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Biomedical subjects

M E Wohl

Publications and source records attributed to M E Wohl.

At least 55 records · Page 3Linked to original sources
PubMed1988

Thoracic gas volume in rabbits by low-frequency ambient pressure changes.

R. Peslin et al. measured thoracic gas volume (TGV) in adults using a new method employing low-frequency ambient pressure changes (APC) (J. Appl. Physiol. 62: 359-363, 1987). We extended that methodology and then tested the hypothesis that this technique was applicable to small mammals. TGV [at functional residual capacity (FRC)] by APC and by conventional Boyle's law was compared in 12 rabbits. The rabbits were anesthetized, tracheostomized, intubated, and placed in a pressure plethysmograph. Although in the method of Peslin et al. box pressure was oscillated at a single frequency, in our extension box pressure was oscillated simultaneously at two frequencies (0.1 and 0.2 Hz). Flow at the airway opening consisted of rapid events due to spontaneous breathing, superposed on slower events due to the alveolar gas compression. The slower events were analyzed to yield alveolar gas compliance and, by Boyle's law, FRC. FRC by APC was highly correlated to FRC by conventional plethysmography (r = 0.85). Compared with the methodology of Peslin et al., our extension relaxes a key limitation and yields systematically higher estimates of FRC. We conclude that this method is applicable to small mammals, despite an inherently more compliant chest wall, and that the methodological extension improves the estimate of FRC.

Animals↗
PubMed1987

Airway size is related to sex but not lung size in normal adults.

Within individuals, lung size as assessed by total lung capacity (TLC) or vital capacity (VC) appears to be unrelated to airway size as assessed physiologically by maximum expiratory flows (MEF). Green et al. (J. Appl. Physiol. 37: 67-74, 1974) coined the term dysanapsis (unequal growth) to express this apparent interindividual discrepancy between parenchymal and airway size. We have reexamined this discrepancy using both physiological and anatomic indexes of airway size. Airway area by acoustic reflectance (AAAR), peak expiratory flow rates (PEFR), MEF, and lung volumes were measured in 26 male and 28 female healthy nonsmoking adults. The effect of sex on these indexes of large airway size was significant when assessed in a subset of males and females whose TLC's were matched (5.0-6.5 liters). Within this subset, male AAAR was 2.79 +/- 0.45 cm2, whereas female AAAR was 1.99 +/- 0.67 cm2 (P less than 0.01). Male's PEFR and MEF after 25% of VC had been expired (MEF25) were 23% greater than those of females within this subset (P less than 0.05). For the entire group of subjects, once these sex-related differences had been accounted for, AAAR was not significantly related to TLC, whereas PEFR and MEF25 remained at best weakly related to TLC. We conclude that tracheal areas in males are significantly larger than those of females even after controlling for TLC and that after controlling for sex-related differences, tracheal size in adults is unrelated to lung size across a broad range of lung sizes.

Adult↗
PubMed1987

In vivo estimation of tracheal distensibility and hysteresis in normal adults.

We used the acoustic reflection technique to measure the cross-sectional area of tracheal and bronchial airway segments of eight healthy adults. We measured airway area during a slow continuous expiration from total lung capacity (TLC) to residual volume (RV) and during inspiration back to TLC. Lung volume and esophageal pressure were monitored continuously during this quasi-static, double vital capacity maneuver. We found that 1) the area of tracheal and bronchial segments increases with increasing lung volume and transpulmonary pressure, 2) the trachea and bronchi exhibit a variable degree of hysteresis, which may be greater or less than that of the lung parenchyma, 3) extrathoracic and intrathoracic tracheal segments behaved as if they were subjected to similar transmural pressure and had similar elastic properties, and 4) specific compliance (means +/- SE) for the intrathoracic and bronchial segments, calculated with the assumption that transmural pressure is equal to the transpulmonary pressure, was significantly (P less than 0.05) smaller for the intrathoracic segment than for the bronchial segment: (2.1 +/- 2.0) X 10(-3) cmH2O-1 vs. (9.1 +/- 2.1) X 10(-3) cmH2O-1. Direct measurements of airway area using acoustic reflections are in good agreement with previous estimates of airway distensibility in vivo, obtained by radiography or endoscopy.

Acoustics↗
PubMed1987

Results of surgical treatment of adults with idiopathic scoliosis.

