Biomedical subjects

S L Peck

Publications and source records attributed to S L Peck.

6 recordsLinked to original sources

PubMed1992

Correlation of the complete version of the Selvester QRS scoring system with quantitative anatomic findings for multiple left ventricular myocardial infarcts.

The correlation between myocardial infarct size estimated by the complete version of the Selvester QRS scoring system and that documented by pathoanatomic studies has been reported for single anterior, inferior and posterolateral infarcts. Although previous studies described electrocardiographic changes in patients with multiple infarcts, no quantitative documentation of the ability of such changes to estimate the total amount of left ventricular infarction has been reported. This study of 32 patients with anatomically documented multiple infarcts shows a significant correlation between QRS-estimated and anatomically documented sizes (r = 0.44; p = 0.01), which is less than that previously reported for single infarcts in the anterior, inferior and posterolateral locations. Several of the 54 electrocardiographic criteria were never satisfied. Criteria for posterior infarction were seldom present, suggesting "cancellation effect" of coexisting anterior infarction. These results will be the basis for future modification of QRS criteria for estimating myocardial infarct size.

Adult↗

PubMed1992

An educational test of health behavior models in relation to emergency helping.

This study used a true experimental design to evaluate the quality and occurrence of emergency helping behavior among university first-aid students in response to a supplemental educational unit designed to improve bystander helping. The educational unit addressed the inhibitors of emergency helping behavior within the framework of bystander behavior models and was delivered using several behavior modification strategies. Using chi-square analysis, it was found that the 43 treatment students exposed to the supplemental unit responded appropriately to a simulated emergency more often than 41 similar control students not exposed to the unit (32.6% vs. 7.3%, p = .004) and that the effect was confined primarily to women (p = .001). Future emergency care education incorporating similar theory-based educational strategies might improve trained bystander responsiveness and thus enhance the efficiency of prehospital care. Theoretical and future research implications are discussed.

Curriculum↗

PubMed1990

Anatomic validation of electrocardiographic estimation of the size of acute or healed myocardial infarcts.

Seventeen new criteria added to the simplified version of the Selvester QRS scoring system to comprise the complete version were evaluated to determine their value in estimating the size of single infarcts. These non-Q-wave criteria might be particularly useful regarding posterolateral infarcts in the distribution of the left circumflex artery. The study population was made up of 21 anterior, 30 inferior and 20 posterolateral single myocardial infarction (MI) patients with no evidences of bundle branch or fascicular blocks, ventricular hypertrophy or previous MI on their final stable electrocardiogram. The complete system's maximum 32 points is capable of indicating MI in 96% of the left ventricle and it estimated a mean electrocardiographic MI size that better approximated the anatomic size compared with the simplified version in all MI locations. The correlation between anatomic and electrocardiographic MI size using the complete system was better and statistically significant for the posterolateral MI group (simplified r = 0.55, p less than 0.01 vs complete r = 0.70, p less than 0.0006). Criteria such as Q and S amplitude less than or equal to 0.3 mV in V1 and less than or equal to 0.4 mV in V2 were particularly helpful. This study documents the improved ability provided by the 17 additional non-Q-wave criteria which have been added in the complete version of this scoring system regarding the sizing of infarcts in the region of the left ventricle supplied by the left circumflex artery.

Electrocardiography↗

PubMed1990

Statistical methods in SUPPORT.

The analysis and interpretation of the data collected in SUPPORT provide great potential for understanding the relationships among treatment choices, patient and physician values and preferences, perceptions about the risks and benefits of treatments, institutional characteristics, and outcomes (as measured by quality of life, survival, and satisfaction). The complicated analyses required to elucidate these relationships will pose many technical challenges in dealing with longitudinal observational data collected from seriously ill patients at multiple sites. Major challenges include the handling of incomplete data, proper parameterization of treatment effects, strategies to avoid various potential biases, validating predictive models, and constructing endpoints that combine survival with quality of life. Within the structure of the SUPPORT study, mechanisms have been established to guide the analyses and to ensure their quality and validity.

Confounding Factors, Epidemiologic↗

PubMed1985

Reduced neutrophil superoxide anion release after prolonged infusions of lidocaine.

Lidocaine is used extensively in coronary care units, yet the effect of lidocaine infusions on neutrophil function has not been known. Lidocaine and other local anesthetics impair leukocyte antibacterial functions when added in vitro. We found that lidocaine added to human neutrophils in vitro markedly impaired the release of superoxide anion (O2-) and the granule enzymes lysozyme and myeloperoxidase after stimulation by phorbol myristate acetate or opsonized zymosan. We then measured production of O2- during stimulation of neutrophils from eight normal subjects, five coronary artery disease patients not receiving lidocaine and 13 coronary artery disease patients receiving lidocaine infusions for at least 12 hr. Release of O2- by cells from lidocaine-treated patients (14.2 +/- 3.8 nmol/2.5 X 10(6) neutrophils per 15 min) was significantly lower than from cells of the normal subjects (78.4 +/- 7.2 nmol; P less than .001) and the coronary patients not receiving lidocaine (70.6 +/- 4.0 nmol; P less than .001). Bactericidal assays at a high concentration (2 mg/ml) of lidocaine demonstrated slight reductions in 2 hr killing rates for Escherichia coli (70% with lidocaine vs. 95% control). Inhibition by lidocaine of the release of toxic oxygen metabolites from neutrophils could potentially reduce infarct size in patients with acute myocardial infarction; but as there is only a slightly reduced ability to kill bacteria, increased susceptibility to infections is unlikely although it cannot be excluded.

Blood Bactericidal Activity↗

PubMed1985

Preoperative cardiac screening before peripheral vascular operations.

Myocardial infarction continues to be a major cause of morbidity and mortality after peripheral vascular operations. In this study, radionuclide angiography (RNA) of the heart was used to delineate the cardiac risk. In 78 patients, there were 53 abnormal RNA studies. Twenty-seven patients with abnormal RNA underwent coronary angiography. Six aortocoronary bypasses were performed prior to or in conjunction with the vascular operation without complications. Ninety major operations were carried out in these 78 patients. There was no myocardial infarction in patients with normal RNA. There were two postoperative fatal myocardial infarctions in patients with abnormal RNA giving a procedure mortality of 2.2 per cent. In 11 patients, the proposed operation was changed. Thirteen patients with abnormal RNA had no cardiac symptoms. Three patients in this subgroup underwent aortocoronary bypass. It was concluded that RNA can effectively identify the cardiac risk in patients undergoing peripheral vascular operations. Routine coronary angiography may be unnecessary as patients with normal RNA have minimal risk of myocardial infarction.

Aged↗