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

Hypertension is common following coronary artery bypass surgery. The safety of labetalol, a recently released combined alpha-1 and beta-adrenergic blocking agent for treatment of hypertension in this clinical situation is controversial. The authors compared the hemodynamic effects of labetalol with those of sodium nitroprusside (SNP) in 91 patients with good left ventricular function and equally severe coronary artery disease and in whom coronary artery bypass surgery had been just completed. They were anesthetized using fentanyl, diazepam, and enflurane. If hypertension developed postoperatively, patients were randomized to receive labetalol, 2 mg/min to a maximum of 300 mg (20 patients) or sodium nitroprusside in 0.5 micrograms.kg-1.min-1 increments by infusion (20 patients) to return blood pressure to normal. Compared with control values, labetalol brought about significant (P less than 0.05) reductions in heart rate, and cardiac index. No change was noted in stroke volume or systemic vascular resistance, but slight increases were found in central venous pressure and pulmonary capillary wedge pressure. Sodium nitroprusside treatment caused significant increases in heart rate and cardiac index while reducing diastolic blood pressure, central venous pressure, and pulmonary capillary wedge pressure. Stroke volume remained unchanged. Following the study period, blood pressure was controlled in all patients with SNP. Total doses of SNP in the 16 h following the study period were significantly less in the labetalol group (46.6 +/- 11.7 mg) versus (116.1 +/- 10.3 mg) in the SNP group (P less than 0.05). In this clinical circumstance, labetalol can be safe and effective for controlling hypertension, but its mechanism of achieving this effect varies from that for sodium nitroprusside.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intravenous labetalol versus sodium nitroprusside for treatment of hypertension postcoronary bypass surgery. 268 94

In a double-blind, placebo controlled study ketanserin, a serotonin S2 antagonist, was administered to hypertensive patients who had undergone coronary artery bypass surgery. Patients were allocated randomly to receive placebo or ketanserin at an infusion rate of 0.05, 1 or 2 mg kg-1 h-1. Sodium nitroprusside was used as escape medication. Ketanserin reduced the nitroprusside requirements and improved the quality of arterial pressure control in all groups, and this was significant in the low- and high-dose groups. There was a significant decrease in heart rate in the low- and high-dose groups compared with placebo, and no effect in patients who received the medium dose of ketanserin. Ketanserin may be a useful treatment for hypertension following coronary artery surgery as it reduced arterial pressure without reflex tachycardia.
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PMID:Effect of ketanserin on sodium nitroprusside requirements, arterial pressure control and heart rate following coronary artery bypass surgery. 278 22

Sodium nitroprusside is commonly used for the induction of hypotension during neurosurgical procedures. Its toxicity stems from hemodynamic compromise as well as from its metabolites, especially the formation of cyanide. A patient is described who underwent craniotomy for hypertensive intracerebral hemorrhage. He gradually recovered following the operation, but needed continued administration of sodium nitroprusside for control of hypertension. On the 7th postoperative day, he deteriorated into coma with evidence of severe edema and herniation on the computerized tomography scan. Cessation of sodium nitroprusside and treatment for cyanide poisoning resulted in resolution of his symptoms within hours. The potential toxicity of sodium nitroprusside, measures to prevent toxicity, and therapeutic steps are discussed.
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PMID:Delayed postoperative neurological deterioration from prolonged sodium nitroprusside administration. Case report. 279 79

Intracellular cyclic GMP concentration was used as a biochemical indicator of endothelium-dependent and organonitrate-induced responses to these vasodilators in cultured porcine aortic smooth muscle and endothelial cells. Sodium nitroprusside (10(-6) M) caused a rapid increase in cyclic GMP levels in confluent smooth muscle cell cultures but not in confluent endothelial monolayers. Adenosine triphosphate (10(-4) M) and methacholine (10(-5) M), two agents that elicit endothelium-dependent relaxation in intact vessels, failed to raise cyclic GMP concentrations in muscle or endothelial cultures alone. When the cell types were grown together in mixed culture, however, treatment with adenosine triphosphate or methacholine induced an elevation in intracellular cyclic GMP levels. These findings suggest that mixed cultures of arterial smooth muscle and endothelial cells can be used to study the phenomenon of endothelium-dependent responses in arterial smooth muscle.
Hypertension
PMID:Evidence for endothelium-derived relaxing factor in cultured cells. 299 65

Forty patients who had undergone coronary artery graft surgery and who required vasodilator therapy for postoperative hypertension were given infusions of either alfentanil or morphine together with bolus doses of midazolam for sedation and analgesia while ventilation was controlled artificially. Sodium nitroprusside (SNP) was administered to both groups using a computer-controlled closed loop system which adjusted the infusion rate to maintain a preset target arterial pressure. Target pressure +/- 5, 10, 15 and 20 mm Hg was maintained longer in the group receiving alfentanil. This group also required less SNP per hour. No difference was noted between the groups in the time taken to regain spontaneous ventilation and to extubation of the trachea, although the alfentanil group tended to be sedated more deeply during the infusion. The main advantage of alfentanil over morphine at doses used in this study was its superior ability to attenuate hypertensive responses to noxious stimuli, providing improved haemodynamic stability.
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PMID:Sedation following cardiac surgery: evaluation of alfentanil and morphine in the presence of a computerized closed loop arterial pressure controller. 314