The outcome of surgical treatment of idiopathic scoliosis in forty-five adults was studied with special attention to pain, function, self-image, and pulmonary function. All of the patients were more than twenty-five years old at operation and had been followed for more than three years. Every patient who was operated on by one of us (J. E. H.) and who met these criteria was evaluated. The magnitude of the curves averaged 66 degrees. Standardized gradations of pain and function showed improvement over-all, but significant impairment remained. There was a reduction in the levels of peak and constant pain, but no change in the frequency of peak pain after operation. The number of patients who were pain-free after surgery was not increased. Functional impairment due to the scoliosis was lessened, and the ability to perform the common activities of daily living was improved, but no important changes in occupation or recreational activity were recorded. Correlations of pain or function, or both, and the changes in either, were found with only two parameters: age at follow-up and physical occupation. Pulmonary function, as measured, did not change. Eighteen (40 per cent) of the patients had a minor complication and ten (20 per cent), a major complication; there was one death, due to pulmonary embolism, of a patient who was excluded from the series. In view of the high rate of complications, the limited gains to be derived from spinal fusion should be assessed and clearly explained to patients before the procedure is undertaken.

Activities of Daily Living↗
PubMed1986

Pulmonary function in older children and young adults with gastroesophageal reflux.

A wide variety of types of pulmonary diseases and respiratory symptoms have been associated with gastroesophageal reflux (GER). Asthma, chronic bronchitis, bronchiectasis, and pulmonary fibrosis have all been linked to GER, but causal mechanisms have been difficult to establish. To characterize pulmonary function abnormalities in older children and young adults (age 7-23 years) with GER, lung function was evaluated in 22 patients being treated for reflux. The patients were divided into two groups: nine subjects (Group 1) had no history of pulmonary symptoms. Thirteen subjects (Group 2) had known pulmonary disease; all had diagnosed asthma, and five had a history of recurrent pneumonia. Lung volumes and spirometry were measured. Airway reactivity was assessed by measuring change in flows following isocapneic hyperventilation of subfreezing air. The presence of "small airway" disease was assessed by air-helium flow volume curves and the single breath oxygen test. Lung size, as indicated by measurement of total lung capacity, was normal in all patients. Flow rates, density dependence of maximal expiratory flow, single breath oxygen test, and tests of airway reactivity were abnormal only in Group 2 patients and were normal in the Group 1 patients. That not all children with GER have abnormal pulmonary function suggests that, if there is a causal relationship between GER and lung disease, it is multi-factorial in nature. Children with GER who do have lung disease have evidence of airway obstruction, maldistribution of ventilation, and increased airway reactivity, but do not have restricted lung volumes.

Adolescent↗
PubMed1986

Dimensions of the growing trachea related to age and gender.

Computed tomography measured the lengths, anteroposterior (AP) diameters, transverse diameters, cross-sectional areas, and contained volumes of the tracheas of 130 subjects in their first two decades. Patients below age 6 were scanned at low lung volumes. The others were scanned at or near total lung capacity. The results are shown by age and gender. There were no differences between boys and girls until age 14, when girls' tracheas stopped growing. The data suggest that male tracheas continue to enlarge (but not lengthen) for a time after growth in height ceases. Mean transverse diameters tended to be greater than mean AP diameters to the age of 6; the diameters were then nearly identical until age 18, when the AP diameters usually became slightly larger. The tracheas were nearly round in cross section, especially at high lung volumes. In individual tracheas, changes from level to level were small. These measurements should be useful in the detection of tracheal abnormalities, in problems in respiratory physiology, and in endotracheal intubation, endoscopy, and tracheostomy.

Adolescent↗
PubMed1986

Bronchiolitis.

Explore the source record for details and available documents.

Adrenal Cortex Hormones↗
PubMed1985

Dimensions of the growing trachea related to body height. Length, anteroposterior and transverse diameters, cross-sectional area, and volume in subjects younger than 20 years of age.

Using computed tomography, we measured the tracheas of 100 subjects younger than 20 yr of age. The 10 youngest were sleeping. The other 90 were awake, and most were measured near total lung capacity. Tracheal length, mean anteroposterior diameter, mean transverse diameter, mean cross-sectional area, and contained volume were plotted against body height for all 100 subjects. The relationships of these dimensions to body height were derived for the 90 subjects examined awake. The resulting regressions had r values of 0.88 to 0.92. The exponents for height were 1.22 to 1.37 for the linear dimensions, 2.58 for area, and 3.80 for volume. We found no differences between the sexes. Variability in diameters and area along individual tracheas was small, especially after early childhood. Such variability as occurred tended to preserve shape slightly more than size. This constancy allows accurate prediction of tracheal area from either tracheal diameter.

Adolescent↗
PubMed1985

Postural hypoxemia in cystic fibrosis.

