In vivo regional diaphragm function in dogs

1989 ◽  
Vol 67 (2) ◽  
pp. 655-662 ◽  
Author(s):  
J. Sprung ◽  
C. Deschamps ◽  
R. D. Hubmayr ◽  
B. J. Walters ◽  
J. R. Rodarte
Keyword(s):  
Mechanical Ventilation ◽  
Chest Wall ◽  
Spontaneous Breathing ◽  
Considerable Variability ◽  
Diaphragm Function ◽  
Left Hemidiaphragm ◽  
Anesthetized Dogs ◽  
Abdominal Surface ◽  
Crural Diaphragm

A biplane videofluorographic system was used to track the position of metallic markers affixed to the abdominal surface of the left hemidiaphragm in supine anesthetized dogs. Regional shortening was determined from intermarker distances of rows of markers placed along muscle bundles in the ventral, middle, and dorsal regions of the costal diaphragm and of one row on the crural diaphragm. Considerable variability of regional shortening was seen in a given row, which was reproducible on repeat study in individual dogs but which differed between mechanical ventilation and spontaneous breathing. There were no consistent patterns among dogs. Regional shortening obtained from the change in length of rows extending from chest wall to central tendon showed no consistent differences among dogs during spontaneous breathing. At equal tidal volumes, all regions (except the ventral costal diaphragm) shortened more during spontaneous breathing than during mechanical ventilation.

Hydraulic conductivity of canine parietal pleura in vivo

1990 ◽  
Vol 69 (2) ◽  
pp. 438-442 ◽  
Author(s):  
D. Negrini ◽  
M. I. Townsley ◽  
A. E. Taylor
Keyword(s):  
Hydraulic Conductivity ◽  
Chest Wall ◽  
Body Position ◽  
Linear Regression Analysis ◽  
Isotonic Saline ◽  
Parietal Pleura ◽  
Autologous Plasma ◽  
Anesthetized Dogs ◽  
Spontaneously Breathing

The hydraulic conductivity (Lp) of the parietal pleura was measured in vivo in spontaneously breathing anesthetized dogs in either the supine (n = 8) or the prone (n = 7) position and in an excised portion of the chest wall in which the pleura and its adjacent tissue were intact (n = 3). A capsule was glued to the exposed parietal pleura after the intercostal muscles were removed. The capsule was filled with either autologous plasma or isotonic saline. Transpleural fluid flow (V) was measured at several transpleural hydrostatic pressures (delta P) from the rate of meniscus movement within a graduated pipette connected to the capsule. Delta P was defined as the measured difference between capsule and pleural liquid pressures. The Lp of the parietal pleura was calculated from the slope of the line relating V to delta P by use of linear regression analysis. Lp in vivo averaged 1.36 X 10(-3) +/- 0.45 X 10(-3) (SD) ml.h-1.cmH2O-1.cm-2, regardless of whether the capsule was filled with plasma or saline and irrespective of body position. This value was not significantly different from that measured in the excised chest wall preparation (1.43 X 10(-3) +/- 1.1 X 10(-3) ml.h-1.cmH2O-1.cm-2). The parietal pleura offers little resistance to transpleural protein movement, because there was no observed difference between plasma and saline. We conclude that because the Lp for intact parietal pleura and extrapleural interstitium is approximately 100 times smaller than that previously measured in isolated stripped pleural preparations, removal of parietal pleural results in a damaged preparation.

Midbrain and medullary control of postinspiratory activity of the crural and costal diaphragm in vivo

2011 ◽  
Vol 105 (6) ◽  
pp. 2852-2862 ◽  
Author(s):  
Hari H. Subramanian ◽  
Gert Holstege
Keyword(s):  
Inhibitory Effect ◽  
Respiratory Neurons ◽  
Abdominal Muscles ◽  
Anesthetized Rats ◽  
Diaphragm Function ◽  
Three Phase ◽  
Crural Diaphragm ◽  
Decerebrate Cats ◽  
Stimulation Of

