Understanding Mechanical Ventilation (eBook)

164921_2_EN_FM_Chapter_OnlinePDF.pdf 1
Understanding MechanicalVentilation 1
164921_2_EN_01_Chapter_OnlinePDF.pdf 20
Historical Aspects of Mechanical Ventilation 20
References 25
164921_2_EN_02_Chapter_OnlinePDF.pdf 28
The Indications for Mechanical Ventilation 28
2.1. Hypoxia 28
2.2 .Hypoventilation 29
2.3 .Increased Work of Breathing 30
2.4 .Other Indications 31
2.5 .Criteria for Intubation and Ventilation 31
References 35
164921_2_EN_03_Chapter_OnlinePDF.pdf 37
Physiological Considerations in the Mechanically Ventilated Patient 37
3.1 .The Physiological Impact of the Endotracheal Tube 37
Box 3.1 Poiseuille’s Law 39
3.2 .Positive Pressure Breathing 39
Box 3.2 Pressure Required for Overcoming Resistance and Elastance 46
3.3 .Lung Compliance 46
3.3.1 .Static Compliance 47
Box 3.3 Calculation of Static Compliance in the Ventilated PatientStatic compliance can be measured on the ventilator as follo 49
Box 3.4 Respiratory System Compliance 49
3.3.2 .Dynamic Compliance 50
Box 3.5 Calculation of Dynamic Compliance in the Ventilated Patient 52
3.4 .Airway Resistance 52
Box 3.6 Calculation of Airflow ResistanceThe resistance to airflow can be expressed by dividing the driving force by the flow 55
Box 3.7 Calculation of Airway Resistance (.R..aw.) in a Ventilated Patient...R..aw. = .P..pk. – .P..pl./V..,where.P..pk..=.p 56
3.5 .Time Constants of the Lung 56
Box 3.8 Time Constants of the LungExample:A lung unit with a normal airway resistance of 1 cm H.2.O/L/s and a normal complia 57
3.6 .Alveolar Ventilation and Dead-Space 57
3.6.1 .Anatomical Dead-Space 58
3.6.2 .Alveolar Dead-Space 58
3.6.3 .Physiological Dead-Space 58
3.7 .Mechanisms of Hypoxemia 64
3.7.1 .Hypoventilation 64
3.7.2 ..V./.Q. Mismatch 68
3.7.3 .Right to Left Shunt 70
Box 3.9 The Shunt Equation 71
3.7.4 .Diffusion Defect 72
3.8 .Hemodynamic Effects 73
Box 3.10 Transmission of Alveolar Pressure to the Pleural Space 77
3.9 .Renal Effects 78
3.10 .Hepatobiliary and Gastrointestinal Effects 80
3.10.1 .Hepatobiliary Dysfunction 80
3.10.2 .Gastrointestinal Dysfunction 81
References 81
164921_2_EN_04_Chapter_OnlinePDF.pdf 88
The Conventional Modes of Mechanical Ventilation 88
4.1 .Mechanical Ventilators 88
4.1.1 .Open-Loop and Closed-Loop Systems 89
4.1.2 .Control Panel 89
4.1.3 .Pneumatic Circuit 90
4.1.3.1 .The Internal Circuit 90
4.1.3.2 .The External Circuit 90
4.1.4 .The Expiratory Valve 90
4.1.4.1 .Phases of the Respiratory Cycle 91
Box 4.1 The Four Phases of the Respiratory Cycle 91
4.1.5 .Variables 91
4.1.5.1 .Control Variables 91
4.1.5.2 .Phase Variables 92
4.1.6 .The Trigger Variable (“Triggering” of the Ventilator) 92
4.1.7 .Limit Variable 93
4.1.8 .Cycle Variable 93
4.1.8.1 .Volume-Cycled Breath 93
4.1.8.2 .Flow-Cycled Breath 94
4.1.8.3 .Time-Cycled Breath 95
4.1.8.4 .Pressure-Cycled Breath 95
