Mismatched connections.

Historically, anaesthetic equipment manufacturers used a number of differently-sized connectors in anaesthetic breathing systems. This gave rise to the potentially dangerous possibility of mismatched taper connections and a failure to create a gas-tight breathing system capable of ventilating a patient. The British Standard 3849 of 1965 attempted to correct this problem but manufacturers' designs, in some cases, still caused problems. The problem was aggravated by a move to adopt a slightly different International Standards Organisation design. By the time that universally-interchangeable connectors were widespread twenty years later disposable breathing systems had replaced the old, heavy metal connectors.

Some observations on early military anaesthesia.

Although anaesthesia was discovered in 1846, pain relief had been used for many years previously. Opium, mandragora, and Indian hemp amongst others have been used since the earliest times as alluded to by many of the classical writers. The use of refrigeration anaesthesia is known to have been recommended a millennium ago although it never had much usage. Very soon after the introduction of ether anaesthesia, it was recommended for military use and the first use by the American forces was in Buena Vista early in 1847 and then again at Vera Cruz. Pirogoff taught and used ether anaesthesia on active service with the Russian forces in the Caucasus in the summer of 1847. Meanwhile Spencer Wells, who was serving with the Royal Navy in Malta, was the first British service medical officer recorded to have used anaesthesia. He went on to write up a series of 106 anaesthetics. The Danes were probably next to use anaesthesia in battle using chloroform in 1848. However, it was not until the Crimean War that anaesthesia began to play an important part in battle surgery with many anaesthetics being given with varying results. The War of the Rebellion was the next war in which anaesthesia was important and the first one in which proper statistics were kept allowing useful analysis. Anaesthesia had irrevocably found its place in battlefield surgery.

The Marrett apparatus: is hospital anaesthetic equipment compatible with field use?

Major Rex Marrett in 1945 was commissioned to design an anaesthetic apparatus for field use to replace the Field Pattern Boyle's apparatus in use during the Second World War. His design was both elegant and avant garde and was capable of being used with all agents and circuitry then in current use. It was an economical machine with vaporizer in circle and carbon dioxide absorption as its chief mode of operation. The equipment and its later developments are described. Eventually the desire for knowing volatile agent concentrations led to its decline with production ceasing in 1976.

The C.O.N. apparatus.

The C.O.N. apparatus developed in the late 1950s utilised a non-explosive mixture of cyclopropane, nitrogen and oxygen. Its development is described.

Conservation ethics and anaesthesia.

The current attitude of conservators towards restoration is to preserve objects and materials in the condition as they are but without attempting to restore them 'as new'. Museum objects have generally ceased to serve their original utilitarian function but have become objects for study, information and inspiration. Conservation and restoration are discussed in relation to anaesthetic exhibits. Conservation is the prevention, detection, containment, control and recovery but risk avoidance and monitoring hopefully will lessen the need for conservation. Some objects such as rubber and plastic items are, by their very nature, prone to ageing, accident and mistreatment. Cleaning and maintenance may lead to loss of original detail and is 'an act of critical interpretation'. Reshaping of distorted objects and repair of broken pieces can sometimes be justified but, in other work, the actual restoration may become part of the object's history that should not be lost in trying to restore something to a presumed earlier state. The mind interprets images by reference to earlier patterns and so imperfections, if not disguised, may be unduly distracting. Museums exist for information, evidence, enlightenment and even entertainment. Conservation must serve these purposes and is not an end in its own right. The professional actions of the conservator must be governed by a total respect for physical, historic, and aesthetic integrity but this must be interpreted widely.

The respiratory depressant effect of morphine. A comparative study in three ethnic groups.

The respiratory response to carbon dioxide was measured in 130 ASA 1 adult male patients from three ethnic groups, European, Nepalese, and Chinese, both before and after premedication with intramuscular morphine sulphate (200 micrograms.kg-1 body weight). Satisfactory results were obtained from 125 patients. Overall, there was no ethnic difference in the effect of morphine on the respiratory response to carbon dioxide, but initially the Chinese group appeared to be more sensitive in their response to carbon dioxide than the Europeans and Nepalese. However, there was a significant correlation between respiratory response to carbon dioxide and pulse rate and on restricting analysis to those patients with a pulse rate equal to or less than 72 beat.min-1, the ethnic difference in carbon dioxide response disappeared. It was concluded that there were no ethnic differences in the respiratory response to carbon dioxide before or after morphine in male Europeans, Nepalese and Chinese but that the respiratory response to carbon dioxide may be influenced by long term physical training.

