Contribution of rib cage and abdominal expiratory muscles to tidal volume in head-up dogs.
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Animals↗
Biomedical subjects
M Estenne
Publications and source records attributed to M Estenne.
Ventilatory compensation for changes in posture after human heart-lung transplantation.
We have studied the contribution of vagal pulmonary receptors to the stability of breathing during postural changes in humans. Quiet breathing was quantified in the seated and the supine postures in 10 patients with chronic pulmonary denervation due to heart-lung transplantation and 10 age and sex matched normal controls. In the vast majority of patients and normal subjects frequency histograms for tidal volume and mean inspiratory flow rate were virtually superimposed seated and supine. There were no significant differences in the mean levels of respiratory variables between postures in either group (except for mean inspiratory flow rate in the patients which was slightly greater seated than supine). Experiments performed on a tilt table in two additional patients showed that the ventilatory response to postural changes was immediate. In addition, the response was maintained after blockade of intact tracheal stretch receptors with aerosolized lidocaine. These results indicate that adequate ventilatory compensation during postural changes does not depend on vagal afferent information arising in intrapulmonary or tracheal airway stretch receptors. The appropriate receptors may be diaphragmatic Golgi tendon organs.
Adolescent↗
Expiratory muscle contribution to tidal volume in head-up dogs.
A change from the supine to the head-up posture in anesthetized dogs elicits increased phasic expiratory activation of the rib cage and abdominal expiratory muscles. However, when this postural change is produced over a 4- to 5-s period, there is an initial apnea during which all the muscles are silent. In the present studies, we have taken advantage of this initial silence to determine functional residual capacity (FRC) and measure the subsequent change in end-expiratory lung volume. Eight animals were studied, and in all of them end-expiratory lung volume in the head-up posture decreased relative to FRC [329 +/- 70 (SE) ml]. Because this decrease also represents the increase in lung volume as a result of expiratory muscle relaxation at the end of the expiratory pause, it can be used to determine the expiratory muscle contribution to tidal volume (VT). The average contribution was 62 +/- 6% VT. After denervation of the rib cage expiratory muscles, the reduction in end-expiratory lung volume still amounted to 273 +/- 84 ml (49 +/- 10% VT). Thus, in head-up dogs, about two-thirds of VT result from the action of the expiratory muscles, and most of it (83%) is due to the action of the abdominal rather than the rib cage expiratory muscles.
Animals↗
Lung volumes, chest wall configuration, and pattern of breathing in microgravity.
We studied the changes in functional residual capacity (FRC), thoracoabdominal volume (Vw), and chest wall configuration in five normal subjects seated in an aircraft flying parabolic trajectories resulting in 20-s periods of microgravity. We measured vital capacity (VC), inspiratory capacity, and tidal volume by integrating airflow at the mouth and changes in rib cage and abdominal volume (delta Vrc and delta Vab, respectively, where delta Vrc + delta Vab = delta Vw) using induction plethysmography. During microgravity (0 Gz) FRC decreased by 413 +/- 70 (SE) ml and VC by 0.37 liter. The decrease in Vw did not differ from that in FRC and was entirely the result of reduction of Vab, the Vrc showing no significant change. During tidal breathing the abdominal contribution (delta Vab/delta Vw) increased from 0.39 +/- 0.08 at 1 Gz to 0.57 +/- 0.08 at 0 Gz. During brief periods of hypergravity (approximately 1.8 Gz) all changes were opposite in sign and relatively smaller. Limited data during "roller coaster" flight patterns suggested that, in contrast to configurational changes, the temporal pattern of breathing was uninfluenced by changes in Gz. We conclude that at the onset of weightlessness there are substantial changes in lung volume and thoracoabdominal configuration. Abdominal contribution to tidal excursions increases but the temporal pattern of breathing is unchanged.
Abdomen↗
The effect of pectoralis muscle training in tetraplegic subjects.
We have previously shown that subjects with traumatic tetraplegia use the clavicular portion of the pectoralis major to expire actively. To determine if we could improve the expiratory function of these subjects, we studied six patients in whom the pectoralis major was trained by repetitive, strenuous, isometric contractions for 6 wk. Six patients receiving conventional respiratory rehabilitation served as control subjects. Training of the pectoralis major produced marked increases in the maximal isometric muscle strength (mean +/- SE: 54.6 +/- 5.8%; p less than 0.005) and in expiratory reserve volume (46.6 +/- 9.9%; p less than 0.005). Functional residual capacity did not change, such that residual volume decreased by 14.1 +/- 2.9% (p less than 0.005). In contrast, the control patients did not develop any significant alterations. We conclude that unlike conventional rehabilitation, training the pectoralis major for strength improves expiratory function in tetraplegic subjects. Therefore, training of this muscle should increase the effectiveness of coughing and might reduce the prevalence of bronchopulmonary infections in such subjects.