4.1.9 .Baseline Variable 95
4.1.10 .Inspiratory Hold 96
4.1.11 .Expiratory Hold and Expiratory Retard 96
4.2 .Volume-Targeted Modes 97
4.2.1 .Volume Assist-Control Mode (ACMV, CMV) 97
Box 4.2 Assist Control 101
4.3 .Intermittent Mandatory Ventilation 101
4.4 .Pressure–Support Ventilation 106
4.5 .Continuous Positive Airway Pressure 111
4.6 .Bilevel Positive Airway Pressure 114
4.7 .Airway Pressure Release Ventilation (APRV) 114
4.7.1 ..B.i.-PAP 115
4.8 .Pressure-Controlled Ventilation 115
4.8.1 .Proportional Assist Ventilation (PAV) 118
4.9 .Dual Breath Control 119
4.9.1 .Intrabreath Control 119
4.9.1.1 .Syn: Dual Control Within a Breath (DCWB) 119
4.9.2 .Interbreath (DCBB) Control 120
4.9.3 .Pressure Regulated Volume Control (PRVC) 120
4.9.4 .Automode 123
4.9.5 .Mandatory Minute Ventilation (MMV) 124
4.9.6 .Volume Support (VS) 125
4.9.7 .Adaptive Support Ventilation.10. (ASV) 126
References 127
164921_2_EN_05_Chapter_OnlinePDF.pdf 131
Ventilator Settings 131
5.1 .Setting... the Tidal Volume 131
5.1.1 .Volume-Targeted Ventilation 131
5.1.2 .Pressure-Targeted Ventilation 132
5.2 .Setting the Respiratory Rate 133
5.3 .Setting the Flow Rate 134
5.4 .Setting the Ratio of Inspiration to Expiration (I:E Ratio) 135
5.5 .Setting the Flow Profile 138
5.5.1 .The Square Waveform 138
5.5.2 .The Decelerating Waveform 139
5.5.3 .The Accelerating Waveform 139
5.5.4 .The Sine Waveform 139
5.6 .Setting the Trigger Sensitivity 139
5.7 .Setting PEEP 140
5.7.1 .Improvement in Oxygenation 140
5.7.2 .Protection Against Barotrauma and Lung Injury 141
5.7.3 .Overcoming Auto-PEEP 142
5.8 .Indications for PEEP 143
5.9 .Forms of PEEP 143
5.10 .Titrating PEEP 143
5.10.1 .Other Advantages of PEEP 146
5.10.2 .Disadvantages of PEEP 147
5.11 .Optimizing Ventilator Settings for Better Oxygenation 147
5.11.1 .Increasing the FIO.2 147
5.11.2 .Increasing the Alveolar Ventilation 148
5.12 .PEEP 148
5.12.1 .Flow Waveforms 148
5.12.2 .Inspiratory Time 149
5.12.3 .Inverse Ratio Ventilation 149
5.12.4 .Prone Ventilation 150
5.12.5 .Reducing Oxygen Consumption 150
5.12.6 .Increasing Oxygen Carrying Capacity 150
5.12.7 .Footnote 151
Box 5.1 The Open Lung Concept 151
References 152
164921_2_EN_06_Chapter_OnlinePDF.pdf 157
Ventilator Alarms 157
6.1 .Low... Expired Minute Volume Alarm 157
6.2 .High Expired Minute Volume Alarm 159
6.3 .Upper Airway Pressure Limit Alarm 160
6.4 .Low Airway Pressure Limit Alarm 162
6.5 .Oxygen Concentration Alarms 162
6.6 .Low Oxygen Concentration (FIO.2.) Alarm 162
6.7 .Upper Oxygen Concentration (FIO.2.) Alarm 163
6.8 .Power Failure 163
6.9 .Apnea Alarm 163
Box 6.1 Lack of Triggering 163
6.10 ....Two-Minute Button 164
References 164
164921_2_EN_07_Chapter_OnlinePDF.pdf 165
Monitoring Gas Exchange in the Mechanically Ventilated Patient 165
7.1 .The Arterial Oxygen Tension 165
7.2 .Pulse Oximetry 172
7.2.1 .Principle of Pulse Oximetry 176
