PubMed Health⌕ Search

Biomedical subjects

M Estenne

Publications and source records attributed to M Estenne.

At least 109 records · Page 6Linked to original sources
PubMed1985

Action of abdominal muscles on rib cage in humans.

To assess the actions of the rectus abdominis and external oblique muscles on the rib cage in humans, these two muscles were stimulated with surface electrodes in four normal supine subjects at functional residual capacity. Changes in anteroposterior and transverse rib cage diameters and changes in xiphipubic distance were measured with pairs of magnetometers. Stimulation of rectus abdominis produced a marked decrease in the xiphipubic distance and in the anteroposterior diameter, thus making the rib cage more elliptic. In contrast, stimulation of the external oblique caused a decrease in the transverse diameter, making the rib cage more cylindrical. When both muscles were stimulated simultaneously, the resultant rib cage distortion depended on the relative voltage at which each muscle was stimulated. Electromyogram recordings showed that there was no cross contamination or activity of the diaphragm during the muscle stimulations. Transdiaphragmatic pressure increased with the voltage of stimulation, suggesting passive lengthening of the diaphragm. X-ray studies were performed in two subjects and confirmed the main magnetometer findings. These studies thus confirm that the rib cage in humans is more easily distortable than conventionally thought. The abdominal muscles can distort it in either direction depending on which muscles are contracting.

Abdominal Muscles↗
PubMed1985

Rib cage and diaphragm-abdomen compliance in humans: effects of age and posture.

The influence of age and posture on compliance of the rib cage (Crc) and diaphragm-abdomen (Cab) compartments of the chest wall was studied in 61 healthy adults (33 men, 28 women) aged 24-75 yr. Chest wall compliance (Cw) was measured by the weighted spirometer technique; Crc and Cab were derived from the slope of the relaxation line of the thoracoabdominal system obtained with two pairs of linearized magnetometers. While Cw was being measured, we monitored electrical activity of the abdominal external oblique muscle with a concentric needle electrode and thoracoabdominal configuration. In 52 subjects, the electromyogram did not show any abdominal muscle activity and the end-expiratory level never departed from the relaxed thoracoabdominal configuration, thus suggesting adequate respiratory muscle relaxation. Aging was associated with significant decreases in Crc and Cab. In the upright posture Crc decreased from 0.164 +/- 0.041 (mean +/- SD) l/cmH2O in the younger subjects (24-39 yr) to 0.114 +/- 0.027 l/cmH2O in the older subjects (55-75 yr). Cab concomitantly fell from 0.032 +/- 0.012 l/cmH2O to 0.020 +/- 0.007 l/cmH2O. These reductions were statistically significant (P less than 0.05-0.01) and were also present in the supine posture. Shifting from the seated to the supine posture did not cause any significant change in Cw but was invariably associated with a decrease in Crc and an increase in Cab.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1985

Relationship between respiratory muscle electromyogram and rib cage motion in tetraplegia.

In an attempt to understand the intersubject variation in rib cage motion in tetraplegia, and to assess the isolated action of the diaphragm on the human rib cage, we studied the pattern of rib cage motion in relation to the pattern of nondiaphragmatic respiratory muscle electromyogram (EMG) in 20 tetraplegic patients breathing at rest in the seated posture. The general pattern included a greater expansion of the lower than of the upper rib cage, and a greater and earlier expansion of the lower rib cage in its transverse than in its anteroposterior (AP) diameter. However, whereas the upper rib cage moved paradoxically inward with inspiration in 11 patients, it did not move or slightly expanded in 9 patients; in 1 of these, all rib cage diameters increased in the same proportion during inspiration as during relaxation. This intersubject variation was not related to the duration of tetraplegia, the pattern of the abdominal muscle EMG, or the presence of continuous spastic EMG activity in the parasternal intercostals. By contrast, it was related in part to the pattern of scalene EMG activity: upper rib cage AP paradox was present in 7 of 8 patients with spastic or silent scalenes but only in 4 of 12 patients with phasic inspiratory scalene EMG activity. When studied during quiet breathing in the supine posture, the 8 subjects with denervated scalene, intercostal, and abdominal muscles still showed inspiratory increase in the rib cage transverse diameter, but in 7 patients the lower rib cage AP diameter decreased in concert with the upper rib cage AP diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Rib cage mechanics in simulated diaphragmatic paralysis.

