The development of inhalation anaesthesia : with special reference to the years 1846-1900... / [Barbara M. Duncum].
- Duncum, Barbara M.
- Date:
- 1947
Licence: In copyright
Credit: The development of inhalation anaesthesia : with special reference to the years 1846-1900... / [Barbara M. Duncum]. Source: Wellcome Collection.
508/664 page 488
![the two bags must be kept as nearly as possible equal in size. It is rarely, if ever necessary to replenish the oxygen bag during the administration, but the foot must be constantly kept on the nitrous oxide key. . . . Should phonation, laughter, excited movement, or struggling assert itself, the administrator should withhold more oxygen for the present, or even . . . turn . . . back the indicator for a few breaths. In forty or fifty seconds from the commencement of the inhalation the indicator may usually be got as far as 5, and in twenty seconds or so more may be allowed to point to 6, or even 8. Generally speaking, it is not advisable to give more oxygen than this. ... It is impos- sible to formulate any definite rules. Considerable practice is necessary ... to know when to give more, and when to give less oxygen. Whilst too much oxygen will be likely to induce laughter, excited movement, stamping, screaming, &c, . . . the anaesthetist must be careful not to proceed too far in the opposite direction. In regulating the increase or decrease of oxygen we must reckon what the future effects of any procedure will be. . . . On the one side we wish to avoid the clonic respiratory movements, &c, which prevent a free and lengthy intake of the anaesthetic ; and on the other any inconvenient signs of incomplete anaesthesia.' 1 In 1897 Hewitt published what he described as a ' small treatise on the administration of nitrous oxide and oxygen for dental operations, dealing more particularly with the practical aspects of the subject'. ' Eleven years have elapsed since I commenced working at this subject', wrote Hewitt. ' The first eight years were mainly devoted to conducting preliminary experimental administrations of various mixtures of nitrous oxide and oxygen and to devising and perfecting apparatus. The last three years have been occupied in ascertaining the precise influence exerted by this or that per- centage of air or of oxygen upon the usual asphyxial phenomena of pure nitrous oxide.' Although Hewitt claimed that the apparatus used by him in 1897 was a ' perfected ' version of that described in 1893, the two did not greatly differ in essentials ; nor had the three years' additional research seriously modified Hewitt's opinion on the correct percentages of oxygen to be administered. ' There is, unfortunately, no rule ', he wrote, ' which will apply to every case. ... A little practice will enable him [the anaesthetist] to avoid the Scylla of asphyxia on the one hand,](https://iiif.wellcomecollection.org/image/b20457200_0512.jp2/full/800%2C/0/default.jpg)
