scholarly journals Influence of acute lung volume change on contractile properties of human diaphragm

1998 ◽  
Vol 85 (4) ◽  
pp. 1322-1328 ◽  
Author(s):  
Michael I. Polkey ◽  
Carl-Hugo Hamnegård ◽  
Philip D. Hughes ◽  
Gerrard F. Rafferty ◽  
Malcolm Green ◽  
...  
Keyword(s):  
Functional Residual Capacity ◽  
Lung Volume ◽  
Phrenic Nerve ◽  
Stimulus Frequency ◽  
Normal Subjects ◽  
Lung Volumes ◽  
Transdiaphragmatic Pressure ◽  
Residual Capacity ◽  
Interstimulus Intervals

The effect of stimulus frequency on the in vivo pressure generating capacity of the human diaphragm is unknown at lung volumes other than functional residual capacity. The transdiaphragmatic pressure (Pdi) produced by a pair of phrenic nerve stimuli may be viewed as the sum of the Pdi elicited by the first (T1 Pdi) and second (T2 Pdi) stimuli. We used bilateral anterior supramaximal magnetic phrenic nerve stimulation and a digital subtraction technique to obtain the T2 Pdi at interstimulus intervals of 999, 100, 50, 33, and 10 ms in eight normal subjects at lung volumes between residual volume and total lung capacity. The reduction in T2 Pdi that we observed as lung volume increased was greatest at long interstimulus intervals, whereas the T2 Pdi obtained with short interstimulus intervals remained relatively stable over the 50% of vital capacity around functional residual capacity. For all interstimulus intervals, the total pressure produced by the pair decreased as a function of increasing lung volume. These data demonstrate that, in the human diaphragm, hyperinflation has a disproportionately severe effect on the summation of pressure responses elicited by low-frequency stimulations; this effect is distinct from and additional to the known length-tension relationship.

Functional adaptation of diaphragm to chronic hyperinflation in emphysematous hamsters

1986 ◽  
Vol 60 (1) ◽  
pp. 225-231 ◽  
Author(s):  
A. Oliven ◽  
G. S. Supinski ◽  
S. G. Kelsen
Keyword(s):  
Lung Volume ◽  
Functional Adaptation ◽  
Lung Volumes ◽  
Transdiaphragmatic Pressure ◽  
Diaphragmatic Muscle ◽  
Volume Curve ◽  
Residual Capacity ◽  
Spontaneous Contractions

Costal strips of diaphragmatic muscle obtained from animals with elastase-induced emphysema generate maximum tension at significantly shorter muscle fiber lengths than muscle strips from control animals. The present study examined the consequences of alterations in the length-tension relationship assessed in vitro on the pressure generated by the diaphragm in vivo. Transdiaphragmatic pressure (Pdi) and functional residual capacity (FRC) were measured in 22 emphysematous and 22 control hamsters 4–5 mo after intratracheal injection of pancreatic elastase or saline, respectively. In 12 emphysematous and 12 control hamsters Pdi was also measured during spontaneous contractions against an occluded airway. To allow greater control over muscle excitation, Pdi was measured during bilateral tetanic (50 Hz) electrical stimulation of the phrenic nerves in 10 emphysematous and 10 control hamsters. Mean FRC in the emphysematous hamsters was 183% of the value in control hamsters (P less than 0.01). During spontaneous inspiratory efforts against a closed airway the highest Pdi generated at FRC tended to be greater in control than emphysematous hamsters. When control hamsters were inflated to a lung volume approximating the FRC of emphysematous animals, however, peak Pdi was significantly greater in emphysematous animals (70 +/- 6 and 41 +/- 8 cmH2O; P less than 0.05). With electrophrenic stimulation, the Pdi-lung volume curve was shifted toward higher lung volumes in emphysematous hamsters. Pdi at all absolute lung volumes at and above the FRC of emphysematous hamsters was significantly greater in emphysematous compared with control animals. Moreover, Pdi continued to be generated by emphysematous hamsters at levels of lung volume where Pdi of control subjects was zero.(ABSTRACT TRUNCATED AT 250 WORDS)

Twitch transdiaphragmatic pressure depends critically on thoracoabdominal configuration