We measured arterial blood gases in the sitting and supine position in 33 patients with cystic fibrosis (CF). Arterial PO2 ranged from 48 to 97 mm Hg in the sitting position and fell by 1 to 23 mm Hg in 26 patients, rose by 1 to 4 mm Hg in five, and was unchanged in two when supine. Mean PO2 change for the group was a 6.5 (+/- 6.8) mm Hg decrease (sitting to supine), and substantial falls were more likely to occur in patients with mild to moderate, rather than severe, obstructive lung disease. There were no significant changes in PCO2 or pH with posture. Postural hypoxemia was not completely explained by greater airway closure as measured by the single-breath nitrogen method in 11 patients or by worse radiographic change in the upper lung zones. Arterial PO2 should always be compared in the same body position in CF patients, preferably while supine. Postural hypoxemia also may contribute to the lower PO2 at night in CF patients.

Adolescent↗
PubMed1984

Reproducibility and accuracy of airway area by acoustic reflection.

To determine the accuracy and reproducibility of measurements of airway area by acoustic reflection (AAAR) we made repeated measurements of tracheal areas in human volunteers, glass airway models, and excised canine tracheae. In 10 adult males, the mean ratio of tracheal AAAR to tracheal areas determined roentgenographically was not significantly different from one (1.06 +/- 0.13 SD). Within-run variability was 10 +/- 4% (CV), mean intrasubject day-to-day variability was 9 +/- 4% (CV). A custom-made mouthpiece is necessary for accurate measurements of AAAR. Mean variability related to differences in mouthpiece construction was 7 +/- 6% (CV). The effect of variations in upper airway and glottic sizes on tracheal AAAR measurements was investigated using glass airway models. In model studies, tracheal AAAR measurements were found to be independent of changes in proximal airway size for glottic apertures greater than or equal to 1 cm2 and upper airway areas less than or equal to 8 cm2. Tracheal area was, however, overestimated by 20% in the rigid-walled glass models. The effects of airway wall rigidity were qualitatively investigated by comparing acoustic and roentgenographic measurements of excised canine tracheae surrounded by either air or petroleum jelly. Differences in the accuracy of measurements of AAAR in vitro and in vivo are probably due to differences in airway wall inertance. These studies suggest that the measurement of AAAR yields an accurate and reproducible result that may be clinically useful for the noninvasive detection of changes in central airway geometry.

Acoustics↗
PubMed1983

Tracheal size and shape: effects of change in intraluminal pressure.

We used CT to examine the tracheas of two healthy adults at functional residual capacity, first at an intratracheal pressure of +20-cm H2O and then at -20-cm H2O. In the intrathoracic portions of the tracheas there was little change in cross-sectional area between the two pressures. However, in the neck the cross-sectional areas decreased by about one third from the higher pressure to the lower. The membranous posterior wall of the woman's extrathoracic trachea bulged backwards strikingly at the higher pressure but was drawn well into the tracheal lumen at the lower pressure. The two tracheas were 6% and 12% shorter at the lower pressure, and the intratracheal volume was 17% to 23% less. The data show that the size and shape of the extrathoracic portion of the normal adult trachea are very responsive to moderate changes in intraluminal pressure.

Female↗
PubMed1982

Effects of posture on flow-volume curve configuration in normal humans.

Tien et al. (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 46: 565-570, 1979) found reproducible details in the configuration of averaged maximal expiratory flow-volume curves and suggested that these details may correspond to sudden relocations of airway choke points. The occurrence of choke points depends on factors affecting local airway pressure-diameter behavior. We postulated that changes in posture as they affect the distribution of lung recoil on airways might change the locations of choke points and thereby alter flow-volume configuration. Twenty normal adults performed five flow-volume curves in each of four postures (standing, supine, right, and left lateral recumbent). Volume was measured with a Krogh spirometer and airflow with a Fleisch No. 4 pneumotachometer. Curves were digitally filtered and plotted relative to upright total lung capacity. Five curves in each posture were averaged at increments of 0.1 l/s of flow and average volumes at given flows were compared using the Student's t test. Significant differences (P less than 0.01) in mean volumes at given flows occurred in all subjects from standing to supine and/or right to left lateral postures. Large changes in configuration were apparent in one of the two postural pairs in eight subjects. We conclude that changes in posture result in significant changes in flow-volume configuration in most normal adults. These findings are consistent with the wave-speed theory of flow limitation and suggest that small changes in local airway stresses can significantly alter the location and motion of airway choke points during forced expiration.

