Prof. Dr. - Ing. Morris Riedel

Acute Respiratory Distress Syndrome (ARDS)

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Morris Riedel Acute Respiratory Distress Syndrome

Selected ARDS Facts

  • Also called noncardiogenic pulmonary edema

  • It is a severe condition that affects around 1 in 10,000 people every year with life threatening consequences [reference: The ALIEN study]

  • Its pathophysiology is characterized by bronchoalveolar injury and alveolar collapse (i.e., ‘atelectasis’) [reference: 1, 2, 3, 4]

Common Practice in Intensive Care Units (ICUs)

  • Using lung recruitment maneuvers (RMs) in ARDS to open up unstable, collapsed alveoli using a brief increase in transpulmonary pressure [reference: 1]

  • A large variety of RMs has been proposed in the literature

  • The most frequently used recruitment maneuver in ARDS Treatment is Sustained Inflation (SI) [reference: 1]

Lung Recruitment Maneuvers (RMs) Challenges

  • Because there is a large variety of RMs available there is also confusion regarding the optimal way to achieve and maintain alveolar recruitment in ARDS

  • Examples of RMs are Sustained Inflation (SI), Maximal Recruitment Strategy (RMS), and Prolonged Recruitment Maneuver (PRM)

  • The Maximal Recruitment Strategy (MRS) was evaluated via several patient trials [references: 1, 2 ]

  • It is very likely that the MRS caused high Degrees of alveolar stress and strain in some patients [reference: 1]

  • The Prolonged Recruitment Maneuver (PRM) is a more recent strategy in which PEEP is fixed to a higher than baseline Level and the positive inspiratory pressure is progressively increased [reference: 1]

  • In many cases the precise mode of action of particular RMs is not well understood [reference: 1 ]

Selected Pulmonary Edema Facts

  • Acute medical emergency due to an increase in pulmonary capillary venous pressure

  • Leads to fluid in the alveoli usually due to acute left ventricular failure

Selected Pulmonology Facts

  • Pulmonology is considered a subspecialty of internal Medicine related to lungs

  • A pulmonologist is a medical doctor that has specialized knowledge and skill in the diagnosis and treatment of conditions and diseases of the lungs

Selected Alveoli Facts

Virtual Patient Related Work: Extended MATLAB Implementation based on Nottingham Physiology Simulator

  1. Das, A., Cole, O., Chikhani, M., Wang, W., Ali, T., Haque, M., Bates, D.G., Hardman, J.G.: Evaluation of Lung Recruitment Maneuvers in Acute Respiratory Distress Syndrome using Computer Simulation, in Critical Care, Vol 19(8), p.8., 2015
    [ DOI ] [ RESEARCHGATE ]

    • Uses Computational Simulation to evaluate and understand the mode of operation of RMs for ARDS patients
    • Employs a high-fidelity computational simulator that reproduces the static and dynamic characteristics of several ARDS patients
    • Study compares the efficacy of three RMs in improving key patient parameters describing oxygenation, CO2 retention, and dynamic compliance
    • Study also investigates the effects of different PEEP settings in maintaining effective lung recruitment across a representative patient spectrum
    • Uses patient-specific computational simulation to analyze how three different lung recruitment maneuvers act to improve physiological responses and investigate how different levels of PEEP contribute to maintaining effective lung recruitment
    • Employs a simulation model that is an Extended MATLAB implementation of several physiological models originally developed within the Nottingham Physiology Simulator [references: 1, 2, 3 ]
    • Design of simulator core models represent a dynamic in vivo cardio-vasculo-pulmonary state using a set of mass-conserving equations based on well established physiological principles
    • Simulates a lung divided into 100 alveolar compartments, with each compartment having a corresponding set of parameters accounting for stiffness, threshold opening pressures and extrinsic pressures as well as airway and vascular resistances – How realistic is this model with 100 alveolar compartments, is the abstraction correct or can it be enhanced?
    • Uses mathematical principles and equations on which the simulator is based and that have been detailed in previous studies and thus validated the ability to accurately represent pulmonary disease states [references: 1, 2 ]
    • Models the recruitment as a time-dependent process by the introduction of a ‘time-constant’ parameter for each collapsed alveolar compartment, denoting the time it takes for the collapsed alveolus to open after a threshold pressure has been reached

Virtual Patient Related Work: Physiology Based Pharmacokinetics/Pharmacodynamics (PBPK/PD) Models – Tutorial

  1. Kuepfer, L., Niederalt, L., Wendl, T., Schlender, J., Willmann, S., Lippert, J., BLock, M., Eissing, T., Teutonico, D.: Applied Concepts in PBPK Modeling: How to Build a PBPK/PD Model, in CPT Pharmacometrics Systems Pharmacology, Vol. 5, Issue 10, pp. 516–531, 2016
    [ DOI ] [ RESEARCHGATE ]

    • Provides a good tutorial for Physiology Based Pharmacokinetics/Pharmacodynamics (PBPK/PD)
    • Introduces to a practical implementation in a typical PBPK model building workflow
    • Gives the example of a PBPK model for ciprofloxacin coupled to a pharmacodynamic model to simulate the antibacterial activity of ciprofloxacin treatment
    • Ciprofloxacin is an antibiotic used to treat a number of bacterial infections and works by stopping the growth of bacteria
    • Ciprofloxacin therefore treats only bacterial infections and does not work for virus infections (e.g., common cold, flu)
    • Ciprofloxacin is known for the fact (like for any antibiotic) that its overuse can lead to its decreased effectiveness

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