Skeletal surgery

The anesthesiologist selects the anesthetic drug that will produce safe anesthesia, analgesia (absence of pain), and in some surgeries, effective skeletal muscle relaxation. General anesthesia is most commonly achieved when the anesthetic vapors are inhaled or administered intravenously (IV). Volatile liquid anesthetics produce anesthesia when their vapors are inhaled. Volatile liquids are liquids that evaporate on exposure to air. Examples of volatile liquids include halothane, desflurane, and enflurane. Gas anesthetics are combined with oxygen and administered by inhalation. Examples of gas anesthetics are nitrous oxide and cyclopropane. 

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. 

Halothane (Fluothane) is a volatile liquid given by inhalation for induction and maintenance of anesthesia Induction and recovery from anesthesia are rapid, and the depth of anesthesia can be rapidly altered. Halothane does not irritate the respiratory tract, and an increase in tracheobronchial secretions usually does not occur. Halothane produces moderate muscle relaxation, but skeletal muscle relaxants may be used in certain types of surgeries. This anesthetic may be given with a mixture of nitrous oxide and oxygen. 

The various skeletal muscle relaxants that may be used during general anesthesia are listed in Table 35-3. These drugp are administered to produce relaxation of the skeletal muscles during certain types of surgeries, such as those involving the chest or abdomen. They may also be used to facilitate the insertion of an endotracheal... 

Born in 1965 in Utrecht, the Netherlands, Marjolein van der Meulen received her Bachelors degree in mechanical engineering from the Massachusetts Institute of Technology in 1987. Thereafter, she received her MS (1989) and PhD (1993) from Stanford University. She spent three years as a biomedical engineer at the Rehabilitation R D Center of the Department of Veterans Affairs in Palo Alto, CA. In 1996, Marjolein joined the faculty of Cornell University as an Assistant Professor in the Sibley School of Mechanical and Aerospace Engineering. She is also an Assistant Scientist at the Hospital for Special Surgery, New York. She received a FIRST Award from the National Institutes of Health in 1995 and a Faculty Early Career Development Award from the National Science Foundation in 1999. Her scientific interests include skeletal mechanobiology and bone structural behavior. 

A 30-year-old female is being prepared for anesthesia before exploratory surgery for a mass in her neck. In addition to using an inhalation anesthetic, a drug is given that causes complete paralysis of the skeletal muscles. 

In skeletal muscle fibers whose motor nerve has been severed, ACh receptors spread in a few days over the entire cell membrane. In this case, succinylcholine would evoke a persistent depolarization with contracture and hyperkalemia. These effects are likely to occur in polytraumatized patients undergoing follow-up surgery. 

Muscle relaxants (myorelaxants) are a large group of chemical compounds that have the ability to relax skeletal muscle. They are a separate class of drags used during intubations and surgery to reduce the need for anesthesia and facilitate intnbation. 

Skeletal muscle relaxants may be nsed for relief of spasticity in nenromnscular diseases, snch as multiple sclerosis, as well as for spinal cord injnry and stroke. They may also be used for pain relief in minor strain injnries and control of the mnscle symptoms of tetanus. Dantrolene (Dantrium) has been nsed to prevent or treat malignant hyperthermia in surgery. 

It is indicated as a narcotic analgesic supplement in general or regional anaesthesia, as an anaesthetic agent with oxygen and skeletal relaxant in selected high risk patients (e.g. open heart surgery). 

It is indicated in skeletal muscle spasm, in surgery, orthopaedic procedures, neurological diseases and tetanus. 

During the 16th century, European explorers found that natives in the Amazon Basin of South America were using curare, an arrow poison that produced skeletal muscle paralysis, to kill animals. The active compound, d-tubocurarine, and its modern synthetic derivatives, have had a major influence on the practice of anesthesia and surgery and have proved useful in understanding the basic mechanisms involved in neuromuscular transmission. 

The biochemical indices of skeletal muscles in plastic surgery of injuries have been investigated in detail for KL-3, because muscles are injured quite frequently (Ref.15) P-81). 

Nonetheless, residual effects of the neuromuscular blocker can persist in some patients long after surgery is complete.6,13 The most serious complication is residual paralysis that is, skeletal muscle contraction remains depressed for several hours after the drug should have worn off.8,18 In extreme cases, this residual paralysis necessitates that the patient remain in intensive care with a mechanical ventilator to provide respiratory support. 

Drugs discussed in this chapter are used to decrease muscle excitability and contraction via an effect at the spinal cord level, at the neuromuscular junction, or within the muscle cell itself. Some texts also classify neuromuscular junction blockers such as curare and succinylcholine as skeletal muscle relaxants. However, these drugs are more appropriately classified as skeletal muscle paralytics because they eliminate muscle contraction by blocking transmission at the myoneural synapse. This type of skeletal muscle paralysis is used primarily during general anesthesia using neuromuscular blockers as an adjunct in surgery was discussed in Chapter 11. Skeletal muscle relaxants do not typically prevent muscle contraction they only attempt to normalize muscle excitability to decrease pain and improve motor function. 

Jasty MC, Bragdon C, Burke D, O Connor D, Lowenstein J, Harris WH. In vivo skeletal responses to porous-surfaced implants subjected to small induced motions. Journal of Bone and Joint Surgery 1997, 79, 707-714. 

The finding that tamoxifen given as adjuvant to surgery improved survival (Fisher et al., 1996) and decreased bone loss (Evans and Turner, 1995 Jordan, 1993) has been a major stimulus to search for other and possibly more potent and specific compounds that would act as antiestrogens in the breast and uterus while having estrogen-like effects in the skeletal and cardiovascular systems. 

Therapeutic uses These blockers are used therapeutically as adjuvant drugs in anesthesia during surgery to relax skeletal muscle. 

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