7.3 .Transcutaneous Blood Gas Monitoring 185
7.4 .Monitoring Tissue Oxygenation 187
7.4.1 .Oxygen Extraction Ratio and DO.2 crit 188
7.5 .Capnography 191
References 199
164921_2_EN_08_Chapter_OnlinePDF.pdf 204
Monitoring Lung Mechanics in the Mechanically Ventilated Patient 204
8.1 .Ventilator Waveforms 204
8.2 .Scalars 205
8.2.1 .The Pressure–Time scalar 205
8.2.1.1 .Airway Pressures 205
Peak Airway Pressures 205
Plateau Pressures 205
Mean Airway Pressure 206
Lung Compliance 206
8.2.2 .Flow-Time Scalar 211
8.2.3 .Volume–Time Scalar 215
8.3 .The Loops 218
8.3.1 .Pressure–Volume Loop 218
8.3.2 .The Flow–Volume Loop 230
8.4 ....Patient-Ventilator Asynchrony 238
8.4.1 .Level of Ventilator Support and Work of Breathing 238
8.4.2 .Complete Support 239
8.4.3 .Partial Support 239
8.4.4 .Patient-Ventilator Asynchrony 240
Box 8.1 Causes of Patient-Ventilator Asynchrony 240
8.4.5 .Triggering Asynchrony 241
8.4.5.1 .Response Time 241
8.4.5.2 .Type of Trigger 242
8.4.5.3 .Ineffective Triggering 242
8.4.6 .Flow Asynchrony 242
8.4.6.1 .Expiratory Asynchrony 246
Delayed Termination of Ventilator Flow 246
Premature Termination of Ventilator Flow 247
Asynchrony Due to Auto-PEEP 248
Measuring Auto-PEEP 251
References 253
164921_2_EN_09_Chapter_OnlinePDF.pdf 256
Mechanical Ventilation in Specific Disorders 256
9.1 .Myocardial Ischemia 256
9.2 .Hypovolemic Shock 259
9.3 .Neurological Injury 260
9.4 .Acute Respiratory Distress Syndrome (ARDS) 263
9.4.1 .Primary and Secondary ARDS 264
9.4.2 .Pathophysiology 265
9.4.3 .Ventilatory Strategies 267
9.4.3.1 .Modes of Ventilation 267
9.4.3.2 .Tidal Volumes 268
9.4.3.3 .Airway Pressures 268
9.4.3.4 .Respiratory Rate 269
9.4.3.5 .Flow Waveforms 269
9.4.3.6 .PEEP 270
9.4.3.7 .Overdistension 271
9.4.3.8 .Inspiratory Time 274
9.4.3.9 .Inverse Ratio Ventilation 274
9.4.3.10 .Recruitment Maneuvers 275
9.4.3.11 .Permissive Hypercapnia 276
9.4.3.12 .Prone Ventilation 278
Box. 9.1 The Starling Equation 265
Box. 9.2 Physiological Effects of Hypercapnia 277
Box. 9.3 Relative Contraindications to the Use of Permissive Hypercapnia 280
9.5 .Obstructive Lung Disease 281
9.5.1 .PaCO.2 283
9.5.2 .Modes of Ventilation in Obstructed Patients 284
9.5.3 .Ventilator Settings in Airflow Obstruction 287
9.5.3.1 .Tidal Volume 287
9.5.3.2 .Respiratory Rate 288
9.5.3.3 .Inspiratory Flow Rate 288
9.5.3.4 .Trigger Sensitivity 290
9.5.3.5 .External PEEP 290
9.5.3.6 .NIV 290
9.5.3.7 .General Principles of Treatment in Asthma and COPD 291
9.5.3.8 .FIO.2 291
9.5.3.9 .ET Size 291
9.5.3.10 .Permissive Hypercapnia 292
9.5.3.11 .General Anesthesia 292
9.5.4 .Bronchopleural Fistula 293
Box. 9.4 The Hyperventilating Patient on Assist-Control Mode with a Low Backup Rate Runs the Risk of Over Distending His Lungs. 289
9.6 .Neuromuscular Disease 294
9.6.1 .Lung Function 297
9.6.2 .Inspiratory Muscle Recruitment in Neuromuscular Disease 299