To determine the action of the parasternal intercostals on the human rib cage, we studied the pattern of rib cage motion in relation to the pattern of respiratory muscle contraction in 4 normal subjects during attempts to perform tidal volume breathing with the parasternal intercostals alone. The dimensions of the chest wall, including the anteroposterior (AP) diameters of the lower rib cage and the abdomen, the transverse diameter of the lower rib cage, and the xiphipubic distance, were measured with linearized magnetometers. The electromyogram (EMG) of the diaphragm was obtained with an esophageal lead, while the EMGs of the intercostal, neck, and abdominal muscles were recorded using concentric needle electrodes. Minimizing diaphragmatic use during inspiration (transdiaphragmatic pressure = 0.08 to 1.54 cm H2O) was accompanied by a recruitment of the parasternals that was substantially greater than that of the scalenes; in 2 of the subjects, the activation of the scalenes at the beginning of inspiration was even delayed relative to the parasternals. The lateral intercostals showed variable changes during the maneuver, but the sternocleidomastoids, pectoralis major, rectus abdominis, and abdominal external oblique muscles were always silent. This pattern of EMG activity was associated with profound deformations of the rib cage. In all 4 subjects, the rib cage expanded considerably more along its transverse than its AP dimension relative to its relaxed configuration, and in 3 subjects, the xiphi-pubic distance decreased rather than increased in early inspiration.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1985

Combined heart-lung transplantation for terminal pulmonary lymphangioleiomyomatosis.

Combined heart-lung transplantation with cyclosporine is reported in a 26-year-old patient who presented with end-stage pulmonary lymphangioleiomyomatosis. The operation was successful and the patient's rehabilitation excellent over the first 7 postoperative months. She then developed obliterative bronchiolitis of unknown origin. To our knowledge, this is the first published report of an out-hospital survival after heart-lung transplantation for terminal nonvascular lung disease.

Adult↗
PubMed1984

Coordination between rib cage muscles and diaphragm during quiet breathing in humans.

The pattern of activation of the scalenes and the parasternal intercostal muscles was studied in relation to the pattern of rib cage and abdominal motion during various respiratory maneuvers in the tidal volume range in five normal humans. Electromyograms (EMG) of the scalenes and parasternal intercostals were recorded with bipolar needle electrodes, and changes in abdominal and rib cage displacement were measured using linearized magnetometers. The scalenes and parasternal intercostals were always active during quiet breathing, and their pattern of activation was identical; in both muscles the EMG activity usually started together with the beginning of inspiration, increased in intensity as inspiration proceeded, and persisted into the early part of expiration. In addition, like the parasternal activity the scalene inspiratory activity persisted until the tidal volume was trivial, increased during tidal inspirations performed with the rib cage alone, and was nearly abolished during diaphragmatic isovolume maneuvers. However, attempts to perform tidal inspiration with the diaphragm alone, while causing an increase in parasternal EMG activity, were associated with a marked reduction or a suppression of scalene EMG activity and a reduced substantially distorted rib cage expansion. In particular, the upper rib cage was then moving paradoxically.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Muscles↗
PubMed1984

Respiratory muscle dysfunction in myotonia congenita.

A patient with myotonia congenita (Thomsen's disease) presented with unpleasant sensations of tightness in the chest and dyspnea, which were maximal at the beginning of exercise and gradually improved as exercise progressed. Lung function tests and maximal static respiratory pressures were within normal limits. Precise electromyographic (EMG) and mechanical studies, however, demonstrated the increased excitability, impaired relaxation, and transient weakness of the respiratory muscles. These studies thus indicate that myotonia congenita may involve the respiratory muscles to the same extent as any other skeletal muscle, and that precise EMG studies are occasionally useful in determining the organic basis of respiratory symptoms.

Adolescent↗
PubMed1984

The mechanism of CO2 retention in cardiac pulmonary edema.

