Fractional Thermal Model of the Lungs Using Havriliak-Negami Function

2011 ◽  
Author(s):  
Mathieu Pellet ◽  
Pierre Melchior ◽  
Youssef Abdelmoumen ◽  
Alain Oustaloup
Keyword(s):  
System Identification ◽  
Thermal Model ◽  
Heart Surgery ◽  
Open Heart Surgery ◽  
Circulatory System ◽  
Blood Stream ◽  
Thermal Systems ◽  
Systems Model ◽  
Fractional Models ◽  
Postoperative Respiratory Complications

This paper is about fractional system identification of a thermal model of the lungs. Usually, during open-heart surgery, an extracorporeal circulation (ECC) is carried out on the patient. In order to plug the artificial heart/lung machine on the blood stream, the lungs are disconnected from the circulatory system. This may results in postoperative respiratory complications. A method to protect the lungs has been developed by surgeon and anesthetist. It is called: bronchial hypothermia. The aim is to cool the organ in order to slow down its deterioration. Unfortunately the thermal properties of the lungs are not well-known yet. Mathematical models are useful and needed in order to improve the knowledge of these organs. As proved by several previous works, fractional models are especially appropriate to model thermal systems (model compacity, accuracy) and the dynamic of fractal systems. Thus, fractional models of the lungs have been determined using time domain system identification with the Havriliak-Negami function. A comparison with integer order models was also carried out. The aim of this paper is to present the results of this study.

scholarly journals Modeling Thermal Systems With Fractional Models: Human Bronchus Application

2021 ◽  
Author(s):  
Jean-François Duhé ◽  
stephane victor ◽  
Pierre Melchior ◽  
Youssef Abdelmoumen ◽  
François Roubertie
Keyword(s):  
Heat Transfer ◽  
Heat Dissipation ◽  
Heart Surgery ◽  
Thermal Modeling ◽  
Open Heart Surgery ◽  
Frequency Domain Analysis ◽  
Conductive Heat ◽  
Human Bronchus ◽  
Fractional Models ◽  
Heat Transfers

Abstract Thermal modeling of systems allows heat and temperature simulations for many applications, such as refrigeration design, heat dissipation in power electronics, melting processes and bio-heat transfers. Sufficiently accurate models are especially needed in open-heart surgery where lung thermal modeling will prevent pulmonary cell dying. For simplicity purposes, simple RC circuits are often used but such models are too simple and lack of precision in dynamical terms. A more complete description of conductive heat transfer can be obtained from the heat equation by means of a two-port network. The analytical expressions obtained from such circuit models are complex and nonlinear in the frequency $\omega$. This complexity in Laplace domain is difficult to handle when it comes to control applications and more specifically during surgery, as heat transfer and temperature control of a tissue may help in reducing necrosis and preserving a greater amount of a given organ. Therefore, a frequency domain analysis of the series and shunt impedances will be presented and different techniques of approximations will be explored in order to obtain simple but sufficiently precise linear fractional transfer function models. Several approximations are proposed to model heat transfers of a human middle bronchus and will be quantified by the absolute errors.

Enhanced Effective Fibrinolysis following the Neutralization of Heparin in Open Heart Surgery Increases the Risk of Post-Surgical Bleeding

1990 ◽  
Vol 63 (02) ◽  
pp. 241-245 ◽  
Author(s):  
Jørgen Gram ◽  
Thomas Janetzko ◽  
Jørgen Jespersen ◽  
Hans Dietrich Bruhn
Keyword(s):  
Blood Loss ◽  
Plasminogen Activator ◽  
Heart Surgery ◽  
Degradation Products ◽  
Open Heart Surgery ◽  
Tissue Type ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator ◽  
Chest Tube Drain ◽  
Median Blood Loss