9.6.3 .Expiratory Muscle Recruitment in Neuromuscular Disease 299
9.6.4 .Bulbar Muscles Involvement in Neuromuscular Disease 300
9.6.5 .Assessment of Lung Function 301
9.6.6 .Mechanical Ventilation in Neuromuscular Disease 301
Box. 9.5 Respiratory Morbidity Associated with Chest Trauma 298
Box. 9.6 Assessing the Adequacy of Cough 300
9.7 .Nonhomogenous Lung Disease 303
9.8 .Mechanical Ventilation in Flail Chest 304
References 305
164921_2_EN_10_Chapter_OnlinePDF.pdf 320
The Complications of Mechanical Ventilation 320
10.1 .Peri-Intubation Complications 321
10.1.1 .Laryngeal Trauma 321
10.1.2 .Pharyngeal Trauma 321
Box 10.1 Complications Related to Pharyngeal Trauma 322
10.1.3 .Tracheal or Bronchial Rupture 322
10.1.4 .Epistaxis 322
10.1.5 .Tooth Trauma 323
10.1.6 .Cervical Spine Injury 323
10.1.7 .Esophageal Intubation 324
10.1.8 .Esophageal Perforation 325
10.1.9. Right Main Bronchial Intubation 325
10.1.10 .Arrhythmias 326
10.1.11 .Aspiration 327
10.1.12 .Bronchospasm 327
10.1.13 .Neurologic Complications 327
10.2 .Problems Occurring Acutely at any Stage 327
10.2.1 .Endotracheal Tube Obstruction 328
10.2.2 .Airway Drying 328
10.2.3 .Upward Migration of the Endotracheal Tube 329
10.2.4 .Self-Extubation 329
10.2.5 .Cuff Leak 330
10.2.5.1 .Dynamic Hyperinflation 330
Box 10.2 Too Little Time to Exhale 333
10.2.6 .Ventilator-Associated Lung Injury (VALI) and Ventilator-Induced Lung Injury (VILI) 333
10.2.6.1 .Barotrauma 333
10.3 .Delayed Complications (Fig. ..10.5..) 337
10.3.1 .Sinusitis 337
10.3.2 .Tracheoesophageal Fistula 338
10.3.2.1 .Cuff Pressures 340
10.3.3 .Tracheoinnominate Artery Fistula 340
10.3.4 .Tracheocutaneous Fistula 341
10.4 .Oxygen-Related Lung Complications 342
10.4.1 .Tracheobronchitis 343
10.4.2 .Adsorptive Altelectasis 343
10.4.3 .Hyperoxic Hypercarbia 344
10.4.4 .Diffuse Alveolar Damage 347
10.4.5 .Bronchopulmonary Dysplasia 348
10.4.6 .Ventilator-Associated Pneumonia 348
References 349
164921_2_EN_11_Chapter_OnlinePDF.pdf 357
Ventilator-Associated Pneumonia 357
11.1 ....Incidence 359
11.2 .Microbiology 359
11.3 .Risk Factors 361
11.3.1 .The Physical Effect of the Endotracheal Tube 361
11.3.2 .Alteration of Mucus Properties 362
11.3.3 .Microaspiration 363
11.3.4 .Biofilms 363
Box 11.1 The Endotracheal Tube and Lower Respiratory Tract Infection 364
Box 11.2 Pathologic Mechanisms in Sinusitis 367
Box 11.3 Serious Complications of Sinusitis.2..,..149 368
Box 11.4 Technique of Broncho-Alveolar Lavage (BAL) 373
Box 11.5 Primary Host-Related Risk Factors for MDR Infection.1 381
11.3.5 .Ventilator Tubings 364
11.3.6 .Gastric Feeds 365
11.3.7 .Sinusitis 366
11.3.8 .Respiratory Therapy Equipment 368
11.4 .Position 368
11.5 .Diagnosis of VAP 369
11.5.1 .Sampling Methods 371
11.5.2 .Interpretation of the Sample 372
11.6 .Prevention of NP/VAP 374
11.6.1 .Hand-Washing 374
