Respiratory load compensation in chronic airway obstruction

1985 ◽  
Vol 59 (6) ◽  
pp. 1947-1954 ◽  
Author(s):  
M. Lopata ◽  
E. Onal ◽  
G. Cromydas
Keyword(s):  
Airway Obstruction ◽  
Lung Volume ◽  
Average Rate ◽  
Minute Ventilation ◽  
Force Output ◽  
Transdiaphragmatic Pressure ◽  
Load Compensation ◽  
Group A ◽  
Group B ◽  
Chronic Airway

To assess respiratory neuromuscular function and load compensating ability in patients with chronic airway obstruction (CAO), we studied eight stable patients with irreversible airway obstruction during hyperoxic CO2 rebreathing with and without a 17 cmH2O X l-1 X s flow-resistive inspiratory load (IRL). Minute ventilation (VE), transdiaphragmatic pressure (Pdi), and diaphragmatic electromyogram (EMGdi) were monitored. Pdi and EMGdi were obtained via a single gastroesophageal catheter with EMGdi being quantitated as the average rate of rise of inspiratory (moving average) activity. Based on the effects of IRL on the Pdi response to CO2 [delta Pdi/delta arterial CO2 tension (PaCO2)] and the change in Pdi for a given change in EMGdi (delta Pdi/delta EMGdi) during rebreathing, two groups could be clearly identified. Four patients (group A) were able to increase delta Pdi/delta PaCO2 and delta Pdi/delta EMGdi, whereas in the other four (group B) the IRL responses decreased. All group B patients were hyperinflated having significantly greater functional residual capacity (FRC) and residual volume than group A. In addition the IRL induced percent change in delta Pdi/delta PaCO2, and delta VE/delta PaCO2 was negatively correlated with lung volume so that in the hyperinflated group B the higher the FRC the greater was the decrease in Pdi response due to IRL. In both groups the greater the FRC the greater was the decrease in the ventilatory response to loading. Patients with CAO, even with severe airways obstruction, can effect load compensation by increasing diaphragmatic force output, but the presence of increased lung volume with the associated shortened diaphragm prevents such load compensation.

Human respiratory muscle blood flow measured by near-infrared spectroscopy and indocyanine green

2008 ◽  
Vol 104 (4) ◽  
pp. 1202-1210 ◽  
Author(s):  
Jordan A. Guenette ◽  
Ioannis Vogiatzis ◽  
Spyros Zakynthinos ◽  
Dimitrios Athanasopoulos ◽  
Maria Koskolou ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Infrared Spectroscopy ◽  
Respiratory Muscle ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Muscle Blood Flow ◽  
Work Of Breathing ◽  
Dilution Method ◽  
Transdiaphragmatic Pressure

Measurement of respiratory muscle blood flow (RMBF) in humans has important implications for understanding patterns of blood flow distribution during exercise in healthy individuals and those with chronic disease. Previous studies examining RMBF in humans have required invasive methods on anesthetized subjects. To assess RMBF in awake subjects, we applied an indicator-dilution method using near-infrared spectroscopy (NIRS) and the light-absorbing tracer indocyanine green dye (ICG). NIRS optodes were placed on the left seventh intercostal space at the apposition of the costal diaphragm and on an inactive control muscle (vastus lateralis). The primary respiratory muscles within view of the NIRS optodes include the internal and external intercostals. Intravenous bolus injection of ICG allowed for cardiac output (by the conventional dye-dilution method with arterial sampling), RMBF, and vastus lateralis blood flow to be quantified simultaneously. Esophageal and gastric pressures were also measured to calculate the work of breathing and transdiaphragmatic pressure. Measurements were obtained in five conscious humans during both resting breathing and three separate 5-min bouts of constant isocapnic hyperpnea at 27.1 ± 3.2, 56.0 ± 6.1, and 75.9 ± 5.7% of maximum minute ventilation as determined on a previous maximal exercise test. RMBF progressively increased (9.9 ± 0.6, 14.8 ± 2.7, 29.9 ± 5.8, and 50.1 ± 12.5 ml·100 ml−1·min−1, respectively) with increasing levels of ventilation while blood flow to the inactive control muscle remained constant (10.4 ± 1.4, 8.7 ± 0.7, 12.9 ± 1.7, and 12.2 ± 1.8 ml·100 ml−1·min−1, respectively). As ventilation rose, RMBF was closely and significantly correlated with 1) cardiac output ( r = 0.994, P = 0.006), 2) the work of breathing ( r = 0.995, P = 0.005), and 3) transdiaphragmatic pressure ( r = 0.998, P = 0.002). These data suggest that the NIRS-ICG technique provides a feasible and sensitive index of RMBF at different levels of ventilation in humans.

