Hypotension anesthesia

Sevoflurane can be used to induce hypotension during neurosurgery. Hypotensive anesthesia has little effect on postoperative liver function (30). 

Lees WR, Schumillian C, Gillams AR (2000) Hypotensive anesthesia improves the effectiveness of radiofrequency ablation in the liver. Radiology 217(P) 228 Lencioni R, Bartolozzi C, Caramella D, et al (1995) Treatment of small hepatocellular carcinoma with percutaneous ethanol injection. Analysis of prognostic factors in 105 Western patients. Cancer 76 1737-1746 Lencioni R, Pinto F, Armillotta N, et al (1997) Long-term results of percutaneous ethanol injection therapy for hepatocellular carcinoma in cirrhosis a European experience. Eur Radiol 7 514-519... 

Eupatin (69, R = H) and Eupatoretin (69, R = CH3), which are isolated from thistle perennials, show moderate cytotoxicity against human carcinoma of the nasopharynx (236). Baicaleia (70) salts exhibit antiallergic and antiinflammatory activity. 3,4,5-Trimethoxyphenoxyacetamides are hypotensives and diuretics and are useful for controlling arrhythmia duting anesthesia (237). 

Isoflurane is a respiratory depressant (71). At concentrations which are associated with surgical levels of anesthesia, there is Htde or no depression of myocardial function. In experimental animals, isoflurane is the safest of the oral clinical agents (72). Cardiac output is maintained despite a decrease in stroke volume. This is usually because of an increase in heart rate. The decrease in blood pressure can be used to produce "deHberate hypotension" necessary for some intracranial procedures (73). This agent produces less sensitization of the human heart to epinephrine relative to the other inhaled anesthetics. Isoflurane potentiates the action of neuromuscular blockers and when used alone can produce sufficient muscle relaxation (74). Of all the inhaled agents currently in use, isoflurane is metabolized to the least extent (75). Unlike halothane, isoflurane does not appear to produce Hver injury and unlike methoxyflurane, isoflurane is not associated with renal toxicity. 

Enflurane (Ethrane) is a volatile liquid anesthetic that is delivered by inhalation. Induction and recovery from anesthesia are rapid. Muscle relaxation for abdominal surgery is adequate, but greater relaxation may be necessary and may require the use of a skeletal muscle relaxant. Enflurane may produce mild stimulation of respiratory and bronchial secretions when used alone Hypotension may occur when anesthesia deepens. 

Cardiovascular Effects. Epidemiologic studies indicate that chloroform causes cardiac efiects in patients under anesthesia. In a cohort of 1,502 patients (exposure less than 22,500 ppm), dose-related bradycardia developed in 8% of the cases, and cardiac arrhythmia developed in 1.3% of the cases (Whitaker and Jones 1965). Hypotension was observed in 27% of the patients and was related to the duration of the anesthesia and to pretreatment with thiopentone. Chloroform anesthesia (exposure 8,000-10,000 ppm) caused arrhythmia (nodal rhythm, first degree atrio-ventricular block, or complete heart block) in 50% of the cases from the cohort of 58 patients and hypotension in 12% (Smith et al. 

Cardiovascular Effects. Chloroform induces cardiac arrhythmia in patients exposed to chloroform via anesthesia (Smith et al. 1973 Whitaker and Jones 1965). Similarly, heart effects were observed upon electrocardiography of an individual who accidentally ingested chloroform (Schroeder 1965). Hypotension was observed in 12-27% of patients exposed to chloroform via anesthesia (Smith et al. 1973 Whitaker and Jones 1965) and also was observed in a patient who ingested chloroform (Storms 1973). 

Clinical reports of patients who underwent chloroform anesthesia indicated that premedication with morphine caused serious respiratory depression when chloroform was co-administered. Thiopentone (thiopental Na, an ultra-short-acting barbiturate anesthetic) was associated with increased incidences of hypotension in chloroform-anesthetized patients (Whitaker and Jones 1965). 

Vasoconstriction. Local application of a-sympathomimetics can be employed in infiltration anesthesia (p. 204) or for nasal decongestion (naphazoline, tetra-hydrozoline, xylometazoline pp. 90, 324). Systemically administered epinephrine is important in the treatment of anaphylactic shock for combating hypotension. 

It is used in hypotensive shock for the purpose of elevating blood pressure, which can result from spinal anesthesia, surgical complications, and head trauma. Synonyms of metaraminol are aramine, isophenylephrin, metaradine, and others. 

Surgery/Anesthesia In patients undergoing major surgery or during anesthesia with agents that produce hypotension, ACEIs will block angiotensin II formation secondary to compensatory renin release. 