11.6.2 .Feeding and Nutrition 375
11.6.3 .Stress Ulcer Prophylaxis 376
11.6.4 .Topical Antibiotics 376
11.7 .Interventions Related to the Endotracheal Tube and Ventilator Circuit 377
11.8 .Treatment of Nosocomial Sinusitis 378
11.9 .Treatment 379
11.9.1 .Antibiotic Resistance 379
11.9.2 .Pharmacokinetics 382
11.9.3 .Duration of Therapy 385
11.9.4 .Lack of Response to Therapy 387
11.9.5 .Drug Cycling 388
References 390
164921_2_EN_12_Chapter_OnlinePDF.pdf 404
Discontinuation of Mechanical Ventilation 404
Box 12.1 The Effect of Sleep Deprivation on the Weaning Process 406
12.1 .Weaning Parameters 406
12.2 .Parameters that Assess Adequacy of Oxygenation 407
12.2.1 .The PaO.2.:FIO.2. Ratio 408
12.2.2 .The A-a DO.2. Gradient 409
12.2.3 .The PaO.2./PAO.2. Ratio 409
12.3 .Parameters that Assess Respiratory Muscle Performance 409
12.3.1 .PI.max 409
12.3.2 .Vital Capacity 410
12.3.3 .Minute Ventilation 411
12.3.4 .Respiratory Rate 411
12.4 .Parameters that Assess Central Respiratory Drive 412
12.4.1 .Airway Occlusion Pressure 412
12.4.2 .Mean Inspiratory Flow (V.t../T.i.) 412
12.5 .Respiratory System Compliance and Work of Breathing 413
12.5.1 .Work of Breathing 413
12.5.2 .Compliance of the Respiratory System 414
12.6 .Integrative Indices 414
12.6.1 .Simplified Weaning Index (SWI) 416
Box 12.2 Simplified Weaning Index (SWI) 416
Box... 12.3. The Compliance, Rate, Oxygenation, and Pressure (CROP) Index 417
Box 12.4 Pressure-Time Product (PTI) 417
12.7 .Methods of Weaning 417
12.7.1 .Trials of Spontaneous Breathing (T-Piece Weaning) 418
12.7.2 .Synchronized IMV 419
12.7.3 .Pressure Support Ventilation (PSV) 420
12.7.4 .Noninvasive Positive Pressure Ventilation (NIPPV) 422
12.7.5 .Extubation 422
Box 12.4 Technique of Extubation 423
References 424
164921_2_EN_13_Chapter_OnlinePDF.pdf 428
Noninvasive Ventilation in Acute Respiratory Failure 428
13.1 .NIV... and CPAP 428
13.2 .Mechanism of Action 428
13.2.1 .Interface 431
13.2.2 .Modes 433
13.2.3 .Devices 434
13.2.4 .Humidification with NIV (see also Chap.... 15) 435
13.3 .Air Leaks 435
Box 13.1 Advantages of NIPPV 437
Box 13.2 Disadvantages of NIPPV 437
13.4 .Indications for NIV 437
13.4.1 .Hypoxemic Respiratory Failure 437
13.4.2 .Hypercapnic Respitatory Failure 439
13.4.2.1 .COPD Exacerbation 439
13.4.2.2 .Decompensated Obstructive Sleep Apnea 440
13.4.3 .Miscellaneous Indications 440
13.4.3.1 .Weaning 440
13.4.3.2 .Acute Respiratory Failure in Immunocompromised Patients 440
13.4.3.3 .Extubation Failure 441
13.4.3.4 .Bronchoscopy in the ICU 441
13.4.4 .Steps for the Initiation of NIV 441
13.4.5 .Complications 442
13.4.5.1 .Skin Ulceration 443
13.4.5.2 .Gastric Distension 443
13.4.5.3 .Otalgia 443
13.4.5.4 .Eye Irritation 444
13.4.5.5 .Hemodynamic Compromise 444
13.4.5.6 .Barotrauma 444
13.4.5.7 .Asphyxiation with Aspiration 444
13.4.5.8 .Monitoring 445
13.4.6 .Contraindications 445
