Effects of longitudinal laparotomy on respiratory system, lung, and chest wall mechanics

In six sedated, anesthetized, paralyzed, and mechanically ventilated guinea pigs, total respiratory system (RT,rs), lung, and chest wall resistances and respiratory system (Est,rs), lung, and chest wall (Est,w) elastances were determined before and after longitudinal laparotomy. Furthermore the resistances were also split into their initial and difference components, with the former reflecting the Newtonian resistances and the latter representing the viscoelastic/inhomogeneous pressure dissipations in the system. For such purpose the end-inflation occlusion during constant inspiratory flow method was used. During laparotomy, a statistically significant increase in respiratory system difference resistance (from 0.086 to 0.101 cmH2O.ml-1.s) significantly augmented RT,rs (from 0.157 to 0.167 cmH2O.ml-1.s). The former was entirely secondary to a significant increase in chest wall difference resistance (0.019 to 0.034 cmH2O.ml-1.s), which naturally raised chest wall total resistance (from 0.030 to 0.047 cmH2O.ml-1.s). Est,rs and Est,w also increased (14.7 and 13.1%, respectively) after abdominal incision. It can be concluded that the midline xiphipubic laparotomy accompanied by the bilateral ventrodorsal infracostal incision increases RT,rs as a consequence of augmented chest wall difference resistance and Est,rs as a result of higher Est,w.

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Total Respiratory System, Lung and Chest Wall Mechanics, Lung Volumes and Gas-Exchange in Morbidly Obese Patients During General Anesthesia

Anaesthesia, Pain, Intensive Care and Emergency Medicine — A.P.I.C.E. ◽

10.1007/978-88-470-2203-4_62 ◽

1996 ◽

pp. 669-674

Author(s):

P. Pelosi ◽

M. Croci ◽

P. Vicardi ◽

A. Lissoni ◽

M. Cerisara

Keyword(s):

Gas Exchange ◽

General Anesthesia ◽

Chest Wall ◽

Respiratory System ◽

Morbidly Obese ◽

Obese Patients ◽

Lung Volumes ◽

Chest Wall Mechanics

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Low-frequency respiratory mechanical impedance in the rat

Journal of Applied Physiology ◽

10.1152/jappl.1987.63.1.36 ◽

1987 ◽

Vol 63 (1) ◽

pp. 36-43 ◽

Cited By ~ 40

Author(s):

Z. Hantos ◽

B. Daroczy ◽

B. Suki ◽

S. Nagy

Keyword(s):

Frequency Dependence ◽

Chest Wall ◽

Low Frequency ◽

Mechanical Impedance ◽

Total Resistance ◽

Low Frequencies ◽

Chest Wall Compliance ◽

Before And After ◽

Airway Opening ◽

Wall Compliance

modified forced oscillatory technique was used to determine the respiratory mechanical impedances in anesthetized, paralyzed rats between 0.25 and 10 Hz. From the total respiratory (Zrs) and pulmonary impedance (ZL), measured with pseudorandom oscillations applied at the airway opening before and after thoracotomy, respectively, the chest wall impedance (ZW) was calculated as ZW = Zrs - ZL. The pulmonary (RL) and chest wall resistances were both markedly frequency dependent: between 0.25 and 2 Hz they contributed equally to the total resistance falling from 81.4 +/- 18.3 (SD) at 0.25 Hz to 27.1 +/- 1.7 kPa.l–1 X s at 2 Hz. The pulmonary compliance (CL) decreased mildly, from 2.78 +/- 0.44 at 0.25 Hz to 2.36 +/- 0.39 ml/kPa at 2 Hz, and then increased at higher frequencies, whereas the chest wall compliance declined monotonously from 4.19 +/- 0.88 at 0.25 Hz to 1.93 +/- 0.14 ml/kPa at 10 Hz. Although the frequency dependence of ZW can be interpreted on the basis of parallel inhomogeneities alone, the sharp fall in RL together with the relatively constant CL suggests that at low frequencies significant losses are imposed by the non-Newtonian resistive properties of the lung tissue.

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Effects of Thoracotomy on Respiratory System, Lung, and Chest Wall Mechanics

CHEST Journal ◽

10.1378/chest.104.6.1882 ◽

1993 ◽

Vol 104 (6) ◽

pp. 1882-1886 ◽

Cited By ~ 5

Author(s):

Ana Claudia M. Rodrigues ◽

Lucio F. Pacheco Moreira ◽

Cláudia L. De Souza ◽

Paola Capparelli D. Pettersen ◽

Paulo Hilário N. Saidiva ◽

...

Keyword(s):

Chest Wall ◽

Respiratory System ◽

Chest Wall Mechanics

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Total Respiratory System, Lung, and Chest Wall Mechanics in Sedated-Paralyzed Postoperative Morbidly Obese Patients

CHEST Journal ◽

10.1378/chest.109.1.144 ◽

1996 ◽

Vol 109 (1) ◽

pp. 144-151 ◽

Cited By ~ 243

Author(s):

Paolo Pelosi ◽

Massimo Croci ◽

Irene Ravagnan ◽

Pierluigi Vicardi ◽

Luciano Gattinoni

Keyword(s):

Chest Wall ◽

Respiratory System ◽

Morbidly Obese ◽

Obese Patients ◽

Chest Wall Mechanics

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Frequency dependence of pulmonary and chest wall mechanics in young and adult cats

