Critical Care Update 2021 Deepak Govil, Subhal Bhalchandra Dixit, Dhruva Chaudhry, Subhash K Todi
INDEX
Page numbers followed by b refer to box, f refer to figure, fc refer to flowchart, and t refer to table.
A
Abscess, epidural 287
Acetaminophen 331, 333
poisoning 333
Acid-base
Calculations
formulae for 242t
principles of 242t
disorders 235
equilibrium, disarray of 242
Acidemia, correction of 108
Acidosis 6
metabolic 235, 242
severe 366
Acinetobacter baumannii 53, 129
Acquired immunodeficiency syndrome 151, 178
Activated partial thromboplastin time 230, 232, 369
Acute exacerbation 28, 32, 32f
management of 32
Acute ischemic score management 255fc
Acute kidney injury 19, 20, 98, 143, 144, 161, 168, 173175, 199, 219, 225, 225t, 226, 230, 234, 234, 331, 345
diagnosis of 173
drug-induced 173, 217, 218, 218t, 220
incidence of 225
management of 173, 175
network 173, 174, 225
prevalence of 225
sepsis-associated 98
staging of 225
transfusion-related 310
Acute respiratory distress syndrome 4, 6, 10, 18, 19, 19t, 23, 35, 43, 48, 143, 144, 151, 270, 293, 298, 333, 344, 345, 364, 397
pathophysiology of 23
Acyclovir 217, 218
Addison's disease 246
Adenoidectomy 321
Adenosine triphosphate 256
Adenovirus 178, 369
Advanced cardiovascular life support 103, 257
Agitation 6
Air
aspiration of 384
embolism 73, 117
detection of 383t
iatrogenic 382
risk of 382t
signs in 383t
symptoms in 383t
types of 382
hunger 300
Airspace consolidation 31
Airway 384
infected congenital cysts of 12
occlusion pressure 5, 40f
pressure 7, 43, 44
Alberta Stroke Program Early Computed Tomography Score 250
Albumin dialysis 331, 332
Alcohol
dehydrogenase 332
intoxication 366
skin preparation 386
Aldehyde dehydrogenase 332
Alkalosis, metabolic 235, 242
Allergic reaction 321
Alveolar macrophages 130
Alveolar pressure 43
Alveolar proteinosis, pulmonary 31
American College of Chest Physicians 13
American College of Physicians 411
American College of Rheumatology Guidance 304
American Diabetes Association 411
American European Consensus Conference 18
American Heart Association 66, 103, 254, 258, 353, 411
American Society for Parenteral and Enteral Nutrition 155, 160
American Society of Anesthesiologists 117
American Society of Regional Anesthesia 286
American Stroke Association 254
American Thoracic Society and School of Critical Care Medicine 18
Amiloride 246
Aminocaproic acid 267
Aminoglycosides 217, 218, 260, 261, 344
Amiodarone 103
Amitriptyline 366
Ammonia production 235
Ammonium 235
Amphotericin B 217, 244, 296
colloidal dispersion 150
lipid complex 150
Ampicillin 218
Amygdala 380
Amyloidosis 243, 244
Anaconda device parts 272f
Analgesia
adequate 36
regional 286
Analgesics 316
Anecdotal reports 300
Anemia 221, 369, 396, 397, 399
causes for 396
treatment goals of 397
Anesthesia
monitoring 317
neuraxial 117
technique 317
thoracic epidural 288
Anesthetic conserving device 272
Aneurysm rupture 365
Angiotensin 11 111
converting enzyme 29, 86, 173, 293, 299
deficiency 110
inhibitors 86, 217, 218, 246
receptor blockers 86, 217, 218
receptor-neprilysin inhibitor 87
Anoxia, cerebral 365
Antibiotics 14, 260, 261, 304
dosing of 63
intransigence, economic hardship of 147
neurotoxic effect of 260t
prophylactic 283
systemic 14
therapy, intravenous 239
Antibody
bispecific 407
dependent enhancement 301, 310
monoclonal 331, 407
testing 263
Anticancer drugs 407t
Anticholinergics 316
Anticoagulants monitoring 232t
Anticoagulation 79, 305
Anticonvulsant therapy 264
Anticyclic citrullinated peptide 29
Antidiuretic hormone 236
Antifibrinolytic agents 266
Antifibrinolytic drugs 266, 267t
Antifungal agent 150, 218
choice of 183
Antifungal stewardship 137, 147, 148t, 152
checklist for 138b
program, need of 147
team
core members of 148f
role of 147
Antifungal strategy 148
Antifungal susceptibility testing 151
Antifungal therapy 148
Antiglomerular basement membrane antibodies 402
Antihypertensive drugs 86
effects of 86t
therapeutic effects of 87t
Anti-inflammatory cytokines 141, 142
Anti-inflammatory immunomodulatory effects 309f
Antimacrophage inhibitory factor 144
Antimicrobial stewardship 148t, 328
Antimicrobial therapy, duration of 14
Antimyeloperoxidase 29
Antineutrophil cytoplasmic antibody 29, 400
Antinuclear antibody 29, 402
Antiplatelet therapy 305
Antipsychotics 318, 381
Antiseptic 386
Anti-tumor necrosis factor-alpha 144
Anxiety 25
Aorta 77
Aortic blood flow 89
Aortic diastolic pressure 369
Aortic valve 78
Aortic velocity-time integral 74
Apheresis 332
Apnea test 366
indeterminate 367
negative 367
performance of 367
steps in 367
timing of 367
troubleshooting during performance of 367t
Apotransferrin 397
Aprotinin 267
Arginine vasopressin 234
Armed Forces Organ Retrieval and Transplantation Authority 281
Arrhythmias 73, 371
Arterial air embolism 382
Arterial blood gas 30, 333, 372
analysis 367, 384
Arterial carbon dioxide, partial pressure of 273, 299
Arterial elastance 91, 92
Arterial thrombosis, acute 321
Arthralgia 144
Arthritis 144
systemic juvenile idiopathic 144
Artificial intelligence 343, 345
uses of 343
Asbestosis 28
Ascending reticular activating system 55
Ascites 144
international club of 174fc
Ascitic fluid lactic dehydrogenase 183
Ascorbic acid 107, 108
Aspergillosis 293
allergic bronchopulmonary 150
invasive pulmonary 150, 293
Aspergillus 150
flavus 150
fumigatus 150, 293
infections 294
niger 150
Asphyxia, neonatal 353
Asphyxiation 365
Aspiration 11, 384
Aspirin 304
Association of Anaesthetists of Great Britain and Ireland 286
Asthma 402
Atmospheric pressure 43
Atrial fibrillation 86
Atrial stiffness 85
Austrian Society for Anaesthesiology, Resuscitation and Intensive Care 323
Autoimmune diseases 222
Autonomic dysfunction 265
Auto-positive end-expiratory pressure 39
Autosomal dominant 243, 244
Autosomal recessive 243, 244
Axillary temperature measurements 353
Axitinib 407
Azathioprine 32, 264
Azithromycin 179
B
Bacteremia, spontaneous 173
Bacteria 178
intestinal 179
Barbiturates 332
Barotrauma 11, 47, 382
Baydur test 44
Behavioral pain scale 286
Benzodiazepines 26, 318, 381
Beta-blockers 246, 332
Beta-D-glucan 138, 148
Beta-lactams 217
Bevacizumab 407
Bicarbonate reabsorption 235
Bickerstaff encephalitis 263
Bioelectrical impedance analysis 163, 164
Biopsy 150
role of 32
Biotrauma 47
Bladder 316
Blastocystis hominis 178
Bleeding 32, 69, 73
bronchial 321
control of 320
gastrointestinal 322
intraoperative 316
mucosal 221
reversal of drug-induced 322, 324
Blinatumomab 144, 407
Blind bronchial sampling 52
B-line scoring 199t
Blood
brain barrier 333
cells 221
C-reactive protein 155
cultures 135, 179
glucose, monitoring 412
investigations 29
pressure 86, 87, 374
diastolic 118
low 90
measurements 117
monitoring 79, 116
noninvasive 372
sudden drop of 321
systolic 282, 366, 367, 369, 372
purification, extracorporeal therapy for 109
stream infection 349
test monitoring, frequency of 233t
transfusion 397
vessels, morphology of 251
volume, central redistribution of 369
Bloodstream infection, central line associated 344
Blunt trauma 12
Body
fluids, microbiological cultures of 303
mass index 73, 374
muscle mass 163
Bolus injections 286
Bone morphogenetic protein 398
Booster training 105
Bradycardia 369
Bradypnea 333
Brain 95, 249, 256, 352
activity of 55
computed tomography of 384
damage, hypoxic-anoxic 256
death 73, 365, 367, 369, 415
causes for 365t
certification, legal aspects of 368
determination of 365
diagnosis of 368t
natriuretic peptide 93
stem
death, donation after 281
encephalitis 366
function, absence of 366
tumors 365
Breath, shortness of 402
Breathing 384
control of 57
effort 4
pattern 4
spontaneous 35, 36f, 37
work of 40, 41f, 45
Bretylium, high-dose 366
British Thoracic Society 33
Broad-spectrum
antibiotic 304
vasopressors 107
Bronchoalveolar lavage 2931, 33, 52, 136, 148
role of 31
B-type natriuretic peptide 303
Burn 313, 327
injury 327, 327f
wound infection
diagnosis of 328
surveillance 328
C
Cadaveric organs, optimizing quality of 282
Caffeine 331
Calcium 158
channel blockers 180
monitoring 233
serum 29
supplementation 108
urinary 29
Calories 160
Camera-equipped feeding tube 168
Campylobacter jejuni 180
Canadian Diabetic Association 411
Cancer therapy 407
Candida
albicans 138, 149, 239
auris 134, 139, 149
infection 133