2000 ◽  
Vol 88 (1) ◽  
pp. 54-60 ◽  
Author(s):  
Rongchang Chen ◽  
Bengt Kayser ◽  
Sheng Yan ◽  
Peter T. Macklem
Keyword(s):  
Functional Residual Capacity ◽  
Lung Volume ◽  
Phrenic Nerve ◽  
Fiber Length ◽  
Radius Of Curvature ◽  
Transdiaphragmatic Pressure ◽  
Velocity Of Shortening ◽  
Residual Capacity ◽  
End Tidal ◽  
Normal Men

We measured the effect of thoracoabdominal configuration on twitch transdiaphragmatic pressure (Pdi, t) in response to supramaximal, transcutaneous, bilateral phrenic nerve shocks in three thin normal men. Pdi, t was measured as a function of lung volume (Vl) in the relaxation configuration, at functional residual capacity (FRC), and at the same end-tidal Vl 1) during relaxation; 2) with the abdomen (Ab) expanded and the rib cage (RC) in its relaxed FRC configuration; 3) with RC expanded and Ab in its relaxed FRC configuration; and 4) in configuration 3 with an active transdiaphragmatic pressure similar to that required to produce configuration 2. In increasing Vl from FRC to configuration 1, Pdi, t decreased by 3.6 cmH2O; to configuration 2 by 14.8 cmH2O; to configuration 3 by 3.7 cmH2O; and to configuration 4 by 2.7 cmH2O. We argue that changes in velocity of shortening and radius of curvature are unlikely to account for these effects and suggest that changes in diaphragmatic fiber length ( L di) are primarily responsible. If so, equivolume displacements of Ab and RC change L di in a ratio of ∼4:1. We conclude that Pdi, t is exquisitely sensitive to abdominal displacements that must be rigorously controlled if Pdi, t is to be used to assess diaphragmatic contractility.

Effect of digitalis on the diaphragm in anesthetized dogs

1987 ◽  
Vol 63 (1) ◽  
pp. 277-284 ◽  
Author(s):  
Y. Kikuchi ◽  
W. Hida ◽  
C. Shindoh ◽  
T. Chonan ◽  
H. Miki ◽  
...  
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Stimulus Frequency ◽  
Dependent Manner ◽  
Phrenic Nerve Stimulation ◽  
Transdiaphragmatic Pressure ◽  
Mechanically Ventilated ◽  
Before And After ◽  
Residual Capacity ◽  
Anesthetized Dogs

We examined the effect of digitalis on diaphragmatic contractility and fatigability in 19 anesthetized mechanically ventilated dogs. The diaphragmatic force was assessed from transdiaphragmatic pressure (Pdi) developed at functional residual capacity against an occluded airway during cervical phrenic nerve stimulation. In a first group of five dogs, Pdi-stimulus frequency relationships were compared before and after administration of ouabain in doses of 0.01, 0.02, and 0.04 mg/kg. In a second group, diaphragmatic fatigue was produced by bilateral phrenic nerve stimulation at 30 Hz. Ten seconds of stimulation and 15 s of mechanical ventilation were repeated for 30 min. The rates of decrease in Pdi were compared between two groups, one of 0.05 mg/kg deslanoside-treated dogs (n = 7) and one of nontreated dogs (n = 7). After ouabain administration Pdi was significantly greater at each frequency in a dose-dependent manner. On the other hand, the rate of decrease in Pdi in the deslanoside group was significantly smaller than that in the nontreated group, whereas deslanoside did not greatly change the Pdi-frequency curves in fresh diaphragm. We conclude that ouabain improves contractility of the fresh diaphragm and that deslanoside has a protective effect against fatigability.

