Static compliance

2012 ◽  
pp. 49-54
Keyword(s):  
Static Compliance

Biologically Variable Ventilation Improves Oxygenation and Respiratory Mechanics during One-lung Ventilation

2006 ◽  
Vol 105 (1) ◽  
pp. 91-97 ◽  
Author(s):  
Michael C. McMullen ◽  
Linda G. Girling ◽  
M Ruth Graham ◽  
W Alan C. Mutch
Keyword(s):  
Tidal Volume ◽  
Respiratory Mechanics ◽  
Lung Ventilation ◽  
Group Effect ◽  
Shunt Fraction ◽  
Static Compliance ◽  
One Lung Ventilation ◽  
Time Interaction ◽  
Variable Ventilation ◽  
Dead Space Ventilation

Background Hypoxemia is common during one-lung ventilation (OLV). Atelectasis contributes to the problem. Biologically variable ventilation (BVV), using microprocessors to reinstitute physiologic variability to respiratory rate and tidal volume, has been shown to be advantageous over conventional monotonous control mode ventilation (CMV) in improving oxygenation during the period of lung reinflation after OLV in an experimental model. Here, using a porcine model, the authors compared BVV with CMV during OLV to assess gas exchange and respiratory mechanics. Methods Eight pigs (25-30 kg) were studied in each of two groups. After induction of anesthesia-tidal volume 12 ml/kg with CMV and surgical intervention-tidal volume was reduced to 9 ml/kg. OLV was initiated with an endobronchial blocker, and the animals were randomly allocated to either continue CMV or switch to BVV for 90 min. After OLV, a recruitment maneuver was undertaken, and both lungs were ventilated for a further 60 min. At predetermined intervals, hemodynamics, respiratory gases (arterial, venous, and end-tidal samples) and mechanics (airway pressures, static and dynamic compliances) were measured. Derived indices (pulmonary vascular resistance, shunt fraction, and dead space ventilation) were calculated. Results By 15 min of OLV, arterial oxygen tension was greater in the BVV group (group x time interaction, P = 0.003), and shunt fraction was lower with BVV from 30 to 90 min (group effect, P = 0.0004). From 60 to 90 min, arterial carbon dioxide tension was lower with BVV (group x time interaction, P = 0.0001) and dead space ventilation was less from 60 to 90 min (group x time interaction, P = 0.0001). Static compliance was greater by 60 min of BVV and remained greater during return to ventilation of both lungs (group effect, P = 0.0001). Conclusions In this model of OLV, BVV resulted in superior gas exchange and respiratory mechanics when compared with CMV. Improved static compliance persisted with restoration of two-lung ventilation.

Mechanics of respiratory system in healthy anesthetized humans with emphasis on viscoelastic properties

1993 ◽  
Vol 75 (1) ◽  
pp. 132-140 ◽  
Author(s):  
B. Jonson ◽  
L. Beydon ◽  
K. Brauer ◽  
C. Mansson ◽  
S. Valind ◽  
...  
Keyword(s):  
Respiratory System ◽  
Driving Force ◽  
Viscoelastic Behavior ◽  
Elastic Recoil ◽  
Inspiratory Flow Rate ◽  
Static Compliance ◽  
Viscoelastic System ◽  
Flow Interruption ◽  
In Series ◽  
Flow Dependency

The classic model of the respiratory system (RS) is comprised of a Newtonian resistor in series with a capacitor and a viscoelastic unit including a resistor and a capacitor. The flow interruption technique has often been used to study the viscoelastic behavior under constant inspiratory flow rate. To study the viscoelastic behavior of the RS during complete respiratory cycles and to quantify viscoelastic resistance (Rve) and compliance (Cve) under unrestrained conditions, we developed an iterative technique based on a differential equation. We, as others, assumed Rve and Cve to be constant, which concords with volume and flow dependency of model behavior. During inspiration Newtonian resistance (R) was independent of flow and volume. During expiration R increased. Static elastic recoil showed no significant hysteresis. The viscoelastic behavior of the RS was in accordance with the model. The magnitude of Rve was 3.7 +/- 0.7 cmH2O.l-1 x s, i.e., two times R. Cve was 0.23 +/- 0.051 l/cmH2O, i.e., four times static compliance. The viscoelastic time constant, i.e., Cve.Rve, was 0.82 +/- 0.11s. The work dissipated against the viscoelastic system was 0.62 +/- 0.13 cmH2O x 1 for a breath of 0.56 liter, corresponding to 32% of the total energy loss within the RS. Viscoelastic recoil contributed as a driving force during the initial part of expiration.

scholarly journals Ex vivo lung perfusion in Brazil

2016 ◽  
Vol 42 (2) ◽  
pp. 95-98 ◽  
Author(s):  
Luis Gustavo Abdalla ◽  
Karina Andrighetti de Oliveira Braga ◽  
Natalia Aparecida Nepomuceno ◽  
Lucas Matos Fernandes ◽  
Marcos Naoyuki Samano ◽  
...  
Keyword(s):  
Respiratory Mechanics ◽  
Ex Vivo ◽  
Lung Perfusion ◽  
Improve Lung Function ◽  
Static Compliance ◽  
Ex Vivo Lung Perfusion ◽  
Time Points ◽  
Physiological Conditions ◽  
The Mean ◽  
A Prospective Study

