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

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.
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PMID:Acute amphetamine abuse. Problems during general anaesthesia for neurosurgery. 53 36

In order to study if rapid elevation of blood pressure is associated with cerebral ischemia, anesthetized (70% N2O) and artificially ventilated rats were subjected to angiotensin-induced hypertension. After a 5 min hypertensive period, cerebral cortex tissue was frozen in situ for subsequent measurements of labile glycolytic metabolites, ammonia, and organic phosphates. The degree of hypertension induced, which gave evidence of blood-brain barrier damage in 7 of 8 rats, did not affect the tissue concentrations of labile metabolites. It is concluded that ischemia does not contribute to the barrier damage, nor is it likely to be the cause of the clinical symptoms that may occur in conscious rats in the same experimental model.
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PMID:Brain energy metabolism in angiotensin-induced acute hypertension in rats. 88 9

In a 31-year old woman with a six year history of headache and hypertension a diagnosis of primary aldosteronism was made on the basis of urine samples containing 45 mug/day of aldosterone. The preoperative systemic blood pressure was 240 mm Hg systolic and 120 mm Hg diastolic. The serum potassium level was 2.6 mEq/L and other laboratory findings were within normal limits. The patient was to undergo operation. Pre-medication consisted of oral pentobarbitone, intramuscular pethidine and atropine. For induction of anaesthesia, enflurane 2.0-2.5% maximum was given with O2 (21/min) and N2O (61/min); no intravenous agents were used. Suxamethonium chloride 40 mg was administered to facilitate endotracheal intubation. Anaesthesia was maintained with enflurane 1.5-2.0% with 50% N2O and O2. Tubocurarine 27 mg was given for muscle relaxation. When the tumour was manipulated, systemic arterial blood pressure was elevated again to 190 mm Hg systolic and 120 mm Hg diastolic. After removal of the tumour, the arterial pressure and heart rate were stable and recovery from anaesthesia was without circulatory or respiratory complications. Plasma aldosterone levels reached a maximum when the tumour was manipulated and fell to normal levels on the second post-operative day. Cortisol levels were not altered markedly even when the tumour was handled. These data imply that adrenocortical response to enflurane anaesthesia as jadged by plasma aldosterone levels would be different from that as estimated by plasma cortisol levels.
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PMID:Enflurane anaesthesia for removal of aldosterone producing adenoma. 126 18

Hypertension is a common phenomenon in patients undergoing aortocoronary bypass grafting. This hypertension increases myocardial oxygen consumption and can be prevented by application of vasodilators. A possible cause is activation of the renin angiotensin system. Magnesium is a potent vasodilator and has a beneficial effect after myocardial ischaemia. The study was performed to analyse the influence of magnesium infusion on the haemodynamic status and plasma renin activity in patients undergoing aortocoronary bypass grafting. METHODS. Eighteen patients (NYHA classification II-III) undergoing bypass surgery were divided into two groups, a magnesium and a control group. The magnesium group (n = 9) received 0.8 mEq/kg per h magnesium aspartate as an infusion for 15 min while still awake. After induction of anaesthesia, the magnesium infusion was reduced to 0.2 mEq/kg per h and stopped after aortic cannulation was completed. Plasma magnesium levels and concentrations within erythrocytes were measured. Anaesthesia was induced by flunitrazepam (0.01 mg/kg), fentanyl (0.005 mg/kg) and pancuronium (0.1 mg/kg). After intubation, patients were normoventilated with N2O/O2 = 1:1 and isoflurane (0.5-1.0 vol%). Additional doses of fentanyl (0.0025 mg/kg) were injected before the incision and before sternotomy. Mean arterial pressure, heart rate, cardiac index, total peripheral resistance, pulmonary vascular resistance, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, left ventricular stroke work index, right ventricular stroke work index, intrapulmonary shunt and plasma renin activity were evaluated at five predefined points: (1) prior to magnesium infusion; (2) after magnesium infusion; (3) 10 min following induction of anaesthesia under steady-state conditions; (4) after sternotomy; (5) after aortic cannulation. RESULTS. Concerning the haemodynamic parameters (MAP, RAP, PAP, PCWP) no significant difference between the two groups could be demonstrated. In the control group peripheral resistance (TPR) was higher following sternotomy and aortic cannulation than in the magnesium group. Magnesium prevented decrease of the cardiac index (CI) under steady-state conditions, during sternotomy and following aortic cannulation. Left and right ventricular stroke work indexes (LVSWI and RVSWI) were higher in the magnesium group. Plasma renin levels were not significantly different between the two groups. CONCLUSION. Patients undergoing cardiac surgery benefit from magnesium administration in the pre-bypass phase. Due to its vasodilating effect, magnesium lowers the output impedance of the left ventricle and improves cardiac pumping function. It opposes detrimental cardiovascular responses to sternotomy and following aortic cannulation. Also of importance is the advantageous effect of magnesium on cardiac arrest elicited by cardioplegia and for reactivation of the ischaemic myocardium.
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PMID:[Hemodynamics of coronary surgery patients following magnesium aspartate infusion]. 148 73