Gravity effects on upper airway area and lung volumes during parabolic flight

1998 ◽  
Vol 84 (5) ◽  
pp. 1639-1645 ◽  
Author(s):  
Maurice Beaumont ◽  
Redouane Fodil ◽  
Daniel Isabey ◽  
Frédéric Lofaso ◽  
Dominique Touchard ◽  
...  
Keyword(s):  
Lung Volume ◽  
Parabolic Flight ◽  
Upper Airway ◽  
Normal Subjects ◽  
Lung Volumes ◽  
Acoustic Reflection ◽  
Volume Functional ◽  
Airway Caliber ◽  
Gravity Effects ◽  
Residual Capacity

We measured upper airway caliber and lung volumes in six normal subjects in the sitting and supine positions during 20-s periods in normogravity, hypergravity [1.8 + head-to-foot acceleration (Gz)], and microgravity (∼0 Gz) induced by parabolic flights. Airway caliber and lung volumes were inferred by the acoustic reflection method and inductance plethysmography, respectively. In subjects in the sitting position, an increase in gravity from 0 to 1.8 +Gz was associated with increases in the calibers of the retrobasitongue and palatopharyngeal regions (+20 and +30%, respectively) and with a concomitant 0.5-liter increase in end-expiratory lung volume (functional residual capacity, FRC). In subjects in the supine position, no changes in the areas of these regions were observed, despite significant decreases in FRC from microgravity to normogravity (−0.6 liter) and from microgravity to hypergravity (−0.5 liter). Laryngeal narrowing also occurred in both positions (about −15%) when gravity increased from 0 to 1.8 +Gz. We concluded that variation in lung volume is insufficient to explain all upper airway caliber variation but that direct gravity effects on tissues surrounding the upper airway should be taken into account.

scholarly journals Respiratory dynamics during laughter

2001 ◽  
Vol 90 (4) ◽  
pp. 1441-1446 ◽  
Author(s):  
Mario Filippelli ◽  
Riccardo Pellegrino ◽  
Iacopo Iandelli ◽  
Gianni Misuri ◽  
Joseph R. Rodarte ◽  
...  
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Dynamic Compression ◽  
Three Dimensional ◽  
Normal Subjects ◽  
Average Frequency ◽  
Abdominal Pressure ◽  
Sudden Increase ◽  
Lung Volumes ◽  
Transdiaphragmatic Pressure

Lung and chest wall mechanics were studied during fits of laughter in 11 normal subjects. Laughing was naturally induced by showing clips of the funniest scenes from a movie by Roberto Benigni. Chest wall volume was measured by using a three-dimensional optoelectronic plethysmography and was partitioned into upper thorax, lower thorax, and abdominal compartments. Esophageal (Pes) and gastric (Pga) pressures were measured in seven subjects. All fits of laughter were characterized by a sudden occurrence of repetitive expiratory efforts at an average frequency of 4.6 ± 1.1 Hz, which led to a final drop in functional residual capacity (FRC) by 1.55 ± 0.40 liter ( P < 0.001). All compartments similarly contributed to the decrease of lung volumes. The average duration of the fits of laughter was 3.7 ± 2.2 s. Most of the events were associated with sudden increase in Pes well beyond the critical pressure necessary to generate maximum expiratory flow at a given lung volume. Pga increased more than Pes at the end of the expiratory efforts by an average of 27 ± 7 cmH2O. Transdiaphragmatic pressure (Pdi) at FRC and at 10% and 20% control forced vital capacity below FRC was significantly higher than Pdi at the same absolute lung volumes during a relaxed maneuver at rest ( P < 0.001). We conclude that fits of laughter consistently lead to sudden and substantial decrease in lung volume in all respiratory compartments and remarkable dynamic compression of the airways. Further mechanical stress would have applied to all the organs located in the thoracic cavity if the diaphragm had not actively prevented part of the increase in abdominal pressure from being transmitted to the chest wall cavity.

Diaphragmatic relaxation rate after voluntary contractions and uni- and bilateral phrenic stimulation

1988 ◽  
Vol 65 (2) ◽  
pp. 675-682 ◽  
Author(s):  
P. G. Wilcox ◽  
A. Eisen ◽  
B. J. Wiggs ◽  
R. L. Pardy
Keyword(s):  
Relaxation Rate ◽  
Phrenic Nerve ◽  
External Pressure ◽  
Transdiaphragmatic Pressure ◽  
Relaxation Parameters ◽  
Exponential Decline ◽  
Residual Capacity ◽  
Rate Of Decline ◽  
Voluntary Contractions

