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Biomedical subjects

M E Wohl

Publications and source records attributed to M E Wohl.

At least 37 records · Page 2Linked to original sources
PubMed1995

Prospective evaluation by computed tomography and pulmonary function tests of children with mediastinal masses.

BACKGROUND: Our ability to predict respiratory compromise during general anesthesia in a child with an anterior mediastinal mass is limited. Two prior reports have found a correlation between adequacy of ventilation during general anesthesia and the tracheal cross-sectional area obtained from computed tomograms (computed tomography [CT] scans). These and other reports have suggested that pulmonary function tests may provide additional information regarding anesthetic risks, but no studies have evaluated the extent of respiratory compromise in children with an anterior mediastinal mass. METHODS: We prospectively evaluated 31 children with mediastinal masses before 34 surgical procedures. At each evaluation the tracheal area (as a percent of the predicted area on the basis of age and gender) was determined by CT. Pulmonary function tests were performed in the sitting and supine positions. The eleven children with either a tracheal area or peak expiratory flow rate (PEFR) of less than 50% of predicted received only a local anesthetic; the majority of children above these levels (17 of 22) received a general anesthetic. RESULTS: Eleven of 31 patients had significant pulmonary restriction as defined by total lung capacity of less than 75% of predicted. Eight patients had a PEFR in the supine position of less than 50% of predicted. PEFR was lower in the supine than the upright position in all patients (median value of decrease, 12%). In 28 of 34 evaluations the child had a tracheal area greater than 50% of predicted, a criterion proposed for safe utilization of general anesthesia. This latter guideline, however, did not identify all patients with significant impairment of pulmonary function; five patients had a PEFR of less than 50% of predicted but tracheal areas of greater than 50% of predicted. All children were administered anesthetics uneventfully with these guidelines. CONCLUSIONS: Although the tracheal area can be accurately measured with the CT scan, this does not identify all children with mediastinal masses and abnormal pulmonary function. A large mass may produce significant restrictive impairment and hence reduction in PEFR by the intrathoracic volume it occupies and yet not cause tracheal compression. It may also reduce the PEFR by narrowing the bronchi distal to the carina. Currently no CT standards exist for measuring bronchial areas in children. Our study did not evaluate whether impaired pulmonary function as measured by PEFR would be predictive of respiratory collapse during general anesthesia because all were excluded and operated on under local anesthesia. General anesthesia was well tolerated in children with tracheal area and PEFR greater than 50% of predicted. Pulmonary function tests in children with anterior mediastinal masses may add valuable information to the anatomic evaluation obtained by CT scan.

Adolescent↗
PubMed1994

Effect of aerosolized recombinant human DNase on exacerbations of respiratory symptoms and on pulmonary function in patients with cystic fibrosis. The Pulmozyme Study Group.

BACKGROUND: Respiratory disease in patients with cystic fibrosis is characterized by airway obstruction caused by the accumulation of thick, purulent secretions, which results in recurrent, symptomatic exacerbations. The viscoelasticity of the secretions can be reduced in vitro by recombinant human deoxyribonuclease I (rhDNase), a bioengineered copy of the human enzyme. METHODS: We performed a randomized, double-blind, placebo-controlled study to determine the effects of once-daily and twice-daily administration of rhDNase on exacerbations of respiratory symptoms requiring parenteral antibiotics and on pulmonary function. A total of 968 adults and children with cystic fibrosis were treated for 24 weeks as outpatients. RESULTS: One or more exacerbations occurred in 27 percent of the patients given placebo, 22 percent of those treated with rhDNase once daily, and 19 percent of those treated with rhDNase twice daily. As compared with placebo, the administration of rhDNase once daily and twice daily reduced the age-adjusted risk of respiratory exacerbations by 28 percent (P = 0.04) and 37 percent (P < 0.01), respectively. The administration of rhDNase once daily and twice daily improved forced expiratory volume in one second during the study by a mean (+/- SD) of 5.8 +/- 0.7 and 5.6 +/- 0.7 percent, respectively. None of the patients had anaphylaxis. Voice alteration and laryngitis were more frequent in the rhDNase-treated patients than in those receiving placebo but were rarely severe and resolved within 21 days of onset. CONCLUSIONS: In patients with cystic fibrosis, the administration of rhDNase reduced but did not eliminate exacerbations of respiratory symptoms, resulted in slight improvement in pulmonary function, and was well tolerated.