krusei 149
nonalbicans 149
parapsilosis 137, 138
Candidemia
diagnosis of 133, 134
management of 133, 135t, 136
risk factors for 134
Candidiasis, COVID-19-associated 134
Capillary leak 144
Capillary refill time 96
Carbamazepine 218, 261, 331, 332
Carbapenem 260
resistant enterobacteriaceae 53
Carbohydrate 158
Carbon dioxide 6, 7, 239
raised partial pressure of 3
Carbon monoxide 24
poisoning 365
Carbonic anhydrase deficiency 243
Cardiac
arrest 67, 67f, 103105, 353, 365
primary 365
survivors 104
critical care 345
death, donation after 281
decompensation 208
dysfunction, echocardiographic evidence of 369
failure 402
function 304
index 97
magnetic resonance imaging 85, 345
output 372
resynchronization therapy 87
surgery 322, 324
system 403
toxicities 410
Cardiomyopathy 144
ischemic dilated 86
Cardiopulmonary bypass machine 77
Cardiorenal syndrome 113
Cardiovascular disease 217
Cardiovascular management 283, 370
Cardiovascular system 374
Care, bundles of 283, 283t
Caspofungin 64
Catecholamine 56
storm 369
Catheter 316
placement and measurement 43
site selection 349
Caudate nucleus 250
Cefatroline 131
Cefotaxime 64
Ceftobiprole 131
Cellular therapy 410
Centers for Disease Control and Prevention 293, 302t, 350
Central nervous system 303, 333, 344, 345, 408
dysfunction 73
infection 151
toxicities 408
Central venous catheter 135, 316, 385, 386
removal of 136
Central venous oxygen saturation 96
Central venous pressure 88, 283, 284, 372, 384
Cephalosporins 218, 260
Cerebellitis 263
Cerebral artery occlusion 252f
Cerebral blood
flow 253, 254, 256
volume 254
Cerebral oxygen delivery 256
Cerebrospinal fluid 148, 257
analysis 263
Cerebrovascular accident 263, 323
Cervical cord injury 366
Cervix, conization of 321
Chapel Hill classification 400, 401f
Chapel Hill conference 401t
Chest
compressions 384
computed tomography
imaging of 24
scans 209
congestion 113
contrast-enhanced computed tomography of 13
high-resolution CT imaging of 24
point of care ultrasonography of 192
radiograph 303, 384
trauma 287
penetrating 12
ultrasound 13, 141f
X-ray 13, 24, 30, 79f, 403f
Chimeric antigen receptor 407
Chlamydia
pneumonia 130
trachomatis 178
Chlorhexidine 386, 386t, 387, 387b
oral hygiene 386
Cholestasis 144
Choriocarcinoma 369
Chronic obstructive pulmonary disease 9, 40, 293, 331
Churg-Strauss syndrome 400, 402, 405
Ciprofloxacin 218, 260
Circulation 384
Cirrhosis 174fc, 175fc, 182
primary biliary 244
Cisplatin 217
Clarithromycin 179
Clinical autoimmune syndromes 262
Clinical thermometers, types of 352
Clonidine 56
Clostridium difficile 130, 178, 180, 353
infections 344
Coagulation
abnormalities 78
profile 303
status 286
Coagulopathy 144
Cocaine 331
Cognitive behavioral therapy 381
Cognitive processing therapy 381
Cold caloric tests, procedure for 366
Collapse, acute 206
Colonization 327
Colony forming unit 52
Color vision, disturbances of 321
Coma
proximate cause of 365
reversible causes of 366t
Common primary vasculitides disorders, clinical presentations of 402t
Communications 341
interdepartmental 340
nonverbal 340
skills 339
Community-acquired infection 13, 129, 131
Complete blood count 303
Complex parapneumonic effusion 12
Complex pleural effusion 12b, 16
complications of 16
management of 12
Compressions plus ventilation 104
Computed tomography 13, 30, 155, 249, 250, 253255
angiogram 251, 251f, 254
angiography 345
perfusion 252, 254
imaging 252
pulmonary angiography 30
scan 20, 163, 167, 295, 323
Confusion 144
assessment method 317
Connective tissue diseases 2830
Continuous flow pumps 78, 79
Continuous glucose monitoring 412
Continuous positive airway pressure 6, 7, 9, 40, 367
Continuous renal replacement therapy 109, 230233, 331, 348
Control arterial pressure 116
Convalescent plasma 307, 309f
donors 309
therapy 307
adverse effects of 310
Copeptin, measurement of 416
Cor pulmonale, acute 205, 206f
Corneal reflex 366
Coronary syndrome, acute 411
Coronavirus disease 2019 10, 21, 29, 63, 221, 294, 302, 303, 307, 308, 340
associated pulmonary aspergillosis 293
infection 301
pandemic 134, 147, 143, 203, 209
Coroners’ consent 368
Corticosteroids 264, 304
Corticotropin stimulation test 415
Cortisol 107
Cough reflex 366
COVID-19 disease 10, 21, 63, 64, 134, 143, 144, 204, 209, 210, 212, 222, 223, 297, 298, 300303, 308, 310, 378, 405
associated pulmonary aspergillosis 293, 296
infection 143, 298, 301, 309
lung ultrasound in 209
management of 123
pandemic 134, 143, 147, 203, 209, 340, 346, 376, 378
pneumonia 212, 294
management of 212
severe 10
transmission of 10
Cranial nerve 256
involvement 263
C-reactive protein 62, 303, 309
Creatine phosphokinase 257
Creutzfeldt Jacob's disease 263
Crisis, acute 28
Critical care
nutrition, biomarkers in 168
outreach team 391
pain observation tools 286
pharmacist 357
radiology 346
Crural diaphragm, electrical activity of 5
Cryoglobulinemia 222, 244
Cryptic infections 182
Cryptosporidiosis 179
Cryptosporidium 179
Crystal nephropathy 218
Cushing's reflex 369
Cushing's syndrome 235
Cyclophosphamide 264
Cyclosporine 246
Cystic disease, medullary 243
Cystinosis 243
Cystitis, emphysematous 238
Cystoisospora belli 178
Cytokine 141
blockade 141, 144
cascade 141
function 141
inflammatory 369
peripheral inflammatory response of 141
proinflammatory 141
release syndrome 408
storm 141, 143
clinical features of 144t
laboratory abnormalities of 144t
syndrome, treatment of 145t
types 141
Cytomegalovirus 64, 178, 409
esophagitis 346
infection 179
Cytopenia 144
D
Damage associated molecular pattern 123, 294
Darbepoetin alpha 398
Data monitoring committee 310
Deafness 244
Deep venous thrombosis 259, 375
prophylaxis for 405
Deferoxamine therapy 150
Delafloxacin 129
Delirium 144, 271, 315, 317, 318
screening tools for 317
types of 315
writing test 318
Delusional memories, development of 379
Dementia 315
Dental extractions 321
Depression 25
myocardial 117
De-resuscitation protocol 201fc
Destination therapy 77
Dexmedetomidine 317, 318
Diabetes insipidus 369, 372, 414, 415
adipsic 417
central 414, 416
nephrogenic 414
Diabetes mellitus 150, 217, 238, 246, 411
Diaphragm
assessment of 188, 189f
sonography, limitations of 189
thickness fraction 188
ultrasound of 188, 207
Diaphragmatic dysfunction 208
Diarrhea 144, 178, 180, 302, 321
diagnostic management of 180
drug-induced 178
Diastolic dysfunction 190
Doppler echocardiographic measurements for 190
Diffusion-weighted imaging 249, 250, 250f, 253255
Digital rectal examination 353
Dihydropyridine 180
calcium antagonists 86
Dihydroxycholecalciferol 124
Diphtheria, management of 307
Disseminated intravascular coagulation 143, 322, 405
Distal renal tubular acidosis, causes of 244t
Distensibility index 193
Diuresis, postobstructive 415
Diuretics 217, 415
resistance 114
therapy, challenges of 114
Dizziness 321
Dobutamine 110
Doll's eye phenomenon 366
Donor optimization measures 282
Drowning 365
Drugs 244, 246, 366
overdose 365
resistant strains, development of 129
Duel energy X-ray absorbtiometry 164
Durable ventricular assist devices, long-term outcomes of 80
Durant's maneuver 384
Dynamic arterial elastance 92
Dyspnea 144, 298300
management of 299
pathophysiology of 298
vanishing 299
E
Early warning system 394
Echinocandins 296
Echocardiogram 303
Echocardiographic parameters 74
Echocardiography 74, 89, 195, 283, 303
machine 348
role of 79
three-dimensional 85
Edema 144
acute pulmonary 73
cerebral 73, 333
hereditary angioneurotic 322, 324
neurogenic pulmonary 369
pulmonary 10, 144
Ehlers-Danlos syndrome 404
Ejection fraction 92, 284
Electrocardiogram 150, 228, 303
Electrocardiography 384
Electroencephalogram 260
Electroencephalography 55, 104, 257, 367
Electrolyte
disturbances 113
free water clearance 235
imbalance 175
Electromyography 4, 55
Electronic medical records 343
Elevated leukocyte count 369
Embolism
pulmonary 33
reduce size of 384
Emergency
neurosurgery 325
room 67f
surgery 316
Empirical antimicrobials, choice of 15t
Empirical therapy 136
Empyema 12, 14
Encephalitis, autoimmune 262, 263
Encephalomyelitis, acute disseminated 263
Encephalopathy 144, 260, 366
hepatic 366
hypoxic 415
hypoxic-ischemic 256, 257
ischemic 73
metabolic 263
End-diastolic volume 374
End-expiratory occlusion maneuver 44f
Endocrine
disorders 366
management 283, 371