Adult↗
Triangularis sterni muscle use during eupnea in humans: effect of posture.
The electromyograms of the triangularis sterni (transversus thoracis), of the abdominal external oblique, and of the deeper abdominal muscle layer (internal oblique or transversus abdominis) were recorded with concentric needle electrodes in twenty normal naive subjects breathing quietly in the supine and the standing posture. The triangularis sterni and abdominal muscles were usually silent in the supine posture. In contrast, all subjects in the standing posture showed activity in the abdominal muscles, and sixteen subjects also had activity in the triangularis sterni. The abdominal muscle activity was principally tonic, unrelated to the phases of the breathing cycle, whereas in fifteen subjects the triangularis sterni activity was confined to expiration. Expiratory activation of the triangularis sterni was more frequently observed in the older than in the younger subjects of the study. These observations indicate that unlike in the supine posture, most normal subjects when breathing at rest in the standing posture recruit both the triangularis sterni and the abdominal muscles. This recruitment may compensate for the adverse effects of the standing posture on the diaphragm and rib cage inspiratory muscles.
Adolescent↗
Mechanical role of expiratory muscles during breathing in upright dogs.
To examine the mechanical effects of the abdominal and triangularis sterni expiratory recruitment that occurs when anesthetized dogs are tilted head up, we measured both before and after cervical vagotomy the end-expiratory length of the costal and crural diaphragmatic segments and the end-expiratory lung volume (FRC) in eight spontaneously breathing animals during postural changes from supine (0 degree) to 80 degrees head up. Tilting the animals from 0 degree to 80 degrees head up in both conditions was associated with a gradual decrease in end-expiratory costal and crural diaphragmatic length and with a progressive increase in FRC. All these changes, however, were considerably larger (P less than 0.005 or less) postvagotomy when the expiratory muscles were no longer recruited with tilting. Alterations in the elastic properties of the lung could not account for the effects of vagotomy on the postural changes. We conclude therefore that 1) by contracting during expiration, the canine expiratory muscles minimize the shortening of the diaphragm and the increase in FRC that the action of gravity would otherwise introduce, and 2) the end-expiratory diaphragmatic length and FRC in upright dogs are thus actively determined. The present data also indicate that by relaxing at end expiration, the expiratory muscles make a substantial contribution to tidal volume in upright dogs; in the 80 degrees head-up posture, this contribution would amount to approximately 60% of tidal volume.
Abdominal Muscles↗
Functional anatomy of the respiratory muscles.
To keep arterial blood gases within acceptable limits, air must be moved rhythmically in and out of the lungs. Such a displacement is accomplished through the expansion/deflation of the chest wall, which results normally from the action of a number of skeletal muscles. To understand how this vital pump works, it is necessary to have a clear understanding of the anatomy and the function of these muscles.
Humans↗
Cardiorespiratory responses to dynamic exercise after human heart-lung transplantation.
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Adult↗
Triangularis sterni muscle use in supine humans.
The electrical activity of the triangularis sterni (transversus thoracis) muscle was studied in supine humans during resting breathing and a variety of respiratory and nonrespiratory maneuvers known to bring the abdominal muscles into action. Twelve normal subjects, of whom seven were uninformed and untrained, were investigated. The electromyogram of the triangularis sterni was recorded using a concentric needle electrode, and it was compared with the electromyograms of the abdominal (external oblique and rectus abdominis) muscles. The triangularis sterni was usually silent during resting breathing. In contrast, the muscle was invariably activated during expiration from functional residual capacity, expulsive maneuvers, "belly-in" isovolume maneuvers, static head flexion and trunk rotation, and spontaneous events such as speech, coughing, and laughter. When three trained subjects expired voluntarily with considerable recruitment of the triangularis sterni and no abdominal muscle activity, rib cage volume decreased and abdominal volume increased. These results indicate that unlike in the dog, spontaneous quiet expiration in supine humans is essentially a passive process; the human triangularis sterni, however, is a primary muscle of expiration; and its neural activation is largely coupled with that of the abdominals. The triangularis sterni probably contributes to the deflation of the rib cage during active expiration.
Adult↗
Mechanism of the postural dependence of vital capacity in tetraplegic subjects.
