Respiratory system compliance as seen from the cardiac fossa

1982 ◽  
Vol 53 (1) ◽  
pp. 57-62 ◽  
Author(s):  
T. C. Lloyd
Keyword(s):  
Left Ventricle ◽  
Chest Wall ◽  
Respiratory System ◽  
Shape Change ◽  
Left Ventricular ◽  
Respiratory System Compliance ◽  
Lung Volumes ◽  
Lung Inflation ◽  
Cardiac Filling ◽  
Different Levels

Changes in cardiac size and shape should impose stresses on the surrounding lung and chest wall. To examine pressure-volume relationships of the cardiac fossa we measured pressures required to increase the pericardial volume of freshly killed dogs at different levels of lung inflation, first by expanding the pericardium uniformly and then by expanding only the left ventricle. In both cases we obtained linear pressure-volume relationships, the slopes of which expressed an apparent compliance. Compliance decreased as lung volumes were increased by raising end-expiratory pressure, and compliance with symmetrical pericardial filling exceeded that with asymmetrical (left ventricular) distension. These compliances were compared with the total respiratory system compliance measured during tidal ventilation, and we found that the compliance of the cardiac fossa was significantly less than would be predicted from lung and chest wall compliances as classically measured. We concluded that the respiratory system imposes a finite compliance load on cardiac filling that raises local epicardial pressure above ambient pleural pressure. This respiratory system load depends upon lung volume and the cardiac shape change.

scholarly journals Thoracic sympathetic block reduces respiratory system compliance

2007 ◽  
Vol 125 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Fábio Ely Martins Benseñor ◽  
Joaquim Edson Vieira ◽  
José Otávio Costa Auler Júnior
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Lung Resection ◽  
Lung Compliance ◽  
Airway Hyperreactivity ◽  
Sympathetic Block ◽  
Respiratory System Compliance ◽  
Double Blind ◽  
Thoracic Epidural ◽  
Student’S T

CONTEXT AND OBJECTIVE: Thoracic epidural anesthesia (TEA) following thoracic surgery presents known analgesic and respiratory benefits. However, intraoperative thoracic sympathetic block may trigger airway hyperreactivity. This study weighed up these beneficial and undesirable effects on intraoperative respiratory mechanics. DESIGN AND SETTING: Randomized, double-blind clinical study at a tertiary public hospital. METHODS: Nineteen patients scheduled for partial lung resection were distributed using a random number table into groups receiving active TEA (15 ml 0.5% bupivacaine, n = 9) or placebo (15 ml 0.9% saline, n = 10) solutions that also contained 1:200,000 epinephrine and 2 mg morphine. Under general anesthesia, flows and airway and esophageal pressures were recorded. Pressure-volume curves, lower inflection points (LIP), resistance and compliance at 10 ml/kg tidal volume were established for respiratory system, chest wall and lungs. Student’s t test was performed, including confidence intervals (CI). RESULTS: Bupivacaine rose 5 ± 1 dermatomes upwards and 6 ± 1 downwards. LIP was higher in the bupivacaine group (6.2 ± 2.3 versus 3.6 ± 0.6 cmH2O, p = 0.016, CI = -3.4 to -1.8). Respiratory system and lung compliance were higher in the placebo group (respectively 73.3 ± 10.6 versus 51.9 ± 15.5, p = 0.003, CI = 19.1 to 23.7; 127.2 ± 31.7 versus 70.2 ± 23.1 ml/cmH2O, p < 0.001, CI = 61 to 53). Resistance and chest wall compliance showed no difference. CONCLUSION: TEA decreased respiratory system compliance by reducing its lung component. Resistance was unaffected. Under TEA, positive end-expiratory pressure and recruitment maneuvers are advisable.

Pulmonary and pericardial limitations to diastolic filling of the left ventricle of the lamb

1994 ◽  
Vol 266 (6) ◽  
pp. H2327-H2333 ◽  
Author(s):  
D. A. Grant ◽  
C. S. Kondo ◽  
J. E. Maloney ◽  
J. V. Tyberg
Keyword(s):  
Left Ventricle ◽  
Chest Wall ◽  
Neonatal Period ◽  
Diastolic Pressure ◽  
Age Groups ◽  
Left Ventricular ◽  
Diastolic Filling ◽  
Closed Chest ◽  
Early Neonatal Period

To determine which tissues limit left ventricular (LV) filling during the early neonatal period we studied LV end-diastolic pressure-diameter relationships in two groups of halothane-anesthetized lambs (five 1-h-old lambs and six 2- to 17-day-old lambs). First, we assessed LV end-diastolic pressure-diameter relations over a range of 5–20 mmHg, when the chest and the pericardium were closed; second, after the chest wall and lungs had been retracted from the heart; and finally, after the pericardium was retracted. In the oldest lambs LV diameter increased significantly [3.5 +/- 0.3% (SE) at an end-diastolic pressure of 10 mmHg; P < 0.05] after retracting the chest wall and the lungs and when the pericardium was still intact. By contrast, retracting the chest wall and lungs did not significantly change LV diameter in the youngest lambs. In both age groups LV diameters were greatest (P < 0.05) after the pericardium was subsequently retracted (the increase was evident at all end-diastolic pressures and averaged 9.0% relative to the closed-chest, closed-pericardium series). These studies confirm that the thoracic tissues substantially limit LV filling in young lambs. Immediately after birth this limitation is almost exclusively related to the pericardium, whereas in older lambs the chest wall-lung combination and the pericardium each contribute.

