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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cerebral hemispheric blood flow and metabolism were measured before and after therapy with intracarotid infusion of combined PBZ and PPL in 15 patients with recent cerebral infarction. HBF was unaltered despite decrease in cerebral perfusion pressure. Cerebral hemispheric oxygen comsumption and carbon dioxide production decreased while cerebral hemispheric lactate production increased. Biphasic cerebral uptake of tyrosine was observed during and immediately after PBZ and PPL infusion. CSF HVA increased, indicating altered DA turnover. CSF 5HIAA levels also increased, suggesting altered 5HT turnover after PBZ and PPL. Release of cyclic AMP from ischemic brain into cerebral venous blood seen in the steady state was abolished after therapy. Cerebral hemodynamic studies suggest a functional balance between monaminergic neurogenic influences in the control of cerebral circulation. Imbalance of such controlling factors in ischemic brain may lead to paradoxical vascular responses to induced hypertension and hypotension. PBZ and PPL enhance such responses perhaps by increasing central neurotransmitter turnover and release. Further shift toward cerebral anaerobic metabolism may occur in ischemic brain following the use of phenoxybenzamine and propranolol. Worsening of neurological deficit occurred in four cases. Combined therapy with PBZ and PPL does not appear beneficial in the therapy of patients with recent stroke.
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PMID:Influence of adrenergic receptor blockade on circulatory and metabolic effects of disordered neurotransmitter function in stroke patients. 0 7

The authors report the values of mean hemispheric blood-flow and cerebral arterial consumption they found in 34 neurosurgical comatous cases in acute state. In basal conditions, mean values of mean hemispheric bloodflow and oxygen consumption are lowered. There seems to be a relation between the values found and the comatous stage on one hand, the prognosis on the other hand. The cerebral response to hypercapnia (16 assays) allows to separate 2 groups, one with a noticeable improvement of cerebral bloodflow, the other with only a minimal response. There was no significant variation of cerebral oxygen consumption in both group. Cerebral response to CO2 seems to be clearly related to the stage of coma (low in the most severe cases) but pronostic incidence remained uncertain. A hypertensive test by means of Aramine (18 assays) allows to separate 3 groups : 1 group (8 cases) where the mean hemispheric bloodflow remained stable during hypertension as did the cerebral oxygen consumption -(autoregulation remained unchanged), 1 group (4 cases) where mean hemispheric bloodflow and cerebral oxygen consumption were lowered (excessive autoregulation), 1 group (6 cases) where mean hemispheric bloodflow increases clearly while under Aramine perfusion (loss of autoregulation). Those dynamic tests, either hypercapnic or hypertensive, allow, in comparing oxygen consumption variations with cerebral bloodflow variations, the distinction between : patients where metabolic autoregulation seems maintained (good prognosis) - (10 cases), patients where metabolic regulation is lost with either "luxury perfusion" (14 cases) - poor prognosis, or "insufficient perfusion" (10 cases). The authors are discussing the treatment concerning those last mentioned patients.
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PMID:[Value of cerebral metabolic exploration in post-traumatic coma states in the acute phase]. 1 86

Cerebral pressure-flow relations were studied in anaesthetized dogs during acute arterial hypertension, induced by compression of the thoracic aorta. In one group of animals steady state measurements were made with the radioactive gas elimination method. In another group the immediate changes of blood flow at a blood pressure change, as indicated by variations in the cerebral venous oxygen saturation, were studied with continuous oximetric analyses of the superior sagittal sinus blood. The initial blood flow was varied by variations of the arterial carbon dioxide tension of injections of papaverine. At low or normal blood flows autoregulation was efficient up to pressures around 180-200 mmHg, while at higher flows the upper autoregulatory pressure limit was found at lower blood pressures. Above the autoregulatory limit-irrespective of the control flow level-there was a rise in blood flow and a decrease in cerebrovascular resistance.
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PMID:The pressure-flow relations of the canine brain in acute mechanically induced arterial hypertension at different levels of cerebral blood flow. 1 92

Herein attention is focused on the documentation of high blood pressure response with detrusor-sphincter dyssynergia in spinal cord injury patients and with its amelioration after extended sphincterotomy. During cystomanometric evaluation of the bladder the monitored blood pressure response in 53 spinal injury patients, 27 non-dyssynergic spinal injury patients and 18 non-spinal injury patients was compared. A high correlation was observed among the magnitudes of blood pressure increase, level of injury and the severity of detrusor-sphincter dyssynergia in spinal injury patients. During cystomanometry blood pressure increases of greater than 20 mm. Hg systolic and 10 mm. Hg diastolic in normotensive paraplegics (below T5) and also in non-spinal injury patients were significant to suspect detrusor-sphincter dyssynergia. In normotensive tetraplegic patients blood pressure increases of greater than 40 mm. Hg systolic and 20 mm. Hg diastolic were significant to suspect detrusor-sphincter dyssynergia. The mechanism of blood pressure increase is elucidated. The management of this high blood pressure response in patients with detrusor-sphincter dyssynergia by drug therapy and extended sphincterotomy is discussed. Based on our experience the use of carbon dioxide for cystomanometry seems preferable in patients with spinal lesions above T5 since expedient deflation of the bladder can prevent an inordinate blood pressure increase.
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PMID:Pressor response during cystomanometry in spinal injury patients complicated with detrusor-sphincter dyssynergia. 3 49

Inhalation of a gas mixture : CO2, 25% -- O2, 37.5% -- N2, 37.5%, provokes regularly in the light anaesthetized rat, an increase of catecholaminemia of central origin, associated with systemic arterial hypertension.
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PMID:[Orthosympathetic stimulation after hypercapnia in the rat]. 9 25