We studied a 58-year-old woman during an acute episode of cardiac pulmonary edema complicated by carbon dioxide (CO2) retention. As pulmonary wedge pressure became greater, metabolic production of CO2 increased by 38 ml/min and minute ventilation by 1.53 L; by contrast, alveolar ventilation remained unchanged due to a concomitant rise in physiologic dead space and, as a result, arterial CO2 tension increased up to 61 mm Hg. With treatment, all these variables returned to baseline values. Subsequent measurement of mouth occlusion pressure (p 0.1) during a CO2 rebreathing trial showed that neuromuscular inspiratory drive response to CO2 was preserved, but that ventilatory response was markedly reduced, presumably because of the severe restrictive and obstructive ventilatory defect and of the loss of inspiratory muscle force demonstrated in the patient. We conclude that CO2 retention in cardiac pulmonary edema involves a combination of: (1) increased CO2 production, (2) rise in physiologic dead space, and (3) severe respiratory mechanical impairment.

Carbon Dioxide↗
PubMed1983

Mechanism of relief of dyspnea after thoracocentesis in patients with large pleural effusions.

In an attempt to understand the mechanism underlying the relief of dyspnea that follows thoracocentesis in patients with large pleural effusions, we measured respiratory mechanics in nine patients before and two hours after removal of 600 to 2,750 ml (mean = 1,818 ml) of pleural fluid. Thoracocentesis resulted in only small changes in pulmonary mechanics: Mean vital capacity and functional residual capacity increased by 300 and 460 ml, respectively, lung recoil pressure slightly decreased, and mean static expiratory compliance increased by 0.021 liter/cm H2O. These changes were inconsistent and could not explain the immediate and remarkable relief of dyspnea noted by the patients. By contrast, thoracocentesis invariably resulted in a shift of the minimal (inspiratory) pleural pressure-volume curve so that the pressures generated by the inspiratory muscles were markedly more negative at any comparable lung volume. This shift was entirely due to the decrease in thoracic cage volume. We suggest that the relief of dyspnea following thoracocentesis results primarily from reduction in size of the thoracic cage, which allows the inspiratory muscles to operate on a more advantageous portion of their length-tension curve.

Aged↗
PubMed1983

Variability in lung elasticity measurements in normal humans.

The variability of quasistatic lung inspiratory and expiratory pressure-volume (P-V) curves has been investigated in 8 young healthy volunteers studied on 4 occasions. The reproducibility of the total lung capacity (TLC) measured by body plethysmography was good, with a mean coefficient of variation of 1.8 +/- 0.9% (SD). The following variables were calculated from the P-V curves: the recoil pressures measured at TLC and 90, 80, 70, 60, and 50% TLC, as well as the compliance at functional residual capacity. For all the variables considered the intraseries variance was similar to the interseries variance so that all the individual results were pooled together. For each variable a coefficient of variation was calculated for each subject, as well as an F ratio to compare the interindividual differences to the intraindividual differences. For the variables obtained from the expiratory P-V curve, the lowest coefficient of variation was found for elastic lung recoil pressure, 90% TLC (6.6 +/- 2.6%, mean +/- SD). The reproducibility of the inspiratory P-V curve was found to be somewhat better than that of the expiratory one, with a coefficient of variation of 3.4 +/- 0.8% at 90% TLC. In absolute terms at that same level, the mean standard error of measurements was 1.2 cm H2O for the expiratory curves and 0.8 cm H2O for the inspiratory ones. It is concluded that in terms of reproducibility the best index of lung elasticity is the recoil pressure measured at 90% TLC and that the inspiratory curve is even better than the expiratory one.

Adult↗
PubMed1983

Chest wall stiffness in patients with chronic respiratory muscle weakness.