Hering-Breuer reflex and respiratory system compliance in the first year of life: a longitudinal study

1994 ◽  
Vol 76 (2) ◽  
pp. 650-656 ◽  
Author(s):  
P. S. Rabbette ◽  
M. E. Fletcher ◽  
C. A. Dezateux ◽  
H. Soriano-Brucher ◽  
J. Stocks
Keyword(s):  
Respiratory System ◽  
Relative Strength ◽  
Reflex Response ◽  
Respiratory System Compliance ◽  
Lung Inflation ◽  
Airway Occlusion ◽  
Age Related ◽  
Healthy Infants ◽  
Occlusion Technique ◽  
Relative Change

The airway occlusion technique for measuring passive respiratory mechanics in infants relies on an ability to evoke the Hering-Breuer lung inflation reflex (HBR). However, there is conflicting evidence regarding the persistence of the HBR beyond the early newborn period. This study was designed to assess maturational changes in HBR activity and passive total respiratory system compliance (Crs) in healthy infants during the 1st yr of life. The strength of the HBR was assessed from the relative change in expiratory time (TE) after brief end-inspiratory airway occlusions compared with resting TE during spontaneous breathing. Crs was measured using the multiple-occlusion technique. Paired measurements of HBR activity and Crs were obtained during sedated sleep in 30 infants at 4–8 wk and at 1 yr of age. Significant HBR activity during tidal breathing persisted throughout the 1st yr of life, with TE increasing during occlusion by at least 26% in every infant. However, the relative strength of the reflex response decreased from a mean of 88.3% (range, 34–160%) at approximately 6 wk to 50.3% (range, 26–125%) by 1 yr of age (P < 0.001). All infants showed an increase in Crs with age, with mean Crs increasing from 60.1 +/- 8.9 (SD) to 149.0 +/- 20.6 ml/kPa between 6 wk and 1 yr. However, there was no apparent relationship between the magnitude of decline in HBR response and the age-related changes in Crs.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Relationship between Abdominal Pressure, Pulmonary Compliance, and Cardiac Preload in a Porcine Model

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Joost Wauters ◽  
Piet Claus ◽  
Nathalie Brosens ◽  
Myles McLaughlin ◽  
Greet Hermans ◽  
...  
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Cardiac Preload ◽  
Volume Index ◽  
Abdominal Pressure ◽  
Stroke Index ◽  
Respiratory System Compliance ◽  
Chest Wall Compliance ◽  
End Diastolic Volume ◽  
Wall Compliance

Rationale. Elevated intra-abdominal pressure (IAP) may compromise respiratory and cardiovascular function by abdomino-thoracic pressure transmission. We aimed (1) to study the effects of elevated IAP on pleural pressure, (2) to understand the implications for lung and chest wall compliances and (3) to determine whether volumetric filling parameters may be more accurate than classical pressure-based filling pressures for preload assessment in the setting of elevated IAP.Methods. In eleven pigs, IAP was increased stepwise from 6 to 30 mmHg. Hemodynamic, esophageal, and pulmonary pressures were recorded.Results. 17% (end-expiratory) to 62% (end-inspiratory) of elevated IAP was transmitted to the thoracic compartment. Respiratory system compliance decreased significantly with elevated IAP and chest wall compliance decreased. Central venous and pulmonary wedge pressure increased with increasing IAP and correlated inversely (r=-0.31) with stroke index (SI). Global end-diastolic volume index was unaffected by IAP and correlated best with SI (r=0.52).Conclusions. Increased IAP is transferred to the thoracic compartment and results in a decreased respiratory system compliance due to decreased chest wall compliance. Volumetric filling parameters and transmural filling pressures are clearly superior to classical cardiac filling pressures in the assessment of cardiac preload during elevated IAP.

Respiratory mechanics in recumbent dogs anesthetized with thiopental sodium

1979 ◽  
Vol 46 (4) ◽  
pp. 716-720 ◽  
Author(s):  
Y. L. Lai ◽  
J. R. Rodarte ◽  
R. E. Hyatt
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Local Deformation ◽  
Static Compliance ◽  
Lung Volumes ◽  
Lateral Decubitus ◽  
Thiopental Sodium

Pressure-volume (PV) and conductance-volume (GV) curves were obtained in trained dogs awake and then anesthetized with thiopental sodium, in the prone left lateral decubitus, and supine positions. By paired analyses, induction of anesthesia had no significant effect on lung volumes, static PV curves of the lung or chest wall, or static compliance of the lung or chest wall. In addition, change of posture had little effect on these variables in either the awake or the anesthetized state. Frequently, however, individual dogs showed changes in lung PV curves after induction of anesthesia or change of posture. These PV curve shifts were not accompanied by predictable changes in GV relations. Therefore, we concluded that such changes in the lung PV curve reflect either local artifacts or local deformation of the respiratory system.

