PubMed Health⌕ Search

Biomedical subjects

R W Corwin

Publications and source records attributed to R W Corwin.

11 recordsLinked to original sources
PubMed1999

The role of the primary care physician in recognizing obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is a common disorder among middle-aged adults. However, OSA is a recently described disorder for which most primary care physicians do not have formal training. The primary objectives of this article are to evaluate what percentage of patients referred by primary care physicians for sleep studies had OSA; to characterize the clinical features of these patients and compare them with our known OSA population; and to determine whether primary care physicians asked key questions contained in a work sheet to make the diagnosis of OSA. METHODS: A retrospective chart review at a hospital-based sleep center that is accredited to evaluate all sleep disorders, not just OSA. The health maintenance organization is a staff model one. PATIENTS: Sixty-nine patients who were referred for a sleep study by a health maintenance organization internist or family practitioner between June 1, 1994, and May 30, 1995. RESULTS: Ninety-six percent of the 68 patients referred for polysomnography had OSA. Most were very symptomatic and obese. These 68 patients represent 0.13% of the primary care patient panel. In addition, most of the patients were referred by a few physicians; 6 (11%) of the 55 physicians ordered 33% of the 68 studies. CONCLUSIONS: Primary care physicians did recognize obese patients with prominent symptoms of sleep apnea. However, only a small percentage of their patient panel was referred, suggesting that this condition is still underdiagnosed. This seems particularly true as most of the sleep studies were ordered by a small group of physicians. Future work incorporating educational interventions is necessary to improve detection and treatment of OSA.

Adult↗
PubMed1994

A clinical and structural comparison of industrial methacholine and provocholine.

Methacholine, provided by industrial sources, has traditionally been used in studies of airways responsiveness. In 1986, a Food and Drug Administration approved formulation of methacholine (Provocholine) was released and replaced industrial methacholine in many pulmonary laboratories. To determine whether methacholine and Provocholine cause an equivalent degree of bronchoconstriction, a double blind, cross-over clinical trial was undertaken. After randomization, 19 medicine residents and respiratory therapists each performed methacholine challenge testing using either methacholine or Provocholine. Forty-eight hours later, each participant returned for repeat challenge testing with the alternate agent. The log of the dose-response slope (logslope) was calculated for each test. The mean logslope with methacholine (-0.15 +/- 1.84) and with Provocholine (-0.26 +/- 1.57) did not differ (paired Student's t test, p = 0.64). Further, excellent agreement was found between each subject's logslope with methacholine and with Provocholine (intraclass correlation coefficient rI = 0.82). Proton beam nuclear magnetic resonance revealed no structural differences between the two compounds. These findings suggest that methacholine from industrial sources and Provocholine are clinically and structurally similar and that the two agents may be used interchangeably in nonspecific bronchial provocation testing.

Adult↗
PubMed1990

Complications associated with thoracentesis. A prospective, randomized study comparing three different methods.

To determine what role the technique plays in complications associated with thoracentesis performed by physicians in training, we undertook a prospective study of thoracentesis in the medical service at our institution in which the sampling method was randomized among needle, needle with catheter, and needle with direct sonographic guidance. Fifty-two spontaneously breathing, cooperative patients with free-flowing effusions obliterating more than half of the hemidiaphragm on an upright, posteroanterior chest roentgenogram were randomized. When we analyzed those complications that were potentially life-threatening (eg, pneumothorax) and/or placed patients at increased risk for further morbidity (eg, pneumothorax, dry tap, inadequate tap), the sonography-guided method was associated with significantly fewer serious complications (0 of 19) than the needle-catheter (9 of 18) or needle-only methods (5 of 15). The sonography-guided method was associated with fewer pneumothoraces (0 of 19) than the needle-catheter (7 of 18) or needle-only methods (3 of 15). The difference between needle-catheter and needle-only methods was not significant. From our results, we conclude that the method by which thoracentesis was performed significantly influenced the spectrum and frequency of complications, and the sonography-guided method was the safest.

Catheterization↗
PubMed1986

Complications associated with thoracocentesis.

In order to determine the spectrum and frequency of complications associated with thoracocentesis, we decided to audit prospectively all thoracocentesis performed in the medical service at our institution. Over a ten-month interval, 125 procedures were performed. We identified 114 (91 percent) prospectively, 11 retrospectively by a computer-assisted review of discharge summaries. Forty-six percent of the procedures were complicated by at least one adverse occurrence. Complications considered major occurred in 14 percent, minor in 33 percent. The major complications included 14 pneumothoraces (three required tube thoracostomies and one percutaneous aspiration), one splenic laceration, one sheared-off catheter, and one pneumohemothorax. The minor complications included pain in 28, persistent cough in 14, dry taps in 16, and subcutaneous fluid collections in four patients. We conclude that thoracocentesis can carry the risk of frequent morbidity even when a lecture and printed guidelines on performing thoracocentesis have been given and experienced individuals are in attendance during the performance of the procedure. Our study suggests a portion of this morbidity may be from poor technique, inability to adequately identify landmarks, and improper utilization of a needle-catheter apparatus. Suggestions for correction of these problems are made.

Humans↗
PubMed1985

The lipid-laden alveolar macrophage as a marker of aspiration in parenchymal lung disease.

