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Biomedical subjects

R W Light

Publications and source records attributed to R W Light.

At least 199 records · Page 11Linked to original sources
PubMed1983

Serial pulmonary function in patients with acute heart failure.

This study delineates the effects of congestive heart failure on routine pulmonary function tests and assesses the changes in pulmonary function as congestive heart failure was treated. Twenty-eight patients had spirometry, lung volumes, and diffusing capacity measurements initially and at frequent intervals after their initial hospitalization for congestive heart failure. Initially the patients had both obstructive (mean forced expiratory volume in 1 s [FEV1], 48.2% +/- 13% predicted) and restrictive (mean forced vital capacity [FVC], 5.6% +/- 15.7% predicted) ventilatory dysfunction, but a normal carbon monoxide diffusing capacity. With treatment, pulmonary function rapidly improved initially and there was no further significant improvements in the mean pulmonary function after two weeks of treatment. However, there was marked interindividual variability and several patients took months to reach their best level of pulmonary function. Even with treatment, the patients retained evidence of obstructive ventilatory dysfunction and at the time of their best spirometry 53% (8/15) of nonsmokers still had an abnormally low FEV1/FVC ratio.

Aged↗
PubMed1982

Mediastinal abscess secondary to vertebral osteomyelitis.

A 29-year-old man with complaints of pain in the low back, both flanks, and midepigastrium was found to have vertebral osteomyelitis. Mediastinal abscess was also diagnosed on the basis of findings on chest x-ray film, thoracic ultrasonography, thoracentesis, and cultures of pleural fluid. Antibiotic therapy was begun, and open drainage with rib resection was performed. After six weeks of treatment, the patient was free of symptoms. We believe this is the first report of mediastinal abscess secondary to vertebral osteomyelitis in an adult since the advent of antibiotics.

Abscess↗
PubMed1982

Identification of pulmonary hypertension in chronic obstructive pulmonary disease from routine chest radiographs.

The mean pulmonary artery pressure (PAP) was measured in 34 patients with moderate to severe chronic obstructive pulmonary disease (FEV1, 1,010 +/- 460 ml)) and was correlated with the following 3 indexes derived from the chest roentgenogram: (1) the hilar thoracic index, (2) the diameter of the descending branch of the right pulmonary artery, (3) the hilar width, and (4) the cardiothoracic ratio. The mean PAP was 29.0 mm Hg and 20 of 34 patients had an elevated mean PAP (greater than 20 mm Hg). Nineteen of the 20 patients (95%) with an elevated mean PAP had a hilar thoracic index of 36 or above, whereas none of the 14 patients with a normal mean PAP had a hilar thoracic index above 35. Nineteen of the 20 patients (95%) with an elevated mean PAP had diameters of the descending branch of their right pulmonary artery of 20 mm or more compared with only 3 of 14 patients (21%) with a normal mean PAP. The PAP best correlated with the hilar thoracic index (r = 0.74, p less than 0.01) and was significantly correlated with the other 3 indexes. However, the accuracy with which the PAP could be predicted was only +/- 21 mm Hg. We conclude that the chest radiograph is useful in screening patients with COPD for elevated PAP, but that it cannot be used to predict the PAP accurately.

Forced Expiratory Volume↗
PubMed1982

Human alveolar macrophages suppress the proliferative response of peripheral blood lymphocytes.

Human alveolar cells were isolated from bronchopulmonary lavage fluids obtained from patients undergoing clinically indicated bronchoscopy. Alveolar cells strongly suppressed the proliferation of peripheral blood lymphocytes in response to mitogens and antigens. Separation of the alveolar cells into adherent and nonadherent fractions indicated that the suppression was mediated by the adherent cells, or alveolar macrophages. Indomethacin at least partially relieved suppression, suggesting the involvement of prostaglandin synthesis. The suppression could be duplicated by supernatants obtained from unstimulated cultures of alveolar cells. Some specificity of suppression was apparent, in that not all proliferating cells were suppressed. T lymphocytes may be more readily suppressed than B lymphocytes, and the most susceptible cells may be a subpopulation of T lymphocytes.

Cell Adhesion↗
PubMed1981

The relationship between arterial blood gases and serum theophylline clearance in critically ill patients.

