Anesthesiology as a special field of endeavor has made clear the many physiologic changes occurring in the patient during anesthesia. The pharmacologic effects of anesthetic agents and techniques on the central nervous system and the cardiovascular and respiratory systems are now better understood. New drugs have been introduced for inhalation, intravenous, spinal, and regional anesthesia. In addition, drugs, such as muscle relaxants and hypotensive or hypertensive agents, are used for their specific pharmacologic effect. Older anesthetic techniques, such as spinal and caudal anesthesia, have been improved by the refinement of the continuous technique and more accurate methods of controlling the distribution of the administered drug. Marked advances in anesthesia have taken place in pulmonary, cardiac, pediatric, and geriatric surgery. Improved management of airway and pulmonary ventilation is reflected in the techniques and equipment available to prevent the deleterious effects of hypoxia and hypercarbia. An increased understanding of the altered hemodynamics produced by anesthesia in the ill patient has resulted in better fluid, electrolyte, and blood replacement preoperatively in patients with a decreased blood volume and electrolyte imbalance, thus allowing many patients once thought to be too ill for surgery, the opportunity for safe operative care.
Although the number of anesthesiologists has increased within recent years, it still is not enough to meet the increased surgical load. Surgeons, therefore, may find that they will be assigned certified registered nurse anesthetists (CRNAs) to administer anesthesia. Although CRNAs have excellent training they must be supervised by a physician. Hence the surgeon must bear in mind that in the absence of a trained anesthesiologist, it is the surgeon who is legally accountable should catastrophe from any cause, compromise the outcome of the surgical procedure. Under these circumstances, the surgeon should be knowledgeable about the choice of anesthetic agents and techniques, and their indications and complications. Further, he or she should be familiar with the condition of the patient under anesthesia by observing the color of blood or viscera, the rapidity and strength of the arterial pulsation, and the effort and rhythm of the chest wall or diaphragmatic respirations. Knowing the character of these conditions under a well-conducted anesthesia, the surgeon will be able readily to detect a patient who is doing poorly.
It is this point of view that has caused us to present in this practical volume the following short outline of modern anesthetic principles. This outline makes no pretense of covering fully the physiologic, pharmacologic, and technical details of anesthesiology, but it offers to the surgeon some basic important information.
The intraoperative role of the anesthesiologist as a member of the surgical team is severalfold, including the assurance of adequate pulmonary ventilation, maintenance of a near-normal cardiovascular system, and conduction of the anesthetic procedure itself. One cannot be isolated from the other.
Preventing the subtle effects of hypoxia ...