Studies on brain stem respiratory neurons suggest that eupnea consists of three phases: inspiration, postinspiration, and expiration. However, it is not well understood how postinspiration is organized in the diaphragm, i.e., whether postinspiration differs in the crural and costal segments of the diaphragm and what the influence is of postinspiratory neurons on diaphragm function during eupnea. In this in vivo study we investigated the postinspiratory activity of the two diaphragm segments during eupnea and the changes in diaphragm function following modulation of eupnea. Postinspiratory neurons in the medulla were stereotaxically localized extracellularly and neurochemically stimulated. We used three types of preparations: precollicularly decerebrated unanesthetized cats and rats and anesthetized rats. In all preparations, during eupnea, postinspiratory activity was found in the crural but not in the costal diaphragm. When eupnea was discontinued in decerebrate cats in which stimulation in the nucleus retroambiguus induced activation of laryngeal or abdominal muscles, all postinspiratory activity in the crural diaphragm was abolished. In decerebrate rats, stimulation of the midbrain periaqueductal gray abolished postinspiration in the crural diaphragm but induced activation in the costal diaphragm. In anesthetized rats, stimulation of medullary postinspiratory neurons abolished the postinspiratory activity of the crural diaphragm. Vagal nerve stimulation in these rats increased the intensity of postinspiratory neuronal discharge in the solitary nucleus, leading to decreased activity of the crural diaphragm. These data demonstrate that three-phase breathing in the crural diaphragm during eupnea exists in vivo and that postinspiratory neurons have an inhibitory effect on crural diaphragm function.

Respiratory muscle length measured by sonomicrometry

1984 ◽  
Vol 56 (3) ◽  
pp. 753-764 ◽  
Author(s):  
S. Newman ◽  
J. Road ◽  
F. Bellemare ◽  
J. P. Clozel ◽  
C. M. Lavigne ◽  
...  
Keyword(s):  
Spontaneous Breathing ◽  
Muscle Length ◽  
Length Change ◽  
Lung Inflation ◽  
Velocity Of Shortening ◽  
Anesthetized Dogs ◽  
Supramaximal Stimulation ◽  
Irreversible Injury ◽  
Anatomical Part

The use of sonomicrometry to study the mechanical properties of the diaphragm in vivo is presented. This method consists of the implantation of piezoelectric transducers between muscle fibers to measure the fibers' changes in length. Ultrasonic bursts are produced by one transducer upon electrical excitation and sensed by a second transducer placed 1–2 cm away. The time elapsed between the generation of the ultrasound burst and its detection is used to calculate the intertransducer distance. Excitation and sampling are done at 1.5 kHz and the output is a DC signal proportional to the length change between the transducers. Neither irreversible injury to the diaphragm nor regional differences within an anatomical part or segment were noted. Measurements were stable within the physiological range of temperature. We measured costal and crural length and velocity of contraction in anesthetized dogs during spontaneous breathing, occluded inspirations, passive lung inflation, and supramaximal phrenic nerve stimulation. We found that shortening during spontaneous breathing was 11 and 6% for crural and costal, respectively. The crural leads the costal in velocity of shortening. Supramaximal stimulation results in a velocity of shortening of 5 resting lengths X s-1. During an occluded inspiration crural shortens as much as in the nonoccluded breath, whereas costal shortens less. During passive lung inflation there is a nearly linear relationship between lung volume and diaphragm length; however, the relationships of chest wall dimensions with diaphragm length are nonlinear and cannot be described by any simple function. Some of the implications of these data on the present understanding of diaphragmatic mechanics are discussed.

Chest wall motion during spontaneous breathing and mechanical ventilation in dogs

1989 ◽  
Vol 66 (3) ◽  
pp. 1179-1189 ◽  
Author(s):  
D. O. Warner ◽  
S. Krayer ◽  
K. Rehder ◽  
E. L. Ritman
Keyword(s):  
Mechanical Ventilation ◽  
Chest Wall ◽  
Blood Volume ◽  
Spontaneous Breathing ◽  
High Speed ◽  
Gas Flow ◽  
Three Dimensional ◽  
Liquid Volume ◽  
Similar Amount ◽  
Rib Cage

We measured the volume change of the thoracic cavity (delta Vth) and the volumes displaced by the diaphragm (delta Vdi) and rib cage (delta Vrc) in six pentobarbital-anesthetized dogs lying supine. A high-speed X-ray scanner (dynamic spatial reconstructor) provided three-dimensional images of the thorax during spontaneous breathing and during mechanical ventilation with paralysis. Tidal volume (VT) was measured by integrating gas flow. Changes in thoracic liquid volume (delta Vliq, presumably caused by changes in thoracic blood volume) were calculated as delta Vth - VT. Absolute volume displaced by the rib cage was not significantly different during the two modes of ventilation. During spontaneous breathing, thoracic blood volume increased during inspiration; delta Vliq was 12.3 +/- 4.1% of delta Vth. During mechanical ventilation, delta Vliq was nearly zero. Configuration of the relaxed chest wall was similar during muscular relaxation induced by either pharmacological paralysis or hyperventilation. Expiratory muscle activity produced 50 +/- 11% of the delta Vth during spontaneous breathing. We conclude that at constant VT the volume displaced by the rib cage is remarkably similar during the transition from spontaneous breathing to mechanical ventilation, while both diaphragmatic volume displacement and changes in intrathoracic blood volume decrease by a similar amount.