Diaphragmatic work of breathing in premature human infants

1987 ◽  
Vol 62 (4) ◽  
pp. 1410-1415 ◽  
Author(s):  
B. G. Guslits ◽  
S. E. Gaston ◽  
M. H. Bryan ◽  
S. J. England ◽  
A. C. Bryan
Keyword(s):  
Lung Disease ◽  
Preterm Infants ◽  
Work Of Breathing ◽  
Mechanical Efficiency ◽  
Strongly Correlated ◽  
Intercostal Muscle ◽  
Human Infants ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Inspiratory Work

Present methods of assessing the work of breathing in human infants do not account for the added load when intercostal muscle activity is lost and rib cage distortion occurs. We have developed a technique for assessing diaphragmatic work in this circumstance utilizing measurements of transdiaphragmatic pressure and abdominal volume displacement. Eleven preterm infants without evidence of lung disease were studied. During periods of minimal rib cage distortion, inspiratory diaphragmatic work averaged 5.9 g X cm X ml-1, increasing to an average of 12.4 g X cm X ml-1 with periods of paradoxical rib cage motion (P less than 0.01). Inspiratory work was strongly correlated with the electrical activity of the diaphragm as measured from its moving time average (P less than 0.05). Assuming a mechanical efficiency of 4% in these infants, the caloric cost of diaphragmatic work may reach 10% of their basal metabolic rate in periods with rib cage distortion. When lung disease is superimposed, the increased metabolic demands of the diaphragm may predispose preterm infants to fatigue and may contribute to a failure to grow.

Detection of diaphragmatic fatigue in man by phrenic stimulation

1981 ◽  
Vol 50 (3) ◽  
pp. 538-544 ◽  
Author(s):  
M. Aubier ◽  
G. Farkas ◽  
A. De Troyer ◽  
R. Mozes ◽  
C. Roussos
Keyword(s):  
Phrenic Nerve ◽  
Chronic Obstructive Lung Disease ◽  
Chronic Obstructive ◽  
Low Frequencies ◽  
Transdiaphragmatic Pressure ◽  
Control Value ◽  
Transcutaneous Stimulation ◽  
Diaphragmatic Fatigue ◽  
Residual Capacity ◽  
Stimulation Of

Transdiaphragmatic pressure (Pdi) was measured at functional residual capacity (FRC) in four normal seated subjects during supramaximal, supraclavicular transcutaneous stimulation of one phrenic nerve (10, 20, 50, and 100 Hz--0.1 ms duration) before and after diaphragmatic fatigue, produced by breathing through a high alinear inspiratory resistance. Constancy of chest wall configuration was achieved by placing a cast around the abdomen and the lower one-fourth of the rib cage. Pdi increased with frequency of stimulation, so that at 10, 20, and 50 Hz, the Pdi generated was 32 +/- 4 (SE), 70 +/- 3, and 98 +/- 2% of Pdi at 100 Hz, respectively. After diaphragmatic fatigue, Pdi was less than control at all frequencies of stimulation. Recovery for high stimulation frequencies was complete at 10 min, but at low stimulation frequencies recovery was slow: after 30 min of recovery, Pdi at 20 Hz was 31 +/- 7% of the control value. It is concluded that diaphragmatic fatigue can be detected in man by transcutaneous stimulation of the phrenic nerve and that diaphragmatic strength after fatigue recovers faster at high than at low frequencies of stimulation. Furthermore, it is suggested that this long-lasting element of fatigue might occur in patients with chronic obstructive lung disease, predisposing them to respiratory failure.

Relationships among pressure, tension, and shape of the diaphragm

1983 ◽  
Vol 55 (6) ◽  
pp. 1899-1905 ◽  
Author(s):  
W. A. Whitelaw ◽  
L. E. Hajdo ◽  
J. A. Wallace
Keyword(s):  
Cross Section ◽  
Radius Of Curvature ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Residual Capacity ◽  
Best Fitting ◽  
Pressure Generator ◽  
Free Membrane ◽  
Relationship Of ◽  
Shape Changes

