PubMed Health⌕ Search

Biomedical subjects

S D Foster

Publications and source records attributed to S D Foster.

At least 19 recordsLinked to original sources
PubMed1991

Anesthetic and hemodynamic effects of dexmedetomidine during isoflurane anesthesia in a canine model.

Dexmedetomidine, an alpha 2-adrenergic agonist, was administered during isoflurane anesthesia to investigate its anesthetic sparing and hemodynamic effects in the canine model. Eleven healthy dogs were anesthetized with isoflurane, intubated, and allowed to breathe spontaneously. The animals were instrumented in order to measure or calculate mean arterial blood pressure (MABP), heart rate (HR), left ventricular end diastolic pressure (LVEDP), cardiac output (CO), and systemic vascular resistance (SVR). Isoflurane minimum alveolar concentration (MAC), baseline hemodynamic measurements, and plasma catecholamine levels were determined. A 20 micrograms/kg bolus of dexmedetomidine was injected intravenously (IV) and MAC and hemodynamic values were redetermined. When isoflurane requirements were 33% of baseline, isoflurane was returned to 90% MAC and the alpha 2-antagonist, atipamezole, was administered. All dogs were treated with 40 micrograms/kg glycopyrrolate throughout the experiment to prevent any bradycardic response. Dexmedetomidine reduced isoflurane MAC by 86%. SVR, MABP, and LVEDP were significantly increased while CO and catechloamine levels were reduced. Atipamezole fully reversed the reduction in anesthetic requirements. MABP and catecholamine levels returned to baseline. SVR and LVEDP increased while CO decreased. The dogs exhibited a profound reduction in anesthetic requirement, reduced catecholamine levels, and changes in hemodynamic parameters with dexmedetomidine administration. The anesthetic sparing effect appears to be mediated by the alpha 2-receptor, since atipamezole reversed the reduction in MAC. Hemodynamic changes may be species or dose related, or due to differences in existing sympathetic tone. The role of dexmedetomidine warrants further study as an adjunct anesthetic agent.

Adrenergic alpha-Agonists↗
PubMed1991

The literature and perspectives on muscle relaxants for rapid sequence induction.

Since the advent of surgical anesthesia, one of the single greatest challenges to providers and researchers has been to develop, test, and promote drugs and techniques to facilitate rapid intubation and security of the airway to diminish risk of regurgitation and gastric aspiration. This article provides a comprehensive, historical perspective of such efforts, including the efficacy of various techniques and muscle relaxant drugs that have been used to further the ideal situation in which airway control would obviate the all-too-common morbidity statistics of gastric aspiration. Special emphasis is given to the review of succinylcholine and vecuronium relative to their roles in rapid sequence induction.

Anesthesia, Inhalation↗
PubMed1991

Pricing, distribution, and use of antimalarial drugs.

Prices of new antimalarial drugs are targeted at the "travellers' market" in developed countries, which makes them unaffordable in malaria-endemic countries where the per capita annual drug expenditures are US$ 5 or less. Antimalarials are distributed through a variety of channels in both public and private sectors, the official malaria control programmes accounting for 25-30% of chloroquine distribution. The unofficial drug sellers in markets, streets, and village shops account for as much as half of antimalarials distributed in many developing countries. Use of antimalarials through the health services is often poor; drug shortages are common and overprescription and overuse of injections are significant problems. Anxiety over drug costs may prevent patients from getting the necessary treatment for malaria, especially because of the seasonal appearance of this disease when people's cash reserves are very low. The high costs may lead them to unofficial sources, which will sell a single tablet instead of a complete course of treatment, and subsequently to increased, often irrational demand for more drugs and more injections. Increasingly people are resorting to self-medication for malaria, which may cause delays in seeking proper treatment in cases of failure, especially in areas where chloroquine resistance has increased rapidly. Self-medication is now widespread, and measures to restrict the illicit sale of drugs have been unsuccessful. The "unofficial" channels thus represent an unacknowledged extension of the health services in many countries; suggestions are advanced to encourage better self-medication by increasing the knowledge base among the population at large (mothers, schoolchildren, market sellers, and shopkeepers), with an emphasis on correct dosing and on the importance of seeking further treatment without delay, if necessary.

Antimalarials↗
PubMed1991

New advances in anesthesia.