The vasoconstrictor actions of epinephrine and norepinephrine have been used to prolong the action of local anesthetics by reducing local blood flow in the region of the injection. Epinephrine has been used as a topical hemostatic agent for the control of local hemorrhage. Norepinephrine is infused intravenously to combat systemic hypotension during spinal anesthesia or other hypotensive conditions in which peripheral resistance is low, but it is not used to combat the hypotension due to most types of shock. In shock, marked sympathetic activity is already present, and perfusion of organs, such as the kidneys, may be jeopardized by norepinephrine administration. 

The clinical uses of these drugs are associated with their potent vasoconstrictor action. They are used to restore or maintain blood pressure during spinal anesthesia and certain other hypotensive states. The reflex bradycardia induced by their rapid intravenous injection has been used to terminate attacks of paroxysmal atrial tachycardia. Phenylephrine is commonly used as a nasal decongestant, although occasional nasal mucosal... 

Anesthesia induction with propofol causes a significant reduction in blood pressure that is proportional to the severity of cardiovascular disease or the volume status of the patient, or both. However, even in healthy patients a significant reduction in systolic and mean arterial blood pressure occurs. The reduction in pressure appears to be associated with vasodilation and myocardial depression. Although propofol decreases systemic vascular resistance, reflex tachycardia is not observed. This is in contrast to the actions of thiopental. The heart rate stabilization produced by propofol relative to other agents is likely the result of either resetting or inhibiting the baroreflex, thus reducing the tachy-cardic response to hypotension. 

A hypotensive patient suspected of having internal bleeding is given a dose lower than the usual amount of an intravenous anesthetic. An acceptable level of anesthesia occurs. How is it possible to achieve anesthesia in this patient with a dose of anesthetic that may be inadequate in a normoten-sive patient with adequate blood volume ... 

Hypotensive emergencies during spinal anesthesia IV Initially, 0.2 mg IV. Subsequent doses should not exceed the previous dose by more than 0.1 to 0.2 mg. Maximum of 0.5 mg per dose. 

Hypotension prophylaxis during spinal anesthesia IM, SC 2-3 mg, 3 or 4 minutes before anesthesia. A dose of 2 mg is usually adequate with low spinal anesthesia 3 mg maybe necessary with high spinal anesthesia. 

Fukusaki M et al Effects of controlled hypotension with sevoflurane anesthesia on hepatic function of surgical patients. Eur J Anaesthesiol 1999 16 111. [PMID 10101627]... 

Etomidate is a carboxylated imidazole that can be used for induction of anesthesia in patients with limited cardiovascular reserve. Its major advantage over other intravenous anesthetics is that it causes minimal cardiovascular and respiratory depression. Etomidate produces a rapid loss of consciousness, with minimal hypotension even in elderly patients with poor cardiovascular reserve. The heart rate is usually unchanged, and the incidence of apnea is low. The drug has no analgesic effects, and coadministration of opioid analgesics is required to decrease cardiac responses during tracheal intubation and to lessen spontaneous muscle movements. Following an induction dose, initial recovery from etomidate is less rapid (< 10 minutes) compared with recovery from propofol. 

During spinal anesthesia, motor paralysis may impair respiratory activity, and residual autonomic nerve blockade can lead to hypotension upon ambulation. Residual autonomic blockade also interferes with bladder function, resulting in urinary retention and the need for bladder catheterization. 

It has also been suggested that terlipressin has vasoconstrictor activity within the splanchnic vascular territory (21). Hypotension developed under general anesthesia in 32 patients undergoing carotid endarterectomy treated with renin-angiotensin inhibitors (22). They were randomized to received terlipressin 1 mg (n = 16) or noradrenaline infusion. Compared with baseline those who received terlipressin had reduced gastric mucosal perfusion for at least 4 hours. There was also reduced oxygen delivery and oxygen consumption index at 30 minutes and 4 hours in those who received terlipressin. 

Morelli A, Tritapepe L, Rocco M, Conti G, Orecchioni A, De Gaetano A, Picchini U, Pelaia P, Reale C, Pietropaoli P. Terlipressin versus norepinephrine to counteract anesthesia-induced hypotension in patients treated with renin-angiotensin system inhibitors effects on systemic and regional hemodynamics. Anesthesiology 2005 102 12-19. 

Mephenteramine [Wyamine). This alpha-1 stimulant is used primarily to maintain or restore blood pressure during hypotensive episodes that may occur during spinal anesthesia. It is typically administered by intravenous or intramuscular injection. 

Methoxamine [Vasoxyl). This drug is used primarily to increase and maintain blood pressure in severe, acute hypotension, especially during general anesthesia and spinal anesthesia. It is usually administered by injection (intramuscularly or intravenously) to allow a rapid onset. 

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