We compared the rate of relaxation of the diaphragm (RRdi) after unilateral phrenic nerve stimulation, bilateral phrenic nerve stimulations, and short sharp voluntary contractions (sniffs). RRdi was measured as the maximum rate of decline in transdiaphragmatic pressure (Pdi) corrected for the change in Pdi [maximum relaxation rate (MRR)/delta Pdi], the time constant (tau) of the later exponential decline in Pdi, and the time to half relaxation (1/2 RT). In five subjects there was no difference in mean RRdi apart from a smaller MRR/delta Pdi (P less than 0.05) for left unilateral compared with either right unilateral or bilateral needle stimulation. However, RRdi varied unpredictably between unilateral and bilateral stimulation of the phrenic nerve in individual subjects. In the same five subjects, sniffs were found to have a slower RRdi than bilateral stimulations (MRR/delta Pdi 0.0064 +/- 0.0007 vs. 0.0074 +/- 0.0018/ms, tau 57.2 +/- 8.7 vs. 48.2 +/- 7.4 ms, 1/2 RT 108.9 +/- 10.9 vs. 73.9 +/- 6.0 ms; all P less than 0.05). The application and inflation of an abdominal binder to an external pressure of 60 mmHg resulted in a decrease in functional residual capacity (-710 +/- 70 ml), but there was no effect on relaxation parameters. Our findings suggest that in the evaluation of RRdi 1) unilateral hemidiaphragmatic stimulations may not accurately reflect the in vivo contractile properties of the diaphragm, 2) sniff maneuvers are not voluntary equivalents of phrenic nerve stimulations, and 3) RRdi is not affected by abdominal binder inflation up to 60 mmHg.

Mechanical implications of in vivo human diaphragm shape

1992 ◽  
Vol 72 (4) ◽  
pp. 1407-1412 ◽  
Author(s):  
M. Paiva ◽  
S. Verbanck ◽  
M. Estenne ◽  
B. Poncelet ◽  
C. Segebarth ◽  
...  
Keyword(s):  
Surface Area ◽  
Functional Residual Capacity ◽  
Three Dimensional ◽  
Vertical Gradient ◽  
Total Surface Area ◽  
Diaphragm Muscle ◽  
Posterior Half ◽  
Transdiaphragmatic Pressure ◽  
Residual Capacity

Using magnetic resonance imaging, we measured the three-dimensional form of the diaphragm in vivo in four supine relaxed subjects at functional residual capacity and calculated its total surface area, the right and left surface areas in the zone of apposition, and the principal radii of curvature as a function of height. The area of apposition comprised 45 +/- 1.5% (SE) of the total surface area of the diaphragm. Available data on the area of the central tendon indicate that a considerable part of the muscular part of the diaphragm is lung apposed. The curvature was linearly related to height over 7 cm of the posterior half of each hemidiaphragm. From the linear portion of this graph and assuming a vertical gradient of transdiaphragmatic pressure of 0.75 cmH2O/cm, we applied the Laplace law and calculated tensions of 54 and 32 g/cm for right and left sides, respectively. We conclude that the shape of at least part of the posterior half of the relaxed human diaphragm in the supine position at functional residual capacity can be explained by the Laplace law, suggesting that both the lung and abdominal contents behave sufficiently as fluids so that they do not impose their shape on the diaphragm. Because diaphragm muscle is partly lung apposed, it is unlikely that the diaphragm functions simply as a piston.

Effects of thoracic volume and shape on electromechanical coupling in abdominal muscles

1984 ◽  
Vol 56 (5) ◽  
pp. 1294-1301 ◽  
Author(s):  
A. R. Hill ◽  
D. L. Kaiser ◽  
D. F. Rochester
Keyword(s):  
Lung Volume ◽  
Electromechanical Coupling ◽  
Muscle Length ◽  
Normal Subjects ◽  
Abdominal Muscle ◽  
Abdominal Muscles ◽  
Lung Volumes ◽  
Residual Capacity ◽  
Abdominal Surface ◽  
The Relationship

