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Biomedical subjects

A F Gelb

Publications and source records attributed to A F Gelb.

At least 19 recordsLinked to original sources
PubMed1992

Physiologic studies of tracheobronchial stents in airway obstruction.

When airway obstruction is due to extraluminal compression and/or dynamic collapse, metal and silicone rubber prosthetic stents may stabilize the affected airway. Through a rigid bronchoscope, we inserted three metal stents in two patients and 18 silicone stents in 15 adult patients with symptomatic tracheobronchial compression and dynamic airway collapse. The underlying cause was malignancy in three patients; benign tracheobronchial malacia in three patients, two of whom refused surgical resection; and tracheobronchial stenosis that developed at the anastomotic site following lung transplantation in 11 patients. Clinical status and lung function studies were analyzed before and after stent insertion. Following stent insertion, airway diameter at least doubled and near normal patency of the affected tracheobronchial tree was achieved in every patient using stents of axial length 4 to 5 cm. The stents were well tolerated clinically, and all patients noted immediate relief of dyspnea. Following stent insertion, the forced vital capacity (FVC) increased from 64 +/- 21% predicted (mean +/- 1 SD) to 73 +/- 19% predicted, p less than 0.1; the forced expiratory volume in 1 s (FEV1) from 49 +/- 25% predicted to 72 +/- 26% predicted, p less than 0.02; the ratio of the FEV1/FVC from 59 +/- 16% to 78 +/- 15%, p less than 0.01; and the maximum flow at 50% expired FVC from 38 +/- 26% predicted to 72 +/- 31% predicted, p less than 0.01.

Adult↗
PubMed1990

Computed tomography and bronchoscopy in chest radiographically occult main-stem neoplasm diagnosis and Nd-YAG laser treatment in 8 patients.

We studied 8 adult patients with variable symptoms of cough, dyspnea, stridor, wheezing, or hemoptysis. Fiberoptic bronchoscopy in all showed complete or nearly complete endobronchial obstruction of a main-stem bronchus by neoplasm with a mean bronchial diameter of 1.9 mm +/- 1.6 mm (mean +/- standard deviation). In 4 patients, a lobar bronchus was also completely obstructed. No mass was visible on chest radiographs of any patient; however, computed tomography in each showed main-stem endobronchial obstruction, lobar obstruction (4 instances in 3 patients), and in 6 patients hypoperfusion of the involved lung. Computed tomographic scan showed additional abnormalities that were unsuspected on viewing chest radiographs or at bronchoscopy, including mediastinal adenopathy in 3 patients and an extraluminal tumor component in 4. After therapy with Nd-YAG laser, main-stem airway diameter increased to a mean of 9.6 mm +/- 1.0 mm (P less than .05) and pulmonary functions improved. Results suggest the complementary role of computed tomography and fiberoptic bronchoscopy in the detection and laser-treatment planning of chest radiographically occult severe neoplastic obstruction of the main-stem bronchus.

Bronchial Neoplasms↗
PubMed1988

Physiologic characteristics of malignant unilateral main-stem bronchial obstruction. Diagnosis and Nd-YAG laser treatment.

To evaluate the effects of severe, unilateral main-stem malignant bronchial obstruction on airway dynamics, we obtained maximal expiratory flow-volume (MEFV) curves in 11 patients 59 +/- 18 yr of age (mean +/- 1 SD), three with and eight without underlying emphysema, before and after laser therapy (10 patients) or lung resection (one patient). Mean main-stem bronchial diameters before and after treatment were 1.1 +/- 1.3 and 9.0 +/- 0.8 mm, respectively (p less than 0.05). In the three patients with underlying emphysema, MEFV curves showed a diffuse intrathoracic obstructive pattern before and after treatment; in the other eight patients, MEFV curves demonstrated an apparently restrictive pattern, with associated airflow obstruction in four, reversible after laser treatment in three of these four. After treatment, all patients exhibited an increase in FVC with a roughly parallel shift of the MEFV curve and little change in the slope of the descending limb of the MEFV curve: FVC improved from 54 +/- 16 to 86 +/- 13% predicted in patients without emphysema and from 54 +/- 16 to 77 +/- 8% predicted in patients with emphysema, whereas the slope of the descending limb of the MEFV curve between 45 and 55% of FVC changed minimally from 2.0 +/- 0.6 to 1.8 +/- 0.5 s-1 in patients without emphysema and from 0.8 +/- 0.3 to 0.8 +/- 0.1 s-1 in patients with emphysema.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1988

Diagnosis and Nd-YAG laser treatment of unsuspected malignant tracheal obstruction.

