Hypotension spinal

Neurotensin. This hormone has been isolated and characterized from acid—acetone extracts of bovine hypothalamus (118) on the basis of its hypotensive activity. Immunoreactive neurotensin is present in mammalian gut and is distributed throughout the central nervous system its highest concentration is in the hypothalamus and in the substantia gelatinosa of the spinal cord (119). Its overall brain distribution is not unlike that of enkephalin ( ) ... 

H26. Holiday, J. W and Faden, A. I Naloxone acts at central opiate receptors to reverse hypotension, hypothermia, and hypoventilation in spinal shock. Brain Res. 19,295-299 (1980). 

The hypotensive action of clonidine could not be explained satisfactorily by effects on the peripheral circulation. Numerous studies therefore considered the possibility of an effect on the central nervous system. Investigations performed on spinalized animals could... 

In patients with hypotension due to high thoracic spinal cord transections (resulting in an essentially complete sympathetic denervation), loss of sympathetic vasomotor control can be compensated by administration of sympathomimetics. 

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. 

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... 

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. 

Paresthesias, weakness and paralysis of lower extremity, hypotension, high or total spinal block, urinary retention or incontinence, fecal incontinence, headache, back pain, septic meningitis, meningismus, arachnoiditis, shivering cranial nerve palsies due to traction on nerves from loss of CSF, and loss of perineal sensation and sexual function Rare... 

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. 

Tizanidine o -Adrenoceptor agonist in the spinal cord Presynaptic and postsynaptic inhibition of reflex motor output Spasm due to multiple sclerosis, stroke, amyotrophic lateral sclerosis Renal and hepatic elimination t duration, 3-6 h Toxicities Weakness, sedation hypotension... 

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. 

Tizanidine (Zanaflex) Tizanidine is used primarily for treating spasticity.14,24 This drug is similar to clonidine, but has less vasomotor effects and is therefore less likely to cause hypotension and other cardiovascular problems. As indicated earlier, tizanidine stimulates alpha-2 receptors in the spinal cord, which results in decreased excitatory input onto the alpha motor neuron. Decreased excitation of the alpha motor neuron results in decreased spasticity of the skeletal muscle supplied by that neuron. 

Chinese medical practitioners in the 15th century recommended ephedra as an antipyretic and antitussive agent. Modem physicians use intravenous ephedrine for the prophylaxis and treatment of hypotension caused by spinal anesthesia, particularly during cesarean section (see Chapter 29). 

The disadvantages of spinal anesthesia are hypotension (ephedrine and methoxamine may prevent this), nausea and vomiting (avoided by thiopental), respiratory depression (treated by artificial respiration), and postoperative headache (treated by increasing the CSF pressure). 

Effects Central stimulant, mild hallucinogen, sympathomimetic with both cholinergic and adrenergic blocking properties, serotonin inhibitor, hypotensive (decreases blood pressure), and activator of spinal ganglis affecting erectile tissue of sexual organs (aphrodisiac). Taken orally first effects occur after 15-30 minutes. 

Neurokinins 9 and 10, which were isolated from porcine spinal cord extracts and synthesized in 1984 by Munekata et al. 28), show a strong hypotensive effect like substance P. 

Adverse effects Severe respiratory depression occurs. Other effects include vomiting, dysphoria, and allergy-enhanced hypotensive effects (Figure 14.4). The elevation of intracranial pressure, particularly in head injury, can be serious. Morphine enhances cerebral and spinal ischemia. In prostatic hypertrophy, morphine may cause acute urinary retention. A serious action is stoppage of... 

Williams JH, Hepner DL. Risperidone and exaggerated hypotension during a spinal anesthetic. Anesth Analg 2004 98 240-1. 

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