Using the weighted spirometer technique we studied chest wall compliance (Cw) in 16 nonobese patients with chronic weakness of the respiratory muscles and 20 healthy control subjects. In order to evaluate the validity of the technique, while Cw was being measured, we monitored thoracoabdominal configuration with 2 pairs of linearized magnetometers and electrical activity of the external oblique with a concentric needle electrode in 3 healthy subjects and 4 patients; in addition, we recorded in 3 subjects the electrical activity from the intercostal muscles and diaphragm throughout the procedure. The method was reproducible within 5.8% and provided Cw values that compared well with those yielded by the relaxation technique. In each subject, the weight-induced shifts in end-expiratory lung volume showed a very good linear correlation with the changes in transrespiratory pressure at end-expiration (r greater than or equal to 0.91). In addition, in none of the subjects tested did the electromyograms reveal any intercostal, diaphragmatic, or abdominal muscle activity at end-expiration, nor did the end-expiratory level ever show a significant departure from the relaxed thoracoabdominal configuration, thus suggesting adequate respiratory muscle relaxation. The reduction in inspiratory muscle force in the patients ranged from 17 to 94% of predicted (mean +/- SE, 43 +/- 6). The decrease in vital capacity, total lung capacity, and functional residual capacity averaged 59, 34, and 15% of predicted, respectively. Both the patient and the control groups showed a large interindividual variability regarding Cw. It varied from 0.117 to 0.258 L/cm H2O (mean +/- SE, 0.162 +/- 0.012) in the patients and from 0.163 to 0.366 L/cm H2O (mean +/- SE, 0.248 +/- 0.013) in the healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Muscles↗
PubMed1981

Limitations of measurement of transdiaphragmatic pressure in detecting diaphragmatic weakness.

Intrathoracic (oesophageal), intra-abdominal (gastric), and transdiaphragmatic (Pdi) pressures were studied in 20 untrained, healthy subjects during a full inspiration and repeated maximal static inspiratory efforts. The pattern of pressure generation during these two types of respiratory manoeuvre was highly reproducible in each subject. By contrast, it varied over a wide range among individuals. In particular a substantial number of subjects naturally had a strong recruitment of their intercostal and accessory muscles and thus, low Pdi values, during both slowly performed and forceful inspiratory manoeuvres. These observations make it clear that Pdi values, as usually obtained, are commonly open to misinterpretation. For this approach to ensure a reliable assessment of diaphragmatic function and detect diaphragm weakness adequately, it appears essential either to monitor the abdominothoracic configuration or to standardise the pattern of respiratory muscle contraction.

Adult↗
PubMed1980

Disturbance of respiratory muscle function in patients with mitral valve disease.

A reduced total lung capacity associated with a normal or decreased lung recoil pressure at full inflation (Pel max) has been noted in patients with valvular heart lesions. In order to investigate the mechanism underlying this inappropriately low Pel max, we measured respiratory mechanics in a group of 15 patients with mitral valve disease uncomplicated by other illness. The total lung capacity was 81 percent of control. The static pressure-volume curve of the long intersected the normal one in the vicinity of functional residual capacity (i.e., the recoil pressure was increased at large lung volumes and diminished at low lung volumes), and both expiratory compliance and Pel max were significantly decreased. In 13 of the 15 patients, the minimal (inspiratory) pleural pressure-volume curve was shifted so that the pressures generated by the inspiratory muscles were less negative than normal at any given lung volume. The decrease in Pel max was proportional to the alteration in muscle pressures. These findings indicate (1) that patients with mitral valve disease have compromised function of the inspiratory muscles, and (2) that this alteration is responsible for the low Pel max. Respiratory muscle weakness contributes to the restriction of lung volume in patients with pulmonary vascular congestion and is probably implicated in cardiac dyspnea.

Adolescent↗
PubMed1980

Effects of parenteral aminophylline on lung mechanics in normal human.

We studied the effects of an intravenous injection of 5.0 mg of aminophylline per kg of body weight on lung mechanics in 8 normal subjects. No change occurred in lung volumes, airway resistance, and maximal expiratory flow-volume and lung pressure-volume curves. Restudy of 4 of the subjects before and after an injection of 8.0 mg/kg of aminophylline did not modify the pattern of response to the drug, despite a serum concentration range of 15.1 to 19.3 mg/l. These findings were, therefore, in contrast with those observed after the administration of atropine or beta-2 adrenergic derivatives. They suggested that the bronchodilator effects of aminophylline may not be due to a direct action of the drug on the bronchial smooth muscle.

Adult↗