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

Hemodynamic monitoring and care of the patient at high risk for anesthesia require a careful and systematic approach. During preoperative evaluation the patient at increased risk must be identified and correctable problems must be solved. The patient's current medications must be reviewed because they may influence the choice of anesthetic approach and may alter the physiologic response to the stresses commonly associated with anesthesia. In addition to conventional clinical and electrocardiographic monitoring, perioperative hemodynamic monitoring may be desirable for patients at special risk, who are likely to have significant associated medical problems or to undergo complicated surgical procedures. No ideal induction agent exists, and hypotension secondary to peripheral vasodilation or myocardial depression, or both, is a potential problem. Patients with an inordinately high risk may benefit from mechanical circulatory assistance prior to induction of anesthesia. Attention to oxygenation, blood volume replacement and the prevention of hypertensive episodes are particularly important during anesthesia so that optimal cardiac performance is ensured and ischemia avoided. The stresses during emergence from anesthesia contribute to lability of the cardiovascular status and hypoxemia. The period of risk does not conclude with immediate recovery from anesthesia but extends through the postoperative phase. Careful monitoring and attention to the control of pain, prevention of hypotension and hypertension, adequate oxygenation, early mobilization and resumption of the administration of cardiac medications are important factors in a successful outcome.
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PMID:Hemodynamic monitoring and care of the patient of high risk for anesthesia. 49 83

Plasma catecholamine levels have been used experiemtally and clinically as the indices of the sympathetic nerve activity. We measured plasma catecholamines using high pressure liquid chromatography in rats to assess the significance of plasma catecholamines as an index of the sympathetic nerve activity and its role in hypertension. Pentobarbital anesthesia depressed plasma catecholamine levels, especially plasma adrenaline. Sodium loading for 5 weeks suppressed plasma noradrenaline, while administration of furosemide (1 mg/kg) produced the elevation of plasma noradrenaline. Experimental hypertension, one-kidney and two-kidney types of Goldblatt hypertension and DOCA-salt hypertension, raised plasma noradrenalines both in acute and chronic phases. The infusion of pressor doses of angiotensin II suppressed plasma noradrenaline by the reflex mechanism. Sar1, Ile8-angiotensin II and SQ 14,225 did not suppress plasma cathecholamine elevation due to hemorrhage. L-Hydroxyldopamine produced elevation of plasma catecholamines in experimental nypertension and controls in rats. After adrenal demedullation, plasma noradrenaline was decreased by the administration of 6-hydroxy-dopamine. Acute reduction of circulating blood volume and blood pressure fall produced the elevation of plasma catecholamine, especially plasma adrenaline. In rats, the adrenal medulla plays an important role in the regulation of blood pressure.
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PMID:Plasma catecholamines determination using high pressure liquid chromatography and their roles in blood pressure regulation and experimental hypertension in rats. 50 4

Preoperative medical evaluation of the hypertensive patient has a dual focus: (1) to establish an appropriate level of blood pressure control before anesthesia and surgery; and (2) to assess the degree of cardiovascular impairment, with particular attention to brain, heart, and kidney. Close communication between clinician and anesthesiologist can do much to ensure the patient's safety. Interpretation of the results of the preoperative examination is aided by the clinician's prior knowledge of the patient: the onset and history of his hypertension, his record of compliance to an antihypertensive regimen, his blood pressure response during previous hospitalizations and surgical procedures. Though there is no longer any question that antihypertensive medications should be continued in the preoperative period, side-effects of thiazide therapy may need treatment before or during surgery. Again, the clinician's fuller knowledge of the patient will help to alert the anesthesiologist to the need for special caution.
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PMID:The preoperative patient wit hypertension. 52 89

Autonomic failure in patients with the Shy-Drager syndrome may produce cardiovascular instability during anaesthesia and surgery. The syndrome is reviewed and the anaesthetic management of a case is described. The choice between general and regional anaesthesia seems to be less important than adequate cardiovascular monitoring and the maintenance of blood pressure with intravenous fluids. Sympathomimetic drugs, if used at all, should be administered in very dilute solutions to avoid hypertension from denervation hypersensitivity. In the postoperative period, symptoms from orthostatic hypotension may be severe and their control requires prolonged postural training, by elevation of the head of the bed, and therapy with 9-alpha-fludrocortisone.
Anaesthesia 1979 Oct
PMID:Shy-Drager syndrome. A review and a description of the anaesthetic management. 53 23

A case of unsuspected acute amphetamine abuse by a 22-year-old girl which led to serious intracranial hypertension during anaesthesia for a neurosurgical procedure is described. It was difficult to maintained anaesthesia with an intermittent positive-pressure ventilation technique using muscle relaxants, N2O and O2 and supplements of fentanyl despite large doses of pancuronium and fentanyl. The differing effects of chronic and acute amphetamine dosage on anaesthetic requirements are reviewed.
Anaesthesia
PMID:Acute amphetamine abuse. Problems during general anaesthesia for neurosurgery. 53 36

