s we celebrate ASA’s 100th anniversary, it is time to reflect upon the great strides made in the medical specialty of anesthesiology. Since its introduction, anesthesiology has undergone significant changes that have made anesthesia safer today than it has ever been in its history (although this is not yet proven scientifically). Although the numerous and impressive advances in anesthesiology are too great to cover in such a small article, I will attempt to identify 10 broad categories that may have contributed to improved patient safety and perioperative outcome.

Nondepolarizing muscle relaxants became a part of the anesthesiologist’s armamentarium in the 1940s. Image courtesy of the Wood Library-Museum of Anesthesiology.

1. Pharmacological Advances
The introduction of anesthesia revolutionized surgical care and thus is considered one of the most important achievements of modern times. Much has changed, though, since the days of induction of anesthesia with open-drop ether. One of the major advances in anesthesia was the introduction of nonflammable inhaled anesthetics, which was followed by the newer shorter-acting inhaled anesthetics (i.e., desflurane and sevoflurane) that probably allowed inhalation anesthesia to remain the mainstay of modern anesthesia practice. The advent of intravenous anesthetics allowed smoother and more rapid induction of anesthesia, while the unique recovery profile of the newer intravenous anesthetic propofol makes it the sedative-hypnotic of choice for induction of anesthesia today. The introduction of muscle relaxants allowed excellent tracheal intubating and surgical conditions, making them a part of a balanced anesthesia technique. Thus the pharmacological advances leading to availability of shorter-acting anesthetics, analgesics and muscle relaxants offered the potential for rapid and smooth induction of anesthesia, rapid recovery from the anesthesia and expansion of ambulatory anesthesia and surgery. The availability of local anesthetics also led to introduction of conduction anesthesia. Spinal and epidural anesthesia have now become excellent alternatives to general anesthesia. In addition regional analgesic techniques, particularly epidural analgesia and now continuous peripheral nerve blocks, are the cornerstones of a multimodal analgesia technique.

Commonly used crystalloids and colloids.

2. Fluid Therapy
Another major advance that has received relatively little attention is the introduction of balanced salt solutions (i.e., crystalloids) and then colloids during surgery. It has been generally assumed in the past that fluid administration had little impact on outcomes. It appears, though, that we have become too casual with the amount and type of fluid administered in the perioperative period, and more recent research indicates that management of fluid therapy intraoperatively has vast potential for influencing intraoperative and postoperative morbidity and mortality. Of course fluid therapy remains one of the most controversial topics in perioperative management, particularly concerning the choice of colloid versus crystalloid solutions.

Laryngeal mask airway. Image courtesy of the Wood Library-Museum of Anesthesiology.

3. Airway Management
One of the fundamental components of safe anesthesia practice is maintenance of a patent airway. The availability of the tracheal tube and the tools for its placement (e.g., laryngoscopes) revolutionized anesthesia practice as it allowed isolation of the trachea and safe delivery of anesthetics as well as adequate ventilation. Soon after the introduction of tracheal tubes and muscle relaxants, tracheal intubation and anesthesia were considered almost synonymous. Another major advance in airway management was the introduction of the laryngeal mask airway (LMA), which has helped to save innumerable patients threatened by difficult airways. The LMA has since been incorporated into the ASA Practice Guidelines for Management of the Difficult Airway (see the ASA “Difficult Airway Algorithm”). In fact the LMA has gained popularity as a general-purpose airway device and is currently used for routine elective surgical procedures as frequently as the tracheal tube.

Penlon Nuffield Ventilator. Image courtesy of the Wood Library-Museum of Anesthesiology.

4. Ventilators & Pumps
Advances in drug delivery systems, both anesthesia gas delivery equipment (i.e., anesthesia machines) and infusion devices, have significantly improved administration of anesthesia. The availability of ventilators in the operating room (O.R.) has allowed uninterrupted control of ventilation. Prior to introduction of ventilators in the O.R., ventilation had to be performed manually, which may sometimes be inadequate due to fatigue or need to perform other responsibilities. Since their introduction, infusion pumps have evolved into sophisticated therapy-specific devices (e.g., general purpose intravenous pump, epidural analgesia and peripheral nerve blocks) that provide more effective patient care and improve patient safety.

American Optical Pulse Oximeter, 1960s. Image courtesy of the Wood Library-Museum of Anesthesiology.

5. Monitoring Devices
Technological advances leading to development of sophisticated monitors such as noninvasive blood pressure monitoring, pulse oximetry and capnography have improved and continue to improve anesthesia care. More recently transesophageal echocardiography and ultrasound-based hemodynamic monitoring provide excellent alternatives to the pulmonary artery catheter and can be used to optimize intraoperative hemodynamics and fluid administration. Another advance, which is the focus of recent debate, is electroencephalography-based monitoring for depth of hypnosis.