Thirteen adult patients underwent palliative Nd-YAG laser treatment for relief of severe dyspnea due to malignant endotracheal obstruction. Three of the 13 patients had underlying chronic airflow obstruction (CAO) due to diffuse obstructive pulmonary disease. Despite dyspnea, cough, wheezing, stridor and/or hemoptysis, the diagnosis was delayed because of a normal chest roentgenogram in eight patients and nondiagnostic pulmonary function studies (including maximal expiratory and inspiratory flow-volume loops) in all three patients with CAO and in four of ten patients without CAO. The location of the tumor was extrathoracic in two patients, including one with CAO; intrathoracic in seven patients, including two with CAO; and combined extra- and intrathoracic in four. Tracheal diameter increased from 3.5 +/- 1.0 mm before, and to 9.8 +/- 2.0 mm after single or multiple laser treatments. Increased patency of the trachea after laser surgery was associated with improvement in expiratory and/or inspiratory flow rates and with symptomatic relief in all patients which persisted for 14.1 +/- 8.7 months (range four to 48 months). These results indicate that severe symptomatic narrowing of the extra- and/or intrathoracic trachea to a diameter of 2 to 5 mm may not be detected by conventional chest radiography or even by sensitive physiologic tests, especially in patients with underlying CAO. The resultant delay in diagnosis defers possible relief of disabling symptoms with palliative therapy, including Nd-YAG laser photocoagulation.

Adult↗
PubMed1987

Neodymium-yttrium-aluminum-garnet laser in lung cancer.

Neodymium-yttrium-aluminum-garnet laser treatments were performed in 70 patients aged 62 +/- 10 (1 SD) years for incomplete malignancy-induced obstruction of the trachea or main bronchi, or both, associated with uncontrolled cough, dyspnea, atelectasis/pneumonia, and hemoptysis. Forty-three patients had been treated with surgical techniques, chemotherapy, or radiotherapy, or all three, while 27 patients were untreated before laser therapy because of acute respiratory distress. Laser treatment produced palliative improvement in 81% of the treated group (35 of 43), with survival of 4.3 +/- 3.9 months. Unsuccessfully laser-treated patients survived 0.7 +/- 0.4 month (p less than .05). Eighty-five percent of the untreated patients (23 of 27) showed postlaser improvement, with survival of 8.5 +/- 6.9 months. Unsuccessfully laser-treated patients survived 1.4 +/- 0.6 months (p less than .05). Twenty-three of the 27 previously untreated patients underwent radiation therapy after laser treatment. Laser treatments also were administered to 23 patients aged 61 +/- 13 years with complete obstruction of the main bronchi. Of this group, 17 patients had been treated and 6 had not been treated before the laser therapy. Laser treatment was successful in 47% of the treated patients (8 of 17), but there was no difference (p greater than .05) in survival between successfully and unsuccessfully treated patients (3.0 +/- 2.5 vs. 2.9 +/- 4.6 months). Similarly, laser treatment was successful in 50% of the untreated patients (3 of 6), and there was also no difference (p greater than .05) in survival between successfully and unsuccessfully treated patients (3.4 +/- 3.5 vs. 3.5 +/- 2.8 months).(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Obstruction↗
PubMed1987

Nd-YAG laser surgery for severe tracheal stenosis physiologically and clinically masked by severe diffuse obstructive pulmonary disease.

Nd-YAG laser surgery was performed on six patients with tracheal stenosis complicating severe diffuse intrathoracic airways obstruction due to emphysema, chronic obstructive bronchitis and/or asthma. Tracheal stenosis was extrathoracic in four patients and both extrathoracic and intrathoracic in two patients. Results suggest that patients with severe chronic obstructive pulmonary disease and asthma have maximal expiratory and inspiratory flow volume patterns that may completely mask extrathoracic and intrathoracic tracheal stenosis. Following relief of tracheal obstruction with laser therapy, substantial improvement can occur both clinically and physiologically, as reflected by symptomatic relief and large increases in Vmax 50I and FVC.

Adult↗
PubMed1985

Exercise-induced bronchodilation in asthma.

