Pulmonary Function Indices in Critical Care Patients

1. Evaluation of Pulmonary Function in the Intensive Care Patient.- 1.1. The Clinically Important Pulmonary Function Index.- 1.1.1. Evaluation and Monitoring of Circulatory Functions.- 1.1.2. Evaluation and Monitoring of Pulmonary Functions.- 1.1.3. “Simple” Measured Values.- 1.1.4. Physiological Models of Pulmonary Function Indices.- 1.1.5. The Clinically Important Pulmonary Function Indices.- 1.2. What Clinicians Expect of Transducers and Data Processing.- 1.2.1. The Chain of Instruments: Data Flow.- 1.2.2. Measuring Head and Measuring Instruments.- 1.2.3. Data Processing.- 1.2.4. Result-output.- 1.3. A Measuring System for Clinical Research.- 1.3.1. Obtaining Primary Data from the Measurements at the Airway Opening.- 1.3.2. Transducers.- 1.3.3. Preprocessing and Storage of Data.- 1.3.4. The Selection of the Pulmonary Indices Presented.- 2. Derivation of the Pulmonary Function Indices.- 2.1. Introduction.- 2.2. Breathing Mechanics.- 2.2.1. The Patient-ventilator Unit.- 2.2.2. Mathematical Model.- 2.2.3. Determining Lung Compliance and Airway Resistance.- 2.2.3.a Pleural Pressure.- 2.2.3.b Approximation of the Pressure-flow-volume Curve.- 2.2.4. Influence of the Lung Mechanics on the Distribution of Ventilation.- 2.3. Lung Volume and Intrapulmonary Gas Mixing.- 2.3.1. Nitrogen Washout.- 2.3.2. Measurement of the Functional Residual Capacity (FRC).- 2.3.3. Gas Mixing in the Acinus: The Stationary Interface.- 2.3.4. Gas Mixing in the Lungs.- 2.3.5. Measurement of the Airway Dead Space (Series Dead Space).- 2.3.6. Washout Efficiency from the Washout Curve (Decay Curve).- 2.4. Transpulmonary Gas Transport: Exchange of O2 and CO2.- 2.4.1. Diffusion from and into the Pulmonary Capillary Blood.- 2.4.2. Dissociation of O2 and CO2 in the Blood.- 2.4.3. The “Riley” 3-compartment Model.- 2.4.4. Analysis of the CO2-diagram.- 2.4.4.a Series Dead Space and Alveolar Ventilation.- 2.4.4.b Alveolar Efficiency of CO2-elimination.- 2.4.4.c Slope of the Alveolar Plateau.- 3. Assessment of Pulmonary Function Indices.- 3.1. Sensors.- 3.1.1. Measuring Head.- 3.1.2. Flow Measurement.- 3.1.2.a Principle of Measurement.- 3.1.2.b Linearity.- 3.1.2.c Calibration.- 3.1.2.d Correction of Errors Caused by Viscosity Changes.- 3.1.2.e Bandwidth.- 3.1.3. Gas Analysis.- 3.1.3.a Measuring Principle.- 3.1.3.b Automatic Sensitivity Control.- 3.1.3.c Linearity and “Cracking Pattern”.- 3.1.3.d Calibration.- 3.1.3.e Transport Delay.- 3.1.3.f Response Time.- 3.1.4. Pressure Measurement.- 3.1.4.a Measuring Principle.- 3.1.4.b Linearity.- 3.1.4.c Bandwidth.- 3.1.5. STPD and BTPS Conditions.- 3.2. Data Processing.- 3.2.1. Hardware and Data Flow.- 3.2.2. Automatic Recognition of the Respiratory Phases.- 3.2.3. Software.- 3.3. Testing the Measuring System.- 3.3.1. Absolute Accuracy.- 3.3.1.a Physical Model of the Lung.- 3.3.l.b Accuracy of Dead Space Determination.- 3.3.1.c Accuracy of the APV Measurements.- 3.3. l.d Decay Curve of the Model Lung.- 3.3.2. Precision of the Indices on the Stable Patient in “Steady State”.- 3.3.3. Reproducibility of the Nitrogen Washout.- 3.4. Use of the Measuring System in the Intensive Care Unit.- 3.5. Sensitivity of the Indices in the Presence of Acute Pathological Changes in the Lungs: Case Studies.- 3.5.1. Hypovolemia Before and After Correction.- 3.5.1.a Results.- 3.5. l.b Comparison with Conventional Methods.- 3.5.2. Acute Bronchial Constriction Before and After Therapy.- 3.5.2.a Results.- 3.5.2.b Comparison with Conventional Indices.- 3.5.3. Transient Processes: Effects of Inflating the Balloon of a Pulmonary Arterial Swan-Ganz Catheter.- 3.5.3.a A Model for Pulmonary Embolism.- 3.5.3.b Measurements in the Patient.- 3.5.3.c Results.- 4. Application I: Standard Values Dring Mechanical Ventilation After Cardiac Surgery.- 4.1. Patients and Examination.- 4.2. The Ventilation.- 4.3. Breathing Mechanics.- 4.4. Accessible Pulmonary Volume.- 4.5. Washout Efficiency and Moment Analysis.- 4.6. CO2 Production and O2 Consumption.- 4.7. Conventional Indices for CO2 Exchange.- 4.8. Specific Indices for CO2 Exchange.- 4.9. Cardiac Output.- 4.10. Correlations.- 5. Application II: A Study on Optimizing Mechanical Ventilation.- 5.1. Problem.- 5.2. Studies by Other Authors.- 5.3. Hypotheses.- 5.4. Patients and Methods.- 5.4.1. Patients.- 5.4.2. Measurements.- 5.4.3. Presentation of the Results.- 5.5. Results and Discussion.- 5.5.1. Effects of Changing the Tidal Volume (VT).- 5.5.2. Effects of the Positive End-expiratory Pressure (PEEP).- 5.5.3. Effects of the Inspiratory Flow Rate (V?I).- 5.5.4. Effects of the End-inspiratory Pause (EIP).- 5.6. Summarizing Discussion and Conclusions.- 5.6.1. Non-quantifiable Observations.- 5.6.2. Optimizing Ventilation.- 5.6.3. Recruitment of Compensatory Mechanisms.- 6. Application III: A Study on Intermittent Mandatory Ventilation (IMV).- 6.1. Patients and Methods.- 6.1.1. Patients.- 6.1.2. Measurements.- 6.1.3. Presentation of Results.- 6.2. Results.- 6.3. Discussion.- 6.3.1. CPPV Compared with IMV.- 6.3.2. IMVMB Compared with IMVSB.- 6.3.3. IMV Compared with CPAP.- 7. Appendices.- 7.1. On the Morphology of the Lungs.- 7.2. Technical Principles of Mechanical Ventilation.- 7.3. Measuring the Pleural Pressure with an Esophageal Balloon.- 7.4. Transport Equation for Convection and Diffusion.- 7.5. Relationship Between Dead Space and V?A/Q? Scatter.- 7.6. Viscosity of Gas Mixture.- 7.7. Determination and Dependencies of the Delay Time Between Flow Sensor and Mass Spectrometer.- 7.8. List of Formulas.- 7.9. Result-Tables.- 7.9.1. Tables to Application I: Standard Values After Cardiac Surgery.- 7.9.2. Tables to Applications II: Effect of Ventilation Variables.- 7.9.3. Tables to Application III: Intermittent Mandatory Ventilation.- References.