ANESTHESIA APPARATUS

Early Delivery Systems

For the first public demonstration of ether anesthesia, Morton used a specially constructed glass bottle with an attached mouthpiece (see Chapter 9 ). In England, John Snow developed a new type of ether inhaler and took up the practice of ether anesthesia as a full-time endeavor. His apparatus provided valves to prevent rebreathing, and although he experimented with methods for carbon dioxide absorption, he did not develop it into a clinically useful technique. John Snow was aware of the difficulties associated with the simple mouthpiece that was used with a noseclip by Wells and Morton. In his book on ether published in 1847, ^[355] he states the following:

For some of the adult patients, after they lost their consciousness, made such strong instinctive efforts to breathe by the nostrils, that the air was forced through the lachrymal ducts, and occasionally they held the breath altogether for a short time, and were getting purple in the face, when the nostrils had to be liberated, for a short time, to allow respiration of the external air, and thus a delay was occasioned.

With the introduction of chloroform, several inhalers were developed to administer the agent. Ferdinand Junker^[356] (1828–1901) devised a simple inhaler, consisting of a bottle to hold liquid chloroform, an inflow tube into which the anesthetist could squeeze air with a hand pump, and an outflow tube directed into the mask. The Junker inhaler underwent several modifications to improve its safety but was rarely used in the United States. Joseph T. Clover^{[357] [358]} (1825–1882), the prominent English anesthetist after John Snow, devised several devices for the administration of nitrous oxide, ether, and chloroform. The Clover bag held more than 16 L of air, with chloroform vapor at approximately 4%. Smaller concentrations could be given by adjusting a valve on the facemask that allowed dilution of the chloroform with air. A clever solution to avoid the problem of high concentrations of chloroform was presented by Augustus Vernon Harcourt (1834–1919) in 1912. This apparatus was one of the several "draw-over" systems that brought the inspired air over a vaporizer heated by a small candle. The chloroform double-necked flask held the liquid chloroform and two beads that rose to the top or sank to the bottom, depending on the temperature of the liquid. Several draw-over chloroform delivery systems are described in Dudley Buxton's 1914 textbook.^[359] The problem with these early delivery systems for longer procedures was the potential for hypoxia and partial rebreathing of expired carbon dioxide.

Other types of anesthesia machines were developed to provide anesthesia with the insufflation method, whereby a small catheter was placed with its tip near the carina to deliver air and ether or chloroform. These were continuous-flow machines that did not rely on respiratory movements for oxygenation and were based on the work of Samuel Meltzer (1851–1920) and John Auer (1875–1948) demonstrating its safe use in animals.^[360] It was one solution to the problem of pneumothorax and respiratory decompensation during thoracic surgery. C. A. Elsberg's (1871–1948) continuous-flow machine was described in 1911 and went through several modifications.^[361] The popular Shipway model was used by Francis E. Shipway (1875–1968) to provide anesthesia to King George V of England for rib resection and drainage of empyema, a feat for which Shipway was knighted. In retrospect, it is clear that these continuous flow machines were not capable of eliminating carbon dioxide in all cases,^[362] and anesthesia machines eventually were developed that allowed to-and-fro respiration through one large-bore endotracheal tube.