Decompensation of brain injured patients during the night is common and has been attributed to the retention of CO2 during sleep. When CO2 is controlled, such nocturnal decompensation needs another explanation; consequently, the records of 21 consecutive patients with acute closed head injuries and increased intracranial pressure were reviewed. There were 185 separate episodes of intracranial hypertension (30 mm Hg or more for 10 minutes or more) in the 21 patients, 124 of which (67%) occurred between 4:00 a.m. and 9:00 a.m. (p less than 0.01). Intravenous pentobarbital (3 to 5 mg/kg) was effective in reducing the intracranial pressure (ICP) to normal levels during 104 of the 124 early morning episodes (84%), whereas mannitol was less effective (7 of 17; 41%). This suggests that an increase in brain blood volume directly related to diurnal rhythm is responsible for the increase in ICP. Severe bradycardia and systemic arterial hypertension were unreliable predictors of elevation in ICP. They preceded or accompanied less than one-fourth of the episodes.
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PMID:The influence of diurnal rhythms in patients with intracranial hypertension: implications for management. 21 32

Using previously inserted catheters, 11 dogs native to high altitude (7.5-23 kg bwt) were studied standing and unsedated in Cerro de Pasco, Peru at 4350 meters. Hemoglobin (Hb), hematocrit (Hct), O2 and CO2 contents, PO2, PCO2 and pH were measured in simultaneously obtained arterial and mixed venous blood samples. Blood pressures were measured in the pulmonary artery and the left ventricle and cardiac output (Q) was determined by dye dilution. Moderately higher values for Hb and Hct were found in these dogs. Hb-O2 affinity was no different than that found in sea level dogs: the P50 in the Andean dogs was 31.6 mm Hg at 38 degrees C and pH of 7.4. Because of the low barometric pressure at 4350 m (458 mmHg) the partial pressures of oxygen in inspired and in alveolar air were lower than at sea level: 84.3 and 56.4 mm Hg, respectively. PAO2 and PVO2, were 55.5 and 32.9 mm Hg while the SAO2 and SVO2 were 79.5 and 50.7%, respectively. Marked hyperventilation was observed (PACO2, 25.6 mm Hg) however, pH was normal. Cardiac output was normal (average 162 plus or minus 39 ml/min/kg). Moderate pulmonary arterial hypertension was observed in the presence of normal left ventricular end diastolic pressure suggesting increased pulmonary vascular resistance.
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PMID:Mechanisms of O2 transport in Andean dogs. 23 72

Interest in new diuretics with less side effects has led to the synthesis of ticrynafen, an uricosuric diuretic. This agent was compared with hydrochlorothiazide in a crossover design study involving 12 hypertensive men. Both agents significantly decreased mean arterial pressure from 8% to 18% in eight of the 12 patients. In addition to reducing body weight, these diuretics induced reversible changes in BUN and carbon dioxide content (increased) and plasma concentration of potassium and chloride ions (decreased). The most important change in renal function was a 2.5-fold increase in fractional urate clearance by ticrynafen associated with reduction of serum uric acid by 62%. Thus, ticrynafen is a promising therapeutic agent in hypertension, adding a unique uricosuric effect that should improve patient compliance.
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PMID:Ticrynafen: a novel uricosuric antihypertensive natriuretic agent. 33 65

Venous distensibility in essential hypertension has been reported to be unchanged or decreased; its pathophysiologic role is uncertain. In 27 male hypertensive patients and 21 normotensive control subjects, forearm venous distensibility and capillary filtration rate at 30 cm of H2O distending pressure were measured by strain gauge plethysmography. Plasma renin activity (PRA), plasma volume (PV) by the Evans blue dye dilution technique, mean arterial pressure (MAP) by cuff, and cardiac output (CO) by the CO2 rebreathing method were also measured. Compared to values in normotensive control subjects, forearm venous distensibility in hypertensive subjects was decreased (P less than 0.05); the forearm venous pressure-volume curves (deflation phase) were shifted in the direction of the pressure axis (P less than 0.02); and the capillary filtration rate was increased (P less than 0.05). Venous distensibility changes in hypertensive subjects were unrelated to PRA, MAP, PV, CO, stroke volume, and total peripheral resistance. These findings confirm previous reports of decreased venous distensibility in hypertension and provide direct evidence for increased capillary filtration rate. In view of the lack of significant correlation between venous distensibility and the measured hemodynamic parameters, a patho-physiologic role for venous distensibility in hypertension could not be established.
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PMID:Decreased venous distensibility in essential hypertension: lack of systemic hemodynamic correlates. 37 15

The effects of an acute cryogenic injury on cerebral flow (CBF) and cerebral vascular reactivity were studied in 12 anaesthetised, ventilated baboons. Autoregulation, defined in this study as intact with a greater than 20% change in cerebrovascular resistance in response to a change in cerebral perfusion pressure, was tested before the lesion by arterial hypotension. Intact autoregulation was found in half the animals, but all animals showed an increase in CBF with hypercarbia. The cryogenic lesion was followed by a marked rise in intracranial pressure, and a fall in CBF which was only partly related to the status of autoregulation beforehand. After injury, arterial hypertension caused an increase in cerebrovascular resistance of more than 20% in half the animals. This response was not related to the presence of autoregulation before the lesion, and was accompanied by a greater impairment of the cerebrovascular response to carbon dioxide, more severe brain oedema, and lower cerebral oxygen consumption, than in the remaining baboons which had a pressure passive response to arterial hypertension. This study confirms that the failure of CBF to increase with arterial hypertension may indicate severe brain damage rather than intact physiological autoregulation.
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PMID:Vascular reactivity in the primate brain after acute cryogenic injury. 41 85


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