End-of-life care pathway, steps of 279
Endoscopic retrograde cholangiopancreatography 382
Endothelial cells, necrosis of 403f
Endotoxin
activity assay 109
elimination 109
Endotracheal aspirate 51
Endotracheal tube 166, 348, 350
position 203
End-systolic elastance 92
End-systolic volume 93
End-tidal carbon dioxide 273, 383
End-tidal nitrogen 383
Energy 160, 161
expenditure 168
requirements 160
Enterobacteriaceae 62
Enzyme-linked immunosorbent assay 150, 179, 308
Epidermal growth factor 169
Epidural analgesia 288
practice 286
Epidural hematoma, catheter-related 287
Epidural neuraxial blockade, complications of 287
Epinephrine 103
Epistaxis 321
Epithelial lining fluid 130
Eplerenone 246
Erlotinib 407
Erythrocyte sedimentation rate 62, 303
Erythropoiesis 396
Erythropoietin 398
endogenous synthesis of 398
Escherichia coli 53, 129, 327
Esophageal pressure 5, 43, 44
swings 4
Esophageal rupture 12
Esophageal stethoscope 383
Esophageal temperature measurements 353
Esophagus, infected congenital cysts of 12
Estimated glomerular filtration rate 225
Ethambutol 179, 261
Ethylene glycol 331333
European Committee on Antimicrobial Susceptibility Testing 151
European Conference on Infections in Leukemia 409
European Medicines Agency 410
European Society for Clinical Microbiology and Infectious Diseases 134
European Society for Clinical Nutrition and Metabolism 159, 160
European Society for Parenteral and Enteral Nutrition Guideline 155
European Society of Anaesthesiology 323
European Society of Intensive Care Medicine 18
European Society of Parenteral and Enteral Nutrition Guidelines 168
European Trauma Registry 267
Euthermia 36, 367
Exchange transfusion 331, 332
Extracellular fluid volume 234
Extracorporeal blood purification 330
Extracorporeal cardiopulmonary resuscitation 61, 66, 67, 67f, 68, 69
Extracorporeal cytokine 109
Extracorporeal life support 18, 59, 61, 66
organization 61, 66, 73
Extracorporeal membrane oxygenation 6, 33, 37, 6163, 63t, 64, 64t, 66, 68, 71, 74f, 109, 308, 348
support 61
Extracorporeal techniques 334fc
Extracorporeal therapy 330, 331, 331t333
modalities of 331
Extracorporeal treatment 332, 334
Extravascular lung water 199
Eye
movement 381
muscles activity 55
F
Fanconi's syndrome 243
Fasciobrachial dystonic seizures 263
Fasciomaxillary surgery 322, 324
Fat 117, 158
Feeding tube
fluoroscopy-guided placement of 168
insertion 168
malposition of 167f
misplacement of 166
Ferumoxytol 398
Fever 328
Fibrinolytic therapy 15
Fibrinopurulent stage 12
Fine end-inspiratory bibasal crackles 28
Fluconazole 64
Fluid 88, 90
attenuated inversion recovery 249, 251, 254
excess administration of 415
management
goals 231fc
stepwise 231, 231f
responsiveness 88, 195
dynamic indices of 88, 89b
static indices of 88, 88b
resuscitation 88
therapy, intravenous 195
Fluoroquinolones 179, 218, 260, 261
Foley catheter 353
Food and Drug Administration 138
Forced vital capacity 299
Formaldehyde 332
Formic acid 332
Fosmanogepix 138
Frailty 155
Framingham risk score 345
Frank-Starling curve 88, 88f, 89
Free water clearance 235
Fungal
antigens, detection of 150
disease, invasive 148
infections 184
familiar 148
invasive 297
risk factors for 183b
peritonitis, spontaneous 183
pneumonia 293, 294f
Fungi 178
Furosemide stress test 227, 228, 245
G
Gadolinium 217
Gag reflex 366
Galactosemia 243
Gamified learning 105
Gamma aminobutyric acid 56, 260
Ganciclovir 64
Gastric
acid, suppression of 179
residual volume 166
Gastroenterology 171, 345
Gastrointestinal
function 179
infection 178
injury, acute 193
symptoms 302
system 144, 404, 408
tract 95
General critical care 344
Gentamicin 260
Giant cell arteritis 401, 403
Giardia lamblia 178
Glasgow coma scale 256, 281, 284
score 323
Glomerular filtration rate 173, 174
Glomerulonephritis 218
membranoproliferative 173
Glucocorticoid 304
therapy 108
Glucose 412
control 411
high level of 239
monitoring, challenges in 411
Glucosuria 244
Glycemic control 26
Glycopeptide-intermediate Staphylococcus aureus 130
Glycosuria 415
Glycosylphosphatidylinositol 138
Goal-directed care 283, 284fc
Gradient echo 249, 251, 254
Graft-versus-host disease 178180
Gram negative organism 386
Gram positive organism 386
Granulomatosis 400, 402404
eosinophilic 400, 402, 403
Granulomatous diseases 28
Ground-glass opacity 30, 31, 294f
Growth
factors like glucagon-like peptide-2 169
hormone 169
retardation of 244
Guide spontaneous breathing activity 45
Guiding fluid resuscitation 204
Guillain-Barre syndrome 366
Gunshot injury 365
Gut dysfunction 169
H
H1N1 307
Haemophilus influenzae 129, 130
Hand hygiene 350
five moments of 351f
six steps of 351f
Handgrip dynamometry 25
Head
and neck imaging 254
cheese sign 31f
injury 365
Heart 95, 352
diastolic dysfunction of 190
disease, pre-existing ischemic 67
failure 33, 86, 87, 92
acute decompensated 113, 115, 217
congestive 211
Society of America 113
transplant 71
Heat 48
Hematologic malignant disease 134
Hematology 389
Hematopoietic stem cell 293
Hematuria 402
Hemodialysis 330, 331
Hemoglobin 283, 369, 396
Hemolysis 73
Hemolytic reactions 310
Hemoperfusion 331, 332
Hemophagocytic lymphohistiocytosis 141, 303
Hemoptysis 321
Hemorrhage
alleviation 322
diffuse alveolar 31, 403, 403f
epidural 267
intracerebral 267, 323, 354
intracranial 254, 344, 345
intraparenchymal 267
postpartum 321, 324, 325
pulmonary 322, 324
severe 322
spontaneous intracranial 365
subarachnoid 323, 344, 354, 415
subdural 267
Henoch-Schönlein vasculitis 402
Heparin 246
unfractionated 232
Hepatic dysfunction 73, 410
Hepatic failure 144, 156
Hepatic vein
Doppler 199
interpretation of 199f
Hepatitis
B virus 308
C virus 308
chronic active 244
Hepatorenal syndrome 173, 175
Hepcidin, role of 396
Herpes simplex 178
encephalitis 263
virus
esophagitis 346
infection 179
High cut-off hemodialysis 334
High-flow nasal cannula 7, 911, 36, 300
application 10f
complications of 11
device 9f
evidence-based indications of 9
humidified 6
High-flow nasal oxygen 10, 33
High-frequency oscillatory ventilation 18
High-resolution computed tomography 29, 30, 294
Hip fracture 316
Histoplasma 178
capsulatum 151
Hodgkin's lymphoma 409
Holotransferrin 397
Honey combing cyst 31
Hormonal therapy, combined 370
Hormones 56
endogenous vasoactive 107
Hospital information system 343
Hospital-acquired infection 13, 327f, 350
Host immune response 239
Human immunodeficiency virus 178, 246, 308, 369
infection 178, 222
Human leukocyte antigen 78
Human T-cell leukemia 369
Humidification 9
Hydrocortisone 415
Hydromorphone-3-glucuronide 334
Hydroxocobalamin 109
intravenous 123
Hydroxychloroquine 304
Hydroxyethyl starch 217, 218
Hyperaldosteronism 235
Hyperbaric oxygen 384
Hyperbola, metabolic 3f
Hypercapnia 6
permissive 33
Hypercarbia 257
Hyperchloremic metabolic acidosis 244, 246
Hyperdense middle cerebral artery sign 250f
Hyperferritinemia 144
Hyperglycemia 150, 158, 257, 369, 412, 413
Hyperinflation 205
Hyperkalemia 245
Hyperlactatemia 333
Hyperleukocytosis 222
Hypernatremia 236, 316
urine electrolyte in 236t
Hyperosmolar coma 366
Hyperparathyroidism, primary 244
Hypertension 86, 217, 365, 369, 402
chronic 90
pulmonary 29
Hyperthermia 257, 333
Hypertonic saline solution 114
Hypertriglyceridemia 158
Hyperventilation 299
Hyperviscosity 223
COVID-19-associated 222
syndrome 221, 223
Hyphema, traumatic 321
Hypnotics 57
Hypoalbuminemia 144
Hypoaldosteronism, idiopathic 246
Hypocaloric feeding, concept of 156
Hypocarbia 257
Hypoglycemia 257, 413
Hypokalemia 245
Hyponatremia 236, 316
urine electrolyte in 236t
Hypophosphatemia, severe 366
Hypotension 144, 217, 257, 316, 311, 366, 369
intraoperative 116, 117
prediction index 118
Hypothalamic corticotropin releasing hormone 379
Hypothermia 258, 331, 353, 354, 366, 367, 369
intraoperative 316
renal effects of 354
systemic consequences of 354
therapeutic 256, 353
Hypothesis 25
Hypotonic urine 416
Hypoventilation 331
Hypovolemia 117, 173, 217
Hypoxemia 6, 26, 144, 298, 299, 316, 366
mechanism of 298
Hypoxia 73, 74, 74f, 257, 316
management of 11
I
Ibrexafungerp 138, 296
Idelalisib 407
Idiopathic pulmonary fibrosis 2830
acute exacerbation of 32f
Imatinib 407
Immune
complex
antigen reactions 402
deposition 402
dysfunction, cirrhosis-related 182
response 179
Immunoglobulin 217, 218, 309
G 303
