Clinical Anaesthesia (eBook)

CLINICAL ANAESTHESIA: Lecture Notes 1
Contents 7
List of contributors 8
Preface 9
Acknowledgements 10
List of abbreviations 11
1 Anaesthetic assessment and preparation for surgery 13
The preoperative assessment clinic 14
Stage 1 14
Stage 2 14
Stage 3 14
The anaesthetic assessment 15
Present and past medical history 15
Cardiovascular system 15
Respiratory system 16
Assessment of exercise tolerance 16
Other important considerations 17
Previous anaesthetics and operations 17
Family history 17
Drug history and allergies 17
Social history 17
The examination 18
Cardiovascular system 18
Respiratory system 18
Nervous system 18
Musculoskeletal system 18
The airway 18
Investigations 20
Additional investigations 20
Cardiopulmonary exercise testing 20
Echocardiography 21
Medical referral 21
Cardiovascular disease 21
Respiratory disease 21
Endocrine disorders 22
Renal disease 22
Haematological disorders 22
The obese patient 22
Cardiovascular system 22
Respiratory system 22
Metabolic and gastrointestinal systems 23
Other issues 23
Risk associated with anaesthesia and surgery 23
Common (1 in 10 to 1 in 100) 23
Uncommon (1 in 1000) 23
Rare (< 1 in 10000)
Risk indicators 24
Classification of operation 25
Prevention of venous thromboembolism 25
Obtaining informed consent 26
What is consent? 26
What do I have to tell the patient? 26
Who should get consent? 27
What constitutes evidence of consent? 28
What about an unconscious patient? 28
FURTHER USEFUL INFORMATION 28
2 Anaesthetic equipment and monitoring 30
Airway equipment 30
Facemasks 30
Simple adjuncts 31
Oropharyngeal airway 31
Nasopharyngeal airway 31
Supraglottic devices 31
The laryngeal mask airway (LMA) 31
The intubating LMA (ILMA) 32
Tracheal tubes 32
Laryngoscopes 34
Direct 34
Indirect 34
Gum elastic bougie 36
The safe delivery of anaesthesia 36
The delivery of gases to the operating theatre 36
Oxygen 36
Nitrous oxide 36
Medical air 37
Vacuum 37
The anaesthetic machine 37
Reduction of pressure 37
Control of flow of gases 37
The addition of anaesthetic vapours 38
Anaesthetic breathing systems 38
Components of a breathing system 38
The circle system 39
Mechanical ventilation 40
Modes of ventilation 40
The modern anaesthetic machine 41
The modern anaesthetic machine 41
Minimizing theatre pollution 41
Scavenging systems 41
Intravascular cannulas 42
Giving sets and fluid warmers 42
Patient warming 42
Cell savers 43
Ultrasound 43
Syringe pumps 43
Measurement and monitoring 43
Monitoring the patient 43
The ECG 43
Non-invasive blood pressure 43
Pulse oximeter 44
Capnometry 45
Vapour concentration analysis 45
Peripheral nerve stimulator 45
Temperature 45
Invasive or direct blood pressure 46
Central venous pressure (CVP) 46
Oesophageal Doppler cardiac output monitoring 46
Pulse analysis cardiac output monitoring 47
Bispectral index (BIS) 48
Blood loss 48
Monitoring the equipment 48
Oxygen supply 48
Breathing systems 48
FURTHER USEFUL INFORMATION 49
3 Drugs and fluids used during anaesthesia 51
Premedication 51
Modification of pH and volume of gastric contents 51
Analgesia 52
Anti-emetics 52
Miscellaneous 52
Intravenous anaesthetic drugs 52
Inhaled anaesthetic drugs 54
Solubility 54
Minimum alveolar concentration 55
Nitrous oxide 55
Systemic effects 55
Total intravenous anaesthesia 56
Neuromuscular blocking drugs 56
Depolarizing neuromuscular blocking drugs 56
Suxamethonium 56
Pseudocholinesterase deficiency 56
Non-depolarizing neuromuscular blocking drugs 57
Anticholinesterases 57
Sugammadex 58
Analgesic drugs 58
Opioid analgesics 58
Pure agonists 58
Tramadol 59
Buprenorphine 60
The pure antagonist 60
The regulation of opioid drugs 60
Supply and custody of schedule 2 drugs 60
Non-steroidal anti-inflammatory drugs (NSAIDs) 61
Paracetamol 61
Anti-emetics 62
Local anaesthetic drugs 62
Mechanism of action 62
Individual drugs 63
Amethocaine 63
Cocaine 63
Lidocaine 64
Bupivacaine 64
Ropivacaine 64
Prilocaine 64
Adrenaline (epinephrine) 64
Calculation of doses 65
Intravenous fluids 65
Crystalloids 65
Colloids 66
Blood and blood components 67
Risks of blood and blood-product transfusions 67
FURTHER USEFUL INFORMATION 68
4 The practice of general anaesthesia 70
Preoperative checks 70
Checking the anaesthetic machine 70