SummaryThe tissue-type plasminogen activator related fibrinolytic system was studied in 24 patients undergoing cardiopulmonary bypass surgery. The degradation of fibrinogen and fibrin was followed during and after surgery by means of new sensitive and specific assays and the changes were related to the blood loss measured in the chest tube drain during the first 24 postoperative hours. Although tissue-type plasminogen activator was significantly released into the circulation during the period of extracor-poreal circulation (p <0.01), constantly low levels of fibrinogen degradation products indicated that a systemic generation of plasmin could be controlled by the naturally occurring inhibitors. Following extracorporeal circulation heparin was neutralized by protamine chloride, and in relation to the subsequent generation of fibrin, there was a short period with increased concentrations of fibrinogen degradation products (p <0.01) and a prolonged period of degradation of cross-linked fibrin, as detected by increased concentrations of D-Dimer until 24 h after surgery (p <0.01). Patients with a higher than the median blood loss (520 ml) in the chest tube drain had a significantly higher increase of D-Dimer than patients with a lower than the median blood loss (p <0.05).We conclude that the incorporation of tissue-type plasminogen activator into fibrin and the in situ activation of plasminogen enhance local fibrinolysis, thereby increasing the risk of bleeding in patients undergoing open heart surgery

The Hemostatic Mechanism after Open-Heart Surgery

1978 ◽  
Vol 39 (02) ◽  
pp. 474-487 ◽  
Author(s):  
E R Cole ◽  
F Bachmann ◽  
C A Curry ◽  
D Roby
Keyword(s):  
Extracorporeal Circulation ◽  
Heart Surgery ◽  
Polyacrylamide Gel Electrophoresis ◽  
Open Heart Surgery ◽  
Coagulation System ◽  
Open Heart ◽  
Time Activity ◽  
Post Surgery ◽  
Plasma Fractions ◽  
The Mean

SummaryA prospective study in 13 patients undergoing open-heart surgery with extracorporeal circulation revealed a marked decrease of the mean one-stage prothrombin time activity from 88% to 54% (p <0.005) but lesser decreases of factors I, II, V, VII and X. This apparent discrepancy was due to the appearance of an inhibitor of the extrinsic coagulation system, termed PEC (Protein after Extracorporeal Circulation). The mean plasma PEC level rose from 0.05 U/ml pre-surgery to 0.65 U/ml post-surgery (p <0.0005), and was accompanied by the appearance of additional proteins as evidenced by disc polyacrylamide gel electrophoresis of plasma fractions (p <0.0005). The observed increases of PEC, appearance of abnormal protein bands and concomitant increases of LDH and SGOT suggest that the release of an inhibitor of the coagulation system (similar or identical to PIVKA) may be due to hypoxic liver damage during extracorporeal circulation.

Blood Coagulation Studies and Extracorporeal Circulation in Man

1967 ◽  
Vol 18 (03/04) ◽  
pp. 634-646 ◽  
Author(s):  
N Thurnherr
Keyword(s):  
Blood Coagulation ◽  
Extracorporeal Circulation ◽  
Blood Clotting ◽  
Heart Surgery ◽  
Open Heart Surgery ◽  
Fibrinolytic System ◽  
Open Heart ◽  
Clotting Factors ◽  
Blood Clotting Factors

SummaryBlood clotting investigations have been executed in 25 patients who have undergone open heart surgery with extracorporeal circulation. A description of alterations in the activity of blood clotting factors, the fibrinolytic system, prothrombin consumption and platelets during several phases of the operation is given.

Monitoring of r-Hirudin Anticoagulation during Cardiopulmonary Bypass – Assessment of the Whole Blood Ecarin Clotting Time

1997 ◽  
Vol 77 (05) ◽  
pp. 0920-0925 ◽  
Author(s):  
Bernd Pötzsch ◽  
Katharina Madlener ◽  
Christoph Seelig ◽  
Christian F Riess ◽  
Andreas Greinacher ◽  
...  
Keyword(s):  
Cardiopulmonary Bypass ◽  
Whole Blood ◽  
Heart Surgery ◽  
Ex Vivo ◽  
Open Heart Surgery ◽  
Clotting Time ◽  
Blood Samples ◽  
Alternative Approach ◽  
Ecarin Clotting Time