intravenous 264, 304
Immunohistochemistry 150
Immunomodulatory therapies 264
Immunonutrition 169
Immunopathogenesis 293, 401
Immunosuppression
pathophysiology of 179
reduction of 150
Immunosuppressive therapies 150
In situ simulation training 105
Inappropriate empiric therapy 129
Indian Academy of Neurology 278
Indian College of Critical Care Medicine 358
Indian Diploma in Critical Care Medicine 358
Indian Fellowship in Critical Care Medicine 358
Indian Society of Critical Care Medicine 277, 358, 372
Industrial accidents 365
Infections 69, 73, 173, 179, 263, 316, 327, 369
antibody-dependent enhancement of 310
management of 372
pulmonary 151
Infectious Diseases Society of America 134
Inferior vena cava 193, 195, 196, 199201
assessment 195, 199
measurement 196f
Inflammation 6
Inflammatory cells, chemotactic for 141
Influenza
associated pulmonary aspergillosis 293
management of 307
Infrared emission detection thermometers 352
In-hospital cardiac arrest 67, 67f, 105
Injury
ischemic 365
mucosal 179
Inotropes 110, 384
Inspiratory muscle endurance 57
Inspired oxygen, fraction of 6, 7, 19
Insular cortex 250
Insular ribbon sign 250f
Insulin 283
Intensive care unit 4, 12, 16, 19, 23, 30, 39, 43, 51, 53, 55, 57, 61, 90, 95, 107, 133, 149, 155, 158, 160, 163, 166, 187, 217, 225, 238, 257, 270, 272, 281, 283, 293, 307, 317, 340, 343, 344, 348, 352, 363, 368, 378, 400
management 258, 374
medications on sleep, effect of 56
Intensive insulin therapy 411
Intercellular adhesion molecule 19, 142
Interferon gamma 142
Interleukin 19, 142, 143, 145
inhibitor 304
Internal capsule 250
Internal carotid artery 251, 255
occlusion 251f
Intra-aortic balloon pump 71, 109
Intracellular organisms 52
Intracranial bleed 267
Intracranial pressure 345
management 258
Intraoperative hypotension 116, 117
prediction of 117
significance of 117
Intrapleural sepsis trials 15
Intrathecal antibiotic toxicity 261
Intrathoracic pressure 384
Intubation care bundle 348
ten components of 349t
Invasive candidiasis 133, 134t, 149
diagnostic tests for 149
Invasive ventilation 7
strategy 33
Iodinated-contrast media 217
Iron
deficiency anemia 396
dextran 398
metabolism, overview of 396
overload 150
substitutes 396, 398
sucrose 398
therapy 397, 398
Isaac's syndrome 263
Isavuconazole 296
Ischemia
delayed cerebral 344
mesenteric 404
myocardial 117, 369
visceral 369
Ischemic stroke management 249
Isoniazid 261
Isopropanol 332
Isospora 178
Itraconazole 151, 296
J
Janus kinase 145
K
Kallikrein inhibitor units 267
Kawasaki disease 301, 305, 401
Ketoconazole 246
Ketosis 333
Kidney 95, 352
disease
chronic 86, 173, 217, 400
end-stage 174
improving global outcomes 173, 174, 225, 225t, 226
injury
molecule-1 235
acute 19, 20, 98, 143, 144, 161, 168, 173175, 199, 219, 225, 225t, 226, 230, 234, 234, 331, 345
management 283
Kissing ventricles 196
Klebsiella pneumoniae 53, 240
L
Laboratory information system 343
Lacazia loboi 151
Lactate 96
dehydrogenase 12
Langerhans cell histiocytosis, pulmonary 30
Laparotomy 288
Large vessel vasculitis 401
Laser Doppler flowmetry 96
Lay rescuer training 104
Lazarus sign 367
Lean body mass 163
Lefamulin 130
Left atrial
conduit volume 85
pressure 198
Left common carotid artery 251
Left ventricular
assist device 71, 79, 80
diastolic dysfunction 86, 197, 198f
grading of 198t
ejection 93
fraction 74, 190, 374
end diastolic
pressure 91, 92
volume 91, 92
end systolic
pressure 91, 92
volume 91, 92
outflow tract 196, 201
pressure volume curve 91
Legionella pneumoniae 130
Leishmania donovani 178
Lentiform nucleus 250
obscuration of 250f
Leucine-rich glioma-inactivated protein 263
Leukemia
acute lymphoblastic 145
chronic myeloid 407
Leukocytic infiltration 402f
Leukocytoclasia 403f
Leukocytoclastic vasculitis 403
Leukocytosis 144, 328
Leukostasis 222
Levofloxacin 179
Levonadifloxacin 130
Levosimendan 110
Lidocaine 103
Light chain deposition disease 243
Lignocaine, intravenous 103
Limb ischemia 69, 73
Linezolid 260
Lipid amphotericin B 184
Lipopolysaccharide 142
Liposomal amphotericin B 150, 295
Liquid crystal display thermometers 352
Lithium 218, 244, 331, 332, 333
Liver 408
Disease
chronic 182, 183, 217
end-stage 183
failure 173, 173t, 175
acute 173, 182
chronic 182
function test 29, 303, 396
resection 324
surgery 325
transplantation 323
Local anesthetic systemic toxicity 287
Local perfusion markers 96
Loewys-Dietz syndrome 404
Loop diuretics, pharmacology of 113
Low tidal volume 33
Lowe syndrome 243
Low-molecular-weight heparin 231, 232
Lung
aeration
assessment 203
patterns 188f
atelectasis 6
biopsy, surgical 32
carcinoma of 12
derecruitment 208
diffusion capacity of 24, 30
disease
diffuse parenchymal 28, 33
drug-induced 28
interstitial 2830, 33
function test 29
injury
acute 25, 369
models of 47f
ventilator-induced 43, 47
perfusion 35
spirometry plus diffusion capacity of 29
strain 36
stress 35
transplant 33
ultrasound 187, 195, 197, 199f, 201, 203, 205207, 209, 211, 212
advantages of 209
aeration score 187t, 204f
drawbacks of 211
patterns 209
zones 188f, 209f
Lupus nephritis 246
Lymphangioleiomyomatosis 29, 30
Lymphatic system 144
Lymphocyte count 31
Lymphoma 263
virus 369
M
Machine learning 343
subtypes of 343b
types of 343b
Macrolides 260, 261
Macronutrients 158
Macrophage 369
activation syndrome 144, 302
migration inhibitory factor 141
Magnesium 158
Magnetic resonance 253, 255
angiography 251, 254
imaging 85, 193, 249, 250, 252f, 253, 257, 260
perfusion imaging 252
Maintenance therapy, steroid-sparing agents for 264
Major orthopedic surgery 322, 324
Major spine surgery 322, 324
Malassezia furfur 151
Malignancy 217, 263
Malnutrition 155
Mannitol 217, 218
Manual muscle testing 25
Marfan's syndrome 404
Masimo signal extraction technology 96
Masks, nonrebreathing 9
Mass spectrometry 135, 150
Maximal voluntary ventilation 57
Mean arterial pressure 89, 97, 107, 116, 283, 284, 372, 384
Mean transit time 253, 254
Measles 369
Mechanical circulatory support 71, 74, 77
device 74
Mechanical ventilation 7, 39, 44, 47, 98, 217, 258, 265, 270, 345
invasive 6, 43, 344
longer duration of 73
Mediastinal infection 151
Mediastinitis 12
Medical
emergency team 391
intensive care unit 411
Medium vessel vasculitis 401
Medullary sponge kidney 244
Melanoma 369
Melatonin 317
Meningitis 287, 365
carcinomatous 263
cryptococcal 183
Meningoencephalitis, herpetic 369
Menorrhagia 321, 322, 324
Mercury thermometers 352
Meropenem 64
Messenger ribonucleic acid 169
Metabolic disorders 366
Metabolic rate 369
Metformin 334
Methanol 331, 332
Methaqualone 366
Methotrexate 217
Methylene blue 109
Methylprednisolone 304
Metronidazole 260
Micafungin 64
Microbiology 13, 129, 238
Microcirculation, peripheral 95
Microsporidium 178
Middle cerebral artery 249, 252f
Middle east respiratory syndrome 10, 307
Migration inhibitory factor 142
Millar Fisher syndrome 263
Milrinone 110
Mineralocorticoid receptor antagonist 87
Minimum alveolar concentration 271
Minute ventilation 39
MIRUS controller
desflurane 274f
isoflurane 274f
sevoflurane 274f
MIRUS setup 275f
Mitochondrial injury 333
Mitra clip procedure 93
Mixed venous oxygen saturation 96
Molecular adsorbent recirculating system, part of 332
Molecular patterns, pathogen associated 123
Monitor microcirculatory peripheral perfusion 98
Monitoring filtration fraction 232
Monitoring peripheral microcirculation 95
methods for 95
Mononeuritis multiplex 402
Moraxella catarrhalis 129, 130
Morphine
6-glucuronide 334
metabolite 334
Morvan's syndrome 263
Motor-evoked potentials, monitoring of 286
Moxifloxacin 179
Mucormycosis 149, 293, 296
pulmonary 296
Multidrug-resistant organisms 63
Multimodal immunomodulatory therapy 264
Multiorgan dysfunction syndrome 301
Multiple-dose activated charcoal 332
Multi-resistant gram-negative bacteria 327
Multisystem inflammatory syndrome 301304
Muscle 95
mass 163
loss of 165
metabolism 163
paralysis 36f
qualitative aspect of 164
Musculoskeletal system 408
Myasthenia gravis, exacerbation of 261
Mycobacteria 178
Mycobacterium
avium complex infection 179
tuberculosis 179
Mycophenolate 264
mofetil 32, 217
Mycoplasma pneumoniae 129, 130
Myeloma, multiple 222, 243, 244
Myocardial infarction, acute 354
Myoclonus
acute posthypoxic 258
management 258
N
N-acetylcysteine 333
Naive T-cells, differentiation of 142f