Of 34 symptomatic adult asthmatic patients (23 men) aged 51 +/- 13 years (mean +/- 1 SD) with moderately severe airways obstruction who underwent maximal exercise testing at room temperature (22 degrees C) and humidity (44 percent RH) using a bicycle ergometer, we identified seven male patients aged 56 +/- 9 years in whom forced expired volume in one second (FEV1) increased greater than or equal to 20 percent over the baseline pre-exercise value (exercise-induced bronchodilation). At maximal exercise, these patients achieved an O2 consumption of 1.4 +/- 0.4 L/min and a minute ventilation of 56 +/- 9 L/min. Baseline FEV1 was 1.3 +/- 0.5 L (SD) (43 +/- 12 percent predicted) and increased to 2.1 +/- 0.5 L at five minutes after exercise and persisted at least 20 minutes. Exercise was repeated in all seven patients on a separate day one to six months later, and results were similar in six. In these seven patients, three minutes of voluntary isocapnic hyperventilation achieving a minute ventilation comparable to that during maximal exercise led to an increase in FEV1 of 20 +/- 18 percent (range 0 to 54 percent). The Vmax50 was 22 +/- 30 percent before, and 10 +/- 21 percent after maximal exercise and 25 +/- 37 percent before, and 11 +/- 22 percent after isocapnic hyperventilation. Pre-treatment with acetylsalicylic acid (mean serum concentration 120 +/- 64 micrograms/ml) in the six patients with reproducible bronchodilation completely blocked exercise bronchodilation in one patient and blunted it in four others. Findings suggest that a subset of adult patients with symptomatic asthma may develop bronchodilation after six to eight minutes of exercise, that exercise-induced bronchodilation may in part be reproduced with isocapnic hyperventilation, and that it may be blocked completely or partially by acetylsalicylic acid, implying mediation by prostaglandins.

Aspirin↗
PubMed1985

Lasers in medicine.

Explore the source record for details and available documents.

Bronchial Neoplasms↗
PubMed1979

P pulmonale in status asthmaticus.

We studied 129 patients during acute, severe asthmatic attacks. Electrocardiograms showed P pulmonale in 49% of patients who had an arterial carbon dioxide tension (PaCo2) greater than or equal to 45 mm Hg and an arterial pH less than or equal to 7.37, whereas P pulmonale was present in only 2.5% of asthmatics who had a PaCO2 less than or equal to 44 mm Hg and a pH greater than or equal to 7.38 (p less than 0.001). P wave and QRS axes were 79 +/- 8 degrees and 80 +/- 20 degrees, respectively, in the presence of P pulmonale. When P pulmonale disappeared, the P wave and QRS axes shifted significantly to the left (p less than 0.001). Electrocardiographic P pulmonale persisted 12 to 60 hr after correction of hypoxemia, hypercapnia, and acidosis. In 7 patients with P pulmonale and respiratory acidosis, cardiac catheterization demonstrated normal artery pressures (PAPs) measured relative to atmospheric pressure. In 12 of these peak inspiratory pulmonary artery transmural pressures (PATPs) were increased. Since increased right heart transumural pressures could result in chamber distention, these data are consistent with the hypothesis that reversible P pulmonale in status asthmaticus is explainable on the basis of markedly negative tidal pleural pressures and increased right heart transmural pressures.

Adolescent↗
PubMed1977

Pulmonary function in nonsmoking subjects with alpha1 antitrypsin deficiency (MZ phenotype).

We measured pulmonary functions in 10 nonsmoking asymptomatic subjects, ages 40.5 years +/- 9.2 years, with alpha1 antitrypsin heterozygous deficiency (phenotype MZ). The subjects were longstanding residents of the greater Los Angeles area. The range of physiologic studies and per cent of normal predicted values were forced vital capacity (FVC), 2.8 to 7.0 liters (86 to 124 per cent predicted); ratio of the forced expiratory volume in 1 second to the FVC, 70 to 86 per cent (86 to 104 per cent predicted); the ratio of the residual volume to total lung capacity, 28 to 44 per cent (94 to 119 per cent predicted); total lung capacity, 4.8 to 9.8 liters (80 to 119 per cent predicted); flow at 50 per cent FVC, 3.1 to 7.8 liters per second (69 to 140 per cent); and volume of isoflow, 7.3 to 26 per cent of forced vital capacity (38 to 137 per cent predicted). In eight patients studied, static deflation pressure volume curves were normal, and at respiratory rate of 60 breaths/min the ratio of dynamic compliance to static compliance did not fall below 84 per cent. We have found that these nonsmoking heterozygotes with alpha1 antitrypsin deficiency have normal pulmonary functions (within 1.67 SD of predicted mean).

Adult↗
PubMed1977

Ventilatory response and drive in acute and chronic obstructive pulmonary disease.

We measured hypercapnic ventilatory responses using the rebreathing technique and ventilatory drive using mouth occlusion pressure in 15 normal subjects (6 with added external inspiratory resistance), 11 asthmatics, and 17 patients with chronic obstructive pulmonary disease (9 with chronic CO2 retention and 8 with normal values for arterial pco2). normal subjects, obstructed normal subjects, asthmatics, and patients with chronic obstructive pulmonary disease without CO2 retention had overlapping ventilatory responses. Ventilatory drive was increased in asthmatics and obstructed normal subject. Patients with chronic obstructive pulmonary disease without CO2 retention maintained a ventilatory drive similar to that of normal subjects, whereas patients with chronic obstructive pulmonary disease with chronic CO2 retention demonstrated blunted ventilatory drives as a group, even though 5 of 9 had normal drives. Patients with CO2 retention also had the greatest obstruction when compared to other groups. In some patients, chronic CO2 retention is primarily a consequence of mechanical end-organ limitation rather than a blunted neurorespiratory center output. Acute airway obstruction is associated with an increased drive, which may become reduced with chronic obstruction.