Adolescent↗
PubMed1994

Reduction in viscosity of cystic fibrosis sputum in vitro by gelsolin.

Obstruction of airways by viscous sputum causes lung damage in patients with cystic fibrosis (CF). Sputum samples from CF patients were shown to contain filamentous actin. Human plasma gelsolin, a protein that severs actin filaments, rapidly decreased the viscosity of CF sputum samples in vitro. Gc globulin and deoxyribonuclease I, proteins that sequester monomeric actin but do not sever actin filaments, were less efficient than gelsolin in diminishing sputum viscosity. These results suggest that gelsolin may have therapeutic potential as a mucolytic agent in CF patients.

Actins↗
PubMed1994

Cystic fibrosis.

Explore the source record for details and available documents.

Anti-Bacterial Agents↗
PubMed1992

Spinal fusion in Duchenne muscular dystrophy: a multidisciplinary approach.

We studied 27 Duchenne muscular dystrophy patients having spinal fusion for scoliosis. One patient died intraoperatively of cardiac arrest; all others have done well with no instances of malignant hyperthermia, postoperative ventilatory system dependence, pneumothorax, persisting infection, neurologic damage, nonunion, or pain. The anesthetic management included primarily intravenous general anesthetics with minimal myocardial depressant effects, avoiding succinylcholine and inhalation agents. Preoperative cardiac studies aided anesthetic management intra-operatively. There was an almost universal sinus tachycardia. Holter monitoring defined 4 of 16 with ventricular premature beats, 4 of 16 with atrial premature beats, and no ventricular tachycardia or atrial flutter or fibrillation. Echocardiogram demonstrated mitral prolapse in 2 of 22, frequent abnormal systolic performance with abnormal shortening fraction less than 28% in 7 of 16, and reduced rate-corrected velocity of fiber shortening in 9 of 15. Afterload was elevated in 7 of 15. The mean forced vital capacity (FVC) preoperatively was 45.3 +/- 15.9% with continuing diminution to 28.7 +/- 14.9% at 3.3 +/- 2.2 years after surgery. The main benefit of surgical stabilization is the relative ease and comfort of wheelchair seating compared with those nonoperated patients who develop progressive deformity. We have not seen lasting improvement or stabilization in FVC following surgery as decreasing function is related primarily to muscle weakness.

Adolescent↗
PubMed1992

Pneumatocele complicating hyperimmunoglobulin E syndrome (Job's Syndrome).

The case of a boy with hyperimmunoglobulin E syndrome or Job's syndrome is presented to demonstrate the occurrence of pneumatoceles in this syndrome as well as their unusual natural history and failure to spontaneously resolve. Surgical resection was required for two complications in this patient, persistent bronchopleural fistula and a pulmonary abscess that destroyed one lung and required pneumonectomy. Pathologic examination of the specimens demonstrated the wall of the cysts consisted of granulation tissue with chronic active inflammation surrounded by infarcted pulmonary parenchyma with coagulative necrosis. The mechanism responsible for increased immunoglobulin E production in this syndrome is unknown, as is the manner in which elevated immunoglobulin E levels impair normal immune function.

Aspergillosis↗
PubMed1991

Nonhomogeneous lung emptying in cystic fibrosis patients. Volume history and bronchodilator effects.

