Apnoea suxamethonium

Another early example of polymorphism involves the drug succinylcholine (suxamethonium), a muscle relaxant used primarily during surgery. Its action lasts only a few minutes because it is very efficiently metabolized by cholinesterases present in the liver and plasma. A few people, about 1 in 3000 who genetically lack this enzyme, develop sustained apnoea as a result of paralysis because its effect is prolonged from 30 minutes to hours. 

Evans RT, Wroe JM. Plasma cholinesterase changes during pregnancy. Their interpretation as a cause of suxamethonium-induced apnoea. Anaesthesia 1980 35(7) 651. ... 

Evans RT, MacDonald R, Robinson A. Suxamethonium apnoea associated with plasmapheresis. Anaesthesia 1980 35(2) 198-201. 

Gesztes T. Prolonged apnoea after suxamethonium injection associated with eye drops containing an anticholinesterase agent. Br J Anaesth 1966 38(5) 408-9. 

P8. Peck, A. W., Hydrolysis of suxamethonium by plasma from subjects responding to the drug with prolonged apnoea, and by plasma from their relatives. Pharmacol. Clin. 2, 6-12 (1969). 

Stovner, J., and Stadskleiv, K., Suxamethonium apnoea terminated with commercial serum cholinesterase. Acta Anaesth. Scand. 20, 211-215 (1976). 

T5. Thompson, J. C., and Whittaker, M., A study of the pseudocholinesterase in 78 cases of apnoea following suxamethonium. Acta Genet. (Basel) 16, 209-222 (1966). 

Wll. Whittaker, M., An additional pseudocholinesterase phenotype occurring in suxamethonium apnoea. Br. J. Anaesth. 40, 579-582 (1968). 

Information is limited but the interactions of suxamethonium with lidocaine, and suxamethonium with procaine appear to be established and of clinical importance. Be alert for signs of increased blockade and/or recura-risation with apnoea during the recovery period from suxamethonium. 

Lindsay PA, Lumley J. Suxamethonium apnoea masked by tetrahydroaminacrine../4/iaesife 5ia... 

Respiratory insufficiency and prolonged apnoea occurred in a patient on two occasions while receiving cyclophosphamide and undergoing anaesthesia during which suxamethonium (succinylcholine) and tubocurarine were used. Plasma cholinesterase levels were found to be low. Anaesthesia without the suxamethonium was uneventful. Seven out of 8 patients subsequently examined also showed depressed plasma cholinesterase levels while taking cyclophosphamide. ... 

An isolated report describes prolonged apnoea in a patient given promazine while recovering from neuromuscular blockade with suxamethonium (succinylcholine). Recovery from the neuromuscular blocking effects of suxamethonium is prolonged by fenta-nyl/droperidoL... 

The observation that patients who had received Innovar (fentanyl/droperidol) before anaesthesia appeared to have prolonged suxamethonium effects, seen as apnoea, prompted further study of this possible interaction. An average delay in recovery from neuromuscular blockade of 36% to 80% was seen in two studies. Another study showed that the droperidol component of Innovar was probably responsible for this interaction. 

Apnoea developed in a number of patients after they were given aprotinin whiie recovering from neuromuscular blockade with suxamethonium (succinyichoiine) alone or with tubocurarine. 

Three patients undergoing surgery who had received suxamethonium (succinyichoiine), alone or with tubocurarine, were given aprotinin intravenously in doses of 2500 to 12 000 KIU (kallikrein inactivator units) at the end of, or shortly after the operation, when spontaneous breathing had resumed. In each case respiration rapidly became inadequate and apnoea lasting periods of 7, 30 and 90 minutes occurred. Seven other cases have been reported elsewhere. ... 

In 1965 a study showed that ecothiopate iodide eye drops could markedly lower pseudocholinesterase levels. It was noted that ... within a few days of commencing therapy, levels are reached at which protracted apnoea could occur, should these patients require general anaesthesia in which muscle relaxation is obtained with succinylcholine . Cases of apnoea due to this interaction were reported the following year, and other cases have been subsequently reported. In one case a woman given suxamethonium (succinylcholine) 200 mg showed apnoea for 5 /2 hours. Other stud-... 

A manic depressive woman taking lithium carbonate with a lithium level of 1.2 mmol/L, underwent surgery and was given thiopental, 310 mg of suxamethonium (succinylcholine) over a period of 2 hours, and 500 mierograms of pancuronium. Prolonged neuromuscular blockade with apnoea occurred. ... 

Two patients, one taking phenelzine and the other who had eeased to do so 6 days previously, developed apnoea following ECT during whieh suxamethonium (succinylcholine) was used. Both responded to injeetions of nikethamide and positive pressure ventilation with oxygen. A later study observed the same response in another patient taking phenelzine. This would appear to be explained by the finding that phenelzine eaused a re-duetion in the levels of plasma cholinesterase (pseudocholinesterase) in 4... 

A man recovering from neuromuseular bloekade with suxamethonium (with some evidence of residual Phase II bloek) developed almost total muscle paralysis and apnoea when given an intravenous infusion of vancomycin. He recovered spontaneously when the vancomycin was stopped, but it took several hours. The neuromuseular blockade due to vecuronium was increased in a patient when given an infusion of vancomycin (I g in 250 mL of saline over 35 minutes). Transient apnoea and apparent cardiac arrest have also been described in a patient following a I-g intravenous injection of vancomycin given over 2 minutes. However, in both of these cases the vancomycin was given more rapidly than the current recommendations. It is now known that rapid infusion of vancomycin can provoke histamine release, which can result in apnoea, hypotension, anaphylaxis and muscular spasm, effects similar to those seen in these two patients. 

The effects of both depolarising neuromuscular blockers (e.g. suxamethonium (succinylcholine)) and competitive neuromuscular blockers (e.g. tubocurarine) can be increased by quinidine. Re-curarisation and apnoea have been seen in patients when quinidine was given during the recoveiy period from neuromuscular blockade. 

Trimetaphan can increase the effects of suxamethonium (succi-nylcholine), which may result in prolonged apnoea. This may possibly occur with other neuromuscular blocking drugs, such as alcuronium. 

A condition in which affected individuals have low levels of an abnormal cholinesterase. This results in a prolonged period of apnoea after the administration of suxamethonium, a muscle relaxant normally broken down by cholinesterase. 

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