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Biomedical subjects

R F Grossman

Publications and source records attributed to R F Grossman.

65 records · Page 4Linked to original sources
PubMed1981

Effect of major burns on alveolar-epithelial permeability in rabbits.

To evaluate the effect of major surface burns on pulmonary epithelial permeability, the authors studied 8 rabbits. After a 60-min baseline period, a 40% body surface area burn was inflicted. Permeability was assessed by following the rate of passage of 2 radiolabeled tracers from alveoli to arterial blood (125I antipyrene, 51Cr EDTA) and correlated with dynamic compliance, airflow resistance, blood pressure, heart rate, and arterial blood gases. Although dynamic compliance and the pH declined and airflow resistance increased (p less than 0.05), there was no significant change in permeability or P(A-a)O2. The authors conclude that extensive surface burns produce alterations in pulmonary mechanics and arterial pH which are not associated with increased alveolar epithelial permeability.

Animals↗
PubMed1980

Effects of oleic acid-induced pulmonary edema on lung mechanics.

In 25 rabbits anesthetized with pentobarbital sodium and paralyzed with succinylcholine chloride, we investigated the contributions of four factors that might cause the decreased static lung compliance found in oleic acid-induced pulmonary edema: 1) foam, 2) accumulation of fluid in the interstitial spaces, 3) loss of ventilatable units secondary to alveolar flooding, and 4) increased surface tension. Pulmonary edema, reflected by a 115% increase in mean post-mortem extravascular bloodless lung water content, decreased compliance 47% and tripled alveolar-arterial PO2 difference. Removing foam by degassing did not affect compliance measurements. Filling the lungs with saline caused similar changes in control and edematous animals. Because the 38% decrease in functional residual capacity was largely attributable to water accumulation, we concluded that loss of ventilatable units accounted for virtually all the decreased static lung compliance. The role of increased surface tension could not be determined directly but was considered relatively less important.

Animals↗
PubMed1980

Carbon monoxide effect on alveolar epithelial permeability.

A carbon monoxide (CO)-intoxicated patient developed increased permeability-type pulmonary edema demonstrated by a normal capillary wedge pressure and production of protein-rich edema fluid. To investigate the effect of CO on alveolar-epithelial permeability, a radio-active labelled isotope, 51Cr-EDTA (MW 377), was instilled into the airways of rabbits. Subsequent egress of the marker from the lungs into arterial blood was determined in serial arterial blood samples. The 51Cr-EDTA counts increased significantly within 15 minutes in the CO-exposed animals, compared with the control animals, while dynamic lung compliance fell, airways resistance rose, and arterial blood pressure decreased. Ultrastructural study of the lungs of CO-exposed animals revealed epithelial and endothelial cell swelling, in terstitial edema, and alveolar type II cells depleted of lamellar bodies. These findings support the possibility that carbon monoxide intoxication is associated with increased alveolar-epithelial permeability.

Adult↗
PubMed1979

The value of edema fluid protein measurement in patients with pulmonary edema.

Alveolar fluid and plasma proteins were analyzed in 24 patients with florid pulmonary edema, in 21 of whom pulmonary capillary wedge pressure (Pcw) was also measured. In all patients with Pcw less than 20 mm Hg, the edema fluid to plasma protein ratio exceeded 0.6; the mean edema fluid to plasma protein ratio in the four patients with cardiogenic edema (increased Pcw) was 0.46. In the 21 patients in whom full data were available, the net intravascular filtration force (Pcw - plasma colloid osmotic pressure) was less than -4 mm Hg, the value at which (according to others) pulmonary edema should occur, in only 10. When the interstitial colloid osmotic pressure, approximated by the osmotic pressure of edema fluid protein, was added, the net filtration force became positive in 17 of 21 patients. Comparison of the protein concentrations of edema fluid and plasma aids in the diagnostic separation of increased permeability from high hydrostatic pressure edema and adds to our understanding of the relative osmotic and hydrostatic forces that contribute to pulmonary edema when the alveolar-capillary membrane is damaged.

Adolescent↗
PubMed1979

Evaluation of transthoracic electrical impedance in the diagnosis of pulmonary edema.

To evaluate the clinical usefulness of measuring transthoracic electrical impedance in patients with pulmonary edema, we studied 27 normal subjects and 33 patients. In normal subjects, impedance increased when body position changed from supine to standing (p less than 0.01) and when lung volume increased from residual volume to total lung capacity (p less than 0.01). Impedance values vari7 omega) when measured hourly without removing the electrodes. In only five of 11 patients with clinically severe pulmonary edema and five of eight with radiologically severe pulmonary edema were impedance values outside the normal range. Changes in impedance values correlated with changes in clinical and radiographic indexes of pulmonary edema. We conclude that (1) single measurements of impedance are useless in diagnosing pulmonary edema, and (2) impedance changes as predicted as pulmonary edema increases and decreases, and these changes are readily detected by simpler methods of evaluation.

Adult↗
PubMed1979

Alveolar-capillary membrane permeability. Correlation with functional, radiographic, and postmortem changes after fluid aspiration.

