Monitoring, past, present, future
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A little over 40 years ago, anesthesiology in the United States became recognized as a specialty. At that time, its practice was largely that of an art, the science of which was yet to come. A finger on the pulse, observation of color, skin turgor, perspiration, and perhaps a blood pressure cuff in adults, and an estimation of the reflex signs of anesthesia were the standards for the assessment of the patient status and ‘the depth of anesthesia’. How far have we come in the intervening years? The journey, as reflected in the experience of one physician, will be held up to the looking-glass; easily as astounding as that through which Alice passed.
Caught as we are in the socio-economic climate of the present, how shall we react? Has the gadgetry and electronics of this day given us a meaningful cost-effective handle on a decreased morbidity and mortality? What impact is there on decision-making and outcome? What indeed is the contribution of the machine versus the newer agents, techniques, and the advanced educational milieu.
The first attempts at monitoring were clearly directed toward the cardiovascular system. The devices developed were simple and non-invasive. The Riva-rocci method of measuring blood pressure was first applied in anesthesia by Harvey Cushing at the turn of the century. But it was 40 years before the electrocardiogram was introduced as an instrument of potential importance. It took another 25 years for it to have general acceptance, and even later for the anesthesiologist to become comfortable with it as a diagnostic tool. In the early 40s, Peterson, at Pennsylvania, began the applications of invasive blood pressure monitoring for clinical purposes. Subsequently, the use of the central venous catheter, and finally the Swan-Ganz catheter, became acceptable. The application for the technology of cardiac output was a long time in gaining clinical credence. However, this last link surely depended on the computer to make it a clinically useful instrument. The measurement of the cardiovascular system was first, because the means were there.
The assessment of respiratory function was more cumbersome, and while the pneumotachygraph was available 40 years ago, its vagaries made it a research tool. Meters for respiration also were available, but too cumbersome for clinical use. The integration of respiratory measurements and blood gas analysis have gone hand-in-hand, the latter far outstripping the former in clinical utility. Shall it be invasive or non-invasive, what is the price? Lastly, our technology has introduced the means for what is a meaningful clinical measurement of neurological and neuromuscular activity. Nerve-muscle stimulators, electromyography, processed electroencephalogram, and the evoked potential as devices for assessment are only the beginning. In all this technological advance there is the ‘black box’ and the electronic marvels that are part of this age. While invasive techniques surely have a place, the utilization of non-invasive techniques like the measurement of oxygen, carbon dioxide, and all the agents that we employ have changed forever the nature of our practice. Finally, the need to document the anesthesia course objectively will, and has already begun, to impact on our practice. How did we get where we are and where are we going will be explored in this personal journey.
Keywordscomputers monitors anesthesia technology electronic personal
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