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Biomedical subjects

G W Divine

Publications and source records attributed to G W Divine.

52 records · Page 3Linked to original sources
PubMed1990

Incremental diagnostic yield of loop electrocardiographic recorders in unexplained syncope.

The Holter monitor, the most frequently used diagnostic test in patients with syncope, is nondiagnostic in over 90% of cases. This study sought to determine the impact of a new noninvasive device, the cardiac loop electrocardiographic (ECG) recorder, after Holter monitoring in 57 patients with unexplained syncope. All patients underwent a standardized evaluation protocol and were the monitor for up to 1 month. In 14 patients, loop recording definitively determined whether an arrhythmia was the cause of symptoms (diagnostic yield 25%; 95% confidence intervals 14 to 38%). Diagnoses included unsuspected ventricular tachycardia (1 patient), high grade atrioventricular block (2 patients), supraventricular tachycardia (1 patient), asystole or junctional bradycardia from neurally mediated syncope (3 patients) and normal cardiac rhythms (the remaining 7 patients). Follow-up of all patients diagnosed as having nonarrhythmic syncope by loop recording showed that none of these patients died suddenly. Cardiac loop ECG recording is an important new diagnostic test in patients with syncope unexplained by Holter monitoring.

Arrhythmias, Cardiac↗
PubMed1990

The impact of psychologic factors on measurement of functional status. Assessment of the sickness impact profile.

In this study the relationship between four psychologic health constructs (depression, anxiety, patient response bias, and hostility) and the Sickness Impact Profile (SIP) measurement of functional status was evaluated. The SIP, Carroll Depression Rating Scale (CDRS); and the Minnesota Multiphasic Personality Inventory (MMPI) were administered to 332 patients hospitalized for treatment of combined medical and psychiatric problems. Pearson's product-moment correlation was high between CDRS and SIP Total score (r = 0.67) and between CDRS and SIP Psychosocial subscale (r = 0.72); correlation was lower between CDRS and SIP Physical subscale (r = 0.44). Six MMPI scales (depression, anxiety, psychasthenia, lie, K, hostility) correlated with SIP Total score (r = 0.18 to 0.50), with SIP Psychosocial score (r = 0.28 to 0.65) and less well with SIP Physical subscale (r = 0.07 to 0.25). Factor analysis of the SIP categories showed two factors with eigenvalues greater than 1. Promax factor rotation showed all SIP Psychosocial categories and all measured psychologic variables loaded most heavily on factor 1. SIP Physical categories loaded most heavily on factor 2. Stepwise multiple regression analysis showed that psychologic variables account for 49% of the SIP total variance, 62% of SIP Psychosocial subscale variance, but only 19% of SIP Physical subscale variance. The CDRS accounts for the major portion of the explained variance with only minor additional contributions from the MMPI scales. We conclude that 1) the SIP discriminates psychosocial and physical dysfunction even in medical patients with extensive psychiatric comorbidity; 2) the SIP measures at least two dimensions of health, one of which is strongly related to depression; and 3) constructs measured by MMPI scales do not have substantial independent contribution to SIP variance.

Adult↗
PubMed1990

Physiological, psychological, and behavioral factors and white coat hypertension.

Patients with hypertension in the clinic but not during daily activities ("white coat" hypertension) may be at lower risk of hypertensive morbidity and mortality than patients with hypertension in both settings ("persistent" hypertension). We hypothesized that the white coat phenomenon was due to greater blood pressure reactivity to the stress of a clinic visit and that, as a consequence, white coat hypertensive patients would display greater blood pressure reactivity to exercise and mental stress, as well as increased emotional reactivity and higher levels of anger, anxiety, or depression. We studied 89 patients with essential hypertension between 29 and 59 years old with ambulatory blood pressure monitoring, treadmill exercise testing with oxygen consumption measurement, mental stress testing (including mental arithmetic, public speaking, and video game tasks), and psychological testing (State-Trait Anxiety Scale, Cook-Medley Hostility Scale, Center for Epidemiologic Studies Depression Scale, emotional reactivity scale). We defined white coat hypertension as a mean ambulatory systolic blood pressure of 135 mm Hg or less and diastolic 85 mm Hg or less and persistent hypertension as a mean ambulatory systolic blood pressure of 140 mm Hg or more or diastolic 90 mm Hg or more. Forty-nine patients were classified as persistent hypertensives and 20 as white coat hypertensives. No significant differences were seen in demographic or clinical characteristics, fitness level, blood pressure response to exercise or mental stress, or psychological characteristics, except that white coat hypertensive patients had lower systolic blood pressures in the clinic and during exercise and greater variability of clinic diastolic blood pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Exercise testing in women with chest pain. Are there additional exercise characteristics that predict true positive test results?

