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Biomedical subjects

T Valenzuela

Publications and source records attributed to T Valenzuela.

11 recordsLinked to original sources
PubMed2004

Electronic g factor of hydrogenlike oxygen 16O7+.

We present an experimental value for the g factor of the electron bound in hydrogenlike oxygen, which is found to be g(expt)=2.000 047 025 4 (15)(44). The experiment was performed on a single 16O7+ ion stored in a Penning trap. For the first time, the expected line shape of the g-factor resonance is calculated which is essential for minimizing the systematic uncertainties. The measurement agrees within 1.1 sigma with the predicted theoretical value g(theory)=2.000 047 020 2 (6). It represents a stringent test of bound-state quantum electrodynamics to a 0.25% level. Assuming the validity of the underlying theory, a value for the electron mass is obtained: m(e)=0.000 548 579 909 6 (4) u. This value agrees with our earlier determination on and allows a combination of both values which is about 4 times more precise than the currently accepted one.

Journal Article↗
PubMed2003

Cost effectiveness of defibrillation by targeted responders in public settings.

BACKGROUND: Out-of-hospital cardiac arrest is frequent and has poor outcomes. Defibrillation by trained targeted nontraditional responders improves survival versus historical controls, but it is unclear whether such defibrillation is a good value for the money. Therefore, this study estimated the incremental cost effectiveness of defibrillation by targeted nontraditional responders in public settings by using decision analysis. METHODS AND RESULTS: A Markov model evaluated the potential cost effectiveness of standard emergency medical services (EMS) versus targeted nontraditional responders. Standard EMS included first-responder defibrillation followed by advanced life support. Targeted nontraditional responders included standard EMS supplemented by defibrillation by trained lay responders. The analysis adopted a US societal perspective. Input data were derived from published or publicly available data. Future costs and effects were discounted at 3%. Monte Carlo simulation and sensitivity analyses assessed the robustness of results. Standard EMS had a median of 0.47 (interquartile range [IQR]=0.32 to 0.69) quality-adjusted life years and a median of 14 100 dollars (IQR=8600 dollars to 21 900 dollars) costs per arrest. Targeted nontraditional responders in casinos had an incremental cost of a median 56 700 dollars (IQR=44 100 dollars to 77 200 dollars) per additional quality-adjusted life year. The results were sensitive to changes in time to defibrillation, incidence of arrest, and number of devices required to implement rapid defibrillation. CONCLUSIONS: Where cardiac arrest is frequent and response time intervals are short, rapid defibrillation by targeted nontraditional responders may be a good value for the money compared with standard EMS. The incidence of arrest should be considered when choosing locations to implement public access defibrillation.

Adult↗
PubMed2001

The chain of survival.

Explore the source record for details and available documents.

Advanced Cardiac Life Support↗
PubMed1998

Potential cost-effectiveness of public access defibrillation in the United States.

BACKGROUND: Approximately 360,000 Americans experience sudden cardiac arrest each year; current treatments are expensive and not very effective. Public access defibrillation (PAD) is a novel treatment for out-of-hospital sudden cardiac arrest that refers to use of automated external defibrillators by the lay public or by nonmedical personnel such as police. A clinical trial has been proposed to evaluate the effectiveness of public access defibrillation, but it is unclear whether such early defibrillation will offer sufficient value for money. Our objective was to estimate the potential cost-effectiveness of public access defibrillation by use of decision analysis. METHODS AND RESULTS: A decision model compared the potential cost-effectiveness of standard emergency medical services (EMS) systems with that of EMS supplemented by PAD. We considered defibrillation by lay responders or police, using an analysis with a US health-care perspective. Input data were derived from published data or fiscal databases. Future costs and effects were discounted at 3%. Monte Carlo simulation was performed to estimate the variability in the costs and effects of each program. Sensitivity analyses assessed the robustness of the results to changes in input data. A standard EMS system had a median cost of $5900 per cardiac arrest patient (interquartile range, IQR, $3200 to $10,900) and yielded a median of 0.25 quality-adjusted life years (IQR, 0.20 to 0.30). PAD by lay responders had a median incremental cost of $44,000 per additional quality-adjusted life year (IQR, $29,000 to $68,900). PAD by police had a median incremental cost of $27,200 per additional quality-adjusted life year (IQR, $15,700 to $47,800). The results were sensitive to changes in the cost and relative survival benefit of PAD. CONCLUSIONS: Although more expensive than standard EMS for sudden cardiac arrest, PAD may be economically attractive. The effectiveness and cost-effectiveness of PAD should be assessed in a randomized, controlled trial.