Theophylline clearances were monitored at 8-h intervals in a group of critically ill patients and changes in the clearances were correlated with changes in the arterial blood gases. A total of 183 samples from 20 patients were analyzed. The initial theophylline clearance ranged from 20 to 89 ml/kg/h. The initial clearances could not be predicted from the patient's age, arterial blood gases, or the presence of congestive heart failure, liver dysfunction, or other medical problems. For individual patients, the theophylline clearance varied markedly during the study, with the mean maximal clearance averaging 54% higher than the mean minimal clearance. Changes in clearances were not correlated with changes in the arterial blood gases. On the basis of this study, we recommend an initial aminophylline infusion rate of 0.5 mg/kg/h in all critically ill patients. Serum theophylline concentrations should then be determined at 24-h intervals until stabilization and at 48-h intervals thereafter with appropriate adjustments in aminophylline doses.

Aged↗
PubMed1981

Nitrobule tetrazolium test in the diagnosis of pleural effusions.

This study evaluated the diagnostic utility of the nitroblue tetrazolium test on pleural fluid. Pleural fluids from 62 patients, including nine with congestive heart failure, 27 with malignant neoplasms, nine with tuberculosis, 14 with pneumonia, and three with collagen vascular disease, were studied. Results of nitrobule tetrazolium were tabulated for each patient for three different cellular types (polymorphonuclear leukocytes, small lymphocytes, and mononuclear cells other than small lymphocytes). The three patients with collagen vascular disease had very high scores on the nitrogen tetrazolium test for all three cellular types. Their average scores were higher than were those of 57 of the other 59 patients. The nitroblue tetrazolium test on pleural fluid was not useful in separating patients with congestive heart failure, pneumonia, malignant neoplasms, or tuberculosis. The results on the nitroblue tetrazolium test did not help to identify those patients with pneumonia who eventually required tube thoracostomy. From this study, we conclude that the nitroblue tetrazolium test on pleural fluid is of limited use diagnostically but may help to identify those individuals with collagen vascular disease involving the pleura.

Collagen Diseases↗
PubMed1980

Reversible melphalan-induced lung damage.

Pulmonary toxicity occurs after the administration of several different chemotherapeutic agents. Pulmonary toxicity due to melphalan alone has not been documented. In the patient we describe respiratory symptoms and pulmonary infiltrates developed twice within two weeks of the second course of a monthly melphalan and prednisone regimen. Open lung biopsy revealed interstitial pneumonitis. The infiltrates cleared on both occasions when melphalan was withheld. Special studies performed seven weeks after the last dose of melphalan had been given revealed that the patient's alveolar macrophages suppressed phytohemagglutinin induced blastogenesis of his peripheral lymphocytes. Melphalan itself did not stimulate the blastogenesis of the peripheral lymphocytes. Melphalan should be added to the list of therapeutic agents that induce pulmonary disease. However, the pathogenesis of the disease remains to be elucidated.

Aged↗
PubMed1980

Parapneumonic effusions.

In this study the incidence and course of pleural effusions (parapneumonic effusions) in patients with acute bacterial pneumonia were prospectively evaluated. Bilateral decubitus chest x-ray films were obtained within 72 hours of admission in 203 patients with an acute febrile illness, purulent sputum and an infiltrate evident on the chest film. Ninety of the 203 patients (44 percent) had pleural effusions. Parapneumonic effusions, which required chest tubes for resolution and/or on which the pleural fluid cultures were positive, were classified as complicated parapneumonic effusions. The 10 patients with complicated parapneumonic effusions had clinical characteristics similar to the remainder of the group and could be separated from the 80 with uncomplicated effusions only by pleural fluid analysis. A pleural fluid pH below 7.00 and/or a glucose level below 40 mg/100 ml are indications for immediate tube thoracostomy. In patients with pleural fluid pH between 7.00 and 7.20 or lactic dehydrogenase (LDH) above 1,000 IU/1,000 ml, tube thoracostomy should be considered, but each case should be individualized; serial studies of the pleural fluid are useful in some of these cases. Patients with pleural fluid pH above 7.20 and pleural fluid LDH below 1,000 mg/100 ml rarely have complicated parapneumonic effusions and do not require serial therapeutic thoracenteses.

Adult↗
PubMed1980

A new method for analyzing multiple-breath nitrogen washout curves.

