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Biomedical subjects

L A Lynn

Publications and source records attributed to L A Lynn.

14 recordsLinked to original sources
PubMed1996

Effect of measurement error on calculated variables of oxygen transport.

The effect of measurement error in pH, PCO2, and PO2 on mathematically derived variables of oxygen transport in patients was delineated by comparing calculated oxygen saturations from a blood-gas machine with measured saturations from a CO-oximeter and further by modeling the error in a computer simulation. Twenty-one critically ill patients aged 30-84 yr were studied. A total of 80 arterial and 80 mixed venous blood gas samples were collected. The intraclass correlation results between measured and calculated arterial (SaO2) and mixed venous (Sv-O2) oxygen saturations were 0.59 and 0.68, respectively. The product-moment correlation for SaO2 was 0.75 and for Sv-O2 was 0.77. The percent error in calculating and measuring oxygen saturation was found to be greater at low PO2 values, whereas percent error of calculating oxygen consumption increased as the PO2 increased. Measurement repeatability at high PO2 is better than at low PO2 for both measured and calculated methods. We conclude from this comparison that measured and calculated SaO2 and Sv-O2 values are not interchangeable. Each can introduce substantial error in calculating oxygen consumption through error propagation and error amplification.

Adult↗
PubMed1994

Screening surgeons for HIV infection: assessment of a potential public health program.

OBJECTIVE: To develop a model to assess the impact of a program of testing surgeons for human immunodeficiency virus (HIV) on the risk of HIV acquisition by their patients. DESIGN: A Monte Carlo simulation model of physician-to-patient transmission of human immunodeficiency virus (HIV) infection using three different rates of physician-to-patient transmission per percutaneous exposure event (0.15%, 0.3%, 0.6%). Data from the model were developed from a review of the medical literature and from subjective probability estimates when data were not available. We used this model to estimate on a national basis the annual number of cases of HIV transmission from surgeons to patients with and without surgeon testing and practice limitations. RESULTS: The annual number of transmitted cases would range from 0.5 (+/- 0.3), assuming a surgeon HIV prevalence of 0.1% and a surgeon-to-patient transmission rate of 0.15%, to 36.9 (+/- 11.6), assuming a surgeon HIV prevalence of 2% and a surgeon-to-patient transmission rate of 0.6%. After one screening cycle, a mandatory screening program would be expected to reduce the annual transmissions to 0.05 (+/- 0.03) and 3.1 (+/- 1.1), respectively. CONCLUSION: Patients are at low risk of acquiring HIV infection from an infected physician during an invasive procedure. The potential costs of such a program extended beyond the costs of testing and counseling. In communities with high HIV prevalence, screening surgeons and limiting their practices may decrease patient access to care. A disability insurance program also would be required to protect surgeons and trainees performing invasive procedures. Screening surgeons for HIV infection would be a costly undertaking that would reduce but not completely eliminate this risk.

AIDS Serodiagnosis↗
PubMed1993

Patient attitudes toward rooming with persons with HIV infection.

BACKGROUND: Early in the HIV epidemic, hospitals developed strict isolation policies for patients with HIV infection, some of which have not been revised. The objectives of this study were to examine patient attitudes about rooming with persons with various medical conditions, including HIV, and to assess their knowledge about the transmission of HIV. METHODS: One hundred four inpatients at a university hospital were surveyed by means of a structured interviewer-administered questionnaire. Patients were asked about preference for a single or double room, and about their objections to rooming with patients with HIV infection and other medical conditions. The questionnaire also examined subject's knowledge about the transmission of HIV. RESULTS: Of 104 inpatients surveyed, 55% objected to rooming with an HIV-seropositive patient. Patients who objected to rooming with an HIV-seropositive patient were also more likely to object to rooming with a disfigured patient (relative risk = 1.5; 95% CI, 1.1 to 2.2), or with a demented patient (relative risk = 1.7; 95% CI, 1.0 to 2.9). Also, patients who objected to rooming with an HIV-seropositive patient had greater misconceptions about the transmissibility of HIV infection. CONCLUSIONS: A significant proportion of patients reported an unwillingness to room with patients with HIV infection, but also had misconceptions about the transmissibility of HIV. Current rooming policies may perpetuate misconceptions about the possibility of causal transmission of HIV.

Attitude to Health↗
PubMed1992

The pharmacoeconomics of HIV disease.

