NZMJ, October 1922

Since the beginning of this century there have been tremendous advances made in all branches of surgery, but I think no branch can show greater progress than had taken place in the science of administration of anæsthetics. In the early days of surgery the anæsthetist held a comparatively unimportant position; his technique was limited, and his experiences were confined to few agents and methods. He was satisfied to keep the patient still and get him out of the theatre alive. As surgery grew, so grew the science of anæsthesia, in fact to a great extent it is to the improvements of anæsthetic technique that modern surgery owes its present high standard of efficiency.

The difficulties of experimenting and trying out new methods are tremendous. The anæsthetist has the patient’s life in his hands and it is difficult to say to what extent he is justified in departing from accepted technique in trying out new methods. An error in the judgement of a surgeon in departing from accepted technique and having a fatal result, does not involve the publicity that follows the similar error of an anæsthetist. However, fortunately for surgery, the growth of the branch as a speciality has attracted men with sound scientific training, whose courageous faith in their convictions, bred of a painstaking experimenting on animals, had led them to introduce methods that have been of incalculable service to surgery. The modern anæsthetist must have a knowledge of the physiological and pathological problems involved in the use of chloroform, ether, ethyl chloride, nitrous oxide, and of local anæsthetics, and in addition must have a sounds knowledge of general medicine and surgery. The patient nowadays, expects more than mere anæsthesia, and the surgeon is realising to what an enormous extent post-operative morbidity is dependent on the anæsthesia, to enhance the constancy of results, and so by all these means generally to enlarge the scope of surgery.

Series of statistics have been published from time to time showing the immediate mortality of anæsthesia. In statistics published ten, twenty or more years ago, one can see easily how much greater is the mortality with certain agents and methods than with others. And yet we see in recent statistics, statistics for periods within a year of to-day, numerous anæsthetic fatalities due to the same agents and methods as were fully proved unsafe at least twenty years ago. Believe me, the time is coming when we shall have to answer for this to the general public. Attention is already drawn to the question, and we cannot with impunity continue using methods that have again and again been proved unsafe.

The first use of inhalation anæsthetics dates back to the decade 1840–1850, during which nitrous oxide, ether, and chloroform were all first used to assuage the pains of operate procedures. The popularity of each waxed and waned in periods. Chloroform was abandoned as a routine anæsthetic in the United States of America in 1890. However, it still held considerable popularity in England until early this century, since when its use has steadily declined in favour. Various committees have been appointed at different times to investigate its action and degree of safety. Their conclusions have been varied. Some have said that the dangers have been due to the concentration of the vapour in the air inspired, and some have said that risk depends on the total dose given. Very few now can deny that there is very much more immediate risk to life from the use of chloroform than there is from the use of any other anæsthetic. And we cannot get away from the fact that prolonged administration of chloroform or of mixtures containing it, may, and often does, lead to such extensive damage to various body cells as to interfere profoundly with metabolic and katabolic processes as to delay recovery, and even imperil the life of the patient.

However, it is quite wrong to condemn the use of chloroform when indications point to its employment. The “ether maniac” may not be so dangerous as the “chloroform maniac”, but he may do considerable harm by refusing to use chloroform when he should.

I am not going further into the choice of anæsthetic for normal cases. It is too big a subject.

There have been very great advances made in the methods of administration of all anæsthetics. The administrations of chloroform has benefited by the introduction of machines such as Vernon Harcourt and Roth Drager, by which accurate percentages of vapour may be missed with the air inhaled by the patient. More marked improvements, however, have been made in the science of ether anæsthesia. First let us consider the material itself. The ether we use is ethylic ether, one of a series formed from the methane hydrocarbons. It is prepared from ethyl alcohol by the action of sulphuric acid. In the course of manufacture certain impurities are apt to contaminate the product. Certain impurities produce outstanding bad symptoms and the usual standards of commercial ethers aim at the elimination of the more obnoxious substances only. Most people who use ether at all extensively must have been struck by the differences in the effects produced by samples of reasonably good anæsthetic ether from different makers. A few years ago, James H. Cotton, of the Toronto General Hospital, Canada, undertook research to attempt to isolate all the impurities of commercial ether and to allocate to each its share of the effects produced. His first step, and it took a year and a half of hard work, was to produce a chemically pure ether. This ether, he states, was so mild in odour, that it could have been used as the basis of any perfume. However, to everyone’s surprise it was a complete failure as an anæsthetic. He used it on a number of cases, and states that he often had to administer up to fourteen ounces to make a patient sufficiently stupid to withstand dental extraction. Instead of sensation being obtunded the patient frequently became hyperæsthetic. Now all this tends to show that all the analgesic, and most of the anæsthetic properties of ether, as we all know it, are due to impurities. I will not go in detail into all the interesting experiments performed with different substances added to the original pure ether, but the result was that pure ether was subjected to processes by which carbon dioxide and certain ethylenes were added and the resultant product is claimed to be much superior to the ordinary ether of commerce. It is marketed as “Cotton process” ether.

Somewhat similar experiments were carried out recently by Dr. Mackenzie Wallis and Dr. Langton Hewer, of St. Bartholomew’s Hospital, London. They prepared pure ether and found its action more intoxicant and anæsthetic.

They state that the usual impurities in commercial ethers are alcohol, water, acetone, mercaptans and thio acids. By oxidation there may be present aldehydes, peroxides and acids.  Irritative effects are due probably to aldehydes and thio acids and toxic effects to the mercaptans.

They then took a good commercial ether that was free from mercaptans, and submitted it to oxidation with potassium permanganate. The resultant product was pleasant to small and was a good anæsthetic. It was then analysed and found to contain certain ketones. Remembering Cotton’s discovery, that the addiction of carbon dioxide and ethylenes to pure ether produced a good anæsthetic, they added ketones, carbo dioxide, and ethylene to pure ether, and so made what they claimed to be a first class, pleasant and non-toxic anæsthetic. The new material is marketed in London as ethensal. I have used it on several occasions and cannot say that I noticed any marked difference, either in the anæsthesia produced or in the after-effects, from the ordinary ether I was using at the time. Still some anæsthetists have reported very favourably upon it, and certainly the research seems to be on very interesting lines, and might easily revolutionise the use of ether.

A great many improvements in the administration of ether have developed in connection with the surgery of the head and neck. Formerly this type of work was performed under chloroform anæsthesia, administered usually with a Junkers’ vapour apparatus. By modern methods of etherisation this whole field is claimed by ether, and the most difficult operations on the air passages can be performed under ether with equal facility to the surgeon and with far greater safety to the patient. The reason that chloroform so long held the field for this work was that it gave a deep quiet anæsthesia with a small percentage of vapour, and also that it so depressed the circulation that bleeding was at a minimum. With careful etherisation with full oxygenisation, and no respiratory embarrassment, the bleeding is not excessive, and a safely deep or light anæsthesia can be conducted that will meet all the needs of a reasonable surgeon.