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

Aspirin has been shown to acutely block the natriuretic effect of spironolactone in the mineralocorticoid-treated normal rat, dog, and man. It has been suggested that aspirin is contraindicated in hypertensive patients receiving spironolactone. Five patients with low-renin essential hypertension and two with hypertension due to primary aldosteronism, all of whom have normalized their blood pressure on chronic spironolactone therapy, were cotreated in a double-blind fashion with either aspirin or aspirin-placebo during alternate six-week periods. Aspirin did not appear to alter the effect of spironolactone on blood pressure, serum electrolytes, urea nitrogen, or plasma renin activity.
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PMID:Failure of aspirin to antagonize the antihypertensive effect of spironolactone in low-renin hypertension. 78 8

Since October 1967 we have performed 76 microsurgical STA--cortical MCA bypass operations. Recently we have had two cases, who died from intracerebellar hematoma following bypass operation. Intracerebellar hematoma is reported primarily due to hypertension (50-80%), and to comprise 10% of all spontaneous intracranial hematomas. Diagnosis of this lesion is frequently missed but can be made by the typical clinical picture (respiratory irregularity, pinpoint pupils, absence of oculovestibular responses, loss of consciousness), and the CT-Scan. If the correct diagnosis is made and operation promptly performed, many patients with subacute or acute intracerebellar hematoma can be saved. The 2 cases presented here had a history of hypertension and anticoagulation (including Colfarit), but had sustained the bypass operation well and showed no neurological deficit immediately after the operation. They had received Rheomacrodex intra- and postoperatively. Quite soon postoperatively, however, the systolic blood pressure rose to 210 mmHg and the patients complained of severe headache. They were treated symptomatically with analgesics and antihypertensive drugs. A short time later they became comatose and died. In order to prevent this complication after bypass surgery, postoperative management of hypertension is mandatory. The combination of antithrombic agents, Colfarit and Rheomacrodox, might have played a role in inducing the hemorrhages. Furthermore strong analgesics should be withheld to prevent their masking neurological deterioration. Intracerebellar hematoma must always be considered in hypertensive or anticoagulated patients, especially because it can be cured with prompt diagnosis and operative treatment.
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PMID:[Intracerebellar Hematoma following microsurgical STA-cortical MCA bypass surgery (author's transl)]. 90 21

Little is known about the effect of low dose, enteric-coated aspirin on human blood platelet function. This study was conducted to evaluate the acute effects of a single daily dose of commercially available enteric-coated aspirin on platelet biochemistry, physiology and function. Blood for these studies was obtained from drug-free volunteer donors prior to ingestion of aspirin or following ingestion, either before breakfast or following lunch. Response of platelets to the action of weak agonists was evaluated. In addition, ability of platelets to convert radiolabeled arachidonic acid to thromboxane was monitored. Results of our studies show that a single daily dose of 50 mg of aspirin taken either before breakfast or after lunch effectively prevented the secondary wave aggregation response, as well as secretion of dense body contents when stimulated by agonists such as epinephrine and ADP. Aspirin ingestion caused a dose-dependent inhibition of platelet cyclooxygenase activity as evidenced by the extent of arachidonic acid converted to thromboxane by platelets exposed to aspirin for different time periods. Based on these observations, it is suggested that low dose aspirin may be very useful and desirable to restrain platelet activity in clinical situations in which increased thromboxane formation may initiate vascular hypertension and platelet hyperactivity.
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PMID:Influence of low dose enteric-coated aspirin on platelet function. 130 83