Women have a notoriously high rate of false positive exercise test results. Since the exercise ST segment response has low specificity in predicting CAD in women, we examined additional exercise parameters in 200 women with a history of chest pain compatible with angina and having ST segment depression greater than or equal to 1 mm recorded during a Bruce treadmill test. All subsequently had coronary arteriography. Two groups were compared: group A (n = 80) with CAD (greater than or equal to 70 percent stenosis of one or more coronary artery) and group B (n = 120) with angiographically confirmed normal coronary arteries (normal or minimal placquing). The exercise criteria analyzed included: (1) chest pain during exercise, (2) percent target heart rate, (3) extent of ST shift, (4) morphology of the ST segment slope, (5) time to normalization of the ST segment, and (6) total exercise duration. Multivariate analysis (using a stepwise logistic regression model) identified four independent exercise variables associated with the likelihood of CAD: (absence of MVP, p = .003; exercise duration less than 5 min, p = .02; ability to reach target heart rate, p = .027; time to ST normalization greater than or equal to 6 min, p less than .001). False positive exercise test results were more likely to occur when the following exercise test variables were present: ability to exercise to stage 3 of the Bruce protocol and a rapid (less than or equal to 4 minutes) normalization of ST shift after cessation of exercise. Attention to these additional exercise variables allows more careful selection of women requiring more definitive (and expensive) testing.

Angina Pectoris↗
PubMed1988

Estimating the dosage of ribavirin aerosol according to age and other variables.

We describe a method for estimating the dosage of aerosolized ribavirin according to age. The calculations were determined by using a computer model of particle deposition, and corrections are described for sex, body weight, fever, and tracheal intubation. Respiratory tract deposition in infants, after they inhaled an aerosol containing 200 micrograms of ribavirin/L, was 1.8 mg/kg per hour; in adults the deposition was 0.9 mg/kg per hour. Adolescent females and older women have less (7%/kg) respiratory tract deposition than do males. Fever will increase deposition about 9%/degree Centigrade (5%/degree Fahrenheit) for each degree of increase above normal temperature. Tracheal intubation will deliver relatively more drug to the lung and no drug to the nasopharynx. Our report shows the regional and total deposition of inhaled ribavirin aerosol in the respiratory tracts of persons in different age-groups from three months to 25 y.

Adolescent↗
PubMed1987

Nocturnal oxyhemoglobin desaturation in COPD patients with arterial oxygen tensions above 60 mm Hg.

We studied 152 COPD patients with a daytime PaO2 greater than or equal to 60 mm Hg using formal polysomnography (EEG, airflow, respiratory muscle movement, ear oximeter) to detect the presence of nocturnal, nonapneic, oxyhemoglobin desaturation. Nine subjects were disqualified by the unexpected discovery of sleep apnea, as were another eight because they could not sleep in the laboratory setting. Of the remaining 135 subjects, 37 (27 percent) desaturated below a baseline sleep saturation of 90 percent for five minutes or more, reaching a nadir saturation of at least 85 percent. Anthropomorphic, pulmonary function, and historic factors comparing desaturators and nondesaturators failed to separate the groups. Awake PaO2 at rest in the desaturators was significantly lower than in the nondesaturators. The PaCO2 was higher in the desaturators. Reversibility of the desaturation phenomenon was demonstrated in three patients during subsequent polysomnographic studies following periods of clinical improvement. Continuous oxyhemoglobin monitoring during sleep remains the only reliable tool for detecting nocturnal desaturation.

Aged↗
PubMed1985

Long-term assessment of unipolar and bipolar stimulation and sensing thresholds using a lead configuration programmable pacemaker.

Acute and long-term pacing thresholds were measured prospectively in 74 patients with a unipolar/bipolar multiprogrammable pacemaker. At implantation, mean current threshold was 0.48 +/- 0.16 mA with unipolar mode and 0.55 +/- 0.16 mA bipolar mode (p less than 0.01). R wave amplitude at implantation was 7.78 +/- 2.4 mV with unipolar and 7.67 +/- 2.1 mV in bipolar mode (p = NS). During long-term follow-up (mean 9.3 months; range 3 to 24), no clinically significant differences in pacing or sensing thresholds were observed between bipolar and unipolar configurations. Lead configuration was changed 23 times in 11 patients. Symptomatic myopotential inhibition was corrected in two patients by reprogramming to the bipolar pacing mode. High thresholds and loss of capture were corrected in two patients by reprogramming to the unipolar pacing mode. The remaining configurational changes were made for improved sensing or pacing thresholds. This study documents, in a large group of patients, the equivalence of long-term unipolar and bipolar pacing and sensing thresholds and, in addition, demonstrates that lead configuration programmability offered some advantage in a subgroup of patients and may have prevented reoperation in five patients.