An ethnic comparison of the sympathetic response to tracheal intubation.

The sympathetic response to orotracheal intubation was examined in five Europeans, 15 Chinese, and seven Nepalese male patients. Plasma adrenaline and noradrenaline concentrations were assayed using high performance liquid chromatography with colorimetric detection. There was a significant rise in noradrenaline concentrations following intubation in the Chinese and the concentrations decreased over 5 min. Similar increases were seen in the Europeans and Nepalese. The mean plasma catecholamine concentrations were comparable, which suggests that there are no ethnic differences in the groups studied. A wide interindividual variation of catecholamine concentrations was found.

Minimum alveolar concentration of halothane: an ethnic comparison.

The minimum alveolar concentration (estimate of spread) of halothane which was determined in 42 Chinese, Nepalese or European patients was found to be 0.70% (0.66-0.74%) in Chinese and 0.70% (0.65-0.76%) in Nepalese and 0.68% (0.65-0.72%) in Europeans, using the Spearman Kärber method of analysis. This preliminary trial suggests that there is no ethnic difference in the minimum alveolar concentration of halothane between Asians and Europeans.

Biotransformation of pethidine: a comparative study of 24 h urine in three ethnic groups.

219 surgical patients of either Caucasian, Chinese or Nepalese origin were given pethidine 1 mg/kg by intramuscular injection as pre-operative medication. Urine was collected for 24 h and analysed for pethidine, pethidinic acid, pethidinic acid conjugates, norpethidine, norpethidinic acid, and norpethidinic acid conjugates. The mean proportion of the percentage of metabolites attributable to oxidative demethylation, hydrolysis and conjugation was almost identical in each ethic group (P > 0.2). It was concluded that there were no differences in the metabolic variability of the biotransformation of pethidine in Asians and Caucasians in whom the urine pH had not been acidified.

Suxamethonium myalgia: an ethnic comparison with and without pancuronium pretreatment.

The incidence of myalgia after suxamethonium was determined in 200 fit military male dental patients of European, Chinese and Nepalese descent. Half received pancuronium 1 mg and the other half received saline pretreatment on a randomised double-blind basis. The percentage incidence of postsuxamethonium myalgia after saline or pancuronium was found to be: Europeans 26%, 13%; Chinese 13%, 7%; Nepalese 20%, 14%. Although pancuronium reduced the incidence of myalgia by about 50% overall, these values were not significantly different from each other. The recovery of spontaneous ventilation following suxamethonium was quicker in the Europeans than in the Asians (p < 0.05). Pancuronium pretreatment also delayed the recovery of spontaneous ventilation and recovery from neuromuscular block (p < 0.05) but this was independent of ethnicity. The Europeans recovered from anaesthesia more quickly than the Asians. It was concluded that ethnicity affected recovery from suxamethonium and from anaesthesia but was not of clinical relevance to the incidence of myalgia in male Asians and Europeans.

Pethidine pharmacokinetics in a heroin addict: a case report.

Tolerance to some of the pharmacological actions of the opiates in drug addicts is well known. This report illustrates the effect on the pharmacokinetics of pethidine of heroin addiction compared with a well-matched control population.

Vecuronium: an anthropometric comparison.

This study set out to determine if there was any resistance to vecuronium in Nepalese studied in Nepal compared with Nepalese, Chinese and European patients studied in Hong Kong. The four groups, each of 10 male and 10 female patients, were intubated 60 s after administration of 0.1 mg.kg-1 vecuronium. The Nepalese patients in Nepal had significantly less satisfactory intubating conditions (p = 0.002). Similarly, male patients had significantly less satisfactory conditions than female patients (p = 0.004). Some anthropometric measurements were significantly different between the patients in Nepal and those in Hong Kong. There were also sex-related anthropometric differences. It is suggested that differences in response to vecuronium could be explained by differences in distribution volume and muscle mass.