In patients ranked ASA 1, laryngoscopy and intubation lead to an average increase in blood pressure of 40 to 50%, and a 20% increase in heart rate. These changes, which are greatest one minute after intubation, last for 5 to 10 min. They are due to sympathetic and adrenal stimulation, which may also result in some arrhythmias. About half the patient with coronary artery disease experience episodes of myocardial ischaemia during intubation when no specific prevention is undertaken. Among the different means available for this, narcotics seem to have a reliable and constant effect, but they may be responsible for postoperative respiratory depression. The protective effect of fentanyl starts at 2 micrograms.kg-1, and is at a maximum at 8 micrograms.kg-1. Lidocaine is the drug used most. Recent studies have questioned its efficacy. In clinical practice, it is particularly effective in preventing the pressor response to tracheal intubation, whatever its route of administration (intravenous or intratracheal), but not the increase in heart rate. Beta blockers with bradycardic, antihypertensive, antiarrhythmic and antiischaemic properties, have been advocated. As opposed to lidocaine, these agents are more effective in preventing the changes in heart rate than the pressor response. Because of their depressor effect on the myocardium, their place still remains to be defined, especially in the cardiac risk patient. Short-acting beta blockers should be preferred. Nitroglycerin is specifically indicated in coronary artery disease. Other agents, such as clonidine or calcium blockers, seem to be less effective or less convenient in preventing the haemodynamic alterations. In clinical practice, prevention will first rely on a sufficient dose of narcotics. In some cases, nitroglycerin or beta blockers may be used so as to decrease the doses of narcotics, without altering their efficacy; however, the risk of hypotension should be constantly borne in mind. If preventing measures have not been taken, short-acting antihypertensive agents (beta blockers, calcium blockers) should be used in patients who develop major hypertension during laryngoscopy and intubation.
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PMID:[Consequences and prevention methods of hemodynamic changes during laryngoscopy and intratracheal intubation]. 135 16

Benzodiazepines for sedation may decrease the PaO2, the arterial O2 saturation (SaO2), and the CO2 response more in the elderly than in the young. The purpose of this study was to assess changes in blood gases due to i.v. midazolam or sublingual flunitrazepam given as premedication in elderly patients for unilateral cataract surgery. METHODS. Fifty patients over 65 years of age with treated arterial hypertension and other co-existing diseases (ASA III-IV) were randomly assigned to have: (1) i.v. midazolam titrated until they became drowsy (17 patients; 2.85 +/- 0.84 mg [mean +/- SD]); (2) sublingual flunitrazepam (16 patients; 0.005 mg/kg); or (3) no sedation (17 patients; controls). On entering the operating theatre, the radial artery was cannulated and the first blood gas analysis was obtained. The premedication was then given. At 5, 10, 20, and 30 min after premedication, before and 10 min after retrobulbar block, before operation, 5 and 15 min after the beginning of the operation, 10 and 20 min after administration of 500 mg acetazolamide i.v. during the operation, and 10 and 20 min after the operation additional arterial blood samples were analysed (a total of 15 measuring points). Pulse oximetry, invasive blood pressure, and ECG were continuously monitored. All patients received oxygen 3 l/min during the operation by nasal cannula. Differences between the three groups were analysed by Student's t-test or U-test and a P value < 0.05 was considered significant. RESULTS. The patient demography, including duration of anaesthesia and operation, was similar in the three groups (Table 1). No significant differences were seen in heart rate, mean arterial pressure, PaO2, pulse-oximetric oxygen saturation (SpO2), base excess, or serum bicarbonate levels. The PaCO2 increased in patients after midazolam (P < 0.01) and flunitrazepam (P < 0.05) until the beginning of the operation compared with the control group (Fig. 3); 20 min after the operation there was still a significant difference between the midazolam group and the controls. SaO2 was significantly (P < 0.05) lower in the midazolam group 10 and 20 min after administration of premedication compared with the control group, but was within physiological limits (Fig. 5). Despite titration, 2 patients had severe respiratory insufficiency 3 min after midazolam: the SpO2 decreased below 85% and the paO2 below 55 mmHg. The paCO2 was higher (P < 0.05) in the midazolam group 10 min after acetazolamide compared with the controls. CONCLUSIONS. The results of the study show the potential hazards of i.v. midazolam in the elderly. If sedation is required for cataract surgery under local anaesthesia, we recommend sublingual flunitrazepam or the use of benzodiazepines with lower hypnogenic effects in the elderly. A thorough preoperative discussion of anaesthesia and the operation might be an adequate substitute for any premedication in high-risk patients; the best blood gas analysis results were obtained in the control group.
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PMID:[Premedication in retrobulbar anesthesia. A blood gas analysis comparison of sublingual flunitrazepam and intravenous midazolam]. 146 54

