascular health, with specific focus on hemodynamic profile. Eighty-nine female university students completed a mental arithmetic stressor while undergoing hemodynamic monitoring. Blood pressure, heart rate, cardiac output, and total peripheral resistance in response to the stressor were examined. Type D personality was assessed using the 16-item Type D scale. Results indicated that there were no between-group differences in magnitude of blood pressure increase, with both Type D and non-Type D individuals demonstrating myocardial response profiles. However, Type D individuals were less “myocardial” than non-Type D individuals. This indicates that a weak myocardial response to an active stressor in Type D individuals may be indicative of hemodynamic maladaptation to stress, implicating CVR as a possible mechanism involved in Type D-cardiovascular health associations.

Nitric oxide and the role of blood pressure variability to the kidney.

Blood pressure variability is buffered by at least two mechanisms: the arterial baroreceptor reflex and nitric oxide (NO). Only recently is the importance of blood pressure variations on cardiovascular control being investigated. Here we report of a study performed in conscious dogs, in which renovascular hypertension was induced. Reduction of renal arterial pressure (RAP) to 85 mmHg for 24 h elicited profound hypertension by 60 mmHg (vs. control: 110 +/- 3 mmHg; P < 0.01). This was accompanied by reduced volume and sodium excretion (-48% of control, P < 0.01 and -80% of control, P < 0.01, respectively) and augmented renin release by more than two-fold (P < 0.01). This intervention was compared with a protocol in which RAP was reduced to the same mean value, however, RAP oscillated by +/-10 mmHg at 0.1 Hz. This manoeuvre led to a transient increase in NO3 excretion in urine (P < 0.01), blunted antidiuresis (-14% of control) as well as antinatriuresis (-40% of control) and attenuated the increased renin release by 30% (P < 0.05). In consequence, the magnitude of blood pressure increase was only half as high as that observed during static reduction of RAP (P < 0.01). It is concluded that blood pressure oscillations to the kidney have a profound influence on water and electrolyte balance and on renin release, which alleviates the onset of Goldblatt hypertension.

Convulsions and hypertension in children

To determine if the magnitude of blood pressure (BP) increase could differentiate convulsion caused by a hypertensive crisis from a primary convulsive disorder, which itself increases BP. Retrospective analysis. Admission to a pediatric intensive care unit (ICU) within a tertiary care center. All children with hypertensive crisis admitted to the pediatric ICU from 1976 to 1990 were studied. Thirty-eight episodes occurred in 36 patients. The charts of children admitted for status epilepticus from 1976 to 1986 were also reviewed. One hundred and fifty-three episodes occurred in 145 patients. BP values at entry to the pediatric ICU in patients with hypertensive crisis were compared with the highest BP values obtained within an hour after cessation of convulsion in 120 patients admitted for status epilepticus. The Z scores for BP, adjusted for age and sex, were compared. The BP values for children in hypertensive crisis with or without convulsions were by far greater than the BP values observed in patients in status epilepticus (p < .0001). For a patient in the postictal phase, a BP > or = 4.0 SD above the mean for age and sex predicted with 78% probability the presence of a hypertensive crisis requiring emergency treatment. If the BP was < 4 SD below the mean, the possibility of a hypertensive crisis was excluded (negative-predictive value 100%). Children with hypertensive crisis, as well as children with status epilepticus, can present with a high BP. In a postictal patient, the magnitude of BP increase is a useful clinical parameter to exclude a hypertensive crisis that requires specific treatment of the BP.

Blood-brain barrier impairment after cardiac resuscitation.

The influence of CPR on the blood-brain barrier (BBB) in dogs was studied by fluorescence microscopy using Evans blue as a BBB tracer. Three of 9 control dogs, whose blood pressure (BP) was increased by more than 130 mm Hg, showed dye extravasation (BBB impairment) into brain tissue, but no extravasation was seen in the other 6 controls whose BP increase was less than 110 mm Hg. In 11 experimental animals, extravasation of Evans blue occurred in 8 of 9 resuscitated dogs after several minutes of cardiac arrest and in 1 of 2 nonresuscitated dogs. In the resuscitated dogs, the maximum systolic BP (peak BP) after restoration of ventricular function ranged from -40 to +210 mm Hg compared to control values. They showed all grades of dye extravasation without significant correlation between the magnitude of BP increase and the severity of dye extravasation. The authors conclude that BBB disruption usually occurs during CPR and causes plasma protein extravasation into brain tissue. Arterial hypertension is a causative factor for BBB disruption, as was seen in the control dogs. In resuscitation, restoration of BP sufficient to overcome intracranial pressure and maintain cerebral blood flow may be high enough to induce BBB disruption because cerebral vessels are fully dilated and functionally impaired due to longstanding anoxia. The rapidity of BP increases after restoration of ventricular function could be another factor which might contribute to BBB impairment.