Pulmonary dead space and airway dimensions in dogs at different levels of lung inflation

1994 ◽  
Vol 76 (5) ◽  
pp. 1896-1902 ◽  
Author(s):  
A. Schulz ◽  
H. Schulz ◽  
P. Heilmann ◽  
P. Brand ◽  
J. Heyder
Keyword(s):  
Dead Space ◽  
Total Lung Capacity ◽  
Diffusion Front ◽  
Lung Volumes ◽  
Lung Inflation ◽  
Lung Capacity ◽  
Stationary Front ◽  
Breathing Maneuver ◽  
Recovery Techniques ◽  
Different Levels

The quasi-stationary front that separates inspired gas from mixed alveolar gas is largely determined by the balance between diffusive and convective forces of gas transport. To investigate parameters influencing this balance, a study was performed on eight anesthetized ventilated beagle dogs. Measurements were made of the volume of pulmonary dead space corresponding to four end-inspiratory lung volumes. Aerosol recovery techniques were used to determine airway sizes at lung depths corresponding to those respective dead space volumes as well as at fixed volumetric depths between 70 and 250 ml. Mean dead space volumes as measured by a single inhalation of He (and SF6) were 112 +/- 15 (SD) ml (127 +/- 15 ml), 120 +/- 18 ml (137 +/- 20 ml), 127 +/- 18 ml (145 +/- 20 ml), and 133 +/- 19 ml (155 +/- 21 ml) at end-inspiratory lung volumes of 64, 71, 79, and 86%, respectively, of total lung capacity. At fixed lung depths the airway diameters increased with higher levels of lung inflation. However, airway diameters “at the end of the dead space” did not change significantly. They were approximately 0.5 mm for SF6 dead space and approximately 0.75 mm for He dead space. These findings support the theoretical prediction that the position of the diffusion front during breathing is strongly dependent on airway geometry and much less dependent on parameters of the breathing maneuver.

Effect of oleic acid injury on lung-heart interaction during ventricular filling

1982 ◽  
Vol 52 (6) ◽  
pp. 1519-1523 ◽  
Author(s):  
T. C. Lloyd
Keyword(s):  
Oleic Acid ◽  
Lung Volume ◽  
Shape Change ◽  
Left Ventricular Pressure ◽  
Lung Compliance ◽  
Left Ventricular ◽  
Diastolic Compliance ◽  
Ventricular Filling Pressure ◽  
Cardiac Filling ◽  
Ventricular Filling

Part of ventricular filling pressure is expended in deforming the lungs and oleic acid lung injury, which reduces lung compliance, might be expected to change the magnitude of this effect. Left ventricular pressure-volume curves from 13 treated and 13 uninjured dogs were compared. Curves were obtained by inflating a balloon in the flaccid left ventricle of the freshly dead dog. The extracardiac compliance component was determined by subtracting ventricular pressures observed when lungs were collapsed from those observed during inflation to levels duplicating both airway pressure and lung volume of uninjured dogs. We found that the respiratory system compliance opposing ventricular filling is much less than is predicted from the compliance opposing tidal ventilation. This suggests that cardiac filling imposes a local shape change rather than a general lung volume change. Injury only slightly decreased cardiac filling compliance although it markedly reduced lung inflating compliance. These results are consistent with citations showing that edema increases lung compliance by altering surface properties and airway closure with little change in tissue deformability. Thus, while edema may alter cardiac performance by changing pleural pressure, it has little influence on the pulmonary component of diastolic compliance.

A method for the assessment of phasic vagal influence on tidal volume

1975 ◽  
Vol 38 (2) ◽  
pp. 335-343 ◽  
Author(s):  
M. Younes ◽  
S. Iscoe ◽  
J. Milic-Emili
Keyword(s):  
Tidal Volume ◽  
Respiratory System ◽  
Spontaneous Breathing ◽  
Volume Changes ◽  
Lung Volumes ◽  
Lung Inflation ◽  
Airway Occlusion ◽  
Tracheal Pressure ◽  
Vagal Cooling ◽  
Vagal Influence

Vagal influence related to lung volume changes results in reduction in tidal volume during spontaneous breathing due primarily to premature termination of inspiration. The strength of this vagal influence was traditionally assessed by the duration of apnea following lung inflation, a method recently shown to be inadequate and potentially misleading. An alternate method is described utilizing analysis of the volume tracing of spontaneous breaths and the tracheal pressure tracing during the first breath following airway occlusion at FRC. A formula was devised which, on the basis of previous observations, should predict the tidal volume to be obtained in the absence of phasic vagal influence. The formula was tested in four pentobarbital-anesthetized rabbits using a technique of vagal cooling which rapidly eliminated the vagal influence under study. It was found that the tidal volume obtained following vagal block could be accurately predicted provided allowances were made for the vagally mediated terminal inhibition during spontaneous breathing and the relative stiffness of the respiratory system at high lung volumes.

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