The minimum degree of renal arterial stenosis needed to cause hypertension was identified by renal arterial angiography of anesthetized dogs. The effects of renal nerves and prostanoids on the critical stenosis were also examined. The left renal artery was constricted concentrically by a radiolucent constrictor device, and the stenosis of the artery was evaluated by cineangiography with the kidney either innervated or denervated. At this time, renal blood flow, renal perfusion pressure, and systemic blood pressure were serially monitored. In another group of dogs, renal venous and aortic blood samples were taken as the stenosis increased; these were assayed for prostaglandin E2 and plasma renin activity. The same experiments were done again after treatment with a cyclooxygenase inhibitor, aspirin DL-lysine (54 mg/kg). With the kidney either innervated or denervated, systemic blood pressure began to increase when the stenosis was more than 70% of the diameter of the renal artery; the renal blood flow decreased when the stenosis was more than 75% of the diameter. Aspirin treatment attenuated the increase in blood pressure but did not affect the autoregulation of the renal blood flow when stenosis was 70% or less. Prostaglandin E2 production increased in the stenotic kidney when the stenosis was more than 70%; aspirin inhibited prostaglandin synthesis and suppressed the stimulation of renin release. These results suggest that whether there is innervation or not, the critical degree of renal arterial stenosis that causes hypertension is more than about 70% of the diameter in the presence of renal prostaglandins; in their absence, the critical point above which hypertension occurs is 75% or more.
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PMID:Critical degree of renal arterial stenosis that causes hypertension in dogs. 147 71

In a randomized double-blind study, the effects of clonidine premedication as a sedative, anxiolytic, analgesic and oculohypotensive agent were studied in 100 elderly patients (62 to 65 +/- 10 years, ASA grade I-II) undergoing elective intraocular surgery under local anaesthesia. The control group (Group A, n = 50) received oral diazepam 0.15 mg/kg 120 min before surgery and Group B (n = 50) received oral clonidine 300 micrograms 120 min before surgery. Two hours after the premedication, there was significantly more sedation (P less than 0.05) and less subjective anxiety (P less than 0.05) in the clonidine group than in the control group. There was a significant fall in intraocular pressure (IOP) from 20 +/- 0.5 to 13 +/- 0.5 mmHg (P less than 0.05) and significant reduction in systolic and diastolic blood pressure (BP) and heart rate (HR) (P less than 0.05) in the clonidine group as compared to the control group. Perioperatively, significantly more supplementation with i.v. diazepam was given in the control group than in the clonidine group (P less than 0.01). The incidence of intra-operative hypertension (P less than 0.01) and tachycardia (P less than 0.05) was significantly greater in the control group than in the clonidine group. A significantly larger number of patients in the clonidine group scored a Post-Anaesthesia Recovery (PAR) score of 10 as compared to the control group (P less than 0.01). There was no statistical difference in the postoperative Visual Analogue Scale (VAS) scores for pain, number of analgesic requests and emesis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Oral clonidine premedication for elderly patients undergoing intraocular surgery. 154 37

Diabetes mellitus is associated with a high incidence of cardiovascular diseases not directly attributable to hyperlipidemia, smoking, or hypertension, but which in part may be explained by an enhanced tendency to thrombosis due to increased platelet activity. The aim of this study was to evaluate platelet function and compare the effectiveness of the antiplatelet drug aspirin on platelet aggregation in diabetic and nondiabetic subjects. Platelet aggregation and composition were examined in 20 male insulin-dependent diabetes mellitus (IDDM) patients and 20 nondiabetic control subjects matched for age and body mass index. All were normotensive with serum total cholesterol less than 6.5 mM. Although within the clinically acceptable normal range, blood pressure was significantly higher in diabetic patients (130/75 mmHg) than in control subjects (123/70 mmHg) (P less than 0.05). Serum thromboxane B2 and ex vivo aggregation of platelets in response to two doses of the agonists collagen and platelet-activating factor (PAF) were similar to nondiabetic subjects. However, after taking 100 mg/day aspirin for 5 days, platelet aggregation to collagen was reduced by 76% in control subjects compared to 56% in IDDM patients (P less than 0.001). Aspirin treatment also reduced the slope of the aggregation curve and increased the lag time (the period between the addition of collagen and the start of irreversible aggregation) significantly more in control than in diabetic platelets. This difference in platelet aggregation could not be attributed to differences in platelet serotonin or thromboxane A2 secretion, the latter being almost completely suppressed by aspirin in each group. Platelet aggregation to PAF was similar in both groups and was not affected by aspirin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential effect of aspirin on platelet aggregation in IDDM. 155 86