Cardiac Pacing, Artificial↗
PubMed1983

Ribavirin aerosol treatment of influenza B virus infection.

In a randomized, controlled study, ribavirin small-particle aerosol was found to be effective in the treatment of influenza B virus infection in a group of college students. Eleven treated patients experienced significantly more rapid defervescence, disappearance of systemic illness, and reduction of virus shedding in nasal secretions than ten control patients treated with a saline aerosol. Antibody response to infection was similar in both groups. The treatment was well tolerated, and hematologic and clinical chemical tests demonstrated no toxicity. The estimated dose of ribavirin aerosol retained was about 2 g in 39 hours of treatment during the first 60 hours in the hospital.

Adult↗
PubMed1983

Cardiopulmonary toxicity in patients with breast carcinoma during plasma perfusion over immobilized protein A. Pathophysiology of reaction and attenuating methods.

Tumoricidal reactions in dogs with spontaneous breast carcinoma occur after perfusion of plasma over protein A derived from Staphylococcus aureus and immobilized in collodion charcoal. When this treatment was extended to humans with breast cancer, hemodynamic and physiologic changes were noted. The evolution and spectrum of these reactions were evaluated during 47 plasma infusions in five patients. Initial treatment conditions consisting of rapid perfusion of plasma over high quantities of immobilized protein A were employed for 12 treatments in two patients. Within 30 minutes after treatments were begun, mean blood pressure, systemic vascular resistance, and stroke volume increased, as did heart rate, cardiac output, and rectal temperature; however, mean pulmonary artery pressure and total pulmonary resistance did not change. At 90 minutes, hypotension developed (lowest mean blood pressure was 59 +/- 14 mm Hg) that was associated with a decrease in systemic vascular resistance and total pulmonary resistance (536 +/- 66 and 146 +/- 44 dynes . second . cm-5, respectively). Cardiac output increased, tachycardia developed, stroke volume decreased, and rectal temperature increased. During the hypotensive phase, values of creatinine clearance and fractional excretion of sodium diminished. Noncardiogenic pulmonary edema appeared occasionally, with bronchospasm noted once. No hemodynamic changes were seen when saline solution was passaged over protein A immobilized in collodion charcoal or when autologous plasma was given without passage over protein A immobilized in collodion charcoal. Treatment conditions were modified by diminishing protein A quantity and plasma volume and slowing plasma perfusion rate, which resulted in significant attenuation of all cardiopulmonary responses. This report, then, defines for the first time the physiologic basis of the cardiopulmonary toxicity in humans after plasma perfusion over immobilized protein A.

Breast Neoplasms↗
PubMed1983

Ribavirin aerosol treatment of influenza B virus infection.

In a randomized, controlled study, ribavirin small particle aerosol was found to be effective in the treatment of influenza B virus infection in a group of college students. Eleven treated patients experienced significantly more rapid defervescence, disappearance of systemic illness, and reduction of virus shedding in nasal secretions than 10 control patients treated with a saline aerosol. Antibody response to infection was similar in both groups. The treatment was well tolerated and hematologic and clinical chemical tests revealed no toxicity. The estimated dose of ribavirin aerosol retained was about 2 g in 35.5 hr of treatment during the first 60 hr in the hospital.

Adult↗
PubMedDate not supplied

Multiple comparisons for relative risk regression: extension of the kappa-ratio method.

We propose a kappa-ratio method for multiple comparisons among disjoint groups in survival analysis, specifically among relative risk estimates from a proportional hazards regression analysis. The new method relates the magnitude of critical values to an overall measure of group heterogeneity. That is, large critical values result from small values of a chi-square statistic for testing between-groups homogeneity. Conversely, large values of the overall statistic lead to small critical values for individual comparisons, even if there are many groups. The adaptivity of the kappa-ratio method contrasts sharply with the conservatism of competing methods.

Analysis of Variance↗
PubMedDate not supplied

Predicting the outcomes of electrophysiologic studies of patients with unexplained syncope: preliminary validation of a derived model.