13.4.7 .Outcomes 445
Box 13.3 Predictors of Failure with NIPPV 446
References 446
164921_2_EN_14_Chapter_OnlinePDF.pdf 454
Negative Pressure Ventilation 454
14.1 .Tank Ventilator (Iron Lung) 455
14.2 .The Body Suit (Jacket Ventilator, Poncho-Wrap, Pulmo-Wrap) 455
14.3 .Chest: Shell (Cuirass) 456
14.4 .Modes of Negative Pressure Ventilation 457
14.5 .Drawbacks of NPV 458
References 459
164921_2_EN_15_Chapter_OnlinePDF.pdf 462
Airway Humidification in the Mechanically Ventilated Patient 462
15.1 .The ...Role of the Nasal Mucosa 462
15.2 .The Isothermic Saturation Boundary 462
Box 15.1 Water Losses 463
15.3 .The Effect of the Endotracheal Tube 463
15.3.1 .Overheated Air 464
Box 15.2 The Consequences of Overcondensation (“Raining Out”) 465
15.4 .Heated Humidifiers 466
15.5 .Heat-Moisture Exchangers (HMEs) 467
15.6 .Airway Humidification During Noninvasive Ventilation 469
References 470
164921_2_EN_16_Chapter_OnlinePDF.pdf 475
Aerosol Therapy in the Mechanically Ventilated Patient 475
16.1 ....Terminology 475
16.2 .The Behavior of Particles 476
16.3 .Devices for Aerosol Delivery 476
16.3.1 .Jet Nebulizers (Syn: Pneumatic Nebulizers) 476
16.3.2 .Ultrasonic Nebulizers 480
16.3.3 .Vibrating Mesh Nebulizers (VMNs) 481
16.3.4 .Nebulization in the Ventilated Patient 481
16.3.5 .Nebulization of Other Drugs 483
16.3.6 .Pressurized Metered-Dose Inhalers (MDIs) 483
References 485
164921_2_EN_17_Chapter_OnlinePDF.pdf 491
Nonconventional Modes and Adjunctive Therapies for Mechanical Ventilation 491
Box 17.1 Inverse Ratio Ventilation 491
17.1 .High-Frequency Ventilation 492
17.2 .High-Frequency Positive Pressure Ventilation (HFPPV) 494
17.3 .High-Frequency Jet Ventilation (HFJV) 494
17.4 .High-Frequency Oscillatory Ventilation (HFOV) 496
17.5 .High-Frequency Percussive Ventilation (HFPV) 497
17.6 .Extracorporeal Life Support (ECLS) 498
17.6.1 .Extracorporeal Membrane Oxygenation (ECMO) 498
17.6.1.1 .VA-ECMO (Veno-Arterial Bypass) 498
17.6.1.2 .VV-ECMO (Veno-Venous Bypass) 499
17.6.2 .Extracorporeal CO.2. Removal 499
17.6.3 .Indications for ECLS 499
17.6.4 .Contraindications to ECLS 500
17.7 .Nitric Oxide 500
Box 17.2 Functions of Endogenous Nitric Oxide 502
Box 17.3 Side Effects of Inhaled Nitric Oxide.31 503
17.8 .Surfactant Therapy 503
Box 17.4 LaPlace’s Law 504
17.9 .Helium–Oxygen Mixtures 505
Box 17.5 Determinants of the Reynold Number 506
17.10 .Liquid Ventilation 506
17.10.1 .Total Liquid Ventilation 508
17.10.2 .Partial Liquid Ventilation 508
17.11 .NAVA 509
17.12 .Conclusion 509
References 510
164921_2_EN_18_Chapter_OnlinePDF.pdf 516
Case Studies 516
18.1 .Case 1 516
18.2 .Case 2 519
18.3 .Case 3 521
18.4 .Case 4 522
18.5 .Case 5 523
18.6 .Case 6 524
18.7 .Case 7 527
18.8 .Case 8 528
18.9 .Case 9 529
18.10 .Case 10 531
18.11 .Case 11 533
18.12 .Case 12 534
164921_2_EN_Index_Chapter_OnlinePDF.pdf 537
Index 537