Objective: To evaluate the use of ex vivo lung perfusion (EVLP) clinically to prepare donor lungs for transplantation. Methods: A prospective study involving EVLP for the reconditioning of extended-criteria donor lungs, the criteria for which include aspects such as a PaO2/FiO2 ratio < 300 mmHg. Between February of 2013 and February of 2014, the lungs of five donors were submitted to EVLP for up to 4 h each. During EVLP, respiratory mechanics were continuously evaluated. Once every hour during the procedure, samples of the perfusate were collected and the function of the lungs was evaluated. Results: The mean PaO2 of the recovered lungs was 262.9 ± 119.7 mmHg at baseline, compared with 357.0 ± 108.5 mmHg after 3 h of EVLP. The mean oxygenation capacity of the lungs improved slightly over the first 3 h of EVLP-246.1 ± 35.1, 257.9 ± 48.9, and 288.8 ± 120.5 mmHg after 1, 2, and 3 h, respectively-without significant differences among the time points (p = 0.508). The mean static compliance was 63.0 ± 18.7 mmHg, 75.6 ± 25.4 mmHg, and 70.4 ± 28.0 mmHg after 1, 2, and 3 h, respectively, with a significant improvement from hour 1 to hour 2 (p = 0.029) but not from hour 2 to hour 3 (p = 0.059). Pulmonary vascular resistance remained stable during EVLP, with no differences among time points (p = 0.284). Conclusions: Although the lungs evaluated remained under physiological conditions, the EVLP protocol did not effectively improve lung function, thus precluding transplantation.

High surface tension pulmonary edema induced by detergent aerosol

1985 ◽  
Vol 58 (1) ◽  
pp. 129-136 ◽  
Author(s):  
G. F. Nieman ◽  
C. E. Bredenberg
Keyword(s):  
Surface Tension ◽  
Pulmonary Edema ◽  
High Surface ◽  
Water Volume ◽  
Oncotic Pressure ◽  
Static Compliance ◽  
Surfactant Activity ◽  
Dioctyl Sodium Sulfosuccinate ◽  
Alveolar Surface

The effect of the detergent dioctyl sodium sulfosuccinate on pulmonary extravascular water volume (PEWV) was studied in adult anesthetized mongrel dogs. The detergent was dissolved as a 1% solution in a vehicle of equal volumes of 95% ethanol and normal saline and administered by ultrasonic nebulizer attached to the inspiratory tubing of a piston ventilator. Two hours following detergent aerosol PEWV measured gravimetrically was increased compared with either animals receiving no aerosol or those receiving an aerosol of vehicle alone. Loss of surfactant activity and increased alveolar surface tension were demonstrated by Wilhelmy balance studies of minced lung extracts, by a fall in static compliance, and by evidence of atelectasis and instability noted by gross observation and by in vivo microscopy. No significant changes in colloid oncotic pressure or pulmonary microvascular hydrostatic pressure were observed. These data suggest that pulmonary edema can be induced by increased alveolar surface tension and support the concept that one of the major roles of pulmonary surfactant is to prevent pulmonary edema.

Lung volumes after antigen infusion in the guinea pig in vivo: effects of vagal section

1978 ◽  
Vol 45 (6) ◽  
pp. 957-961 ◽  
Author(s):  
J. M. Drazen ◽  
S. H. Loring ◽  
C. Venugopalan
Keyword(s):  
Total Lung Capacity ◽  
Hypersensitivity Reactions ◽  
Immediate Hypersensitivity ◽  
Similar Extent ◽  
Static Compliance ◽  
Lung Volumes ◽  
Lung Capacity ◽  
In Vivo Effects ◽  
Gas Volume

The effects of intravenous antigen infusion on lung volumes and quasi-static deflationary pulmonary compliance in guinea pigs previously sensitized to ovalbumin were studied in vivo. Ovalbumin infusion significantly increased minimal gas volume to a similar extent in animals with intact or cut vagi. Total lung capacity fell only in animals with intact vagi. Quasi-static compliance fell in both groups of animals, but the fall was significantly greater in animals with intact vagi. These data demonstrate that immediate hypersensitivity reactions alter lung volumes and the elastic properties of the lung by both vagal dependent and vagal independent mechanisms.