In spontaneous asthma after a deep inhalation (DI) obstruction occurs in direct proportion to disease severity. Since this has been associated with peripheral inflammation, which is present in cystic fibrosis (CF), we tested whether worsening obstruction after DI also occurs in CF in 12 patients. We assessed volume history effects by comparing isovolumic expiratory flows (Vmax) during forced exhalation begun at the end of tidal inspiration (partial P) with those begun at TLC (maximal M) to obtain M/P. As in asthma there was a correlation between M/P and FEV1 (% predicted; r = 0.64, p less than or equal to 0.03, n = 12). To control for a time dependency effect due to preferential emptying of fast compartments early in both the P and M maneuvers, we compared Vmax obtained from a first partial (P1) with a second (P2) obtained after inspiration to TLC and slow exhalation to the same starting volume as P1 (P2/P1). In contrast to asthma the P2/P1 was greater than the M/P and not related to disease severity. A further index of nonhomogeneous lung emptying was the relationship between M/P and the slope ratio at 70% TLC (r = -0.67, p less than or equal to 0.03). After isoetharine inhalation the M/P decreased (-0.12 +/- 0.12, p less than or equal to 0.01) but no change was apparent in P2/P1, indicating further increases in the degree of nonhomogeneity. We conclude that although volume history effects on M/P are similar in asthma and CF, this is due to a predominance of parenchymal hysteresis in the former and nonhomogeneity in the latter, which worsens with bronchodilator use.

Bronchodilator Agents↗
PubMed1990

Changes in the contribution of the rib cage to tidal breathing during infancy.

As the shape, compliance, and deformability of the rib cage (RC) change during infancy, RC participation in quiet breathing may increase. We used respiratory inductive plethysmography (RIP) to determine the relative contributions of the RC and abdomen (AB) to tidal volume (VT) in 20 studies in 14 healthy infants 1 to 26 months of age during quiet natural sleep. RIP was calibrated with simultaneous flow measurements (anesthesia mask and pneumotachograph) by the least squares method of statistical analysis. We analyzed segments of breathing with and without flow measurement for RIP-derived VT, change in RC volume (Vrc) and AB volume (Vab) with each breath and the RC contribution to tidal breathing (%RC = Vrc/Vrc + Vab). The %RC increased with age: %RC = 1.4 age (months) + 33 (r = 0.69, p less than 0.01). After 9 months of age, %RC resembled that found in quietly sleeping adolescents. Mask placement increased VT in all but one subject (mean increase, 29 +/- 23% of baseline +/- SD; p less than 0.001, paired t test). In infants younger than 10 months of age, mask placement also increased %RC (without mask, 40 +/- 9%; with mask, 46 +/- 10% p less than 0.02). We conclude that by 1 yr of age, the RC contribution to tidal breathing during quiet sleep is similar to that of the adolescent, suggesting that major developmental changes in RC shape, compliance, and deformability take place during infancy.

Abdominal Muscles↗
PubMed1990

The lungs and airways in achondroplasia. Do little people have little lungs?

Achondroplasia is a unique model of the effects of skeletal dysplasia and dwarfism on the respiratory system. We measured chest dimensions, spirometry, lung volumes, maximal expiratory flow volume curves, nasal and airways resistance, closing volume, maximal inspiratory/expiratory pressures, and tracheal area by acoustic reflection in 12 healthy subjects with achondroplasia. Anterior-posterior thoracic diameter was mildly reduced in men. Vital capacity for all subjects was 108 percent +/- 18.6 percent (SD) of that predicted for achondroplastic subjects, but was reduced when compared with values for people of average stature that were predicted, based on either sitting height or thoracic height. The reduction was relatively greater in male than in female subjects. The RV/TLC and FRC/TLC ratios were normal. Other measurements were similar to those in average-statured adults. We conclude that achondroplasia results in a reduction in vital capacity out of proportion to what would be expected if these subjects had normal limb size. Although the lungs may be small, they are functionally normal, as are the airways.

Achondroplasia↗
PubMed1989

Dimensions of the trachea to age 6 years related to height.

In an effort to establish normal values for both investigational and patient care purposes, computed tomography was used to determine the length, diameters, cross-sectional area, and volume of the tracheas of 34 children up to the age of 6 years. The measurements were taken when patients were asleep or resting quietly during tidal breathing, at perhaps 30-60% of total lung capacity. The results were related to body height (in infancy, to body length). There was virtually no difference between boys and girls. Each mean diameter correlated well with mean cross-sectional area. Tracheal diameters and area were reasonably constant over the length of individual tracheas. The slopes of the functions relating height to tracheal dimensions in these 34 infants and young children were slightly less steep than those previously measured near total lung capacity in 90 older children and adolescents.