Nasal high flow 6
Nasogastric tube 316
correct positioning of 166
Nasopharyngeal dead space 9
Nasopharyngeal temperature measurements 352
National Accreditation Board for Hospitals and Healthcare Providers 278
National Audit Project 287
National Cancer Institute 408
National Institute for Health and Care Excellence 281, 284
National Medical Commission 361
National Organ and Tissue Transplant Organization 281, 282, 365, 372
National Productivity Council and National Digital Health Mission Program 361
Natural disasters 150
Nausea 144, 321
Near-infrared spectroscopy 96
Nebulization 321
Necrotizing fasciitis 193
Neoformans, cryptococcus 151, 178, 239
Nephrectomy 239
Nephritis, acute interstitial 218
Nephrocalcinosis 243, 244
Nephrocritical care 345
Nephrolithiasis 243, 244
Nephropathy
contrast-induced 218
obstructive 246
Net acid excretion 243
Neuraxial infections 287
Neurocognitive disorders, perioperative 316
Neurocritical Care Society 353
Neuroinvasive theory 299
Neuroleptic malignant syndrome 263
Neurology, close monitoring of 287
Neuromuscular blocking agents 49, 366
Neuromuscular syndromes 263
Neuropathy
peripheral 261
predominantly axonal 261
Neurotoxic snake envenomation 366
Neurotoxicity, antibiotics-associated 260
Neurotransmitter gamma aminobutyric acid 322
Neutropenic enterocolitis 178
Neutrophil gelatinase-associated lipocalin 235
Nitric oxide 108
inhibitors 109
N-methyl D-aspartate-receptor 256, 262
Nodules 31
perilymphatic 31f
Nonanion gap metabolic acidosis 235
Noncatecholamine vasopressors 107
Noncontrast computed tomography 249, 254, 256
Nonconvulsive status epilepticus 257, 260
Noninvasive positive pressure ventilation 6, 349
Nonshockable rhythm 67
Nonsteroidal anti-inflammatory drugs 57, 173, 217, 218
Non-transplant organ retrieval centers 282
Norepinephrine 107, 111
intraoperative 116
very high-dose 107
Normocapnea 367
Normoglycemia 259
Normothermia 354
Norovirus 178
Nosocomial infections 51
mechanism of 62
Numerical rating scale 286
Nutrition 153, 155, 158, 283
components of 158
enteral 160
goal of 155
management of 169, 372
Nutritional status, assessment of 163
O
Obesity 155
Obstetric rapid response
system, components of 393f
teams 391
Ocular toxicities 410
Oculocephalic reflex 366
Oculovestibular reflex 366
Omadacycline 130
Oncology 389
Opioid 57, 334
overdose 104
poisoning 334
sparing anesthesia 317
Optic neuropathy 261
Oral anticoagulants 332
Oral care, chlorhexidine for 386t, 387b
Oral surgery 322, 324
Organ
autoregulation 89
donation 365
consent for 368
exclusion criteria for 369
suitability for 369
donor
management, principles of 369
medical management of 370t
dysfunction, acute 369
severe chronic 68
involvement, frequency of 404t
recovered per donation 281
system 374
Orthotopic liver transplant 176
Osmotic nephropathy 218
Ototoxicity 261
Out-of-hospital cardiac arrest 67, 98, 105
Overweight 155
Oxygen
arterial partial pressure of 369
challenge test 96
delivery 6
device 9, 11
end-tidal partial pressure of 298
partial pressure of 19
saturation 383
therapy 9
P
Packed red blood cells 372
Pain 245
abdominal 302, 402
assessment 316
control 287
scales 286
Pancreatitis
acute 156, 288
necrotizing 134
Paracetamol 333
Paracoccidioides brasiliensis 151
Paradoxical air embolism 382
Parapneumonic effusion 14
classification of 15t
stages of 12
treatment of 13
Paraproteinemias 243
Parasites 178
Parenchyma 249, 253
Partial neuromuscular blockade 37
Partial thromboplastin time 302
Parvovirus 369
Passive external method 355
Patent foramen ovale 207f, 382
Patient self-inflicted lung injury 35, 40
Patient-ventilator asynchrony 36
Peak aortic pressure variation 89
Pediatric multisystem inflammatory syndrome 301
Penicillins 218, 260
Penicillium marneffei 151
Penumbra 252
Perfusion 252
imaging, modalities of 253t
index 9598
weighted imaging 253, 255
Pericarditis 402
Perioperative delirium 315
Peripheral perfusion 97
index 96
Peripheral vascular disease 217
Peripherally inserted central catheter 386
Peritoneal dialysis 331
Peritonitis 173
cryptococcal 183
spontaneous bacterial 175
Personal protective equipment 64
kits 340
Pharmacogenomics 111
Pharmacokinetics 63
Pharmacological prophylaxis 316
Pharmacotherapy 381
Pharmacy Board of India 361
Phenytoin 218, 332
Phosphate 158
Phosphodiesterase inhibitor 110
Pichia anomala 151
Piperacillin 64
Plain computed tomography 251
Plaque reduction neutralization test 308, 310
Plasma
cell dyscrasias 221
exchange 223, 331
hyperosmolality 416
proteins 221
Plasminogen activator inhibitor 19
Plateau pressure 33, 47
Plethysmographic variability index 118
Pleural effusion 29, 199f
Pleural fluid analysis 13
Pneumaturia 239
Pneumocystis jirovecii 28, 178, 409
infections 295
Pneumomediastinum 10
Pneumonia 173, 293
bacterial 12
community-acquired 129
cryptogenic organizing 30, 31f
eosinophilic 31
hypersensitivity 31
interstitial 31f
nonspecific interstitial 28, 30, 30t, 31f
nosocomial 386
organizing 28
ventilator-associated 51, 52, 166, 203, 207, 258, 350, 386
Pneumonitis 144
hypersensitivity 28, 29, 30, 31f
Pneumothorax 11, 29, 117, 205, 206
diagnosis of 207fc
episodes of 10
Point of care ultrasonography 164, 192194, 196, 201, 203
role of 193f, 195
Polyangiitis 400, 402404
microscopic 400, 402, 404
Polyarteritis nodosa 173, 401, 402, 402f, 404, 405
Polycythemia 222
Polymerase chain reaction 136, 293
Polymorphonuclear leukocytes 320
Polymyxins 260
Polysomnography 55
Polytrauma 286
Polyuria 415
Poor communication, consequences of 339b
Portal vein Doppler 199
interpretation of 200f
Posaconazole 296
Positive end expiratory pressure 6, 18, 19, 33, 36, 40, 41f, 43, 47, 88, 206, 210, 349, 367, 372
Positive pressure ventilation 117, 382
Post-anesthesia care unit 315
Postcardiac arrest care 98, 104
Post-COVID dyspnea 299
Postextubation respiratory failure 9
Postextubation stridor, prediction of 207
Postintensive care
exercise study 363
syndrome 364
Post-left ventricular assist device 78
Postoperative cognitive dysfunction 315
Postrenal transplant rejection 243
Postsurgical intensive care unit 98
Post-transplant rejection 244
Post-traumatic stress disorder 25, 378
Potassium
disorders 236
fractional excretion of 235
hydroxide 296
Preemptive therapy 136
Pregnancy 117
early 321
Pressure support ventilation 7
Prophylaxis therapy 136
Prostaglandin 108
Protein 158, 160, 161
binding 330
modifications 161
requirements 160
Proteinase 29
Proteinuria 402
Prothrombin time 73, 302, 303, 369
Proton
pump inhibitors 218
secretion of 235
Proximal renal tubular acidosis, causes of 243t
Pseudomonas aeruginosa 129, 327
Psychiatric syndromes 262
Psychotherapy 381
Pulmonary arterial
obstructive pressure 372
occlusion pressure 283
Pulmonary artery 77, 283
catheter 353, 383
occlusion pressure 88
temperature measurements 353
Pulmonary system 403
Pulsatile flow 78
Pulse
contour analysis 89
oximetry 95, 96
pressure variation 89, 92
wave velocity 180
Pyelitis, emphysematous 238
Pyelonephritis 238
emphysematous 238, 239, 239f, 240
Pyonephrosis 193
Q
Quinolones 260
R
Rabies 369
Radiocontrast dyes 218
Raised intracranial pressure 265, 273
Randomized controlled trial 66, 109, 226, 267, 288, 307, 333
Rapid eye movement 55
Rapid response system 391, 392
components of 391, 391f
Rapid sequence intubation 257, 349
Rapid shallow breathing index 5, 39, 345
Rash 144, 402
Rectal temperature measurements 353
Rectus femurs 164
Red blood cell production 396
Refeeding syndrome 155
Refractory vasodilatory shock 107
contributing mechanisms of 108fc
Regional organ and tissue transplant organization 365
Remdesivir 304
Renal artery involvement 404
Renal biopsy 219
Renal damage
area of 218t
biomarkers of 218t
Renal disease 219
end-stage 334
intrinsic 173
Renal dysfunction 73
Renal failure 144, 156, 175fc, 369
Renal function 219t
deterioration of 113
test 29, 303, 366
Renal injury 73
Renal insufficiency, severe 321
Renal management 371
Renal plasma flow 253
Renal replacement therapy 89, 175, 219, 225, 226, 400
advantages of 225t
disadvantages of 225t
timing of 225
Renal system 404
Renal toxicities 410
Renal transplant rejection 246
Renal tubular acidosis 242, 243, 246, 246t
Renal vein Doppler 199
interpretation of 200f
Renal, age, purulence, infection source, and dietary factors scoring system 16, 16t