It is well established that unlike normal subjects patients with cervical cord transection have an increase in VC when changing from the seated to the supine posture. To investigate the mechanism of this paradoxical increase, we measured static lung volumes in both the seated and supine posture in 14 consecutive patients with tetraplegia (C4-C7) and in 4 patients with paraplegia (Th4-Th7). The increase in VC in the supine compared with the seated posture was (mean +/- SE) 0.41 +/- 0.07 L (16.0% of the seated value) in the tetraplegic subjects and 0.40 +/- 0.01 L (11.2% of the seated value) in the paraplegic subjects (p less than 0.001). However, TLC in all subjects was 0.28 +/- 0.05 L smaller in the supine posture (p less than 0.001), thus indicating that the larger VC in this posture is related to a reduction in residual volume (RV) rather than to an increased mechanical advantage of the diaphragm. The reduction in RV in the supine posture was consistent, averaging 0.72 +/- 0.06 L (29.1% of the seated value) in the tetraplegic subjects and 0.62 +/- 0.21 L (37.6 percent of the seated value) in the paraplegic subjects (p less than 0.001). Inflating blood pressure cuffs at the bases of the legs prior to the assumption of the supine posture diminished the reduction in RV with recumbency by only 0.10 +/- 0.02 L. In contrast, the postural dependence of RV was abolished when the abdomen was tightly supported by elastic straps and maintained constant in configuration during postural changes.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Sarcoidlike lung granulomatosis induced by aluminum dusts.
Interstitial lung disease developed in a 32-yr-old chemist after working 8 yr in a dusty atmosphere containing aluminum powders. Bronchoalveolar lavage disclosed a helper T-lymphocyte alveolitis, and transbronchial lung biopsies showed sarcoidlike epithelioid granulomas. These granulomas contained dust identified by mineralogic analyses as consisting mainly of aluminum particles. Nasal and liver biopsies and a Kveim test did not reveal extrapulmonary granulomatous infiltration. An extensive immunologic work-up showed none of the abnormalities classically seen in sarcoidosis, but peripheral blood lymphocytes exhibited blastic transformation in the presence of soluble aluminum compounds. About 1 yr after cessation of exposure, a chest radiograph and lung function tests remained essentially unchanged, but signs of alveolitis disappeared. This observation suggests that aluminum may cause granulomatous lung disease accompanied by a helper T-lymphocyte alveolitis, similar to that of berylliosis and sarcoidosis. Further observations would be necessary to show if this constitutes an early stage of aluminum-induced fibrosis (aluminum lung).
Adult↗
Human heart-lung transplantation: physiologic aspects of the denervated lung and post-transplant obliterative bronchiolitis.
Eighteen sequential follow-up measurements of pulmonary function were obtained over a period of 21 months after heart-lung transplantation in a patient who had undergone surgery for end-stage pulmonary lymphangioleiomyomatosis. In the early postoperative period, there was a moderate decrease in VC and TLC but gas exchange was maintained at essentially normal levels. The most conspicuous features of postoperative lung function were a very low airway resistance and an increase in FEV1/VC ratio above 95%. These alterations were associated with an unusual shape of the maximal expiratory flow-volume (MEFV) curve. Instead of showing a uniform decrease in expiratory flow as expiration proceeds to residual volume, the post-transplant MEFV curve showed a peak followed by a gently sloping plateau ending at a knee where flow suddenly fell. The knee occurred after exhalation of 80% VC. From the sixth postoperative month, the patient developed rapidly increasing air-flow obstruction, which proved to be due to obliterative bronchiolitis. As air-flow obstruction worsened, the knee on the MEFV curve progressively occurred at a higher lung volume, the flow plateau shortened, and flow after the knee became smaller at a given volume. From the ninth postoperative month, it was no longer possible to identify a plateau-knee configuration on the MEFV curve, which resembled that seen in severe obstructive airway disease.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[The place of corticoids in asthma].
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Asthma↗
Mechanism of active expiration in tetraplegic subjects.
Traumatic tetraplegia produces paralysis of all the well-recognized muscles of expiration. Yet, tetraplegic subjects usually have a small expiratory reserve volume on spirographic examination. To understand the mechanism that enables these patients to empty their lungs actively, we studied the pattern of chest-wall motion during voluntary expiration. We found negligible changes in abdominal dimension, but all subjects had a marked and reproducible decrease in the dimension of the upper rib cage. Electrical measurements established that the subjects had active use of the clavicular portion of the pectoralis major, and changing the orientation of these muscle fibers by maintaining the shoulders in abduction reduced their expiratory reserve volume by about 60 percent (P less than 0.001). We therefore conclude that the clavicular portion of the pectoralis major plays a crucial part in the mechanism of active expiration in tetraplegic subjects. Training of this muscle bundle could, by increasing its strength and endurance, improve the effectiveness of coughing in such subjects and perhaps diminish the prevalence of bronchopulmonary infections.