Analysis of Variance↗
PubMed1989

Bronchopulmonary dysplasia: radiographic appearance in middle childhood.

Chest radiographs were compared for three groups of children 8-9 years old: 23 survivors of bronchopulmonary dysplasia (BPD), 33 survivors of hyaline membrane disease without BPD, and 35 survivors of premature birth without neonatal respiratory problems. Only four children in the second group and three in the third had abnormal lungs. Linear shadows, apparently representing strands of fibrosis or deep pleural fissuring, were seen more frequently (15 of 23) in the BPD group than in the others (P less than .0001). Seventeen children in the BPD group had definite pulmonary abnormalities, none of them severe. The anteroposterior dimension of the chest in survivors of BPD tended to be decreased (P less than .001 vs that of reported control subjects).

Aging↗
PubMed1989

Effect of changes in lung volume on respiratory system compliance in newborn infants.

Total respiratory system compliance (Crs) at volumes above the tidal volume (VT) was studied by use of the expiratory volume clamping (EVC) technique in 10 healthy sleeping unsedated newborn infants. Flow was measured with a pneumotachograph attached to a face mask and integrated to yield volume. Volume changes were confirmed by respiratory inductance plethysmography. Crs measured by EVC was compared with Crs during tidal breathing determined by the passive flow-volume (PFV) technique. Volume increases of approximately 75% VT were achieved with three to eight inspiratory efforts during expiratory occlusions. Crs above VT was consistently greater than during tidal breathing (P less than 0.0005). This increase in Crs likely reflects recruitment of lung units that are closed or atelectatic in the VT range. Within the VT range, Crs measured by PFV was compared with that obtained by the multiple-occlusion method (MO). PFV yielded greater values of Crs than MO (P less than 0.01). This may be due to braking of expiratory airflow after the release of an occlusion or nonlinearity of Crs. Thus both volume recruitment and airflow retardation may affect the measurement of Crs in unsedated newborn infants.

Humans↗
PubMed1989

A new technique to demonstrate flow limitation in partial expiratory flow-volume curves in infants.

Partial expiratory flow-volume (PEFV) curves in infants are generated by applying a compressive pressure over the chest wall with an inflatable jacket. This study addresses two issues: pressure transmission to and across the chest wall and whether flow limitation can be identified. Eleven infants sedated with chloral hydrate were studied. Pressure transmission to the chest wall, measured with neonatal blood pressure cuffs placed on the infant's body surface, was 72 +/- 4% of jacket pressure during compression maneuvers. The pressure transmission to the air spaces, determined by measuring airway pressure during a compression maneuver against an occluded airway, was 56 +/- 6% of jacket pressure. A significant amount of the applied pressure is therefore lost across both the jacket and chest wall. Rapid pressure oscillations (RPO) were superimposed on static jacket pressures while expiratory flow was measured. Absence of associated oscillations of flow measured at the mouth was taken to indicate that flow was independent of driving pressure and therefore limited. Flow limitation was demonstrable with the RPO technique in all infants for jacket pressures greater than 50 cmH2O; however, it was evident at jacket pressures less than 30 cmH2O jacket pressure in four infants with obstructive airway disease. The RPO technique is a useful adjunct to the compression maneuver utilized to generate PEFV curves in infants because it facilitates the recognition of expiratory flow limitation.

Humans↗
PubMed1989

Transition from dynamically maintained to relaxed end-expiratory volume in human infants.