Sodium nitroprusside was administered to 58 neonates, including 11 with severe respiratory distress syndrome, 15 with persistent pulmonary hypertension of the newborn, 28 with clinical shock, three with systemic hypertension, and two with pulmonary hypoplasia, all refractory to conventional intensive therapy. Nitroprusside was infused at 0.2 to 6.0 micrograms/kg/min for periods of 10 minutes to 126 hours. Infants with severe respiratory distress syndrome had increased PaO2 and decreased PaCO2 or peak inspiratory pressure, and nearly all (82%) survived. Infants with persistent pulmonary hypertension of the newborn had variable responses; improvement did not correlate with survival, but survival (47%) was identical to that in an earlier series of infants given tolazoline. Infants in shock had improved perfusion, urine output, and serum bicarbonate levels, and these responses were significantly related to survival. Hypertension was controlled in all three hypertensive infants. Adverse effects were very uncommon. Toxic effects were not observed. Sodium nitroprusside is effective and can be used safely in circulatory disorders in the neonate.
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PMID:Use of sodium nitroprusside in neonates: efficacy and safety. 391 95

Sodium nitroprusside (NP) is a potent vasodilator that also inhibits platelet aggregation. To test the hypothesis that NP causes both of these effects by altering the balance between prostacyclin (PGI2) produced by endothelial cells and thromboxane A2 (TXA2) produced by platelets, we incubated each of these cell types with NP for 5 minutes and assayed the PGI2 and TXA2 produced. NP at pharmacologically achieved doses (0.01--30 micrograms/ml) inhibited platelet aggregation and resultant TXA2 synthesis in a dose- and time-dependent manner (p less than 0.001). The inhibition was not dependent on cAMP production, external calcium concentration, or suppression of TXA2 synthesis. NP did not alter the production of PGI2 by cultured human endothelial cells as measured by radioimmunoassay for 6-Keto-PGF1 alpha, the stable hydrolysis product of PGI2. However, supernates of NP-treated endothelial cells containing low, noninhibitory concentrations of NP unexpectedly inhibited platelet aggregation. This inhibition of platelet aggregation was due to synergy between PGI2 (0.1--3 nM) and NP (p interaction less than 0.03). The synergistic inhibition by NP and PGI2 of platelet aggregation and TXA2 synthesis in vivo may explain some of the beneficial actions of NP in the treatment of hypertension and congestive heart failure.
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PMID:The interaction of sodium nitroprusside with human endothelial cells and platelets: nitroprusside and prostacyclin synergistically inhibit platelet function. 629 3

The relaxation response to endothelium-dependent (acetylcholine and the calcium ionophore A23187) and independent (sodium nitroprusside) vasodilators was examined in isolated aortic ring segments from age-matched genetically hypertensive (GH) and normotensive (N) rats (New Zealand strain). Tissues were initially contracted with methoxamine to achieve similar levels of contractile force. The IC20, IC40 and IC50 values for acetylcholine, A23187 and sodium nitroprusside were shifted significantly to the right (P less than 0.05) in aortic rings from GH rats compared to the corresponding values in N rats. The maximal relaxation achieved by acetylcholine and A23187 was significantly depressed in aortas from GH rats (P less than 0.05). Sodium nitroprusside elicited the maximal relaxation in both groups of tissues. These results demonstrate that there exists a generalized defect in the relaxant ability of vascular smooth muscle from GH rats. In addition, our findings suggest that this defect is coupled with a decreased responsiveness to endothelium-dependent vasodilators in this particular animal model of hypertension.
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PMID:Decreased endothelium-dependent relaxation in New Zealand genetic hypertensive rats. 644 14

Sodium nitroprusside has been used to alter blood pressure in severe hypertensive disease of pregnancy; however, concern exists in regard to potential lethal complications from cyanide toxicity in both mother and fetus. We recently evaluated levels of cyanide in the liver of an infant stillborn to a woman in whom sodium nitroprusside was used to control gestational hypertension secondary to mitral valve disease. The fetal liver demonstrated levels of cyanide below toxic ranges. Biologic activity, potential toxicity, and treatment of toxic symptoms of nitroprusside are discussed.
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PMID:Sodium nitroprusside for control of severe hypertensive disease of pregnancy: a case report and discussion of potential toxicity. 672 Jul 94

To assess the effects of sodium nitroprusside on the deleterious hemodynamic effects of clamping and unclamping of the aorta during resection of thoracoabdominal aortic aneurysm without the use of a shunt, 50 patients were studied. The risk factors included coronary artery disease (44%) associated with previous myocardial infarction (28%), hypertension (70%), congestive heart failure (6%), chronic obstructive pulmonary disease (34%), asthma (2%), and renal insufficiency (2%). Sodium nitroprusside infusion (3 micrograms/kg/min) was started before clamping and discontinued before unclamping of the aorta. The infusion rate was adjusted to maintain blood pressure and pulmonary capillary wedge pressure within the range of control. During cross-clamping cardiac index in the patients remained unchanged and even increased on unclamping, suggesting that left ventricular function was efficiently protected during these periods. All the patients survived the surgery, and the 30 day mortality was only 4%. Our data indicate that major aortic surgery can be carried out safely with the use of nitroprusside rather than of mechanical techniques to provide proximal decompression.
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PMID:Use of nitroprusside during surgery for thoracoabdominal aortic aneurysm. 674 71


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