Journal of Applied Physiology ◽

10.1152/jappl.1994.76.5.2037 ◽

1994 ◽

Vol 76 (5) ◽

pp. 2037-2046 ◽

Cited By ~ 4

Author(s):

F. R. Shardonofsky ◽

J. Sato ◽

D. H. Eidelman

Keyword(s):

Chest Wall ◽

Respiratory System ◽

Viscoelastic Model ◽

Dynamic Compliance ◽

Compartment Model ◽

Volume Data ◽

Chest Wall Mechanics ◽

Tissue Resistance ◽

Single Compartment Model ◽

Adult Cats

The frequency (f) dependence of pulmonary and chest wall mechanics was assessed in nine kittens and four cats. Kittens and cats were anesthetized, paralyzed, and mechanically ventilated at various f between 0.13 and 1.6 Hz and 0.09 and 0.79 Hz, respectively. Resistance and dynamic compliance pertaining to the respiratory system (Rrs and Cdyn,rs), lungs (RL and Cdyn,L), and chest wall (RW and Cdyn,W) were estimated by fitting a single-compartment model to data obtained from regular ventilation. Static lung and chest wall compliances (Cst,L and Cst,W) were computed from quasi-static pressure-volume data. Lung tissue resistance (Rti) was estimated with alveolar capsules in open-chest animals. The f dependence of the two-compartment viscoelastic model of the respiratory system was assessed by computing the effective resistance [Rmod,rs(omega)] and compliance [Cmod,rs(omega)] from data obtained at the lowest experimental f. Both Cdyn,L and Cdyn,W decreased with increasing f in all animals. Cdyn,L/Cst,L and Cdyn,W/Cst,W were lower in kittens than in cats. RL and RW decreased markedly with f in all animals. Rti/RL showed a marked f dependence, its values being similar in both young and adult cats at their respective resting f. CstW/Cst,L ratio was higher in kittens than in cats. A better agreement was found between Cmod,rs(omega) and Cdyn,rs than between Rmod,rs(omega) and Rrs.

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Effects of abdominal opening on respiratory system mechanics in ventilated rats

Journal of Applied Physiology ◽

10.1152/jappl.1989.66.6.2496 ◽

1989 ◽

Vol 66 (6) ◽

pp. 2496-2501 ◽

Cited By ~ 12

Author(s):

W. A. Zin ◽

M. A. Martins ◽

P. R. Silva ◽

R. S. Sakae ◽

A. L. Carvalho ◽

...

Keyword(s):

Respiratory System ◽

Lung Volume ◽

Open Abdomen ◽

Rib Cage ◽

Mechanically Ventilated ◽

Respiratory System Mechanics ◽

Before And After ◽

Residual Capacity ◽

The Difference ◽

Lateral Diameter

In 16 anesthetized paralyzed mechanically ventilated rats, respiratory system mechanics and rib cage dimensions were determined both before and after wide abdominal opening. In eight animals the end-inflation occlusion method disclosed statistically significant postoperative increases in respiratory system elastance (from 4.84 to 6.49 cmH2O.ml-1) and resistance (from 0.224 to 0.300 cmH2O.ml-1.s); the latter resulted from a rise of its uneven component (from 0.161 to 0.209 cmH2O.ml-1.s). In the remaining rats, rib cage morphometry at functional residual capacity after surgery showed significant decreases in lower rib cage circumference and anteroposterior and lateral diameters, whereas there was an increase in upper rib cage circumference and a fall in its lateral diameter. When these parameters were measured at end-inspiratory lung volume, the difference between intact and open abdomen were less striking; only lower rib cage circumference and upper rib cage lateral diameter significantly decreased postoperatively. Because surgery induced an expiratory volume of only 0.1 ml, it can be concluded that abdominal opening redistributed regional volumes within the lung, leading to increased unevenness in the system.

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Effects of vagotomy on respiratory mechanics in newborn and adult pigs

Journal of Applied Physiology ◽

10.1152/jappl.1986.60.6.1992 ◽

1986 ◽

Vol 60 (6) ◽

pp. 1992-1999 ◽

Cited By ~ 19

Author(s):

M. G. Clement ◽

J. P. Mortola ◽

M. Albertini ◽

G. Aguggini

Keyword(s):

Chest Wall ◽

Respiratory System ◽

Respiratory Mechanics ◽

Breathing Patterns ◽

External Work ◽

Vagal Control ◽

Before And After ◽

Wall Compliance ◽

Bilateral Vagotomy ◽

System Time

We have examined breathing patterns and respiratory mechanics in anesthetized tracheostomized newborn piglets and adult pigs and the changes determined by cervical bilateral vagotomy. Piglets had a respiratory system compliance and resistance, on a per kilogram basis, respectively, higher and smaller than the adults. After vagotomy neither variable changed in the newborn, but resistance dropped in the adult. This may suggest that efferent vagal control of bronchomotor tone is more pronounced in the adult. Respiratory system time constant was longer in newborns both before and after vagotomy. The distortion of the chest wall, examined as the ratio between the volume inhaled spontaneously and the passive volume for the same abdominal motion, was more marked in newborns, reflecting their higher chest wall compliance. The work per minute, computed from the pressure and volume changes, was larger in piglets. After vagotomy the external work per minute was not different; however, the larger tidal volumes were accompanied by a larger chest distortion. This may indicate that vagal control of the breathing pattern, by limiting the depth of inspiration and hence the amount of chest distortion, has implications on the energetics of breathing.

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