Renal, endocrine, hematologic, and gastrointestinal management 259
Renin angiotensin-aldosterone system 87, 110, 113
Respiratory drive 3, 4
monitoring tools for 5t
Respiratory failure 33f, 33fc
acute hypoxemic 9, 37
Respiratory infections, lower 386
Respiratory management 283, 371
Respiratory muscles 5
Respiratory rate 39, 349, 374
Respiratory system 43f
Resuscitation 193
cardiopulmonary 103, 372, 384
individualized management of 104
Reticular opacities 31
Reverse transcriptase polymerase chain reaction 302, 303, 309
Rezafungin 138
Rheumatoid
arthritis 28
disease 29
factor 29, 221
Rheumatologic system 144
Rhinosporidium seeberi 151
Ribavirin 64
Ribonucleic acid 309
Richmond agitation sedation scale 271, 318
Rickets, retardation of 244
Rifabutin 179
Rifampicin 217, 218
Right common carotid artery 251
Right ventricle end-systolic area 197f
Right ventricular
assist devices 78
dysfunction 78
Risk, injury, failure, loss and end-stage renal disease 225, 226
Rituximab 264, 407, 409
Road traffic accidents 150, 365
Rotavirus 178
Routine brain surgery 325
Royal College of Pediatrics and Child Health 302t
Ruxolitinib 145
S
Saccharomyces cerevisiae 151
Salicylates 331333
Salicylic acid 333
Salt 158
Sarcoidosis 28, 29, 31f
Sarcopenia 155
Scleroderma 28
Sclerosis, multiple 263
Sedation 56
agitation scale 318
use of 270
Seizures 144, 257, 258, 260, 263, 265, 321, 333
history of 321
Selective digestive decontamination 387
Selective oral decontamination 387
Selective serotonin reuptake inhibitors 381
Selepressin 111
Sensor based feed delivery system 166, 167f
Sepsis 88, 89, 97, 121, 123, 134, 145, 217, 286, 287, 328, 333, 344
cytokine in 141
effect of 56
global burden of 123
identifying source of 192
management of 123, 193
pathophysiology of 123
point of care ultrasonography in 192
recovery phase of 415
refractory 62
severe 364
Septic shock 93, 97, 121, 134
corticosteroids therapy of 415
prevention of 415
Sequential organ failure assessment score 61, 72, 97, 162
Serotonin norepinephrine reuptake inhibitors 381
Serum creatinine levels 218
Severe acute respiratory syndrome 10, 302, 307
coronavirus 134, 209, 293, 298, 302, 303, 308, 309, 405
Shock 107, 144, 333, 366
cardiogenic 71, 77
refractory 107, 108
septic 93, 97, 121, 134
Shred sign 192
Sick euthyroid syndrome 369
Sidestream dark field imaging 96
Siltuximab 145
Single-photon emission computerized tomography 345
Sinusitis 402
Six-minute walk test 24, 29, 30
Sjögren's syndrome 221, 243, 244
Skeletal abnormalities 244
Skeletal muscle 65, 163
Skin 95, 403
antisepsis 349
infection 173
perfusion 96
point of care ultrasonography of 193
Sleep 55, 56
cycle, disruption of 316
deprivation, biologic effects of 56
deprivation, psychological effects of 56
disturbance 55
loss 56
physiology of 55
quality 56
Small peptide therapeutics 331
Society of Critical Care Medicine 411
Task Force Guidelines 352
Sodium 123, 158
disorders 235
ferric gluconate 398
fractional excretion of 235, 236
urinary 234
Soft-tissue, point of care ultrasonography of 193
Solid organ
transplant 134, 150, 293
tumors 134
Somatosensory-evoked potentials 286
Sophisticated therapy 23
Species-specific targeted therapy 137t
Spirometry 29, 30
Spironolactone 246
Split pleura sign 13
Spontaneous breathing 35, 36f, 37
trail 39, 187, 188
Spontaneous circulation 66
rapid return of 68
return of 104, 257
Sporothrix schenckii 151
ST elevation myocardial infarction 391
Standard digital thermometers 352
Staphylococcus aureus 61, 62, 129
methicillin-resistant 51, 327
Steroid 150, 304
high-dose 33
Stewardship program, core elements of 148t
Streptococcus pneumonia 129
Streptococcus pneumoniae 129, 130
Streptococcus pyogenes 129
Stress 36, 369
Stroke 80, 249
acute 68, 249, 249f, 253t
ischemic 249, 252, 254, 353
volume 91, 92
volume variation 89, 92, 118, 283
Strongyloides stercoralis 178
Subcutaneous edema, Cobble stone appearance of 200f
Sulcal effacement 250f
Sulfa-containing drugs 218
Sulfamethoxazole 260
Supportive therapy 223
Suprachiasmatic nucleus 55
SurgerY
abdominal 288
site of 316
Surgical intensive care unit 411
Susceptibility-weighted imaging 249, 251
Sympathetic nervous system 113
Syndrome of inappropriate antidiuretic hormone secretion 236
Synthetic human angiotensin 110
Systemic antifungal therapy 150
Systemic antimicrobial therapy 328
Systemic lupus erythematosus 29, 221, 244, 263
Systolic dysfunction 190
T
T lymphocytes 369
Tachycardia 144, 369
Tacrolimus 217, 246
Takayasu's arteritis 401, 403
Tazobactam 64
Tedizolid 130
Temperature 283
management 258, 370
measurement, sites of 352
modulation 258
Temporal artery temperature measurements 353
Terlipressin 109, 111
Tetracyclines 260
Theophylline 332
Therapeutic plasma exchange 109, 223, 331, 332
Thermoregulatory control, loss of 369
Thiamine 109, 124
deficiency 263
Thirst, measurement of 417
Thoracentesis 14, 14b
Thoracic spine infections 12
Thoracic surgeries 288
Thorax, computed tomography of 303, 384
Thrombocytopenia 369
drug-induced 73
heparin-induced 80
Thromboembolism 73
Thrombotic vessel occlusion 402f
Thrombus formation, risk of 321
Tidal volume 5, 39
Tigecycline 64
Tissue
donation, consent for 368
donors 369
perfusion 95
plasminogen activator 15, 266, 320
ultrasound 200
Tocilizumab 144, 145, 305
Tonsillectomy 321
Top-down method 282
Topical antimicrobial
agents 327
therapy 328
Total lung capacity 189, 299
Total parenteral nutrition 158
Toxic alcohols 331, 333
Toxin removal, principles of 330
Toxoplasma gondii 151, 178
Tracheal tube 350
Trametinib 407
Tranexamic acid 266, 267, 267t, 320, 322325
contraindications of 321
current indications 320
pharmacology of 320
Transbronchial lung
biopsy 32
cryobiopsy 32
Transcranial Doppler 251, 383
Transcutaneous oxygen measurement 96
Transesophageal echocardiography 79f, 80f, 383
Transferrin supplementation 399
Transfusion 283
Trans-Golgi network 142
Transpulmonary pressure 36f, 43, 44
guided ventilation 43
measurement, rationale for 44
utility of 44
Transthoracic echocardiography 32
Transtubular potassium gradient 236
Trapezius squeeze 366
Trastuzumab 407
Trauma 217, 313, 320
audit and research network 267
emergency 323, 325
Traumatic brain injury 266, 267, 267t, 345, 354, 415
Trichloroethylene 366
Tricuspid
annular plane systolic excursion 196, 197
regurgitation 198
Trimethoprim 246, 260
Tube thoracostomy 15
Tuberculosis, abdominal 179
Tubular necrosis, acute 173, 218, 235
Tubulointerstitial disease 243, 246
Tumor
necrosis factor 19, 124, 141, 142
pituitary 415
screening 264
surgical treatment of 264
Tympanic membrane temperature measurements 353
Tyrosine kinase inhibitors 407, 409
U
Ultrasonography
machine 13, 164, 196, 201, 348
use of 164, 349
Ultrasound
guided
central venous catheter placement 349b
ventilation 203
images, storage of 211
muscle measurements 169
use of 190
United Network for Organ Sharing-Donor Management Goals 283
Upper gastrointestinal endoscopy 168
Upper urinary tract 321
Urate, fractional excretion of 236
Uremic encephalopathy 366
Urinary bladder temperature measurements 353
Urinary electrolyte measurement 234
Urinary neutrophil gelatinase-associated lipocalin 175
Urinary tract infection 173, 238
catheter-associated 350
Urine
analysis 303
anion gap 235, 243
electrolytes 234
clinical applications of 234
osmolar gap 243
output 168
Urological surgery 324, 325
V
Valproate 331
Valproic acid 218, 332
Valsalva maneuver 385
Vancomycin 64, 217, 218
resistant enterococci 327
Vascular injury 73, 266
Vascular system 144
Vasculitic disorders 403, 404t
Vasculitides
diagnosis of 402
primary 401t
systemic 400
Vasculitis 144, 263, 400
Chapel Hill classification of 401f
classification of 400
clinical studies of 400
cryoglobulinemic 403
diagnostic clues for 402
drug-induced 402
pathology of 401
primary 401
Vasodilator therapy 92
Vasodilatory nitric oxide 107
Vasoplegia 111
Vasopressin 107, 111
resistance 414
Vasopressor 218
therapy, predictor of 97
Vastus
intermedius 164
lateralis 164
medialis 164
Venoarterial extracorporeal membrane oxygenation 61, 7173, 75
Venous air embolism 382
Venous excess ultrasound score 196, 199201
Venous thromboembolism 323, 375
Venovenous extracorporeal membrane oxygenation 61
Ventilation
complications of 206
curve 3
initiation of 203
noninvasive 7, 10, 35
optimization of 203
Ventricular assist devices 7780
classification of 77t
complications of 79
contraindications of 77, 78t
history of 77
implantation of 78
indications of 77
types of 77
Ventricular diastolic dysfunction 85
Ventricular fibrillation 68
Ventricular outflow tract 193
Ventriculoarterial coupling 85, 86, 92, 93
Venturi mask 7, 9
Vexus score 200t
Video-assisted thoracoscopic surgery 15, 32
Vili, pathophysiology of 47
Viruses 178
Vitamin 123
B 127
supplements, role of 123
B1 107, 109, 124
B12 123
C 108, 123, 124, 127
metabolite of 123
supplements, role of 123
transporter 123
deficiency 243
overdose 244
supplements, role of 123
supplements, role of 123
Volutrauma 47
Vomiting 144, 302, 321
von Willebrand factor 19
Voriconazole 217
W
Waldenstrom macroglobulinemia 221, 222
Wangiella jeanselmei 151
Water deprivation test 416
Waterfall sign 211f
Weaning failure, ultrasound assessment of 187
Wegener's granulomatosis 402, 400
White blood cells 141, 183, 222
Wilson's disease 243
World Health Organization 301
X
X-ray chest 303
Y
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1Respiratory
  1. Monitoring Respiratory Drive in Spontaneous and Mechanically Ventilated Patients
    Praveen Khilnani
  2. High-flow Nasal Cannula: Use, Abuse, or Misuse
    Prashant Saxena, Arun Dewan, Ritesh Aggarwal
  3. Management of Complex Pleural Effusion in Intensive Care Unit
    Manoj K Goel, Ajay Kumar, Gargi Maitra
  4. Acute Respiratory Distress Syndrome Phenotype: Clinical Relevance
    Pragyan Routray, Debasis Mishra, Samir Samal
  5. Long-term Consequences of ARDS and its Management
    Padmakumar AV, Chandan GS, Pooja Prathapan Sarada
  6. Diffuse Parenchymal Lung Disease: A Real Challenge
    Abhijit Paul, Ritam Chakraborty, Mrinmoy Mitra
  7. Patient Self-inflicted Lung Injury
    Pavan Kumar Vechum, R Ebenezer
  8. Role of P0.1 in Difficult Weaning
    Amarja Ashok Havaldar
  9. Transpulmonary Pressure-guided Ventilation: Where do We Stand?
    Divya Pal, Rahul Harne
  10. VILI Prevention: Is Mechanical Power-targeted Therapy the Ultimate Goal?
    Lawni Goswami
  11. Predicting Microorganism in Ventilator-associated Pneumonia: Is Surveillance Culture the Answer?
    Tanmay Banerjee, Payel Bose, Abhishek Bhattacharjee
  12. Effect of Critical Care Illness on Sleep
    Jayesh Dobariya, Milap Masharu2

Monitoring Respiratory Drive in Spontaneous and Mechanically Ventilated PatientsCHAPTER 1

Praveen Khilnani
 
INTRODUCTION
“Respiratory drive” may be considered as the intensity of neural message to breathe.1 Under healthy circumstances, it is controlled by feedback pathway from central and peripheral chemoreceptors (pH changes secondary to rising CO2 or hypoxia or due to accumulation of acids from anaerobic metabolism such as lactate). Additional inputs are from chest wall muscles, diaphragm, airways, and lungs via mechanoreceptors (vagal mediated) affecting the respiratory drive. It is also affected by behavioral factors such as talking, swallowing, and exercise. In pathological situations, such as, inflammation due to toxemia (endotoxins during sepsis), postsurgical pain, temperature, inflammation of brainstem, stroke or severe traumatic brain injury, and respiratory drive could be affected (abnormally high or suppressed). Hypocapnia during mechanical ventilation does not abolish respiratory drive.2 Limbic system plays important role in breathing patterns affected by emotional factors such as fear and anxiety.3