Hemodynamic changes were studied during two different anesthetic techniques in 54 patients undergoing coronary artery bypass grafting (CABG). All patients had normal to moderately impaired left ventricular function and were randomly assigned to two groups. In 27 patients, high thoracic epidural analgesia (TEA) with bupivacaine 0.375% plus sufentanil 1:200,000 (ie, 5 micrograms/mL) was used in combination with general anesthesia with midazolam/N2O; in the other 27 patients, general anesthesia (GA) with midazolam and sufentanil was used. After induction of epidural analgesia, heart rate and mean arterial pressure (MAP) decreased. Changes in cardiac index, systemic vascular resistance, and pulmonary capillary wedge pressure were not observed, whereas the stroke volume index increased significantly. After induction of intravenous anesthesia MAP decreased (20%) in both groups. During the pre-bypass period, metaraminol was used in 7 of 27 patients in the GA group and in 5 of 27 patients in the TEA group to treat hypotension. Inotopic drugs were used in 5 patients in the GA group and in none in the TEA group to treat a low CO. Ten GA patients and 4 TEA patients developed hypertension after sternal spread and the GA patients required more nitroprusside. Four GA patients developed electrocardiographic evidence of prebypass ischemia and, therefore, more nitroglycerin was needed for treating myocardial ischemia. More sodium nitroprusside was needed in the GA group during cardiopulmonary bypass (CPB) and the post-bypass period to treat hypertension with a high SVR. In conclusion, hemodynamic stability was more pronounced in the TEA than the GA group before and after CPB.
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PMID:Coronary artery bypass grafting using two different anesthetic techniques: Part I: Hemodynamic results. 847 38

A prospective randomized study was undertaken to evaluate the efficacy of electrostimulation anaesthesia (ESA) when compared with neurolept anaesthesia (NLA). One hundred patients scheduled for hysterectomy received either ESA or NLA. Higher levels of mean arterial pressure and heart rate in the ESA group make this technique less suitable for patients with a history of arterial hypertension. A higher dose of muscle relaxants was used in the ESA group. Measured stress variables like plasma glucose, cortisol, and iron indicate maintenance of the stress response during ESA. The postoperative questionnaire revealed intraoperative recall in 12% of ESA patients. We conclude that "pure" ESA based on a N2O regimen should be avoided.
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PMID:Clinical evaluation of electrostimulation anaesthesia for hysterectomy. 189 49

The ability of continuous infusions of opioids to control hypertension at the end of neurosurgical procedures without compromising prompt emergence was studied in patients undergoing craniotomy for supratentorial tumours. Four infusion regimens were compared in a randomized double-blind fashion; three of alfentanil and one of fentanyl. Low-dose alfentanil was administered to nine patients (35.1 micrograms.kg-1 then a continuous infusion of 16.2 micrograms.kg-1.hr-1); mid-dose alfentanil to eight patients (70.2 micrograms.kg-1 then 32.4 micrograms.kg-1.hr-1); high-dose alfentanil to eight patients (105.3 micrograms.kg-1 then 48.6 micrograms.kg-1.hr-1). Eight additional patients were given fentanyl (8.3 micrograms.kg-1 then 1.6 micrograms.kg-1.hr-1). Using published values for the pharmacokinetic variables of alfentanil and fentanyl, modelling predicted stable concentrations of 60, 120, 180 ng.ml-1 for the alfentanil infusion regimens respectively and 2 ng.ml-1 with the fentanyl regimen. Maintenance anaesthesia comprised the opioid infusion, 50% N2O in O2 and isoflurane titrated to control mean arterial pressure (MAP) within 20% of ward MAP. Isoflurane was discontinued after closure of the dura. Nitrous oxide was discontinued at the same time as reversal of neuromuscular blockade. The opioid infusion was discontinued with closure of the galea. A greater time-averaged isoflurane concentration was required to control MAP within the prescribed limits in the low alfentanil group (ANOVA; P less than 0.05). The PaCO2 at two, five and 30 min after extubation were not different among groups. The times from discontinuing N2O to eye opening and tracheal extubation were not different. The time to follow commands was longer in the low alfentanil group (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Continuous opioid infusions for neurosurgical procedures: a double-blind comparison of alfentanil and fentanyl. 191 54