Abdomen↗
Rib cage motion and muscle use in high tetraplegics.
In an attempt to assess the action of the sternocleidomastoid muscles on the human rib cage, we studied the pattern of rib cage motion in 2 patients with complete transection of the upper cervical cord. Measurements of rib cage motion were obtained with magnetometers and chest roentgenograms, and concentric needle electrodes were used to record the electromyograms (EMG) of various respiratory muscles. Spontaneous quiet breathing elicited a large amount of phasic inspiratory EMG activity not only in the sternocleidomastoids, but also in the trapezii, platysma, mylohyoid, and sternohyoid muscles. This pattern of muscle use was associated with substantial rib cage deformation. During spontaneous inspiration both patients showed a clear-cut decrease in lower rib cage transverse diameter, and they both had a cranial displacement of the sternum and an increase in upper rib cage anteroposterior diameter that was disproportionately larger than the increase in lower rib cage anteroposterior diameter. Radiographic measurements confirmed these deformations but also demonstrated that the upper rib cage transverse diameter increased rather than decreased with inspiration. These results indicate that: (1) Patients with high tetraplegia use many neck muscles in addition to the sternocleidomastoids to breathe; (2) The synchronous contraction of these muscles acts to pull the sternum cranially, expands the upper rib cage, and causes paradoxical inward displacement of the lateral walls of the lower rib cage; (3) As in dogs, the motion of the upper rib cage in humans is more tightly linked to the sternum than that of the lower rib cage.(ABSTRACT TRUNCATED AT 250 WORDS)
Abdominal Muscles↗
The effects of tetraplegia on chest wall statics.
The static elastic properties of the chest wall have been studied in 20 seated patients in the late stages of traumatic tetraplegia. Chest wall compliance (Cw) was measured using the weighted spirometer technique, and the slope of the relaxation line of the thoracoabdominal system obtained with 2 pairs of linearized magnetometers was used to derive rib cage (Crc) and diaphragm-abdomen (Cab) compliance. The values were compared with those obtained in 61 healthy adults studied with the same procedure. Chest wall compliance and Crc values in the patients were reduced to 72 and 55% of control values (p less than 0.001), respectively, and 9 of 20 patients had Crc values at least 2 SEE below normal. By contrast, Cab values in all patients were increased to 170% of control values (p less than 0.001), and 7 patients had values more than 2 SEE above normal. These alterations were not related to the duration of the disease or to the presence or absence of spastic activity in the parasternal intercostals. Both the decreased rib cage compliance and increased abdominal compliance may contribute to reducing rib cage contribution to tidal volume in tetraplegic subjects. As a corollary, the pattern of rib cage motion in such subjects can only approximately define the isolated action of the diaphragm on the normal human rib cage.
Abdominal Muscles↗
Phrenic and diaphragm function after coronary artery bypass grafting.
We studied respiratory mechanics and phrenic nerve and diaphragm function in 12 patients on the day before and eight to 13 days after coronary artery bypass grafting. The average vital capacity, functional residual capacity, and total lung capacity decreased by 20.5%, 9.5%, and 14.7% respectively after operation. Eleven patients showed less negative maximum inspiratory mouth pressures at any given lung volume after surgery and the magnitude of the change correlated with the reduction in total lung capacity. In 11 of the 12 patients the conduction times of the right and left phrenic nerves did not change substantially after operation and the ratio of inspiratory electrical activity (Edi) of left and right hemidiaphragms was similar before and after the procedure. One patient, however, showed a considerable increase in left phrenic nerve conduction time and a reduction in the left to right Edi ratio postoperatively. In three patients diaphragm function was also assessed by changes in transdiaphragmatic pressure during supramaximal phrenic nerve stimulation and voluntary increase in inspired volume; in none of the three patients did the transdiaphragmatic pressure swings show any significant change in the postoperative period. These data indicate that phrenic nerve paralysis only occasionally accounts for the postoperative loss of lung volume after coronary artery bypass grafting surgery. The mechanism of these abnormalities therefore remains to be determined.
Coronary Artery Bypass↗