Adult↗
PubMed1981

Immunodeficiency associated with loss of T4+ inducer T-cell function.

We investigated the immune function of a patient with anergy and acquired hypogammaglobulinemia. Despite normal numbers of B cells and T4+ inducer and T5+ suppressor T cells, this patient's lymphocytes did not produce immunoglobulin, proliferate in response to soluble antigens, or generate helper factors in vitro. In addition, her T4+ T cells did not express la molecules after stimulation by soluble antigen. In mixing experiments, her T cells did not induce immunoglobulin secretion by B cells from a normal, HLA-D-identical sibling; this failure was not due to excessive suppression, since the patient's T cells did not abrogate immunoglobulin production by the normal sibling's T and B cells. Moreover, the patient's B cells secreted immunoglobulin in the presence of the sibling's T4+ cells. In contrast to the deficient inducer cells, the patient's T5+ T cells were capable of expressing suppressor-cell functions. These results indicate that immunodeficiency may occur because of a selective loss of T4+ inducer function.

Agammaglobulinemia↗
PubMed1980

Polyalveolar lobe: anatomic and physiologic parameters and their relationship to congenital lobar emphysema.

Polyalveolar lobe is one of the recently described pathological entities that can give rise to congenital lobar emphysema (CLE). In polyalveolar lobe, the total alveolar number as determined by microscopic point-counting of randomly taken lung sections is increased three to fivefold. The airways and arteries are normal for age in number, size and structure. Follow-up over 10-20 yr of patients operated upon for congenital lobar emphysema, including those of polyalveolar lobe etiology shows that these patients do well clinically. All patients have some pulmonary function abnormalities, specifically a decrease in airway conductance, and forced expiratory volume. It is not possible to distinguish patients with polyalveolar lobes from other CLE patients on the basis of pulmonary function data. All patients had normal lung volumes and vital capacities, despite losing 8%-20% of their pulmonary parenchyma. Based on compensatory lung growth, it may be preferable to operate earlier, rather than later in these cases.

Child, Preschool↗
PubMed1980

Airway area by acoustic reflections measured at the mouth.

We tested the hypothesis that features of upper airway and tracheal geometry can be inferred from acoustic reflection data recorded at the mouth. In six subjects we computed inferences of airway cross-sectional area vs. distance and compared them with measurements obtained from orthogonal radiographic projections of the trachea. The acoustic data show local area maxima at the uvula and hypopharynx and local minima at the oropharynx and the glottis. With subjects breathing air the inferred tracheal areas markedly exceeded the radiographic measurements. With subjects breathing 80% He-20% O2 there was good intrasubject agreement between acoustic and radiographic data in spite of large intersubject variability. The average coefficient of variation of tracheal area determinations for five trials in all subjects was 0.16. These studies suggest that features of airway geometry between the mouth and carina can be determined accurately and noninvasively in individual subjects from high-frequency reflection data measured at the mouth.

Acoustics↗
PubMed1980

Lung growth and airway function after lobectomy in infancy for congenital lobar emphysema.

To characterize the outcome of lobectomy in infancy and the low expiratory flows which persist after lobectomy for congenital lobar emphysema, 15 subjects with this history were studied at age 8-30 yr. Total lung capacity was normal in all, but higher values (P < 0.05) were observed in nine subjects with upper lobectomy than in five subjects with right middle lobectomy. Ratio of residual volume to total lung capacity was correlated (P < 0.05) with the amount of lung missing as estimated from normal relative weights of the respective lobes. Xe(133) radiospirometry in eight subjects showed that the operated and unoperated sides had nearly equal volumes at total lung capacity, but that the operated side was larger than the unoperated side at residual volume. Perfusion was equally distributed between the two sides. Similar findings were detected radiographically in four other subjects. Forced expiratory volume in 1 s and maximal midexpiratory flow rate averaged 72 and 45% of predicted, respectively. Low values of specific airway conductance and normal density dependence of maximal flows in 12 subjects suggested that obstruction was not limited to peripheral airways. Pathologic observations at the time of surgery and morphometry of the resected lobes were not correlated with any test of pulmonary function. These data show that lung volume can be completely recovered after lobectomy for congenital lobar emphysema in infancy. The volume increase occurs on the operated side, and probably represents tissue growth rather than simple distension. The response to resection is influenced by the particular lobe resected and may be associated with decreased lung recoil near residual volume. Low expiratory flows in these subjects could be explained by several mechanisms, among which a disproportion between airway and parenchymal growth in infancy (dysanaptic growth) is most compatible with our data.

Adolescent↗