The shape of the diaphragm dome was calculated from transdiaphragmatic pressure and tension in the diaphragm. It was assumed that the muscle acts as a free membrane, attached at its edges to the inside of a vertical rib cage circular in cross section, that the attachments are inferior to the point at which the dome makes contract with the rib cage, and that the abdomen is filled with fluid with a hydrostatic gradient in pressure. The shape is different from a section of a sphere, with a radius of curvature substantially greater at the apex of the dome than at the sides. Observed shapes of human hemidiaphragm domes at functional residual capacity are not spherical but closely match the calculated shapes. Best-fitting shapes correspond to transdiaphragmatic pressures of about 3 cmH2O transdiaphragmatic pressure, suggesting that such a pressure and corresponding tension are present in the human diaphragm when it is at rest in an erect subject. In this model; as lung volume increases and the diaphragm shortens, its shape changes in such a way that the ratio between transdiaphragmatic pressure and tension in the diaphragm remains nearly constant, rather than increasing with volume. Such a model can explain the observation that the length-tension relationship of the muscle is much more important than curvature in determining the effectiveness of the diaphragm as a pressure generator.

Pleural pressure increases during inspiration in the zone of apposition of diaphragm to rib cage

1988 ◽  
Vol 65 (5) ◽  
pp. 2207-2212 ◽  
Author(s):  
W. F. Urmey ◽  
A. De Troyer ◽  
K. B. Kelly ◽  
S. H. Loring
Keyword(s):  
Esophageal Pressure ◽  
Pleural Pressure ◽  
Abdominal Pressure ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Direct Measurements ◽  
Anesthetized Dogs ◽  
Theoretical Mechanism ◽  
Phrenic Stimulation ◽  
Anatomic Region

The zone of apposition of diaphragm to rib cage provides a theoretical mechanism that may, in part, contribute to rib cage expansion during inspiration. Increases in intra-abdominal pressure (Pab) that are generated by diaphragmatic contraction are indirectly applied to the inner rib cage wall in the zone of apposition. We explored this mechanism, with the expectation that pleural pressure in this zone (Pap) would increase during inspiration and that local transdiaphragmatic pressure in this zone (Pdiap) must be different from conventionally determined transdiaphragmatic pressure (Pdi) during inspiration. Direct measurements of Pap, as well as measurements of pleural pressure (Ppl) cephalad to the zone of apposition, were made during tidal inspiration, during phrenic stimulation, and during inspiratory efforts in anesthetized dogs. Pab and esophageal pressure (Pes) were measured simultaneously. By measuring Ppl's with cannulas placed through ribs, we found that Pap consistently increased during both maneuvers, whereas Ppl and Pes decreased. Whereas changes in Pdi of up to -19 cmH2O were measured, Pdiap never departed from zero by greater than -4.5 cmH2O. We conclude that there can be marked regional differences in Ppl and Pdi between the zone of apposition and regions cephalad to the zone. Our results support the concept of the zone of apposition as an anatomic region where Pab is transmitted to the interior surface of the lower rib cage.

scholarly journals Mechanisms of exercise intolerance in Global Initiative for Chronic Obstructive Lung Disease grade 1 COPD

2014 ◽  
Vol 44 (5) ◽  
pp. 1177-1187 ◽  
Author(s):  
Jordan A. Guenette ◽  
Roberto C. Chin ◽  
Sicheng Cheng ◽  
Paolo B. Dominelli ◽  
Natya Raghavan ◽  
...  
Keyword(s):  
Work Of Breathing ◽  
Pressure Ratio ◽  
Chronic Obstructive Lung Disease ◽  
Exercise Intolerance ◽  
Chronic Obstructive ◽  
Respiratory Drive ◽  
Obstructive Pulmonary Disease ◽  
Transdiaphragmatic Pressure ◽  
Generating Capacity ◽  
Neuromuscular Abnormalities

The purpose of this study was to determine if a dissociation existed between respiratory drive, as estimated by diaphragmatic electromyography (EMGdi), and its pressure-generating capacity during exercise in mild chronic obstructive pulmonary disease (COPD) and whether this, if present, had negative sensory consequences.Subjects meeting spirometric criteria for mild COPD (n=16) and age and sex-matched controls (n=16) underwent detailed pulmonary function testing and a symptom limited cycle test while detailed ventilatory, sensory and respiratory mechanical responses were measured.Compared with controls, subjects with mild COPD had greater ventilatory requirements throughout submaximal exercise. At the highest equivalent work rate of 60 W, they had a significantly higher: total work of breathing (32±17 versus 16±7 J·min−1; p<0.01); EMGdi (37.3±17.3 versus 17.9±11.7% of maximum; p<0.001); and EMGdi to transdiaphragmatic pressure ratio (0.87±0.38 versus 0.52±0.27; p<0.01). Dyspnoea–ventilation slopes were significantly higher in mild COPD than controls (0.17±0.12 versus 0.10±0.05; p<0.05). However, absolute dyspnoea ratings reached significant levels only at high levels of ventilation.Increased respiratory effort and work of breathing, and a wider dissociation between diaphragmatic activation and pressure-generating capacity were found at standardised work rates in subjects with mild COPD compared with controls. Despite these mechanical and neuromuscular abnormalities, significant dyspnoea was only experienced at higher work rates.