Regional ventilation during spontaneous breathing and mechanical ventilation in dogs

1987 ◽  
Vol 63 (6) ◽  
pp. 2467-2475 ◽  
Author(s):  
R. D. Hubmayr ◽  
J. R. Rodarte ◽  
B. J. Walters ◽  
F. M. Tonelli
Keyword(s):  
Mechanical Ventilation ◽  
Chest Wall ◽  
Spontaneous Breathing ◽  
Vertical Gradient ◽  
Lung Parenchyma ◽  
Regional Ventilation ◽  
Regional Lung ◽  
Residual Capacity ◽  
Wall Deformation ◽  
Diaphragm Motion

We evaluated the effects of the different patterns of chest wall deformation that occur with different body positions and modes of breathing on regional lung deformation and ventilation. Using the parenchymal marker technique, we determined regional lung behavior during mechanical ventilation and spontaneous breathing in five anesthetized recumbent dogs. Regional lung behavior was related to the patterns of diaphragm motion estimated from X-ray projection images obtained at functional residual capacity (FRC) and end inspiration. Our results indicate that 1) in the prone and supine positions, FRC was larger during mechanical ventilation than during spontaneous breathing; 2) there were significant differences in the patterns of diaphragm motion and regional ventilation between mechanical ventilation and spontaneous breathing in both body positions; 3) in the supine position only, there was a vertical gradient in lung volume at FRC; 4) in both positions and for both modes of breathing, regional ventilation was nonlinearly related to changes in lobar and overall lung volumes; and 5) different patterns of diaphragm motion caused different sliding motions and differential rotations of upper and lower lobes. Our results are inconsistent with the classic model of regional ventilation, and we conclude that the distribution of ventilation is determined by a complex interaction of lung and chest wall shapes and by the motion of the lobes relative to each other, all of which help to minimize distortion of the lung parenchyma.

Effects of preserved spontaneous breathing activity during mechanical ventilation in experimental intra-abdominal hypertension

2010 ◽  
Vol 36 (8) ◽  
pp. 1427-1435 ◽  
Author(s):  
Dietrich Henzler ◽  
Nadine Hochhausen ◽  
Ralf Bensberg ◽  
Alexander Schachtrupp ◽  
Sonja Biechele ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Spontaneous Breathing ◽  
Abdominal Hypertension ◽  
Spontaneous Breathing Activity

Influence of Tracheal Obstruction on the Efficacy of Superimposed High-frequency Jet Ventilation and Single-frequency Jet Ventilation

2015 ◽  
Vol 123 (4) ◽  
pp. 799-809 ◽  
Author(s):  
Robert Sütterlin ◽  
Antonella LoMauro ◽  
Stefano Gandolfi ◽  
Rita Priori ◽  
Andrea Aliverti ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Chest Wall ◽  
High Frequency ◽  
Blood Gases ◽  
Single Frequency ◽  
Jet Ventilation ◽  
Lung Volumes ◽  
High Frequency Jet Ventilation ◽  
Tracheal Obstruction

Abstract Background: Both superimposed high-frequency jet ventilation (SHFJV) and single-frequency (high-frequency) jet ventilation (HFJV) have been used with success for airway surgery, but SHFJV has been found to provide higher lung volumes and better gas exchange than HFJV in unobstructed airways. The authors systematically compared the ventilation efficacy of SHFJV and HFJV at different ventilation frequencies in a model of tracheal obstruction and describe the frequency and obstruction dependence of SHFJV efficacy. Methods: Ten anesthetized animals (weight 25 to 31.5 kg) were alternately ventilated with SHFJV and HFJV at a set of different fHF from 50 to 600 min−1. Obstruction was created by insertion of interchangeable stents with ID 2 to 8 mm into the trachea. Chest wall volume was measured using optoelectronic plethysmography, airway pressures were recorded, and blood gases were analyzed repeatedly. Results: SHFJV provided greater than 1.6 times higher end-expiratory chest wall volume than HFJV, and tidal volume (VT) was always greater than 200 ml with SHFJV. Increase of fHF from 50 to 600 min−1 during HFJV resulted in a more than 30-fold VT decrease from 112 ml (97 to 130 ml) to negligible values and resulted in severe hypoxia and hypercapnia. During SHFJV, stent ID reduction from 8 to 2 mm increased end-expiratory chest wall volume by up to 3 times from approximately 100 to 300 ml and decreased VT by up to 4.2 times from approximately 470 to 110 ml. Oxygenation and ventilation were acceptable for 4 mm ID or more, but hypercapnia occurred with the 2 mm stent. Conclusion: In this in vivo porcine model of variable severe tracheal stenosis, SHFJV effectively increased lung volumes and maintained gas exchange and may be advantageous in severe airway obstruction.

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