Cost-Benefit Analysis↗
PubMed1990

A simulation model for evaluating a set of emergency vehicle base locations: development, validation, and usage.

This paper describes our experiences in developing a simulation model for evaluating a set of emergency response vehicle base locations. The project was undertaken jointly by the University of Arizona and the Tucson Fire Department. The issues of model development, data collection, model validation, and experimentation are discussed. The critical nature of the problem and the clients' lack of experience with mathematical models, made model validation the major step in gaining user acceptance. We show that looking solely at standard performance statistics such as the calls successfully serviced, may lead to the acceptance of an invalid model. We also show that the high level of detail used in many simulation models for evaluating base locations is unnecessary in the current case. An analysis evaluating two alternative sets of locations for the Tucson system is discussed.

Ambulances↗
PubMed1988

Fast Track: urgent care within a teaching hospital emergency department: can it work?

We performed a ten-week study to understand the feasibility of a fast track system within a teaching hospital setting. Our results show that 50% or fewer of patients entering an emergency department during evening and weekend day hours can be seen in Fast Track. Average turnaround time for all patients in the ED was 161 minutes. The average for all Fast Track patients was 94.5 minutes; if laboratory and/or radiographs were ordered the average was 121.5 minutes; with no laboratory/radiographs, 79.1 minutes. Urinalysis, strep screen, and complete blood count accounted for 80% of all laboratory work. Roentgenograms of the ankle, foot, and knee accounted for 80% of all radiographs. An evaluation questionnaire showed enhanced satisfaction with a reduction in the number of complaints from 79% to 22%. The Fast Track system failed when there was a predominance of acutely ill patients in the ED, as house officers were pulled to care for the acutely ill patients.

Arizona↗
PubMed1988

Railroad accidents: a metropolitan experience of death and injury.

A review of all railroad-related deaths and significant injuries that occurred in a medium-sized metropolitan area from January 1, 1979, to June 30, 1986, was conducted. Autopsy reports were obtained for each fatality, and pre-hospital data were retrieved for all railroad-related injuries resulting in emergency medical services dispatch. There were ten fatalities (24%) and 31 survivors. The average age was 31.2 years (range, 1 to 67). Thirty-seven (90%) were men. Eleven persons (27%) were intoxicated (average blood alcohol of 279 mg/dL; range, 140 to 460). Of the 30 survivors transported, hospital records were available for 24. Thirteen were hospitalized and ten underwent surgery. Six major amputations occurred among survivors. Six patients had an Injury Severity Score of more than 15. Three mechanisms of injury occurred: falls on or from a train (56%); pedestrians hit by a train (41%), which accounted for all fatalities; and a train-automobile accident. This is the first comprehensive review of all significant railroad-related injuries in a metropolitan area.

Accidents↗
PubMedDate not supplied

Medical versus regulatory necessity: regulation of ambulance service in Arizona.

Governmental regulation of emergency medical services and transportation differs from state to state. In Arizona, the Department of Health Services (ADHS) regulates the provision of ambulance service through a "certificate-of-necessity" (CON) process. Paramedic rescue services provided by municipalities are not, by statute, mandated to comply with these ADHS regulations. We review the way in which criteria for the determination of ambulance need were adopted by this state agency and the effects of their application in Tucson, Arizona. Approximately one million dollars and 5,500 unnecessary "code 3" (lights and siren activated) emergency vehicle trips were mandated by the ADHS need criteria, over a twelve-month period. We conclude that non-scientifically-derived regulatory criteria may conflict with prudent medical control of prehospital emergency medical services (EMS).

Ambulances↗
PubMedDate not supplied

Optimal prehospital cardiovascular care.

Optimal prehospital cardiovascular care may improve the morbidity and mortality associated with acute myocardial infarctions (AMIs) that begin in the community. Reducing the time delays from AMI symptom onset to intervention begins with maximizing effective patient education to reduce patient delay in recognizing symptoms and seeking assistance. Transportation delays can be minimized by appropriate use of 911 systems and improving technological 911 support. Patient triage to heart centers from the prehospital setting requires strict and comprehensive definition of the criteria for these centers by competent, unbiased clinical societies or governmental agencies. Prehospital 12-lead electrocardiograms and initiation of thrombolytic therapy can provide acute diagnosis and early treatment, thus facilitating faster processing and more directed in-hospital intervention. They also minimize over- and undertriage of patients to cardiac centers. Although evidence from investigational trials suggests that many of these procedures are effective, more research is required to ensure correct implementation and quality assurance at all emergency service levels.

Chest Pain↗