Raised partial pressure of carbon dioxide (PaCO2) level increases minute ventilation (Figs. 1A and B). “Brain curve” indicates the minute ventilation via neural respiratory drive for a given PaCO2; and the “ventilation curve” describes the actual minute ventilation occurred for a given PaCO2. Under healthy circumstances, the brain curve coincides with the ventilation curve and PaCO2 and the measured minute ventilation are in close linear correlation. Slope of this linear correlation represents the “brain respiratory drive.”4
zoom view
Figs. 1A and B: 4 (A) In health, brain and ventilation curves overlap and the ventilation response (i.e., the change in minute ventilation induced by a change in PaCO2) reflects the neural respiratory drive. The metabolic hyperbola is obtained assuming a dead space of 0.3 and a metabolic CO2 production (VCO2) of 200 mL/min. Brain and ventilation curves are overlapping and are calculated assuming at PaCO2 of 39.5 mm Hg, a ventilation of 6.5 L/min, linearly increasing to 30 L/min at a PaCO2 of 49 mm Hg. (B) In ARDS, the metabolic hyperbola is shifted upward due to increase of dead space (0.5) and VCO2 (250 mL/min). Brain and ventilation curves are calculated assuming a ventilation of 6.5 L/min at 28 mm Hg PaCO2 (increasing to 30 L/min at 33 mm Hg PaCO2) and a ventilation of 5 L/min at 40 mm Hg PaCO2 (increasing to 25 L/min at 52 mm Hg PaCO2), respectively.
4In acute respiratory distress syndrome (ARDS), there is a discrepancy in brain curve and the ventilation curve. ARDS will shift the ventilation curve to the right (lower minute ventilation despite higher PaCO2) due to increased respiratory load and muscle weakness (see Figs. 1A and B). During ARDS, brain curve is shifted to the left (higher minute ventilation despite lower PaCO2) due to multiple concomitant pathologic conditions, including hypoxemia, acidosis, inflammation, pain anxiety, and discomfort.
 
Why is Respiratory Drive Important?
During mechanical ventilation for acute respiratory failure in patients breathing spontaneously, excessive respiratory drive can overstimulate lung-protective stretch reflexes (e.g., Hering–Breuer reflex) that primarily are aimed at limiting the lung volume. Overstimulation and stretching lead to greater lung injury and inflammation. This generates a vicious circle of worsening injury (a term recently coined “patient self-inflicted lung injury”, P-SILI).5
Double-triggering and breath-stacking in assist-control modes can also occur with excessive respiratory drive,6 resulting in higher lung stress.
High respiratory drive can also lead to diaphragmatic weakness in acute respiratory failure.
Eccentric (lengthening) contractions during expiration or during patient–ventilator dyssynchrony may be particularly injurious possibly resulting in prolonged mechanical ventilation and intensive care unit (ICU) stay.7
During weaning also, excessive respiratory drive and ventilatory demands can increase dyspnea leading to weaning failure and/or extubation failure. Patients with high respiratory drive experience dyspnea (“air hunger”) while being mechanically ventilated particularly when the flow delivery by the ventilator is insufficient (“flow starvation”).
 
How to Measure and Monitor Respiratory Drive?
Direct measure of the central respiratory centers activity is not yet possible.
Respiratory drive may be indirectly assessed (categorized according to their “distance” from the respiratory centers) by various tools (Table 1).8
Three broad categories for assessment are—(1) neural output (i.e., electrical activity of the diaphragm triggered via phrenic nerve impulse), (2) breathing effort, assessed by changes in pressure induced by the respiratory muscles (i.e., swings in pleural pressure or P0.1); and (3) ventilatory response, indicated by the tidal volume (Vt) and respiratory rate (breathing pattern).
 
Neural Output
The electrical activity of the crural diaphragm (EAdi) is indicative of the phrenic nerve activity as neural output of the respiratory centers to the diaphragm, in healthy subject. EAdi is now available on a particular type of ventilator such as Maquet®, SERVO-i, or SERVO-u.
Signals are sensed by placing a specialized nasogastric catheter fitted with electrodes. These are used to estimate respiratory drive and inspiratory effort. The signal amplitude range can vary considerably between individuals and it is difficult to establish the reference range.
Electromyography can also be obtained by surface electrodes. It is used for assessment of the activity of diaphragm and extradiaphragmatic muscles. Main limitation is that it is technically demanding and not routinely available.
 
Breathing Effort
Esophageal pressure swings (ΔPes) and respiratory muscle pressure (Pmus) indicate inspiratory effort triggered by the neural respiratory drive.9 The pressure generated by the respiratory muscles (Pmus) is calculated as the difference between the static recoil pressure of the chest wall (plateau pressure) and ΔPes. Pmus values > 10 cmH2O indicate high effort.10
Measuring the airway occlusion pressure or P0.1, i.e., the pressure developed in the occluded airway 100 ms after the onset of an inspiratory effort is used as an indirect parameter.11,12 It is available on most modern ventilators. P0.1 is independent of respiratory mechanics and the patient's reaction. It is not affected by respiratory muscle weakness. Average of three to four values may be used due to breath to breath variation as a fairly reliable index of the patient's drive.
 
Breathing Pattern
In healthy subjects, increases in ventilatory demand are met by initial increases in Vt with constant inspiratory time (Ti), resulting in high mean inspiratory flow (Vt/Ti), indicative of high drive (Table 1). Similarly, high Vt (and high Vt/Ti) in spontaneously breathing patients with ARDS suggests injurious increases in respiratory drive both during noninvasive13 and invasive mechanical ventilation.14 High Vt/Ti consistently reflects high drive. Main limitations of measurement of mean inspiratory flow are that EAdi needs to be measured and it is affected by muscle function.
Severe muscle weakness may result in some discrepancy between drive and effort.
Esophageal manometry can be used to assess inspiratory effort to quantify the pressure–time product per minute (PTP) or the work of breathing (WOB) of the respiratory muscles.15
It can be employed at the bedside with relative ease, but many clinicians are unfamiliar with the technique.
Maximal inspiratory effort can also be used as an indirect measure of respiratory drive though it is affected by muscle weakness. It can be estimated noninvasively by diaphragm ultrasound. Diaphragm thickening during inspiration (quantified by the diaphragm thickening fraction, TFdi) reflects diaphragm shortening during contractile activation.
5Diaphragm thickening fraction is correlated with PTP16 and EAdi. PTP is approximately 86 ± 21 cmH2O s/min,17 and TFdi is approximately 20 ± 15%.18
TABLE 1   Monitoring tools for respiratory drive.8
Parameter
Physiological level
Monitoring tool
Advantages
Limitations
EAdi
Neural output
Esophageal catheter with electrodes
Close to neural drive; tracks changes in neural drive (due to changes in diaphragm function, respiratory mechanics or ventilator assistance)
Interindividual variability; assesses only diaphragm activity; available only on one type of ventilator
Electromyography
Neural output
Surface electrodes
Assessment of the activity of diaphragm and extradiaphragmatic muscles
Technically demanding; not routinely available
P0.1
Breathing effort
Ventilator
Automatic measurement available on some ventilators; not affected by respiratory mechanics and moderate muscle weakness; good correlation with work of breathing
Breath-to-breath variability; indirect measure in some ventilators; accuracy of absolute values varies according to the ventilator mode
Dyspnea
Neural output and breathing effort
Guided questions, visual scales, clinical assessment (e.g., respiratory distress observation scale)
Comprehensive parameter; may reflect the distance between brain and ventilation curve
Relies on patient collaboration and ability to communicate; affected by emotional and cognitive factors (pain, anxiety, delirium, etc.)
Esophageal pressure swings
Breathing effort
Esophageal manometry
Estimates contributions of extradiaphragmatic muscles
Insensitive to the effort required to expand the chest wall; affected by muscle function
Pmus
Breathing effort
Esophageal manometry
Best indicator of effort, well-correlated with work of breathing
Requires measurement of elastic chest wall recoil pressure under passive conditions; affected by muscle function
Use of accessory inspiratory and expiratory muscles
Breathing effort
Visual inspection
Assessment of the activity of extradiaphragmatic muscles
High interobserver variability, qualitative assessment; affected by muscle function
Respiratory rate
Ventilatory response
Ventilator or visual inspection
Easy to assess at the bedside
Interindividual variability in values at rest and during stress; affected by respiratory mechanics, muscle function, pain, and emotional state
RSBI
Ventilatory response
Ventilator
Easy to assess at the bedside
Affected by respiratory mechanics and muscle function; developed as a predictor of weaning failure and not as a surrogate for drive
Mean inspiratory flow (Vt/Ti)
Ventilatory response
Ventilator/esophageal catheter with electrodes or manometry
High Vt/Ti consistently reflects high drive
Neural inspiratory time requires EAdi; affected by muscle function
(EAdi: electrical activity of the crural diaphragm; P0.1: airway occlusion pressure; Pes: esophageal pressure; Pmus: pressure generated by the respiratory muscles; RSBI: rapid shallow breathing index; Vt: tidal volume; Ti: inspiratory time)
The upper threshold of effort in patients that succeed in a trial of spontaneous breathing on a T-piece is a PTP of 200 cmH2O s/min. Because of interobserver and intraobserver variability, specific expertise is required in ultrasonography.
Clinical parameters such as use of accessory inspiratory and expiratory muscles, respiratory rate, RSBI (rapid shallow breathing index) can all be used at bed side by visual inspection and/or use of ventilator graphic panel. Accessory inspiratory and expiratory muscle use assessment has high interobserver variability and therefore loses objective assessment. Respiratory rate shows limitations in form of factors such as interindividual variability in values at rest and during stress; affected by respiratory mechanics, muscle function, pain, and emotional state. RSBI is affected by respiratory mechanics and muscle function and actually developed more as a predictor of weaning failure rather than specific to monitor respiratory drive.
Respiratory drive can also affect expiratory effort, difficult to quantify as it requires intra-abdominal pressure measurement.