Alveolar Recruitment in Pulmonary and Extrapulmonary Acute Respiratory Distress Syndrome

2007 ◽  
Vol 106 (2) ◽  
pp. 212-217 ◽  
Author(s):  
Arnaud W. Thille ◽  
Jean-Christophe M. Richard ◽  
Salvatore M. Maggiore ◽  
V Marco Ranieri ◽  
Laurent Brochard
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Tidal Volume ◽  
Distress Syndrome ◽  
Alveolar Recruitment ◽  
High Peep ◽  
Static Compliance ◽  
Volume Curve ◽  
Pressure Volume Curve

Background Alveolar recruitment in response to positive end-expiratory pressure (PEEP) may differ between pulmonary and extrapulmonary acute respiratory distress syndrome (ARDS), and alveolar recruitment values may differ when measured by pressure-volume curve compared with static compliance. Methods The authors compared PEEP-induced alveolar recruitment in 71 consecutive patients identified in a database. Patients were classified as having pulmonary, extrapulmonary, or mixed/uncertain ARDS. Pressure-volume curves with and without PEEP were available for all patients, and pressure-volume curves with two PEEP levels were available for 44 patients. Static compliance was calculated as tidal volume divided by pressure change for tidal volumes of 400 and 700 ml. Recruited volume was measured at an elastic pressure of 15 cm H2O. Results Volume recruited by PEEP (10 +/- 3 cm H2O) was 223 +/- 111 ml in the pulmonary ARDS group (29 patients), 206 +/- 164 ml in the extrapulmonary group (16 patients), and 242 +/- 176 ml in the mixed/uncertain group (26 patients) (P = 0.75). At high PEEP (14 +/- 2 cmH2O, 44 patients), recruited volumes were also similar (P = 0.60). With static compliance, recruitment was markedly underestimated and was dependent on tidal volume (226 +/- 148 ml using pressure-volume curve, 95 +/- 185 ml for a tidal volume of 400 ml, and 23 +/- 169 ml for 700 ml; P &lt; 0.001). Conclusion In a large sample of patients, classification of ARDS was uncertain in more than one third of patients, and alveolar recruitment was similar in pulmonary and extrapulmonary ARDS. PEEP levels should not be determined based on cause of ARDS.

scholarly journals STATIC COMPLIANCE BEFORE ND AFTER VAGINAL DELIVERY

1971 ◽  
Vol 43 (4) ◽  
pp. 418 ◽  
Author(s):  
J.V. FARMAN ◽  
M.E. THORPE
Keyword(s):  
Vaginal Delivery ◽  
Static Compliance

ProtoFold: Part II — A Successive Kineto-Static Compliance Method for Protein Conformation Prediction

2004 ◽  
Author(s):  
Kazem Kazerounian ◽  
Khalid Latif ◽  
Carlos Alvarado
Keyword(s):  
Force Field ◽  
Protein Conformation ◽  
Energy State ◽  
Computer Software ◽  
Alpha Helix ◽  
Static Compliance ◽  
Joint Torques ◽  
Atomic Force ◽  
Protein Prediction ◽  
Static Effect

This paper presents an efficient and novel computational protein prediction methodology called Kineto-Static Compliance Method. Successive Kineto-Static Fold Compliance is a methodology for predicting a protein molecule’s motion under the effect of an inter-atomic force field without the need for molecular dynamic simulation. Instead, the chain complies under the Kineto-Static effect of the force field in such a manner that each rotatable joint changes by an amount proportional to the effective torque on that joint. This process successively iterates until all of the joint torques have converged to zero. This configuration is equivalent to a stable, globally optimized potential energy state of the system or, in other words, the final conformation of the protein. This methodology is implemented in a computer software package named ProtoFold. In this paper, we have used Protofold to predict the final conformation of a small peptide chain segment, an alpha helix, and the Triponin protein chains from a denatured configuration. The results show that torques in each joint are minimized to values very close to zero, which demonstrates the method’s effectiveness for protein conformation prediction.

A Comparison of Kinetostatic and Multibody Dynamics Models for Simulating Protein Structures

2007 ◽  
Author(s):  
Hai-Jun Su ◽  
Jesse Parker ◽  
Kazem Kazerounian ◽  
Horea Ilies
Keyword(s):  
Potential Energy ◽  
Molecular Dynamic Simulation ◽  
Molecular Dynamic ◽  
Dynamic Simulation ◽  
Multibody Dynamics ◽  
Energy State ◽  
Protein Structures ◽  
Rigid Bodies ◽  
Static Compliance ◽  
Protein Molecules

This paper presents an initial comparison of two approaches to energy minimization of protein molecules, namely the Molecular Dynamic Simulation and the Kineto-Static Compliance Method. Both methods are well established and are promising contenders to the seemingly insurmountable task of global optimization in the protein molecules potential energy terrain. The Molecular Dynamic Simulation takes the form of Constrained Multibody Dynamics of interconnected rigid bodies, as implemented at the Virtual Reality Application Center from Iowa State University. The Kineto-Static Compliance Method is implemented in the Protofold Computer package developed in the Mechanical Engineering Department at the University of Connecticut. The simulation results of both methods are compared through the trajectory of potential energy, the Root Mean Square Deviation (RMSD) of the alpha carbons, as well as based on visual observations. The preliminary results indicate that both techniques are very effective in converging the protein structure to a state with significantly less potential energy. At present, the converged solutions for the two methods are, however, different from each other and are very likely different from the global minimum potential energy state.

Sign in / Sign up

Export Citation Format

Share Document