The Origins, Evolution, and Spread of Anesthesia Monitoring Standards: From Boston to Across the World.

In the mid-1980s, the anesthesia departments at hospitals affiliated with Harvard Medical School were faced with a challenge: mounting medical malpractice costs. Malpractice insurance was provided by the Controlled Risk Insurance Company (CRICO), a patient safety and medical malpractice insurance company owned by and providing service to the Harvard medical community. CRICO spearheaded an effort to reduce these costs and ultimately found a way to decrease the risks associated with anesthesia. Here, we chronicle events that led to the dramatic changes in medical practice that resulted from the activities of a small group of concerned anesthesiologists at Harvard-affiliated hospitals. We place these events in a historical perspective and explore how other specialties followed this example, and end with current strategies that minimize the risk associated with anesthesia. We conducted interviews with principals who formulated original standards of patient monitoring. In addition, we consulted documents in the public domain and primary source material. Efforts of these pioneers resulted in the establishment of the seminal Harvard-based anesthesia monitoring standards for minimal monitoring. What followed was an unprecedented transformation of the entire field. After the implementation of these standards at Harvard-affiliated hospitals, the American Society of Anesthesiologists (ASA) adopted "Standards for Basic Anesthetic Monitoring" for use during the administration of all anesthetics in the United States. Other nations have since adopted similar guidelines and these practices have resulted in significant improvements in patient safety. Currently, we estimate mortality due to anesthesia in healthy patients to be 1:400,000-perhaps as much as 10 times lower since the early 1980s. What began as an attempt to lower medical malpractice costs in a group of university hospitals became a worldwide effort that resulted in improvements in patient safety. Other specialties have adopted similar measures. Currently, an attitude and appreciation of safety are exemplified by several practices that include among others-the adherence to these patient safety guidelines, simulator training, the promulgation of standards and guidelines by ASA, and the use of a safety checklist before induction of anesthesia.

The History of Target-Controlled Infusion.

Target-controlled infusion (TCI) is a technique of infusing IV drugs to achieve a user-defined predicted ("target") drug concentration in a specific body compartment or tissue of interest. In this review, we describe the pharmacokinetic principles of TCI, the development of TCI systems, and technical and regulatory issues addressed in prototype development. We also describe the launch of the current clinically available systems.

The history of neuroanesthesiology: the people, pursuits, and practices.

Neuroanesthesiology has a rich history. Although advances in research and clinical practice were cornerstones for the development of this field, other equally critical factors came into play. These include the development of subspecialty societies, formal dissemination of information through textbooks and journal publications, and, most importantly, strong leadership. This article reviews important advances within the subspecialty and many individuals behind those advances. The analysis and speculative synthesis provide insights into the current status of neuroanesthesiology and possible directions for the subspecialty's future.

Arterial waveform analysis for the anesthesiologist: past, present, and future concepts.

Qualitative arterial waveform analysis has been in existence for millennia; quantitative arterial waveform analysis techniques, which can be traced back to Euler's work in the 18th century, have not been widely used by anesthesiologists and other clinicians. This is likely attributable, in part, to the widespread use of the sphygmomanometer, which allows the practitioner to assess arterial blood pressure without having to develop a sense for the higher-order characteristics of the arterial waveform. The 20-year delay in the development of devices that measure these traits is a testament to the primitiveness of our appreciation for this information. The shape of the peripheral arterial pressure waveform may indeed contain information useful to the anesthesiologist and intensivist. The maximal slope of the peripheral arterial pressure tracing seems to be related to left ventricular contractility, although the relationship may be confounded by other hemodynamic variables. The area under the peripheral arterial pressure tracing is related to stroke volume when loading conditions are stable; this finding has been used in the development of several continuous cardiac output monitors. Pulse wave velocity may be related to vascular impedance and could potentially improve the accuracy of waveform-based stroke volume estimates. Estimates of central arterial pressures (e.g., aortic) can be produced from peripheral (e.g., brachial, radial) tracings using a Generalized Transfer Function, and are incorporated into the algorithms of several continuous cardiac output monitors.

Techniques of intraoperative monitoring for spinal cord function: their past, present, and future directions.

PURPOSE: The authors discuss the use of intraoperative monitoring of spinal cord function as an essential part of operations in which the spinal cord is at risk. Although early documented cases of intraoperative monitoring were during operations to correct spinal deformities such as scoliosis, intraoperative monitoring has also increased safety during other operations, such as tumor resection and arteriovenous malformation ablation. METHODS: The authors highlight details involved in monitoring spinal cord function intraoperatively and discuss historical, current, and future perspectives on the use of these monitoring techniques as an essential part of operations in which the spinal cord is at risk. RESULTS: Intraoperative monitoring techniques mitigate the risk of post-operative deficits to the spinal cord by detecting injuries before they become permanent and while they can be reversed. CONCLUSIONS: Intraoperative spinal cord monitoring is safe, cost-effective, and valuable in reducing post-operative sensory and motor deficit. This technique should continue to be refined and its use consistently applied in any procedure where injury to the spinal cord is possible.

Intraoperative imaging in neurosurgery: where will the future take us?