PURPOSE: To develop and validate a predictive model that would allow clinicians to determine whether an electrophysiologic (EP) study is likely to result in useful diagnostic information for a patient who has unexplained syncope. PATIENTS: One hundred seventy-nine consecutive patients with unexplained syncope who underwent EP studies at two university medical centers comprised the training sample. A test sample to validate the model was made up of 138 patients from the clinical literature who had undergone EP studies for syncope. DESIGN: Retrospective analysis of patients undergoing EP studies for syncope. The data collector was blinded to the study hypothesis; the electrophysiologist assessing outcomes was blinded to clinical and historical data. Clinical predictor variables available from the history, the physical examination, electrocardiography (ECG), and Holter monitoring were analyzed via two multivariable predictive modeling strategies (ordinal logistic regression and recursive partitioning) for their abilities to predict the results of EP studies, namely tachyarrhythmic and bradyarrhythmic outcomes. These categories were further divided into full arrhythmia and borderline arrhythmia groups. RESULTS: Important outcomes were 1) sustained monomorphic ventricular tachycardia (VT) and 2) bradyarrhythmias, including sinus node and atrioventricular (AV) conducting disease. The results of the logistic regression (in this study, the superior strategy) showed that the presence of organic heart disease [odds ratio (OR) = 3.0, p less than 0.001] and frequent premature ventricular contractions on ECG (OR = 6.7, p less than 0.004) were associated with VT, while the following abnormal ECG findings were associated with bradyarrhythmias: first-degree heart block (OR = 7.9, p less than 0.001), bundle-branch block (OR = 3.0, p less than 0.02), and sinus bradycardia (OR = 3.5, p less than 0.03). Eighty-seven percent of the 31 patients with important outcomes at EP study had at least one of these clinical risk factors, while 95% of the patients with none of these risk factors had normal or nondiagnostic EP studies. In the validation sample, the presence of one or more risk factors would have correctly identified 88% of the test VT patients and 65% of the test bradyarrhythmia patients as needing EP study. CONCLUSION: These five identified predictive factors, available from the history, the physical examination, and the initial ECG, could be useful to clinicians in selecting those patients with unexplained syncope who will have a serious arrhythmia identified by EP studies.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Quantitative analysis of the outpatient oral case presentation: piloting a method.

OBJECTIVE: To measure the content of oral outpatient case presentations and to assess the correlation of objective assessments of this content with subjective ratings provided by the clinic attending physician. DESIGN: Blinded assessment via audiotape of 36 oral case presentations of new patient evaluations by 23 medical residents. SETTING: Outpatient general medical clinic. PARTICIPANTS: Duke University Medical Center medical residents during their outpatient rotation. MEASUREMENTS AND MAIN RESULTS: Important deficiencies were found in oral case presentation content. Specifically, psychosocial data were often missing (employment history) was mentioned in 28% of presentations; illicit drug use, in 17%; household social structure, in 11%; sexual history, in 6%). An assessment and a plan were mentioned only 56% and 69% of the time, respectively. No correlation was seen between an objective "content score" and the attending physician's subjective rating of the quality of the presentation (r = 0.09). CONCLUSIONS: 1) The outpatient care presentation can be quantitatively assessed in a simple, straightforward manner; 2) outpatient case presentations have important deficiencies in content; and 3) preceptors' evaluations of case presentations may be based upon factors other than content of the presentation.

Ambulatory Care↗
PubMedDate not supplied

The unit of analysis error in studies about physicians' patient care behavior.

OBJECTIVE: To estimate the frequency with which patients are incorrectly used as the unit of analysis among statistical calculations in published studies of physicians' patient care behavior. DESIGN: Retrospective review of studies published during 1980-1990. ARTICLES: 54 articles retrieved by a computerized search using medical subject headings for physicians and study characteristics. Article selection criteria included the requirement that the physician should have been the correct unit of analysis. INTERVENTION: Presence of the error was determined by consensus using published criteria. MAIN RESULTS: The error was present in 38 articles (70%). The number of study physicians was reported in 35 articles (65%). The error was found in 57% of articles that reported the number of study physicians and in 95% of those that did not. The error rate was not lower among articles published more recently nor among those published in journals with higher rates of article citations in the medical literature. CONCLUSION: The unit of analysis error occurs frequently and can generate artificially low p values. Failure to report the number of study physicians can be a clue that this type of error has been made.

Data Interpretation, Statistical↗
PubMedDate not supplied

Physicians' awareness of mammography charges.

Although physicians commonly report cost as a barrier to screening mammography, their awareness of mammography charges is unknown. Using a statewide sample, we assessed accuracy of primary care physicians' estimates of mammography charges among 506 eligible physicians who returned questionnaires. Differences between estimated charges and actual charges at their mammography referral facilities were small (mean = $2.74, median = 0) and unrelated to physicians' specialty, age, gender, or practice type. We conclude that physicians are cognizant of mammography charges. Overestimates in charges may not explain low mammographic screening rates.

Awareness↗