Succinylcholine with anesthesia

Surgery In patients receiving cholinesterase inhibitors, administer succinylcholine with extreme caution before and during general anesthesia. Use prior to ophthalmic surgery only as a considered risk because of the possible occurrence of hyphema. Pregnancy Category C. 

Suxamethonium sensitivity," prolonged paralysis of respiratory muscle function caused by failure to cleave the short-acting muscle relaxant succinylcholine widely used in anesthesia, was made testable with a simple bedside assay in 1968 (Motulsky and Morrow). However, that test was not incorporated widely into practice. Most anesthesiologists felt they could simply monitor all patients and "bag" those not resuming respiratory action, without testing for a trait that would be found in only one of 2000 patients. 

The effect of a standard dose of succinylcholine lasts only about 10 min. It is often given at the start of anesthesia to facilitate intubation of the patient. As expected, choUnesterase inhibitors are unable to counteract the effect of succinylcholine. In the few patients with a genetic deficiency in pseudocholinesterase (= nonspecific cholinesterase), the succinylcholine effect is significantly prolonged. 

Porphyria is not the only disorder that may he inadvertently precipitated by the administration of a drug. Malignant hyperthermia is a serious, life-threatening complication of general anesthesia with halothane, methoxyflurane, and succinylcholine. It occurs in 1 in 20,000 people. Clinically, it is characterized hy high body temperature (41°C), muscle rigidity, and cardiovascular collapse. 

Drug interactions Co-administration of dinoprostone in patients receiving intravenous oxytocic agents such as oxytocin may result in uterine hyperstimulation and is therefore contraindicated. Severe hypertension has been reported when oxytocin was given 3 to 4 hours following prophylactic administration of a vasoconstrictor in conjunction with spinal anesthesia. Oxytocin may enhance the neuromuscular blockade of succinylcholine. 

In the operating room, a child receives succinylcholine as a muscle relaxant to facilitate intubation and anesthesia. The operation proceeds until it is time for recovery, when the child does not begin breathing. A hurried discussion with the father discloses no additional problems in the family, but he does say that he and his wife are first cousins. The most likely possibility is... 

Succinylcholine relaxes muscles during anesthesia by competing with the molecule normally responsible for neuromuscular transmission. Which of the following phrases describes the appropriate treatment for a disease involving this neurotransmitter ... 

NMBAs are further differentiated by their duration of action during anesthesia. Succinylcholine and mivacurium are common ultra-short-acting competitive NMBAs (5-10 min). An intermediate duration of action (30-45 min) is maintained with the use of atracurium, cisatracurium, rocuronium and vecuronium. A long-lasting duration of action (90-100 min) is observed with d-tubocurarine, doxacurium, metocurine, pancuronium and pipecuronium. 

A life-threatening syndrome characterized by muscle rigidity, hyperthermia, hypertension, acidosis, and hyperkalemia. Associated with the use of skeletal muscle relaxants, especially succinylcholine, used in anesthesia regimens. Genotypic susceptibility may be related to mutations in the genes encoding ryanodine receptors and/or a protein component of the L-type calcium channel in skeletal muscle. 

Used mainly in anesthesia protocols or in the ICU to afford muscle relaxation and/or immobility. Occasionally used to treat tetanus. These muscle relaxants interact with nicotinic receptors at the skeletal muscle end plate. Nicotinic receptors are comprised of five subunits, two of which (alpha) bind ACh, a requirement for opening of the Na+ channel. Most drugs in this class bind competitively to one of the alpha subunits to prevent depolarization (receptor antagonists) one drug (succinylcholine) binds noncompetitively and opens the Na+ channel, causing excessive depolarization and desensitization. 

Methohexital (1 mg/kg in 1% solution given at a rate of 1 mL/5 seconds) is used for induction of anesthesia lasting 5 to 7 minutes. Maintenance of anesthesia may be accomplished by intermittent injections of 1% solution or by continuous IV drip of a 0.2% solution. Intermittent injections of about 20 to 40 mg (2 to 4 ml of a 1% solution) may be given as required, usually every 4 to 7 minutes. For continuous drip, the average rate of administration is about 3 mL of a 0.2% solution/min (1 drop/second). Methohexital should not be mixed in the same syringe or administered simultaneously during IV infusion through the same needle with acid solutions, such as atropine sulfate, metocurine iodide, and succinylcholine chloride. 

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