1. In 13 patients with hypertension and renal artery stenosis the stenosis was dilated by an intra-arterial balloon catheter under local anaesthesia. 2. In all but one instance arteriography after the dilatation showed considerable widening of the stenosed area. 3. Six patients had a temporary increase of serum creatinine that lasted only a few days. 4. In seven patients, who had a prolonged transit time at renography, this marker of renal blood flow improved after the dilatation. 5. The effect of the dilatation on the blood pressure in this group of patients, selected on arteriographic criteria only, was variable, but comparable with results of renovascular surgery. 6. Dilatation of renal artery stenosis by an intra-arterial balloon catheter is a promising treatment for patients with hypertension and renal artery stenosis. It is a rapid procedure needing only local anaesthesia. Complications in our experience so far are minor.
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PMID:Intraluminal dilatation of renal artery stenosis. 54 Apr 66

The cardiovascular effects of induction of anesthesia with minaxolone, a new water soluble steroid agent, have been studied in 12 normotensive patients and 5 patients with treated hypertension. The arterial pressure, heart rate and ECG were continuously recorded before and during induction of anesthesia with Minaxolone 0.5 mg kg-1. Cardiac output measurements were made in the awake patient, at 3 minutes after the induction of anesthesia and 2 minutes after an increment of the drug. In both groups of patients, induction of anesthesia led to a decrease in systolic arterial pressure and a smaller decrease in diastolic arterial pressures. This was coupled with an increase in the heart rate. The decrease in cardiac output was similar in both the normal and treated hypertensive patients. Administration of an increment of minaxolone (0.1 mg kg-1) did not produce further significant changes in the cardiovascular variables. The results of this study show that the changes in hemodynamic variables with minaxolone are comparable with those seen following induction of anesthesia with other intravenous agents, with the one difference in that there was only minimal change in the diastolic arterial pressure.
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PMID:Cardiovascular studies during induction with minaxolone. 54 58

The cardiovascular responses to acute mental "stress" were compared in the Milan strain of spontaneously hypertensive rats (MHS) and in normotensive control rats (NR). Blood pressure and heart rate were followed in pairs of awake MHS and NR, while defence reactions were provoked by alerting stimuli (noise, vibration). No differences were noted between the two groups in response to "stress" although resting heart rate in MHS was lower than in NR. Administration of atropine or propranolol to MHS and NR showed the MHS to have a higher resting vagal tone and lower sympathetic tone than the NR. Subsequent (at least two weeks later) hemodynamic investigation, under nembutal anesthesia, showed no difference in cardiac output between MHS and NR but a higher stroke volume, presumably related to the lower heart rate in MHS. Thus, total peripheral resistance was increased in MHS as was the ratio left ventricular weight/body weight, and in good proportion to the blood pressure rise. Thus MHS differ substantially in both their responses to "stress" and also hemodynamically from the Okamoto strain of spontaneously hypertensive rat (SHR), being the so far most studied and best known model of essential hypertension in man. In MHS the hypertension is more of a systolic type and is of primarily renal origin. As such, MHS provide another model for investigating the polygenic nature of hypertension in man.
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PMID:Cardiovascular control in the Milan strain of spontaneously hypertensive rat (MHS) at "rest" and during acute mental "stress". 55 79

Ethanol has been shown to aggravate the blood-brain barrier (BBB) dysfunction in cerebral trauma and in cerebral gas embolism, possibly by changing the endothelial cell membrane. No difference in protein extravasation was found between intoxicated and control rats under nitrous oxide anesthesia after the injection of bicuculline, a drug that hemodynamically gives rise to high blood pressure in combination with cerebral vasodilatation. In contrast there was a statistically significant increase in protein leakage in conscious intoxicated rats. The fact that ethanol increased the vulnerability only in conscious rats might indicate that nitrous oxide and ethanol have a common effect on the endothelial cell membranes or that nitrous oxide neutralizes an action of ethanol. Protein leakage induced by acute hypertension is more severe in rats anesthetized with nitrous oxide than in conscious rats, a difference that might to some extent be related to an effect of nitrous oxide on the endothelial cells. Further studies are needed to evaluate the influence of ethanol and nitrous oxide on the endothelial cell membrane.
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PMID:Hypertension-induced protein leakage in the brain in ethanol-intoxicated conscious and anesthetized rats. 57 Mar 39

Autonomic hyperreflexia (AH) is a clinical syndrome associated with the development of severe hypertension. It usually occurs in patients with high-level chronic spinal cord injury, and in response to stimuli associated with the distension of a hollow viscus. Protection against AH by the prophylactic use of pentolinium tartrate (Ansolysen) in doses of 10-15 mg was evaluated in a controlled study of unanaesthetized patients who were either quadriplegic or paraplegic and who were undergoing rectal and bladder surgical procedures. When compared with the control group, the systolic and diastolic arterial pressures during operation were significantly less (P less than 0.05) and remained near normal in the pretreated patients. The use of pentolinium to prevent or control AH during surgical procedures in patients with chronic spinal cord damage is a simple alternative to spinal or general anaesthesia.
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PMID:Autonomic hyperreflexia: intraoperative control with pentolinium tartrate. 58 88


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