An index of permeability of the alveolar-capillary membrane was derived from the relative extraction from the lung into arterial blood of 2 tracers, 125I-antipyrine and 51Cr-ethylenediaminetetraacetate. The effect on this index of aspirating 2 ml of isotonic saline, distilled water, or 10(-1) M hydrochloric acid per kg of body weight was studied in 3 groups of rabbits. The severity and time course of changes in the permeability index were correlated with changes in lung mechanics, gas exchange, serial chest roentgenograms, ratio of extravascular lung water to dry weight, and histologic findings. Aspiration of saline produced no change in the permeability index; aspiration of water produced a large mean +/- SEM increase in the index, from a baseline of 0.025 +/- 0.002 to 1,050 +/- 0.054 (P less than 0.001), but this value returned to baseline 15 min later. After hydrochloric acid, the permeability index increased from a baseline of 0.027 +/- 0.003 to 1.068 +/- 0.098 (P less than 0.005), with no evidence of resolution after 60 min. Changes in lung mechanics, gas exchange, and roentgenograms were smallest after aspiration of distilled water and greatest after aspiration of hydrochloric acid. The functional changes after aspiration of water and saline recovered at a rate proportional to the known clearance rates of these liquids from the lung. The changes after hydrochloric acid either showed no tendency toward recovery or, in the case of the roentgenograms, worsened with time. There were no detectable histologic abnormalities or an increase in the ratio of extravascular lung water to dry weight after aspiration of water or saline, but there were extensive histologic abnormalities and a 70 per cent increase in lung water after acid. The increase in the permeability index after aspiration of water was too transient to exert a deleterious effect. In contrast, the persistence of the increase in the permeability index after hydrochloric acid was associated with persistent functional changes attributable to the considerable increase in lung water.

Animals↗
PubMedDate not supplied

Radioiodine-associated thyroid cancers.

Numerous investigations document that exposure to low dose external therapeutic radiation leads to the development of benign and malignant thyroid neoplasms. There is considerable controversy, however, concerning whether radioactive iodine (131I) causes thyroid cancer. The aim of this investigation was to examine our experience and that in the literature related to this problem. From 1982 to March 1993 seven of 373 patients (1.9%) with thyroid cancer who were treated by one surgeon had a history of treatment with radioactive iodine for Graves' disease and toxic nodular goiter. Sixty-five patients have previously been reported in the literature from 1957 to present. Our patients (five women, two men) ranged in age from 26 to 80 years (mean 57 years). The interval between the exposure to the internal radiation and development of cancer ranged from 3 to 29 years (mean 11.4 years), and the mean age at the time of 131I treatment was 45 years (18-76 years). The therapeutic dose of 131I was 5 to 100 mCi (mean 25.3 mCi) in our patients. Two of our patients received 131I twice. The age of patients reported in the literature at the time of 131I treatment ranged from 7 to 74 years (mean 48 years). The mean therapeutic dose of 131I was 20.6 mCi (1.25-180.0 mCi) and the latent period was documented for a mean 8.7 years (0.25-28.0 years) in these patients. Three of 29 patients in the literature received 131I twice. Fine-needle aspiration cytology of thyroid nodules was positive for cancer in six of our patients (86%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma, Follicular↗
PubMedDate not supplied

Summary of Canadian guidelines for the initial management of community-acquired pneumonia: an evidence-based update by the Canadian Infectious Disease Society and the Canadian Thoracic Society.

Community-acquired pneumonia (CAP) is a serious illness with a significant impact on individual patients and society as a whole. Over the past several years, there have been significant advances in our knowledge and understanding of the etiology of the disease, and an appreciation of problems such as mixed infections and increasing antimicrobial resistance. The development of additional fluoroquinolone agents with enhanced activity against Streptococcus pneumoniae has been important as well. It was decided that the time had come to update and modify the previous CAP guidelines, which were published in 1993. The current guidelines represent a joint effort by the Canadian Infectious Disease Society and the Canadian Thoracic Society, and they address the etiology, diagnosis and initial management of CAP. The diagnostic section is based on the site of care, and the treatment section is organized according to whether one is dealing with outpatients, inpatients or nursing home patients.

Anti-Infective Agents↗
PubMedDate not supplied

Management of acute exacerbation of chronic bronchitis.

In chronic bronchitis, a common respiratory illness marked by chronic productive cough and caused largely by cigarette smoking, bacterial exacerbations are thought to be a common cause of progressive airway damage. Common bacterial pathogens, found in 50% to 60% of episodes, include Haemophilus influenzae (the most common), as well as Haemophilus parainfluenzae, Streptococcus pneumoniae and Moraxella catarrhalis. Bacterial resistance to antibiotics, especially beta-lactam drugs such as amoxicillin, is increasingly common in these pathogens. In this illness, clinical risk stratification based on age, history and comorbidity is an important strategy. Patients in the lowest risk group likely have viral infections and require no specific treatment. Patients in the higher risk groups require aggressive treatment to avoid treatment failure, which can lead to prolonged hospitalization and complications. Preventive therapies (smoking cessation and influenza vaccination) are worthwhile measures for these patients.

Bronchitis↗
PubMedDate not supplied

The relationship of absorption characteristics and gastrointestinal side effects of oral antimicrobial agents.

Normal bowel flora play an important role in preserving gastrointestinal (GI) function. They inhibit colonization by pathogenic bacteria, help in the metabolism of by-products of drugs and endogenous substances, aid in the synthesis of vitamins, and stimulate nonspecific host immune systems that protect against potential pathogens. Antimicrobial agents that are poorly absorbed from the GI tract can substantially alter the bowel flora. Narrow-spectrum antimicrobial agents are less likely to disrupt the bowel flora than broad-spectrum agents. Drugs that undergo extensive enterohepatic circulation can also disrupt normal flora. Knowledge of the extent of GI absorption, bile excretion, and spectrum of activity allows prediction of the likelihood of GI side effects. For example, clindamycin, which is relatively poorly absorbed and has significant bile secretion, is associated with a high incidence of diarrhea. The use of an antibiotic with a relatively narrow spectrum, excellent GI absorption, and minimal bile excretion should reduce the incidence of GI side effects.

Administration, Oral↗