Measurements closer to the brain centers reflect the neural drive, while lung stress as a result of actual ventilation stimulated by the neural drive determines severity of P-SILI.19
To assess for the presence of “air hunger/dyspnea,” it may be useful to directly query patients about respiratory discomfort if they are sufficiently interactive.
Mechanism of dyspnea involves afferent information on the respiratory motor output from the brainstem and the motor cortex,20 feedbacks from the chemoreceptors and the mechanoreceptors of the lung and chest wall.21 The overall feeling of dyspnea depends on this motor and sensory 6information, modulated to a great extent by emotion.22 Bedside assessment of dyspnea can actually allow estimation of the distance between brain and ventilation curves.
The optimal target range for respiratory drive and inspiratory effort during mechanical ventilation is uncertain. In healthy subjects, breathing at rest, P0.1 varies between 0.5 and 1.5 cmH2O,1 WOB ranges from 2.4 to 7.5 J/min and from 0.2 to 0.9 J/L.14
Goligher et al7 demonstrated that an intermediate range of inspiratory effort (TFdi 15–30%) is associated with the shortest duration of mechanical ventilation.
Achieving this range of inspiratory effort might prevent injury to the lung and diaphragm caused by high respiratory drive. The upper safe limit of respiratory drive to prevent diaphragm and lung injury in an individual patient is variable depending upon maximal diaphragm strength, the severity and type of lung injury (i.e., the presence of solid-like lung behavior),23 severity of systemic inflammation,24 perfusion of oxygenated blood to the respiratory muscles, oxygen consumption of respiratory muscles, and the resultant effect on oxygen delivery to the other vital organs.
Currently “gold standard” for clinical evaluation of respiratory drive does not exist, therefore a multimodal assessment might be the most informative approach.
 
CLINICAL IMPACT OF ABNORMAL RESPIRATORY DRIVE IN SUBJECTS WITH ACUTE RESPIRATORY DISTRESS SYNDROME
Partially, supported modes of ventilation in ARDS patients offer the advantage of decreasing sedation, improving hemodynamics and preserving respiratory muscle function. However, preserving spontaneous breathing in patients with ARDS is still controversial because, uncontrolled respiratory drive can cause vigorous spontaneous breathing efforts, potentially worsening lung and diaphragm injury.
In patients with ARDS, the effects of respiratory drive on the lung should always be monitored and high respiratory drive, either appropriate or inappropriate, should be controlled since it has been recognized as an important cause of excessive lung stress and P-SILI.
Table 2 shows various strategies available to modulate respiratory drive—various respiratory support modes and settings, medications, and non-pharmacologic interventions.
 
INVASIVE MECHANICAL VENTILATION AND ITS EFFECT ON RESPIRATORY DRIVE
Table 3 depicts physiologic effects of various modes of invasive and noninvasive measures of respiratory support on respiratory drive, driving pressures (DP), and transpulmonary pressures (PL).
The initial management in almost all patients with acute respiratory failure includes various forms of noninvasive respiratory support—nasal high flow (NHF) also synonymously used with humidified high flow nasal cannula (HHFNC) commonly used in newborns, infants and children, continuous positive airway pressure (CPAP), and noninvasive positive pressure ventilation (NIV).
TABLE 2   Determinants of increased respiratory drive in ARDS, associated mechanisms, and potential interventions to control drive.8
Determinant
Common etiologies
Mechanisms
Potential interventions (as appropriate)
Hypercapnia
↑ Dead space, ↑ lung and chest wall elastance, ↑ CO2 production
Stimulation of central and peripheral chemoreceptor
Ventilatory support; fever and pain control; sedation; ECCO2R
Hypoxemia
↑ Intrapulmonary shunt, V/Q mismatch, ↑ VO2/DO2
Stimulation of peripheral chemoreceptors
FiO2, PEEP; mechanical ventilation cardiovascular support (fluids, inotropes, and vasopressors, red cell transfusion); ECMO
Metabolic acidosis
Shock, acute kidney injury
Stimulation of central and peripheral chemoreceptors
Cardiovascular support; bicarbonate; RRT
Inflammation
ARDS, P-SILI, sepsis
Increased sensitivity of peripheral chemoreceptors to hypoxemia; stimulation of lung chemoreceptors (C-fibers); direct stimulation of respiratory centers by cytokines
Etiologic treatment; lung- and diaphragm protective mechanical ventilatory support
Lung atelectasis
Pulmonary edema, inflammatory cells, reabsorption atelectasis
↓ Inhibitory activity from lung slow adapting mechanoreceptors
PEEP and respiratory support; prone positioning; physiotherapy
Agitation
Anxiety, pain, respiratory distress
↑ Descending input
Respiratory support; sedation or anxiolysis; nonpharmacologic (and potentially pharmacologic) treatments of delirium
Poor patient–ventilator interaction
↑ Lung and chest wall elastance leading to flow starvation and increased inspiratory load; intrinsic PEEP causing delayed triggering
↑ Descending input due to discomfort; ↑ inspiratory load due to mismatch between mechanical inflation and neural inspiratory time; stimulation of central and peripheral chemoreceptors in the case of hypercapnia
Adjust ventilation settings, change ventilation modes, titrate sedation, consider neuromuscular blockade
(ARDS: acute respiratory distress syndrome; CO2: carbon dioxide; DO2: oxygen delivery; ECCO2R: extracorporeal CO2 removal; ECMO: extracorporeal membrane oxygenation; FiO2: fraction of inspired oxygen; PEEP: positive end-expiratory pressure; P-SILI: patient self-inflicted lung injury; RRT: renal replacement therapy; VO2: oxygen consumption; V/Q: ventilation/perfusion)
Nasal high flow may reduce drive by washout of CO2 from upper airways, decrease CO2 production following decreased inspiratory effort, improve oxygenation, and improve dynamic 7lung compliance. CPAP improves oxygenation by means of application of positive airway pressure and improvement of lung mechanics. NIV unloads respiratory muscles from inspiratory effort, thereby reducing CO2 production; improves oxygenation by providing PEEP.
TABLE 3   Physiologic effects of different modes of noninvasive and invasive respiratory support and ventilation.8
Neural drive
Mechanisms decreasing drive
Mechanisms increasing drive
Driving PL
Mechanisms decreasing driving
PL
Mechanisms increasing driving
PL
Noninvasive support
Venturi mask
High
Increased set FiO2
Lung collapse, hypoxemia
High
--
High effort and poor respiratory mechanics
HFNC
Reduced
Increased alveolar FiO2, small PEEP effect, CO2 washout
Residual lung collapse
Decreased
Decreased effort
Poor respiratory mechanics
Helmet CPAP
Reduced
Higher PEEP
CO2 rebreathing
Unchanged or increased
Improved respiratory mechanics
High effort
NIV
NIV from high to almost suppressed
Higher PEEP, positive pressure support
Discomfort
Increased
Improved respiratory mechanics
Positive airway pressure during inspiration + residual effort
Invasive ventilation
PSV
From high to almost suppressed
Higher PEEP, positive pressure support
Asynchronies, discomfort, poor patient ventilator flows matching
Normal to high
Improved respiratory mechanics
Positive airway pressure during inspiration + residual effort
APRV
Reduced
Higher PEEP, mandatory breaths
Discomfort, low Vt
Decreased
Improved respiratory mechanics, decreased effort
High effort
Assist/control MV
Low
Higher PEEP, fixed Vt or DP
Asynchronies, discomfort, low Vt
Normal to high
Improved respiratory mechanics
Positive airway pressure during inspiration + residual effort
(APRV: airway pressure release ventilation; CO2: carbon dioxide; CPAP: continuous positive airway pressure; DP: driving pressure; FiO2: fraction of inspired oxygen; HFNC: high flow nasal cannula; MV: mechanical ventilation; NIV: noninvasive ventilation; PEEP: positive end-expiratory pressure; PL: transpulmonary pressure; PSV: pressure support ventilation; Vt: tidal volume)
Initial phase of deep sedation and occasionally, a period of neuromuscular blockade immediately after initiation of invasive mechanical ventilation, reduces the respiratory drive and, eliminates breathing effort. Once assisted breathing is restored, uncontrolled high respiratory drive becomes a challenge to deal with on an ongoing basis. Choice of a ventilation strategy to reduce the dissociation between the brain and ventilation curves becomes of paramount importance, while ensuring minimal or no lung injury. Adjusting settings to decrease this dissociation may improve dyspnea and prevent abnormal breathing patterns (e.g., rapid shallow breathing).
Modes such as pressure or volume assist control and pressure support are used commonly. During assist control, higher peak inspiratory flow delivered might match the need of dyspneic ARDS patients but, at the same time, presence of high inspiratory drive could lead to high Vts, which are not lung-protective.
Volume assist control with set Vt can still generate occult pendelluft and regional overdistension leading to lung injury.23
During pressure support ventilation (PSV), main benefits include unloading of the respiratory muscles, improved mechanics, and better oxygenation.
Medications that may induce respiratory depression are commonly used for sedation and analgesia in ICU patients; their effects need to be closely monitored. Use of sedatives or analgesics for the sole purpose of control of respiratory drive may be disadvantageous. One should look first for the main reason leading to increased respiratory drive (e.g., “fighting the ventilator” or pain) and choose the medication that specifically targets it.
Partial muscular paralysis by low-dose neuromuscular blocking agents was shown in a recent study, to obtain protective Vts and inspiratory pressures in patients with ARDS and uncontrolled high respiratory drive during mechanical ventilation.24 As a word of caution, use of neuromuscular blocking agents will induce a sudden uncoupling between respiratory drive and muscular efficiency. Patient comfort, therefore, needs to be monitored closely.
 
CONCLUSION
The available evidence suggests that excessive respiratory drive can lead to worsening of lung stress, inflammation, and injury; should be avoided whenever possible but optimal strategies for manipulating drive and inspiratory effort need to be studied systematically. Various tools available for assessing the respiratory drive have inherent limitations and therefore multimodal assessment may be the best modality available for bedside monitoring of respiratory drive of a ventilated patient as well as a spontaneously breathing patient receiving various forms of nonrespiratory support. Monitoring of the 8respiratory drive and interventions which confine their effects within physiologic limits should be top priorities for the ICU physician caring for subjects with ARDS.
Many of the technological advances are being integrated in newer ventilators to allow bedside measurements of respiratory drive.
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