Multiple-breath nitrogen washout (MBNW) curves from 39 normal and 45 patients with varying degrees of airway obstruction were analyzed with the following equation: log log [(F0N2 - F infinity N2)/(FN2 - F infinity N2)] = B log (V/FRC) +A, where F0N2 is the initial, F infinity N2 is the equilibrium, and FN2 is the end-tidal fractional nitrogen concentration after a volume (V) of air in liters have been exchanged, and FRC is the measured functional residual capacity of the individual. All 84 curves were well described with the equation when all points corresponding to FN2 below 0.40 were used. The coefficient of determination (r2) exceeded 0.990 in 56/84 (67%) of the transformed curves and the lowest coefficient of determination was 0.946. This suggests that the MBNW can be described by two numbers, B called the index of uniformity, and A the index of efficiency. The ability of these two indices and the lung clearance index (LCI) to identify individuals as abnormal and to separate groups with varying degrees of airway obstruction was compared. B identified more individuals (33/45) as abnormal than did A(15/45) or LCI (19/45). B was also superior to A or LCI in separating groups with varying degrees of airway obstruction. This analysis allows the complex MBNW curve to be described by two numbers that vary depending on the degree of airway obstruction.

Adult↗
PubMed1980

Observations on pleural fluid pressures as fluid is withdrawn during thoracentesis.

In 52 patients with pleural effusions, pleural pressures were measured initially and serially as pleural fluid was withdrawn. Pleural fluid aspiration was continued until the pleural pressure fell below -20 cmH2O, or the patient developed excessive symptoms, or no more fluid could be obtained. The initial pleural pressure ranged from +8 to -21 cmH2O. The rate of pleural pressure change as fluid was withdrawn was highly variable. In 13 of 52 procedures (25%), thoracentesis was terminated because the pressure fell below -20 cmH2O. Negative initial pleural pressures and/or rapid changes in the pressures as fluid was withdrawn were suggestive of malignancy or trapped lung. The measurement of pleural pressures in patients with pleural effusions may be useful diagnostically. More importantly, because large changes in pleural pressures are not readily detectable by the operator, pleural pressures should be monitored when large amounts (> 1,000 ml) of pleural fluid are removed to increase the safety of the procedure.

Drainage↗
PubMed1979

Cefazolin vs penicillin. Treatment of uncomplicated pneumococcal pneumonia.

Cefazolin sodium, 500 mg intramuscularly twice daily, was compared with penicillin G procaine, 600,000 units intramuscularly twice daily, in the treatment of 82 patients with pneumococcal pneumonia. Patients were randomly assigned except when there was a history of penicillin allergy. The patients received treatment for five days or until they were afebrile for 48 hours. No patients experienced side effects or allergic reactions. All patients recovered satisfactorily without relapses. Cefazolin in the previously described dosage is as effective as penicillin in the treatment of pneumococcal pneumonia.

Cefazolin↗
PubMed1979

Albuterol and isoproterenol in bronchial asthma. Efficacy and toxicity of drugs administered via intermittent positive pressure breathing.

This study compared the efficacy and side effects of 1.25, 2.5, 5, 10, and 15 mg of albuterol and isoproterenol hydrochloride administered by intermittent positive pressure breathing (IPPB) to 12 patients with reversible airway obstruction. Equal doses of the two medications induced similar peak increases in pulmonary function, but the increase following albuterol persisted longer. The degree of bronchodilation was impressive; 15 mg of albuterol induced a mean increase over six hours of 82% in the forced expiratory volume in one second. Significant cardiovascular side effects were more common after isoproterenol than after albuterol. Albuterol is superior to isoproterenol as a bronchodilator when administered by IPPB because, for a given peak bronchodilation, cardiovascular side effects are fewer and bronchodilation persists longer with albuterol. The optimal dose of isoproterenol hydrochloride is 2.5 to 5.0 mg and the optimal dose of albuterol is 10 mg when these drugs are given by IPPB.

Adult↗
PubMed1979

Hypoxemia during exercise in patients with chronic obstructive pulmonary disease.

Arterial oxygenation at rest and during maximal treadmill exercise was studied in a group of 17 patients with chronic obstructive pulmonary disease. Patients who developed exertional hypoxemia (subgroup 1) were compared to others who did not (subgroup 2). There was no significant difference between the 2 subgroups at rest in terms of mixed venous PO2, cardiac output, or venous admixture. Subgroup 1 had more severe respiratory impairment than subgroup 2, but there was marked overlap of their respective lung volumes and flows. Both subgroups showed the same extent of desaturation of mixed venous blood during maximal treadmill exercise, so that exertional hypoxemia cannot be explained on the basis of low mixed venous O2. The marked difference between subgroup 1 and subgroup 2 was that the latter showed decreased venous admixture on exercise. Because of the relative constancy of mixed venous blood desaturation, arterial saturation was closely correlated with venous admixture both at rest (r = 0.931) and during exercise (r = 0.985).

Arteries↗