Intraoperative MRI (ioMRI) dates back to the 1990s and since then has been successfully applied in neurosurgery for three primary reasons with the last one becoming the most significant today: (1) brain shift-corrected navigation, (2) monitoring/controlling thermal ablations, and (3) identifying residual tumor for resection. IoMRI, which today is moving into other applications, including treatment of vasculature and the spine, requires advanced 3T MRI platforms for faster and more flexible image acquisitions, higher image quality, and better spatial and temporal resolution; functional capabilities including fMRI and DTI; non-rigid registration algorithms to register pre- and intraoperative images; non-MRI imaging improvements to continuously monitor brain shift to identify when a new 3D MRI data set is needed intraoperatively; more integration of imaging and MRI-compatible navigational and robot-assisted systems; and greater computational capabilities to handle the processing of data. The Brigham and Women's Hospital's "AMIGO" suite is described as a setting for progress to continue in ioMRI by incorporating other modalities including molecular imaging. A call to action is made to have other researchers and clinicians in the field of image guided therapy to work together to integrate imaging with therapy delivery systems (such as laser, MRgFUS, endoscopic, and robotic surgery devices).

Magnetic resonance neurography and diffusion tensor imaging: origins, history, and clinical impact of the first 50,000 cases with an assessment of efficacy and utility in a prospective 5000-patient study group.

OBJECTIVE: Methods were invented that made it possible to image peripheral nerves in the body and to image neural tracts in the brain. The history, physical basis, and dyadic tensor concept underlying the methods are reviewed. Over a 15-year period, these techniques-magnetic resonance neurography (MRN) and diffusion tensor imaging-were deployed in the clinical and research community in more than 2500 published research reports and applied to approximately 50,000 patients. Within this group, approximately 5000 patients having MRN were carefully tracked on a prospective basis. METHODS: A uniform Neurography imaging methodology was applied in the study group, and all images were reviewed and registered by referral source, clinical indication, efficacy of imaging, and quality. Various classes of image findings were identified and subjected to a variety of small targeted prospective outcome studies. Those findings demonstrated to be clinically significant were then tracked in the larger clinical volume data set. RESULTS: MRN demonstrates mechanical distortion of nerves, hyperintensity consistent with nerve irritation, nerve swelling, discontinuity, relations of nerves to masses, and image features revealing distortion of nerves at entrapment points. These findings are often clinically relevant and warrant full consideration in the diagnostic process. They result in specific pathological diagnoses that are comparable to electrodiagnostic testing in clinical efficacy. A review of clinical outcome studies with diffusion tensor imaging also shows convincing utility. CONCLUSION: MRN and diffusion tensor imaging neural tract imaging have been validated as indispensable clinical diagnostic methods that provide reliable anatomic pathological information. There is no alternative diagnostic method in many situations. With the elapsing of 15 years, tens of thousands of imaging studies, and thousands of publications, these methods should no longer be considered experimental.

Origins of intraoperative MRI.

Neurosurgical diagnosis and intervention has evolved through improved neuroimaging, allowing better visualization of anatomy and pathology. This article discusses the various systems that have been designed over the last decade to meet the requirements of neurosurgical patients and opines on the potential future developments in the technology and application of intraoperative MRI. Because the greatest amount of experience with intraoperative MRI comes from its use in brain tumor resection, this article focuses on the origins of intraoperative MRI in relation to this field.

Intraoperative monitoring of facial and cochlear nerves during acoustic neuroma surgery. 1992.

Preservation of facial nerve function during acoustic neuroma surgery can be improved significantly by monitoring of facial electromyography (EMG) during surgery. Mechanical trauma during dissection causes EMG activity that can be played over a loudspeaker for direct feedback to the surgeon. Electrical stimulation can be used to locate the nerve even when it is out of direct view, and the threshold for stimulation provides a measure of facial (or other motor nerve) integrity. Cochlear nerve function also can be monitored by the recording of auditory brain stem responses or compound action potentials from an electrode placed on the nerve at the brain stem root entry zone.

History of the development of intraoperative spinal cord monitoring.

In the early 1970s, spinal instrumentation and aggressive surgical technology came into wide use for the treatment of severe spinal deformities. This background led to the development of intraoperative spinal cord monitoring by orthopaedic spine surgeons themselves. The author's group (T.T.) and Kurokawa's group invented a technology in 1972 to utilize the spinal cord evoked potential (SCEP) after direct stimulation of the spinal cord. In the United States, Nash and his group started to use SEPs. Following these developments, the Royal National Orthopaedic Hospital group of Stanmore, UK employed spinal somatosensory evoked potential in 1983. However, all of these methods were used to monitor sensory mediated tracts in the spinal cord. The only way to monitor motor function was the Wake up test developed by Vauzelle and Stagnara. In 1980, Merton and Morton reported a technology to stimulate the brain transcranially and opened the doors for motor tract monitoring. Presently, in the operating theatre, monitoring of motor-related functions is routinely performed. We have to remember that multidisciplinary support owing to the development of hardware and, software and the evolution of anesthesiology has made this possible. Furthermore, no single method can sufficiently cover the complex functions of the spinal cord. Multimodality combinations of the available technologies are considered necessary for practical and effective intra-operative monitoring (IOM). In this article, the most notable historic events and articles that are regarded as milestones in the development of IOM are reviewed.