We prospectively evaluated lower respiratory secretions obtained by bronchoalveolar lavage and stained with Oil-Red-O in patients with a variety of parenchymal diseases and in normal subjects. Our subjects included aspirators (n = 9), nonaspirators (n = 40), and normal subjects (n = 9). By grading the amount of intracellular Oil-Red-O per 100 alveolar macrophages, we computed a semiquantitative, lipid-laden alveolar macrophage index. The mean index for aspirators of 207 +/- 80 was significantly greater than the mean indexes of nonaspirators (121 +/- 97, p less than 0.02) and normal subjects (0.6 +/- 1.7, p less than 0.001). An index of greater than or equal to 100 had a sensitivity and negative predictive value of 100% each, a false negative rate of 0%, and a specificity of 57%. We conclude that (1) the mere presence of lipid-laden alveolar macrophages in lower respiratory secretions is a nonspecific marker of parenchymal lung disease; (2) the computation of a lipid-laden alveolar macrophage index may be helpful in excluding aspiration as a cause of parenchymal lung disease.

Adult↗
PubMed1984

Uptake of antibiotics by human alveolar macrophages.

To provide additional criteria for therapy of pulmonary infections caused by facultative intracellular bacteria, we studied the uptake of 12 antibiotics by alveolar macrophages (AM) obtained from healthy, young volunteers by bronchoalveolar lavage. These human AM were incubated with radiolabeled antibiotics for periods as long as 2 h. Entry of antimicrobials into the cells was determined by means of a velocity-gradient centrifugation technique. Antibiotic uptake was expressed as the ratio of the cellular to the extracellular drug concentration (C/E). Penicillin G, cefamandole, and gentamicin were taken up poorly by human AM (C/E = 0.5 to 0.8). Isoniazid achieved a cellular concentration similar to the extracellular level of the drug (C/E = 0.9). Chloramphenicol, rifampin, tetracycline, and lincomycin, drugs that are lipid-soluble, were concentrated several-fold by AM (C/E = 2 to 5). The remaining antibiotics tested, clindamycin, erythromycin, erythromycin propionate, and ethambutol, were markedly concentrated by AM (C/E = 9 to 23). Accumulation of clindamycin (C/E = 23) was a rapid, active, energy-requiring process, which appeared to be dependent upon mitochondrial oxidative metabolism. The ability of the tested antimicrobial agents to enter human AM correlates well with the efficacy of these drugs in treatment of certain intracellular pulmonary infections.

Anti-Bacterial Agents↗
PubMed1984

Postnasal drip causes cough and is associated with reversible upper airway obstruction.

We prospectively evaluated nine patients with cough from postnasal drip for evidence of extrathoracic upper airway obstruction. Patients compared before treatment to normal control subjects had physiologic evidence of extrathoracic upper airway obstruction; their mean FIF50%/FEF50% and FIF25-75%/FEF25-75% ratios of 0.88 and 0.98 were significantly less than the values in control subjects of 1.28 and 1.37 (p less than 0.001). With specific therapy, postnasal drip decreased, cough disappeared and upper airway obstruction physiologically and physically resolved in all patients. We conclude that: 1) when postnatal drip is causally associated with cough, flow-volume loops can provide objective documentation of this clinical association; 2) flow-volume loops can be used as an objective method in comparing the efficacy of different therapeutic agents for cough due to postnasal drip; and 3) normal predicted values of extrathoracic airway function should not include measurements from patients who have recently recovered from cough associated with postnasal drip.

Adolescent↗
PubMed1982

The transiency of oropharyngeal colonization with gram-negative bacilli in residents of a skilled nursing facility.

To determine the duration and persistence of gram-negative bacillary (GNB) oropharyngeal colonization over a specified period and the risk of subsequent GNB pneumonia developing in nursing home patients, we prospectively cultured for 31 weeks the oropharynges of patients in a skilled nursing facility. Over a 31-week period, an average of 13.8 percent of the patients showed colonization (weekly prevalence rates ranged from 0 to 29 percent). No patient had pneumonia during the study period. We concluded that the presence of GNB in the oropharynx of our patients is transient, continually changing over an extended period, and that GNB colonization as a transient occurrence is not directly associated with an increased risk of GNB pneumonia. Our data also emphasize the limitations of previously described single-culture survey studies in predicting the importance of GNB oropharyngeal colonization.

Adult↗
PubMed1980

Antibiotic uptake by alveolar macrophages.

Optimal therapy of infections caused by bacteria able to survive within phagocytes requires the use of antibiotics which inactivate these intracellular organisms. To define characteristics that determine entry of antimicrobial agents into phagocytes, we studied the uptake of 14 radiolabeled antibiotics by rabbit AM. Cell-antibiotic mixtures were incubated for 2 hr, and at intervals antibiotic uptake was determined by velocity-gradient centrifugation (separation of cells from extracellular antibiotic). Many drugs failed to penetrate AM readily. Cellular concentrations of penicillin G and three cephalosporin antibiotics were much lower than extracellular levels (C/E = less than 0.1 to 0.4). Gentamicin, isoniazid, and tetracycline attained C/E values of 0.5 to 0.8. The more lipid-soluble antibiotics, refampin, lincomycin, and chloramphenicol, were concentrated approximately twofold (C/E = 2) in AM. Ethambutol (C/E = 7) and two erythromycin preparations (C/E = greater than 20) were markedly accumulated by macrophages. In comparison with other antibiotics tested, the uptake of clindamycin was both massive and rapid (C/E = 50 by 30 min). Ethambutol, erythromycin and clindamycin uptakes by AM are dependent upon oxidative metabolic processes. Detailed characterization of clindamycin uptake confirmed that the drug is accumulated by an active transport system. These findings, in association with studies of antibiotic-mediated influence on phagocytes, should provide information useful in establishing guidelines for optimal antibiotic usage.

Animals↗