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Biomedical subjects

Tod B Sloan

Publications and source records attributed to Tod B Sloan.

7 recordsLinked to original sources
PubMed2006

Using EEG to monitor anesthesia drug effects during surgery.

The use of processed electroencephalography (EEG) using a simple frontal lead system has been made available for assessing the impact of anesthetic medications during surgery. This review discusses the basic principles behind these devices. The foundations of anesthesia monitoring rest on the observations of Guedel with ether that the depth of anesthesia relates to the cortical, brainstem and spinal effects of the anesthetic agents. Anesthesiologists strive to have a patient who is immobile, is unconscious, is hemodynamically stable and who has no intraoperative awareness or recall. These anesthetic management principles apply today, despite the absence of ether from the available anesthetic medications. The use of the EEG as a supplement to the usual monitoring techniques rests on the observation that anesthetic medications all alter the synaptic function which produces the EEG. Frontal EEG can be viewed as a surrogate for the drug effects on the entire central nervous system (CNS). Using mathematical processing techniques, commercial EEG devices create an index usually between 0 and 100 to characterize this drug effect. Critical aspects of memory formation occur in the frontal lobes making EEG monitoring in this area a possible method to assess risk of recall. Integration of processed EEG monitoring into anesthetic management is evolving and its ability to characterize all of the anesthetic effects on the CNS (in particular awareness and recall) and improve decision making is under study.

Anesthesia, General↗
PubMed2005

Implementing a simpler approach to mission-based planning in a medical school.

Changes in the education, research, and health care environments have had a major impact on the way in which medical schools fulfill their missions, and mission-based management approaches have been suggested to link the financial information of mission costs and revenues with measures of mission activity and productivity. The authors describe a simpler system, termed Mission-Aligned Planning (MAP), and its development and implementation, during fiscal years 2002 and 2003, at the School of Medicine at the University of Texas Health Science Center at San Antonio, Texas. The MAP system merges financial measures and activity measures to allow a broad understanding of the mission activities, to facilitate strategic planning at the school and departmental levels. During the two fiscal years mentioned above, faculty of the school of medicine reported their annual hours spent in the four missions of teaching, research, clinical care, and administration and service in a survey designed by the faculty. A financial profit or loss in each mission was determined for each department by allocation of all departmental expenses and revenues to each mission. Faculty expenses (and related expenses) were allocated to the missions based on the percentage of faculty effort in each mission. This information was correlated with objective measures of mission activities. The assessment of activity allowed a better understanding of the real costs of mission activities by linking salary costs, assumed to be related to faculty time, to the missions. This was a basis for strategic planning and for allocation of institutional resources.

Academic Medical Centers↗
PubMed2004

Electrophysiologic monitoring during surgery to repair the thoracoabdominal aorta.

The repair of aneurysms and dissections that involve the thoracoabdominal aorta represent a major stress to the cardiovascular surgery team because of the feared complication of paraplegia. Here, the etiology of this complication is explained through a description of the relevant surgical anatomy and characteristics of hemodynamic support. In addition, recent advances in the neurophysiologic assessment of the descending motor pathways and their application to perioperative monitoring are discussed.

Aortic Dissection↗
PubMed2002

Anesthetics and the brain.

The action of anesthetics on the nervous system can be understood by considering their possible interactions with neuronal function. Anesthesia may be produced by a change in the balance of inhibitory synapses (notable via GABAa receptors) and excitatory synapses (notably glutamate receptors). Our knowledge of the specific mechanisms of anesthetic drugs and the structures in the CNS remains inadequate to explain the anesthetic state by one mechanism. The action of anesthetics can also be considered based on the action of the drugs on cerebral physiology, notably CMR, CBF, metabolic coupling, and autoregulation. Some specific anesthetic recommendations can be made for certain neurosurgical procedures and pathology based on the effects on physiology.

Anesthetics↗
PubMed2002

Anesthesia for intraoperative neurophysiologic monitoring of the spinal cord.

Intraoperative neurophysiologic monitoring (INM) using somatosensory and motor evoked potentials (MEPs) has become popular to reduce neural risk and to improve intraoperative surgical decision making. Intraoperative neurophysiologic monitoring is affected by the choice and management of the anesthetic agents chosen. Because inhalational and intravenous anesthetic agents have effects on neural synaptic and axonal functional activities, the anesthetic effect on any given response will depend on the pathway affected and the mechanism of action of the anesthetic agent (i.e., direct inhibition or indirect effects based on changes in the balance of inhibitory or excitatory inputs). In general, responses that are more highly dependent on synaptic function will have more marked reductions in amplitude and increases in latency as a result of the synaptic effects of inhalational anesthetic agents and similar effects at higher doses of intravenous agents. Hence, recording cortical somatosensory evoked potentials and myogenic MEPs requires critical anesthetic choices for INM. The management of the physiologic milieu is also important as central nervous system blood flow, intracranial pressure, blood rheology, temperature, and arterial carbon dioxide partial pressure produce alterations in the responses consistent with the support of neural functioning. Finally, the management of pharmacologic neuromuscular blockade is critical to myogenic MEP recording in which some blockade may be desirable for surgery but excessive blockade may eliminate responses. A close working relationship of the monitoring team, the anesthesiologist, and the surgeon is key to the successful conduct and interpretation of INM.

Anesthesia↗