Anaesthesia and neuromuscular block

Until the mid-19th century such surgery as was possible had to be undertaken at tremendous speed. Surgeons did their best for terrified patients by using alcohol, opium, hyoscine, or cannabis. With the introduction of general anaesthesia, surgeons 

The details surrounding the first use of surgical anaesthesia were submerged in bitter disputes on priority following an attempt to take out a patent for ether. The key events around this time were  

Balanced surgical anaesthesia (hypnosis with analgesia and muscular relaxation) with a single drug requires high doses that will cause adverse effects such as slow and unpleasant recovery, and depression of cardiovascular and respiratory function. In modem practice, different drugs are used to attain each objective so that adverse effects are minirnised. 

After surgery, drugs will play a part in  

Patients are often already taking drugs affecting the central nervous and cardiovascular systems and there is considerable potential for interaction with anaesthetic drugs. 

---

The above and reports from other workers (awaiting publication at the time of writing), strongly suggest that this type of neuromuscular blocking agent constitutes a notable advance in anaesthesia. The properties of pancuronium, which make it of special value in the poor-risk or asthmatic patient may be briefly summarized as ... 

Whittaker M. Plasma cholinesterase variants and the anaesthetist. Anaesthesia 1980 35 174-97. Zhang M-Q. Drug-specific cyclodextrins the future of rapid neuromuscular block reversal Drugs of the Future 2003 28 347-54. 

Neuromuscular blocking agents (curare alkaloids and certain synthetic compounds), which interfere with transmission from motor nerve endings to the membrane of the skeletal muscle, are of great practical interest. They are used in anaesthesia (to reduce the muscle tonus) and in psychiatric electroshock therapy (to reduce the intensity of... 

Pollard B J 2001 Neuromuscular blocking agents. Anaesthesia and Intensive Care Medicine 2 281-285... 

Quite apart from the neuromuscular blocking agents used in anaesthesia, a number of drugs possess actions that impair neuromuscular transmission and, in appropriate circumstances, give rise to ... 

Wulf H, Ledowski T, Linstedt U, Proppe D, Sitzlack D. Neuromuscular blocking effects of rocuronium during desflurane, isoflurane, and sevoflurane anaesthesia. Can J Anaesth 1998 45(6) 526-32. 

It exerts a weak and feeble neuromuscular blocking activity which fails to produce signifieant muscle relaxation except imder deep ether anaesthesia. It has been found to potentiate the neuromuscular blockade caused by tubocurarine and to antagonize the action of decamethonium. Paradoxically, it has been used successfully to prolong and potentiate the relaxant effects of suxamethonium chloride. Besides, it has also been reported to decrease suxamethonium-induced muscular fasciculations. 

Ledowski T, Wulf H, Ahrens K, Weindimayr-Goettel M, Kress H-G, Geldner G, Scholz J. Neuromuscular block and relative concentratiens of mivacurium isomera under isoflurane veraus propofol anaesthesia. EurJ Anaesfftesiol (2003) 20, 821-5. 

The neuromuscular blockade due to suxamethonium (succinyl-choline) can be increased and prolonged by lidocaine, procaine and possibly procainamide. These local anaesthetics all have some neuromuscular blocking activity and may theoretically also enhance the block produced by competitive neuromuscular blockers. Increased toxicity occurred when mivacurium and prilocaine were given together for regional anaesthesia. 

A randomised, placebo-controlled study involving 60 patients found that a 5000 unit/kg intravenous bolus dose of ulinastatin given before induction of anaesthesia, and again 2 minutes before intravenous vecuronium lOOmicrograms/kg, delayed the onset of neuromuscular blockade compared with placebo (250 compared with 214 seconds). The recovery from neuromuscular block (measured as return of post-tetanic count) was significantly shorter after ulinastatin than placebo (11 compared with 17.7 minutes). The effects of ulinastatin were thought to be due to an increase in the release of acetylcholine at the neuromuscular junction and enhanced vecuronium elimination due to increases in liver blood flow and urine volume. ... 

This review will discuss only new data on the side effects of the neuromuscular blocking agents and certain other muscle relaxants which have become available since the appearance of SED VIII. The well-established side effects of this group of drugs will be only briefly mentioned for more information the reader is referred to SED VIII and to standard works on clinical anaesthesia and pharn acology. 

Paralysis is preceded by muscular fasciculation, and this may be the cause of the muscle pain experienced commonly after its use. The pain may last 1-3 days and can be minimised by preceding the suxamethonium with a small dose of a competitive blocking agent. Suxamethonium is the neuromuscular blocker with the most rapid onset and the shortest duration of action. Tracheal intubation is possible in less than 60 seconds and total paralysis lasts up to 4 min with 50% recovery in about 10 min (t / for effect). It is particularly indicated for rapid sequence induction of anaesthesia in patients who are at risk of aspiration — the ability to secure the airway rapidly with a tracheal tube is of the utmost importance. If intubation proves impossible, recovery from suxamethonium and resumption of spontaneous respiration is relatively rapid. Unfortunately, if it is impossible to ventilate the paralysed patient s lungs, recovery may not be rapid enough to prevent the onset of hypoxia. 

---