Acute Disease↗
PubMed1977

The volume of isoflow and increase in maximal flow at 50 percent of forced vital capacity during helium-oxygen breathing as tests of small airway dysfunction.

The purpose of this report is to review the role of helium in the early detection of obstructive pulmonary disease. The underlying physiologic mechanisms of the volume of isoflow (the volume at which flow was the same with the subject breathing air and breathing a mixture of 80 percent helium and 20 percent oxygen) and increases in maximal flow at 50 percent of vital capacity (Vmax50) after breathing helium are reviewed. These tests are able to detect physiologic abnormalities in asymptomatic subjects when the results of other tests are normal; and following cessation of smoking, abnormal results may be reversible. The volume of isoflow is increased when maximal flow is reduced because of loss of elastic recoil or increase in upstream resistance. The increase in Vmax50 after breathing helium appears to be relatively specific for the caliber of the small airways, being uninfluenced by loss of elastic recoil; it can further help to localize the major site of obstruction to either small or large airways. At present, random screening for early unsuspected disease is not warranted, and these tests remain an investigative tool.

Evaluation Studies as Topic↗
PubMed1976

Hemodynamic and alveolar protein studies in noncardiac pulmonary edema.

Hemodynamic data were obtained within 15 hours of admission in 11 previously healthy patients (20 to 51 years of age, 7 men and 4 women) who had developed transient, reversible pulmonary edema without cardiac dilation in association with near-death from freshwater drowning (2 cases), pentobarbital overdose, heroin overdose (2 cases), smoke inhalation, chest trauma, sepsis (2 cases), pancreatitis, or prolonged abdominal surgery with suspected sepsis. Using a balloon-tipped flow-directed catheter, the pulmonary artery systolic/diastolic pressures (in mm Hg) were 25/12, 22/9, 31/11, 26/15, 20/10, 35/15, 40/15, 32/18, 20/10, 24/10, and 20/7; the corresponding pulmonary capillary wedge pressures (in mm Hg) were 8, 9, 6, 14, 6, 6, 15, 15, 10, 10, and 5, respectively. Plasma colloidal osmotic pressures measured in the latter 5 cases were 26, 18, 18, 18, and 15 mm Hg, respectively. In addition, the protein content of the alveolar fluid was 5.1, 3.4, 4.0, and 7.1 g per 100 ml in 4 patients. The concentration and distribution of the protein in plasma and alveolar fluid were very similar. These findings provide strong efidence that altered capillary permeability is responsible for the pulmonary edema.

Blood Pressure↗
PubMed1975

Sensitivity of volume of isoflow in the detection of mild airway obstruction.

The relative sensitivity of volume of isoflow test for detecting obstruction was compared to that of other tests, including flow at 60 per cent of total lung capacity, closing volumes, and frequency dependence of dynamic lung compliance. The volume of isoflow was measured in a waterless spirometer after 3 vital capacity inspirations of a mixture of 80 per cent oxygen. We studied 22 asymptomatic, healthy smokers (18 men and 4 women, 32.5 +/- 7.2 years of age, who smoked 5 to 20 pack-years). Thirteen smokers had an abnormal volume of isoflow, yet only 4 had an abnormal flow at 60 per cent of total lung capacity and 2 had an abnormal closing volume. Abnormal frequency dependence of dynamic lung compliance was demonstrated in 3 of 7 smokers tested with an abnormal volume of isoflow; none was detected in 7 smokers tested with normal volume of isoflow. Static pressure-volume curves and diffusing capacity were normal in all smokers with an abnormal volume of isoflow, and after bronchodilator inhalation, volume of isoflow improved in one half of the subjects. These results suggest reversible, intrinsic airway obstruction in the presence of normal flow at 60 per cent of total lung capacity and closing volume. Furthermore, volume of isoflow was a more sensitive test that flow at 60 per cent total lung capacity, closing volume, or frequency dependence of dynamic lung compliance.

Adult↗
PubMed1975

Effect of aging on lung mechanics in healthy nonsmokers.

The purpose of the present investigation was to determine the effects of aging on air flow limitation. In 22 healthy nonsmoking subjects, we constructed maximum expiratory flow-static recoil pressure curves. Analysis indicates that with aging there was a progressive increase in the critical transmural pressure. The conductance of the S segment was not dependent on age, with the exception of a significant increase in the oldest group. This is probably due to a more peripheral location of the equal pressure point secondary to a loss of lung recoil or to increased resistance, or both.

Adult↗