The influence of sodium nitroprusside (SNP) on cerebral blood flow and cerebrovascular autoregulation at doses that produced 36% +/- 3% (slight) and 52% +/- 4% (moderate) reductions of mean arterial blood pressure (MABP) was evaluated in mechanically ventilated fentanyl/N2O-anesthetized pigs. The blood flow of the frontal hemispheres was evaluated by sagittal sinus outflow, which was determined by an electromagnetic method. Integrity of cerebral autoregulation was evaluated by two formal tests: one hypertensive challenge with an angiotensin infusion (n = 12) and one hypotensive challenge with reduced venous return to the heart (blockade of the vena cava, n = 7). The tests were performed before, during, and after hypotension. Cerebral blood flow tended to increase during hypotension, but this change was not significant. Impaired autoregulation was seen in both tests during slight hypotension (MABP = 89 +/- 3 mm Hg) with an SNP infusion of 12 +/- 3 micrograms.kg-1.min-1. Cerebral autoregulation was completely abolished at both tests during moderate hypotension (MABP = 61 +/- 2 mm Hg with an SNP infusion of 38 +/- 7 micrograms.kg-1.min-1). Despite a posthypotensive increase in cerebral blood flow without rebound hypertension, the autoregulatory response to angiotensin-induced hypertension was restored within 15-25 min. The autoregulatory response to a decrease in MABP was impaired for more than an hour after discontinuation of the SNP infusion. No acidosis was observed. The authors conclude that during slight and moderate SNP-induced hypotension, there was a dose-dependent impairment of cerebral autoregulation. Further, the autoregulatory response to the hypotensive challenge after SNP hypotension was markedly delayed, whereas the response to hypertension was rapidly restored.
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PMID:Nitroprusside-induced hypotension and cerebrovascular autoregulation in the anesthetized pig. 195 75

Sixty-two patients with mild hypertension were randomly assigned to receive no treatment, or 160 mg propranolol, or 200 mg metoprolol daily starting one week before elective surgery under anesthesia. The last dose was given two hours before anesthesia. Anesthesia consisted of induction with midazolam (2.5-5 mg) followed by thiopental (250-500 mg) and was maintained with 60% inspired N2O in oxygen and 0.4% enflurane inspired. Airway carbon dioxide was monitored continuously by a CO2 analyzer. Preoperative blood pressures were equally reduced by the two beta blockers. During anesthesia, however, blood pressure further decreased in the metoprolol group but not in the propranolol group. The authors conclude that propranolol is less effective than metoprolol in mildly hypertensive patients during surgery under anesthesia, owing probably to a pressor response from propranolol during the stress of surgery. They also conclude, however, that the amount of blood pressure reduction by cardioselective beta blockade (metoprolol) may not be needed and that anesthesia itself is an effective means of reducing the blood pressure.
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PMID:A pressor effect of noncardioselective beta blockers in mildly hypertensive patients during surgery under anesthesia. 195 69

A 23-year-old woman with Marfan's syndrome was scheduled for Cesarean section at 31 week gestation because of progressive aortic dissection. Since she had undergone two surgical corrections for scoliosis (Harrington rod instrumentation) 5 and 12 years ago, we selected general anesthesia. She had been taking diltiazem and propranolol for hypertension and tachycardia. Anesthesia was induced with thiopental 75 mg iv followed by O2-N2O-enflurane (4%) by face mask. Following iv administration of vecuronium 4 mg and tracheal injection of 4% lidocaine 120 mg, the trachea was intubated without a significant hemodynamic change. Anesthesia was maintained with O2-N2O-enflurane (0.5-1.5%) before delivery. Following delivery, enflurane was discontinued and small doses of fentanyl iv (total 0.2 mg) were given with iv infusion of nitroglycerin (0.2-0.5 micrograms.kg-1.min-1) during surgery. Bleeding after delivery was controllable by iv infusion of oxytocin. The Apgar score was good (9 at 1 min and 10 at 5 min respectively). Post-operative course was uneventful. Therapeutic abortion or Cesarean section should be performed as soon as possible in a patient with dissecting aortic aneurysm because of increasing risk of aneurysm rupture during pregnancy. During the surgery, minimal hemodynamic changes are required to prevent the rupture.
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PMID:[General anesthesia for cesarean section in a patient with Marfan's syndrome associated with dissecting aortic aneurysm]. 205 91


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