To assess the effects of lung volume and chest wall configuration on electromechanical coupling of the abdominal muscles, we examined the relationship between abdominal muscle pressure ( Pmus ) and electrical activity ( EMGab ) in eight normal subjects during expiratory efforts at lung volumes ranging from functional residual capacity (FRC) to FRC + 2.0 liters. At and above FRC, increases of lung volume did not significantly alter either the Pmus - EMGab relationship or abdominal surface linear dimensions, although expiratory efforts displaced the abdomen inward from its relaxed position. We attribute the constancy of delta Pmus /delta EMG above FRC to the negligible effects of increasing lung volume on abdominal configuration and muscle length. Expiratory efforts performed at lung volumes below FRC resulted in a wider range of abdominal indrawing . Under these conditions the EMGab required to augment Pmus by 30–40 cmH2O increased as the abdomen was displaced inward. This decrease of delta Pmus /delta EMGab appears to reflect muscle shortening, flattening of the abdominal wall, and possibly deformation of the rib cage.

scholarly journals Length and curvature of the dog diaphragm

2006 ◽  
Vol 101 (3) ◽  
pp. 794-798 ◽  
Author(s):  
Aladin M. Boriek ◽  
Ben Black ◽  
Rolf Hubmayr ◽  
Theodore A. Wilson
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Muscle Length ◽  
Lung Compliance ◽  
Chronic Obstructive ◽  
Phrenic Nerve Stimulation ◽  
Lung Volumes ◽  
Obstructive Pulmonary Disease ◽  
Transdiaphragmatic Pressure ◽  
Residual Capacity

Transdiaphragmatic pressure is a result of both tension in the muscles of the diaphragm and curvature of the muscles. As lung volume increases, the pressure-generating capability of the diaphragm decreases. Whether decrease in curvature contributes to the loss in transdiaphragmatic pressure and, if so, under what conditions it contributes are unknown. Here we report data on muscle length and curvature in the supine dog. Radiopaque markers were attached along muscle bundles in the midcostal region of the diaphragm in six beagle dogs of ∼8 kg, and marker locations were obtained from biplanar images at functional residual capacity (FRC), during spontaneous inspiratory efforts against a closed airway at lung volumes from FRC to total lung capacity, and during bilateral maximal phrenic nerve stimulation at the same lung volumes. Muscle length and curvature were obtained from these data. During spontaneous inspiratory efforts, muscle shortened by 15–40% of length at FRC, but curvature remained unchanged. During phrenic nerve stimulation, muscle shortened by 30 to nearly 50%, and, for shortening exceeding 52%, curvature appeared to decrease sharply. We conclude that diaphragm curvature is nearly constant during spontaneous breathing maneuvers in normal animals. However, we speculate that it is possible, if lung compliance were increased and the chest wall and the diameter of the diaphragm ring of insertion were enlarged, as in the case of chronic obstructive pulmonary disease, that decrease in diaphragm curvature could contribute to loss of diaphragm function.

Rib cage deformation during static inspiratory efforts

1979 ◽  
Vol 46 (6) ◽  
pp. 1071-1075 ◽  
Author(s):  
N. A. Saunders ◽  
S. M. Kreitzer ◽  
R. H. Ingram
Keyword(s):  
Lung Volume ◽  
Respiratory Muscles ◽  
Normal Subjects ◽  
Esophageal Pressure ◽  
Lung Volumes ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Opposite Change ◽  
Accessory Muscles ◽  
Lateral Diameter

Patterns of rib cage (RC) deformation were studied in six normal subjects during moderate static inspiratory efforts such that esophageal pressure (Pes) as an index of transthoracic pressure fell to between -30 and -60 cmH2O during each maneuver. At lung volumes below 50% inspiratory capacity (IC), static inspiratory efforts deformed RC to a more elliptical shape; RC lateral diameter became smaller and RC lateral diameter became larger. However, at high lung volumes (greater than 50% IC) the opposite change in RC dimensions occurred despite similar changes in Pes, i.e., the RC became more circular. These differences in RC deformation did not appear to be a possive consequence of increased lung volume because the RC could be voluntarily deformed to a more circular shape at low lung volume when a) subjects performed static inspiratory efforts mainly with their intercostal and accessory muscles rather than their diaphragm as judged by a smaller change in transdiaphragmatic pressure for the same Pes; or b) subjects statically contracted their diaphragm with it held in a relatively flattened configuration as assessed by a large abdominal AP dimension. We suggest that deformation of the RC during static inspiratory efforts is not as predictable as has previously been suggested but depends on the pattern of contraction and configuration of the respiratory muscles.

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