scholarly journals MEASUREMENT OF TRANSDIAPHRAGMATIC PRESSURE

1989 ◽  
Vol 62 (2) ◽  
pp. 238
Author(s):  
M.C. DERRINGTON
Keyword(s):  
Transdiaphragmatic Pressure

Naloxone alters the early response to an inspiratory flow-resistive load

1989 ◽  
Vol 67 (5) ◽  
pp. 1747-1753 ◽  
Author(s):  
A. T. Scardella ◽  
T. V. Santiago ◽  
N. H. Edelman
Keyword(s):  
Tidal Volume ◽  
Blood Gases ◽  
Inspiratory Flow ◽  
Abdominal Muscles ◽  
Base Line ◽  
Resistive Load ◽  
Endogenous Opioid ◽  
Transdiaphragmatic Pressure ◽  
Arterial Blood ◽  
Gastric Pressure

In a previous study in unanesthetized goats, we demonstrated that cerebrospinal fluid levels of beta-endorphin were significantly elevated after 2.5 h of inspiratory flow-resistive loading. Naloxone (NLX) (0.1 mg/kg) administration partially and transiently reversed the tidal volume depression seen during loading. In the current study, we tested the hypothesis that endogenous opioid elaboration results in depression of respiratory output to the diaphragm. In six studies of five unanesthetized goats, tidal volume (VT), transdiaphragmatic pressure (Pdi), diaphragmatic electromyogram (EMGdi), and arterial blood gases were monitored. A continuous NLX (0.1 mg/kg) or saline (SAL) infusion was begun 5 min before an inspiratory flow-resistive load of 120 cmH2O.l-1.s was imposed. Our data show that the depression of VT induced by the load was prevented by NLX as early as 15 min and persisted for 2 h. At 2 h, Pdi was still 294 +/- 45% of the base-line value compared with 217 +/- 35% during SAL. There was no difference in EMGdi between the groups at any time. However, the augmentation of Pdi was associated with a greater increase in end-expiratory gastric pressure in the NLX group. We conclude that the reduction in VT and Pdi associated with endogenous opioid elaboration is not mediated by a decrease in neural output to the diaphragm, but it appears to be the result of a decrease in respiratory output to the abdominal muscles.

Costal diaphragm curvature in the dog

1993 ◽  
Vol 75 (2) ◽  
pp. 527-533 ◽  
Author(s):  
A. M. Boriek ◽  
S. Liu ◽  
J. R. Rodarte
Keyword(s):  
Mechanical Ventilation ◽  
Muscle Fiber ◽  
Lung Volume ◽  
Spontaneous Breathing ◽  
Total Lung Capacity ◽  
Muscle Fibers ◽  
Transdiaphragmatic Pressure ◽  
Lung Capacity ◽  
Principal Axes ◽  
Quadratic Surface

The curvature of the midcostal region of the diaphragm in seven dogs was determined at functional residual capacity (FRC) and end inspiration during spontaneous breathing and mechanical ventilation and at total lung capacity in the prone and supine positions. Metallic markers were attached to muscle fibers on the abdominal surface of the diaphragm, and the dog was allowed to recover from surgery. The three-dimensional positions of the markers were determined by biplane videofluoroscopy. A quadratic surface was fit to the bead positions. The principal axes of the quadratic surface lie nearly along and perpendicular to the muscle fibers. In both the supine and prone positions, the values of the principal curvatures were similar at FRC and end inspiration during spontaneous breathing, when muscle tension and transdiaphragmatic pressure both increase with increasing lung volume, and during mechanical ventilation and passive inflation to total lung capacity, when both decrease relative to their magnitude at FRC. No abrupt change of curvature, which might be expected at the edge of the zone of apposition, was apparent. The curvature along the muscle fiber was 0.35 +/- 0.07 cm-1; the curvature perpendicular to the muscle fiber was much smaller, 0.06 +/- 0.01 cm-1. The costal region of the diaphragm displaces and shortens as lung volume increases, but its shape, as described by its curvatures, does not change substantially.

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