Anaesthesia adjuncts

Morphine Morphine (C17H19NO3), a habit forming Class A analgesic drug, is the major bioactive constituent of opium poppy seeds. Like other opium constituents (opiates), e.g. heroin, morphine acts directly on the CNS to relieve pain. Morphine is used for the treatment of post-surgical pain and chronic pain (e.g. cancer pain), and as an adjunct to general anaesthesia, and... 

Atanassoff PG, Alon E, Pasch T. Recovery after propofol, midazolam, and methohexitone as an adjunct to epidural anaesthesia for lower abdominal surgery. Eur J Anaesthesiol 1993 10(4) 313-8. 

Local anaesthesia is generally used when loss of consciousness is neither necessary nor desirable and also as an adjunct to major surgery to avoid high-dose general anaesthesia. It can be used for major surgery, with sedation, though many patients prefer to be unconsciousness. It is invaluable when the operator must also be the anaesthetist, which is often the case in some parts of the developing world. 

Anaesthesia in MH-susceptible patients is achieved safely with total intravenous anaesthesia using propofol and opioids. Dantrolene for intravenous use must be available in every surgical theatre. The relation of malignant hyperthermia syndrome with neuroleptic malignant syndrome (for which dantrolene may be used as adjunctive treatment, see p. 388) is uncertain. 

Suxamethonium is a neuromuscular blocking drug frequently used as an adjunct to anaesthesia it causes muscle paralysis (see Chapter 12). Normally it is metabolized by an enzyme, plasma pseudocholinesterase. One in 2500 of the population has a less active form of the enzyme. The effect of this is that the duration of action of suxamethonium is extended from about 6 minutes to 2 hours. 

Premedication is intended to prevent the parasympathetic effects of anaesthesia (excessive salivation and bronchial secretion and a reduction in heart rate) and to reduce anxiety or pain. Premedication and adjuncts to general anaesthesia are discussed further on page 234. 

Four main groups of drugs are used as premedication and as adjuncts to general anaesthesia sedatives antimuscarinic drugs muscle relaxants and analgesics. Table 12.2 shows actions and examples of drugs used to supplement general anaesthesia. 

Muscle relaxants are also known as neuromuscular blocking drugs. They are used as adjuncts to general anaesthesia, to cause muscle relaxation where this would aid the surgical process. Artificial ventilation is required because respiratory muscles are also paralysed. 

Side effects of NSAIDs are discussed in Chapter 7 and later in this chapter, but are unlikely to be a problem with short-term use as adjuncts to general anaesthesia. 

Premedication is the use of drugs to reduce a patient s anxiety and to prevent parasympathetic effects of the anaesthetic. Muscle relaxants and analgesics are used as adjuncts to anaesthesia, respectively to cause muscle relaxation and aid surgery and to reduce patient discomfort post-operatively. 

Adjuncts used in addition to contrast agents in diagnostic radiography, under patient group directions, include laxatives, drugs to relax the bowel, normal saline and topical anaesthesia. 

Pancuronium - muscle relaxant (non-depolarizing neuromuscular blocker) adjunct to general anaesthesia... 

Its actions are similar to those of tubocurarine choride. It is mostly employed as an adjunct to anaesthesia so as to achieve deeper muscular relaxation to facilitate surgical procedures. 

Heikkila J, Jalonen J, Arola M, Kanto J, Laaksonen V. Midazolam as adjunct to high-dose fentanyl anaesthesia for coronary artery bypass grafting operation. Acta Anaesthesiol Scand (1984) 28, 683-89. 

Sporadic attempts were made during the nineteenth and early twentieth centuries to use curare for the treatment of certain conditions, principally rabies, tetanus, epilepsy and spastic paralysis, and chorea, where it seemed that the muscular relaxation brought about by the drug would have beneficial effects. But the rarity of the substance, the tremendous variation in its activity, and the inability to standardize the product prevented any widespread use (22, 27). However that may be, as early as 1912 Lawen used a sample of Boehm s curarine as an adjunct to anaesthesia, thus anticipating the work of Griffith and Johnson (below) by some 30 years. It is unfortunate that this pioneering effort never received due recognition (22 p. 110,485 pp. 135-136). 

---