Newborn infants, in contrast to adults, dynamically maintain end-expiratory lung volume (EEV) above relaxation volume. The purpose of this study was to determine at what age children develop a breathing strategy that is relaxed, i.e., determined by the mechanical characteristics of the lung and chest wall. Forty studies were performed in 27 healthy infants and children aged 1 mo to 8 yr during natural sleep. Volume changes were recorded with the use of respiratory inductance plethysmography (RIP). The volume signal was differentiated to yield flow. Flow-volume representations were generated for a random sample of the recorded breaths to determine the predominant breathing strategy utilized, i.e., relaxed, interrupted, or indeterminate. The respiratory pattern was predominantly interrupted below 6 mo of age and predominantly relaxed over 1 yr of age. Mixed patterns were observed in children 6-12 mo of age. The number of breaths that could not be classified (indeterminate) decreased with age. Respiratory frequency measured from the sample of breaths decreased with age and was accompanied by an increase in expiratory time. We conclude that a relaxed EEV develops at the end of the first year of life and may be related to changes in the mechanical properties of the chest wall associated with growth as well as changes in respiratory timing.

Analog-Digital Conversion↗
PubMed1989

Changes of time constants during infancy and early childhood.

We used respiratory inductance plethysmography to record tidal respiration in 27 healthy unsedated infants and children 1 mo to 8 yr of age during sleep. Rib cage and abdominal outputs were present at approximately equal gains and summed to obtain an estimate of volume. Flow-volume curves were generated from the uncalibrated volume signal and its flow derivative. Expiratory time constants (tau) were obtained by visually drawing a line through the linear portion of the expiratory flow-volume relationship. tau increased significantly during the first 10 mo of life. After 10 mo, the estimated rate of increase of tau for older children was less than 5% of the estimated initial rate and not significantly different from zero. Prolongation of tau was paralleled by an increase in expiratory time (Te), and no changes in Te/tau were observed in the first 2 yr of life. These changes in tau likely reflect the increase in lung compliance induced by rapid alveolar growth during infancy. After the first year, expiratory time constants appear to remain relatively constant and may be consistent with balanced changes in compliance and resistance beyond infancy.

Aging↗
PubMed1989

Diaphragmatic excursion after pleural sclerosis.

Chemical sclerosis of the pleural space is used to prevent recurrence of spontaneous pneumothorax. To test whether sclerosis restricts diaphragmatic excursion, we measured diaphragmatic excursion by ultrasonography in subjects with unilateral pleural sclerosis and compared it with diaphragmatic excursions in normal subjects, in subjects with cystic fibrosis (a diffuse bilateral lung disease), and in those who underwent surgical procedures that obliterate the pleural space. In five subjects with unilateral chemical sclerosis, diaphragmatic excursion was significantly less on the sclerosed side than on the contralateral side (10.7 +/- 1.3 vs 17.3 +/- 1.7 mm, mean +/- SEM; p less than .01). Compared with those of normal subjects, the side-to-side differences in excursion were increased by pulmonary disease (p less than .03) and additionally by unilateral sclerosis (p less than .015). There was no significant difference between diaphragmatic excursions on left and right sides of subjects without history of pleural disease. These data suggest that chemical pleural sclerosis causes a measurable reduction in diaphragmatic excursion on the affected side. The physiologic significance of this effect is not known.

Adolescent↗
PubMed1988

Relationship between maximal expiratory flows and lung volumes in growing humans.

We examined airway vs. lung parenchymal growth, as inferred from maximal expiratory flows (MEF) and lung volumes (V), respectively, to determine whether the interindividual variability of airway size (inferred from MEF) changes during lung growth and whether a young child with large (or small) airways for his parenchymal size (inferred from V) maintains relatively large (or small) airways for his lung size as he grows to adulthood. Serial measurements of MEF and V were obtained from a cohort of healthy 6- to 27-yr-old males (n = 26) and females (n = 21) over a period of 18 yr. Data were analyzed using logarithmic transformation of the power law equation, MEF = aVb, to fit a regression line to each subject's data points. These growth trajectories were satisfactorily modeled as parallel lines with 20-30% variability of their y-intercepts, indicating that substantial intersubject variability of MEF relative to V is present in early childhood and remains constant during growth. The results further indicate that MEF does track V during lung growth. We conclude that dysanapsis originates in early childhood.

Adolescent↗