SummaryThe use of recombinant ® hirudin as an anticoagulant in performing extracorporeal circulation systems including cardiopulmonary bypass (CPB) devices requires a specific and easy to handle monitoring system. The usefulness of the celite-induced activated clotting time (ACT) and the activated partial thromboplastin time (APTT) for r-hirudin monitoring has been tested on ex vivo blood samples obtained from eight patients treated with r-hirudin during open heart surgery. The very poor relationship between the prolongation of the ACT and APTT values and the concentration of r-hirudin as measured using a chromogenic factor Ila assay indicates that both assays are not suitable to monitor r-hirudin anticoagulation. As an alternative approach a whole blood clotting assay based on the prothrombin-activating snake venom ecarin has been tested. In vitro experiments using r-hirudin- spiked whole blood samples showed a linear relationship between the concentration of hirudin added and the prolongation of the clotting times up to a concentration of r-hirudin of 4.0 µg/ml. Interassay coefficients (CV) of variation between 2.1% and 5.4% demonstrate the accuracy of the ecarin clotting time (ECT) assay. Differences in the interindividual responsiveness to r-hirudin were analyzed on r-hirudin- spiked blood samples obtained from 50 healthy blood donors. CV- values between 1.8% and 6% measured at r-hirudin concentrations between 0.5 and 4 µg/ml indicate remarkably slight differences in r-hirudin responsiveness. ECT assay results of the ex vivo blood samples linearily correlate (r = 0.79) to the concentration of r-hirudin. Moreover, assay results were not influenced by treatment with aprotinin or heparin. These findings together with the short measuring time with less than 120 seconds warrant the whole blood ECT to be a suitable assay for monitoring of r-hirudin anticoagulation in cardiac surgery.

Open heart surgery in patients with cold agglutinins: Is the fear justified?

2007 ◽  
Vol 55 (S 1) ◽  
Author(s):  
N Madershahian ◽  
T Wittwer ◽  
J Strauch ◽  
J Wippermann ◽  
UFW Franke ◽  
...  
Keyword(s):  
Heart Surgery ◽  
Open Heart Surgery ◽  
Open Heart ◽  
Cold Agglutinins

Off-Pump Coronary Artery Bypass Surgery May Produce a Hypercoagulable Patient

2005 ◽  
Vol 6 (2) ◽  
pp. 94 ◽  
Author(s):  
Robert L. Quigley ◽  
David W. Fried ◽  
John Pym ◽  
Richard Y. Highbloom
Keyword(s):  
Coronary Artery ◽  
Coronary Artery Bypass ◽  
Heart Surgery ◽  
Artery Bypass ◽  
Open Heart Surgery ◽  
Anticoagulation Therapy ◽  
Maximum Amplitude ◽  
Platelet Activity ◽  
Off Pump ◽  
Pump Coronary Artery Bypass

<P>Background: The incidence of thromboembolic events following traditional open heart surgery has not been clinically significant. However, with beating heart surgery, for which cardiopulmonary bypass (CPB) is not required, the incidence of spontaneous intravascular thrombosis may be similar to that encountered after general surgeries. Compounding this risk is that many cases of off-pump coronary artery bypass (OPCAB) surgery are reserved for the elderly patient with multiple comorbidities. The few studies to date that have assessed the coagulation profile in OPCAB patients have been limited to the first 24 hours after surgery. </P><P>Methods: We prospectively studied 17 OPCAB and 6 on-pump patients over 4 days (hospital course) with daily thromboelastography. A coagulation index (CI) (reflecting R and K times, a angle, and maximum amplitude [MA]) was calculated for the patients, who served as their own controls. </P><P>Results: The OPCAB patients demonstrated 3 days postoperatively a 17% increase in coagulation compared with the baseline. Specifically, the CI consistently revealed an elevation in the a angle and the MA, both of which reflect increased fibrinogen and platelet activity. On the other hand, 3 days following surgery the CI of the CPB group was tightly clustered around their respective baseline CI values, which had recovered from a significant decrease immediately after surgery. </P><P>Conclusion: A state of hypercoagulability, as measured by thromboelastography, exists in the OPCAB patient beyond the first postoperative day, and this finding suggests that prophylactic postoperative anticoagulation therapy targeting fibrinogen and platelet activity may be indicated for these patients.</P>

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