Human immunodeficiency virus (HIV) infection is a major public health problem in all parts of the world. For the United States, federal spending on HIV disease for 1982 to 1989 was $US5.5 billion. Projections indicate that AIDS spending may reach 1.6% of total health expenditures in 1992, while the indirect costs of HIV infection may be 5 times as great as the direct costs. In the developing world, the cost per person with HIV infection may be 0.8- to 9-fold greater than the per capita gross national product (GNP). Pharmacoeconomic analysis has been used to assess 2 important therapeutic options in caring for HIV patients: zidovudine therapy for asymptomatic illness, and prophylaxis for Pneumocystis carinii pneumonia (PCP). The cost-effectiveness ratio for zidovudine therapy, $US6553 to $US70 526 per year of life saved, compares favourably with ratios for other medical therapies. Prophylaxis against Pneumocystis carinii pneumonia has been shown to be most efficient using oral dapsone or cotrimoxazole (trimethoprim-sulfamethoxazole). Pharmacological therapy for HIV is costly, however, and may limit the access to new therapies for patients in the developing world. Concurrent economic assessment of therapies during phase III trials may serve as an essential part of the research that will advance international efforts to combat this disease.

Cost-Benefit Analysis↗
PubMed1991

Cost effectiveness of low-dose zidovudine therapy for asymptomatic patients with human immunodeficiency virus (HIV) infection.

We did a cost-effectiveness analysis of zidovudine therapy for asymptomatic patients with human immunodeficiency virus (HIV) infection. The incremental direct medical costs of zidovudine therapy were determined, and data on the effects of therapy were derived from the report of the Acquired Immunodeficiency Syndrome (AIDS) Clinical Trials Group Protocol 019. Zidovudine therapy has an annual incremental cost of $2653 per person. The cost per year of life saved ranges between $6553 and $70 526, depending on which epidemiologic model of potential long-term zidovudine effect is used (in sensitivity analyses, the cost per year of life saved ranges between $2649 and $250 546). Although expensive, zidovudine therapy has the potential to yield a substantial survival benefit to patients. The cost effectiveness of zidovudine therapy compares favorably with that of other common medical therapies.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Bedside respiratory analysis by pocket computer.

A computer program is presented which analyzes acid-base and respiratory variables. This program's advantages include limited data input, hand-held portability, error identification, and succinct analysis statements. It is a useful adjunct to daily care of the critically ill.

Acid-Base Imbalance↗
PubMed1982

The cytotoxic and mutagenic effects of 5-bromodeoxyuridine-plus-black-light treatment in cultured mammalian cells.

The cytotoxic and mutagenic effects of the incorporation of 5-bromodeoxyuridine (BrdU) followed by exposure to black light were investigated with Chinese hamster ovary (CHO) cells in cell culture. Mutation induction at the hypoxanthine-guanine phosphoribosyl transferase (hgprt) locus was determined by selection for 6-thioguanine resistant (TGr) mutants (CHO/HGPRT system). BrdU alone has been shown to be mutagenic only at concentrations of 50 micro M or greater. This study was performed in an effort to determine whether BrdU is actually incorporated into the hgprt gene when lower, nonmutagenic concentrations are employed. Neither BrdU (1-20 micro M) nor exposure to black light alone was mutagenic, but the combined treatment did result in the induction of TGr mutants. The mutant frequency increased with increasing light exposure at constant BrdU and with increasing BrdU at constant light exposure. These results show that BrdU is incorporated into the hgprt gene, but that this does not result in mutation induction in the absence of light exposure. Such a BrdU-plus-light procedure might be applied to studies of DNA repair at this locus, since mutation induction requires both BrdU incorporation and subsequent exposure to black light.

Animals↗
PubMedDate not supplied

Coronary precautions: should caffeine be restricted in patients after myocardial infarction?

The effect of caffeine on heart rate, blood pressure, and cardiac rhythm has long been a controversial issue. A review of the literature reveals numerous articles evaluating the effects of caffeine on normal subjects, fewer evaluating the effects of caffeine on patients with cardiac disease and patients after myocardial infarction. Although the findings for the various populations have been inconsistent, recent studies with large cohorts have clarified the issue. Moderate consumption of caffeine does not significantly increase the risk of a coronary event nor increase the frequency of cardiac arrhythmias. This conclusion applies to healthy persons, patients with ischemic heart disease, and those with serious ventricular ectopy. Patients with cardiac disease should be allowed to consume four to five cups of caffeinated beverages per day while in the coronary care unit or progressive care unit under the surveillance of nursing staff.

Arrhythmias, Cardiac↗