Pharmacologic advances in anesthesia over the last decade have focused on drug safety, shorter durations of action, reversibility, and ease of administration. This is reflective of major changes in the focus of patient care from inpatient to outpatient settings as well as from available risk management data that support the investigation of these new drugs. The pharmacologic advances discussed included those drugs in current practice as well as experimental drugs yet to be released for general clinical use. Inhaled agents, such as isoflurane and perhaps the experimental agent, desflurane, will maintain or achieve their popularity because of the relative ease of administration and wide margins of safety. Propofol, the most recent intravenous anesthetic available for clinical use, has already gained wide acceptance because of its dual function as an induction and maintenance agent and its appropriateness for use in the ambulatory surgical population. The role of midazolam in anesthesia practice has increased to such an extent that it has largely supplanted the use of diazepam (Valium). The introduction of the antagonist, flumazenil, will undoubtedly enhance the safety and efficacy of midazolam as well as broaden its applicability of use across various patient populations. Several of the newer synthetic narcotics, such as alfentanil and sufentanil, have replaced other narcotics formerly used in anesthesia practice, such as meperidine and morphine, primarily because of their short action and lack of significant side effects. The use of muscle relaxants as a critical component of anesthetic management has led to the development of a number of new drugs in this classification. Pharmacologic management of patients under anesthesia will at some future date likely include the administration of alpha 2 agonists. Administration of these drugs can reduce anesthetic requirements of traditional agents by as much as 50%. As research continues, new drugs will be incorporated into the practice of anesthesia, ones that will promote rapid uptake, low toxicity, intense analgesia, easy reversibility, shorter durations, and fewer side effects. One measure of success relative to pharmacologic development in anesthesia is the recent and dramatic decreases in patient morbidity and mortality figures over the last decade. This attests to the rapid growth and development of not only improved patient monitoring systems but also newly improved "agents of sleep."

Anesthesia↗
PubMed1990

Prostacyclin levels during orthotopic liver transplantation.

Many anesthesia providers involved in orthotopic liver transplantation (OTL) have become increasingly aware of the incidence of hypotension immediately following revascularization of the donor liver. Postreperfusion syndrome (PRS) is usually characterized by a decrease in systemic blood pressure of at least 30 torr with a duration of 5 minutes or more. Several researchers have suggested that the etiology of this hypotension may be related to acute hyperkalemia, acidosis, hypothermia, reflex systemic vasodilation, or some yet unidentified prostaglandin liberated from the gut at reanastomosis. The potential role of prostacyclin as the primary etiologic agent responsible for this syndrome was studied. Serum prostacyclin measurements were obtained in seven patients 1 minute before and 5 minutes after revascularization. Coincident measures were taken of preselected cardiovascular parameters. Five patients demonstrated increased levels of prostacyclin during clamping of the portal vein and four experienced significant hypotension at reperfusion. In the five patients demonstrating hypotension, a decrease in heart rate and systemic vascular resistance and an increase in cardiac output and PCWP was noted. It is concluded that one or more endogenous prostacyclins may play an important role in the etiology of postreperfusion syndrome.

Adolescent↗
PubMed1990

Review of the two sample t tests.

The t test is a valuable statistical manipulation of moderate strength to determine whether a significant difference exists between the means of two groups, either paired or unpaired. Generally, the larger the t value, the greater chance of its statistical significance. Sample size also will influence the point at which t becomes significant, that is, the larger the size of n, the smaller the t required to become significant. As the number of degrees of freedom becomes larger, a smaller t value is sufficient to reject the null hypothesis, and as variability increases, the true chance for significant difference decreases. It should be noted that a common error in the use of the t test occurs with excessive repetition of the test on the same dataset. A resultant type 1 error will be introduced that incorrectly concludes that significant differences have been demonstrated when, in fact, they have resulted not from significance but from repeated statistical application. In other words, if a .05 level of significance is used repeatedly on a dataset, the investigator is assuming that there is a 1 in 20 chance of finding a significant difference when there is no true difference between variables. It becomes obvious that if 20 repeated applications of the t test were performed, one would expect to find one significant difference by chance alone when no true difference exists. If more than 10 applications of the t test are being conducted on the same dataset, the investigator should lower the level of significance (.01) on each individual t test of the entire set so fewer null hypotheses are rejected. t Tests numbering 40 to 50 should have an alpha level of .005. An alternative approach would be to consult a statistician and use multivariate statistical procedures.

Analysis of Variance↗
PubMed1988

A clinical evaluation system for anesthesiology residents.

Practitioners, educators, and residents in anesthesiology are concerned about issues of reliable evaluation, as advocated by such groups as the American Board of Anesthesiology and the Society for Education in Anesthesia. Further, there is a growing demand by accrediting bodies that training programs demonstrate a consistent and equitable means of evaluating residents' performance. In this article, the authors describe the development of the evaluation system employed by the Baylor College of Medicine and its affiliated hospitals to assess the clinical progress of residents in anesthesiology. The system evaluates the residents' progress in terms of levels of performance that are based on case complexity and degree of staff intervention.

Anesthesiology↗