The ASA Closed Claims Project database began keeping detailed statistics on anesthetic mishaps in 1985.

6. Closed Claims Project
An important and far-reaching undertaking of ASA was the development of the Closed Claims Project in 1985. The Closed Claims Project database has allowed correlation between anesthetic care and the occurrence of adverse events. Identification of the source of injury provides anesthesiologists and others with information of specific areas of emphasis. In the late 1980s, for instance, information from the database revealed respiratory-related events to be the single most important source of liability and also that many of these events could have been prevented. This data prompted ASA to develop guidelines relating to pulse oximetry, capnography and management of the difficult airway, which were mentioned previously in this article and which led to number 7 in my list of important achievements in anesthesiology history.

7. Standards & Guidelines
The development of standards and guidelines represent a major milestone in the specialty and are directly related to the activities of ASA. The “Standards for Basic Anesthetic Monitoring” and several updates since their introduction represent just some of the many ASA efforts that have significantly improved anesthesia care and patient safety. The success of the standards led to the development of evidence-based guidelines and practice parameters for specific clinical situations or procedures, such as the aforementioned Practice Guidelines for Management of the Difficult Airway.

An intensive care unit at the University of Illinois Research and Educational Hospitals in Chicago circa 1955. Photo taken from The Recovery Room — Immediate Postoperative Management, W.B. Saunders Company; 1956.

8. Perioperative Care
Anesthesiologists functioning as perioperative physicians spearheaded the introduction of preoperative clinics that allow preoperative optimization of patients and improved postoperative management, including development of organized acute pain services and multidisciplinary approaches to chronic pain management. Establishment of intensive care units (ICU) has been a major advancement in medical care, and anesthesiologists have been at the forefront of involvement and development in ICU management. Noted anesthesiologist Peter Safar, M.D., developer of cardiopulmonary resuscitation and creator of the nation’s first paramedic ambulance service, formed the country’s first ICU in 1958. Within a decade, almost all U.S. hospitals had at least one ICU.

9. Board Certification
The administration of the certification examination by the American Board of Anesthesiologists marked another important milestone in anesthesiology in the United States. The examination became possible soon after ASA’s formation and recognition of anesthesiology as a separate medical specialty. The certification and maintenance of certification of anesthesiologists and subspecialists in pain medicine and critical care medicine assesses competence and thus may be associated with improved quality of care and patient safety.

10. Anesthesiology Research
Obviously none of the advances discussed above would have been possible without research. When Crawford W. Long, M.D., administered the first ether anesthetic for surgery in 1842, he helped to initiate a shift in the way physicians viewed surgical treatment and trauma. Anesthesiologist researchers soon came to lead research endeavors in an attempt to create a controlled and predictable state of anesthesia care. Research anesthesiologists recognized the importance of vital sign monitoring, helped to determine the importance of pulse and respiratory rate during surgical procedures and developed ventilation and heart monitor machines. Anesthesiologist-led research into neural transmission is changing the way pain is treated, and anesthesiologists are active in genetic research that, though it seems like science fiction now, will some day revolutionize anesthesia care.

Many of the important achievements in anesthesiology have a tendency to be taken for granted, and our history of progress and development in such a relatively short span of time can often go unnoticed. Our specialty has gone through (and continues to go through) an amazing evolution. The development of new drugs and technological innovation continue to change our practices, which have been refined over the years and have increased in complexity and sophistication. Recent years have seen an unprecedented rate of progress, and I am sure that anesthesiology will continue to change with further improvements in patient safety and perioperative outcome. Such improvements will happen through a better understanding of drug effects, particularly with advances in genetic technology, use of sophisticated delivery systems, including anesthesia machines with superior ventilators and alarms systems, and improved smart-infusion pumps that utilize closed-loop technology. In the future, robotics will surely play a key role in patient care, and perhaps anesthesia will be delivered remotely. Improved training using simulators and advanced communications through the Internet as well as outcomes analyses should further reduce perioperative mortality as well as morbidity.

ASA and anesthesiology have accomplished much in the last 100 years, but, as has always been the case in anesthesiology’s storied yet short history, the best is yet to come. Here’s looking to another 100 years and the hundreds of new things that will change anesthesiology for the better!

Girish P. Joshi, M.D., is Professor of Anesthesiology and Pain Management and Director of Perioperative Medicine and Ambulatory Anesthesia, University of Texas Southwestern Medical Center, Dallas, Texas.

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