Eighty patients undergoing abdominal surgery were studied to evaluate ECG changes in perioperative period and also identify the factors influencing the incidence and the severity of postoperative ventricular arrhythmia. Holter ECG was recorded with CM5 and NASA leads from the night before operation to the night of the 2nd postoperative day. Tachycardia (greater than or equal to 100 beats.min-1) was found in 46.3% of the patients preoperatively and in 55% postoperatively. Bradycardia (less than or equal to 50 beats.min-1) was found in 30% of the patients mostly in the night prior to the operation, while only 1 patient (1.3%) demonstrated bradycardia postoperatively. SVPCs were observed in high incidence ranging from 75% preoperatively to 85% postoperatively. Two patients had paroxysmal supraventricular tachycardia postoperatively. VPCs were observed in 42.5% of the patients preoperatively and in 53.8% postoperatively. Warning arrhythmias which were ranked as more dangerous than Lown 2 were observed in 15% of the patients preoperatively, in 11.3% intraoperatively and in 23.8% postoperatively. Serious arrhythmias which needed immediate treatment were found in 6.3% of the patients preoperatively, in 10% intraoperatively and in 11.3% postoperatively. ST depression was recorded in 11 patients at CM5 and 2 patients at NASA leads. Chi-square and Hayashi's multidimensional quantification analyses were applied to determine the relationship between postoperative VPCs and pre- and intra-operative clinical factors. Factors such as age, type of surgery, intraoperative VPCs, ASA classification, ischemic changes in preoperative ECG, intraoperative blood loss, operation time, Goldman score, untreated hypertension as well as ischemic heart disease and abnormal findings of Master ECG were considered to be contributing to the high incidence and the severity of post-operative VPCs. When multidimensional quantification analysis is applied to the data, the occurrences of no VPCs, occasional VPCs, warning VPCs and serious VPCs could be predicted in postoperative patients.
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PMID:[Holter electrocardiographic findings in surgical patients during the perioperative period]. 156 May 81

Laryngoscopy and intubation cause an adrenergic response manifested by tachycardia and hypertension. Various pharmacological agents, including fentanyl, have been administered prior to induction in an attempt to attenuate the adrenergic response but they all have limitations. Esmolol, an ultrashort-acting cardioselective beta blocker, has been administered by infusion to successfully protect surgical patients from the stresses of intubation. The objective of our study was to determine if esmolol would be equally effective when administered in a bolus with and without fentanyl. Forty-four ASA I and II females undergoing elective surgery were randomly divided into four groups and received the following agents prior to intubation: Group 1-esmolol 1 mg/kg and fentanyl 2 micrograms/kg, Group 2-placebo (normal saline), Group 3-esmolol 1 mg/kg and Group 4-fentanyl 3.5 micrograms/kg. Groups 1 and 4, which received fentanyl, demonstrated significantly less elevation in blood pressure. Esmolol appeared to attenuate increases in heart rate. Esmolol has a tissue distribution time of 2 minutes and an elimination half-life of 9 minutes. The window of its availability to the tissues is narrow, and timing of bolus administration is more critical than in administration by infusion. Doses in excess of 1 mg/kg appear to be necessary for effective control of heart rate. However, when used with fentanyl, esmolol provides effective protection against the adrenergic response to laryngoscopy and intubation.
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PMID:Evaluation of esmolol and fentanyl in controlling increases in heart rate and blood pressure during endotracheal intubation. 167 49


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