Checking the patient 70
Sign in 71
Preparation for anaesthesia 71
Monitoring the patient 71
Intravenous access 72
Central venous cannulation 72
The internal jugular vein 72
Subclavian vein 73
Equipment for central venous catheterization 73
Arterial cannulation 74
Technique of cannulation 74
Preoxygenation 74
Induction of anaesthesia 74
Maintaining the airway 75
Oropharyngeal airway 75
Nasopharyngeal airway 76
Problems with airways 77
Facemasks 77
Supraglottic airway devices 78
Insertion of a supraglottic airway 78
Tracheal intubation 79
Equipment for tracheal intubation 79
The technique of oral intubation 79
Confirming the position of the tracheal tube 80
Complications of tracheal intubation 81
Hypoxia, due to 81
Trauma 81
Reflex activity 81
Keeping patients warm 82
Maintenance of anaesthesia 82
Inhalational anaesthesia 82
TIVA using propofol 82
Advantages of total intravenous anaesthesia 83
Disadvantages of total intravenous anaesthesia 83
Spontaneous ventilation 83
Mechanical ventilation 83
The effects of positive pressure ventilation 83
Transfer into the operating theatre 84
Positioning the patient 84
The supine position 84
The lateral position 85
The prone position 85
Time out 86
Assessment of neuromuscular blockade 86
Intraoperative fluids 87
The accrued deficit 87
Intraoperative requirements 87
The anaesthetic record 88
Emergence from anaesthesia 88
Sign out 88
1. Spontaneous ventilation, inhalational drug for maintenance, supraglottic airway 88
2. Mechanical ventilation, inhalational drug for maintenance, tracheal tube 89
FURTHER USEFUL INFORMATION 89
5 Local and regional anaesthesia 91
The role of local and regional anaesthesia 91
Local and regional anaesthetic techniques 92
Infiltration analgesia 92
Brachial plexus block 93
Transversus abdominis plane (TAP) block 93
Epidural anaesthesia 93
Spinal anaesthesia 95
Contraindications to epidural and spinal anaesthesia 96
Monitoring during local and regional anaesthesia 96
Complications of central neural blockade 96
Hypotension and bradycardia 96
Nausea and vomiting 96
Post dural puncture headache 97
Local anaesthetic toxicity 97
Management of toxicity 97
Circulatory collapse 97
Regional anaesthesia: in awake or anaesthetised patients? 98
FURTHER USEFUL INFORMATION 98
6 Special circumstances 100
Anaesthesia for emergency surgery 100
Reducing the risks of aspiration 100
Cricoid pressure (Sellick’s manoeuvre) 101
Rapid sequence induction of anaesthesia 101
Anaesthesia for obstetric patients 101
Aortocaval compression 102
Anaesthesia for thoracotomy 103
Aspiration of gastric contents 104
Management 104
Aspiration at induction 104
Aspiration intraoperatively with supra-glottic airway 105
Anaphylaxis 105
Causes of allergic reactions 106
Immediate management 106
Subsequent management 106
Investigations 106
Malignant hyperpyrexia (hyperthermia) (MH) 107
Presentation 107
Immediate management 107
Dantrolene 107
Investigation of the family 107
Anaesthesia for malignant hyperpyrexia-susceptible patients 107
Difficult intubation 107
Failed intubation 108
Needle cricothyroidotomy 110
FURTHER USEFUL INFORMATION 110
7 Post-anaesthesia care 112
The post-anaesthesia care unit 112
Discharge of the patient 113
Postoperative complications and their management 113
Hypoxaemia 113
Alveolar hypoventilation 113
Ventilation and perfusion mismatch within the lungs 115
Diffusion hypoxia 116
Pulmonary diffusion defects 116
A reduced inspired oxygen concentration 116
Management of hypoxaemia 116
Devices used for delivery of oxygen 116
Variable-performance devices: masks or nasal cannulae 116
Fixed-performance devices 117
Hypotension 118
Step 1: Assess the circulating volume (preload) 118
Treatment 118
Step 2: Assess cardiac output 118
Treatment 118
Step 3: Assess for vasodilatation 119
Hypertension 120
Postoperative nausea and vomiting (PONV) 120
Postoperative intravenous fluid therapy 120
Minor surgery 120
Major surgery 122
Third space losses 122
Clinical assessment 123
Biochemistry 123
Monitoring 123
The stress response 123
Postoperative analgesia 124
Factors affecting the experience of pain 124
Management of postoperative pain 124
Assessment of acute pain 124
Analgesic drugs used postoperatively 125
Analgesic techniques used postoperatively 126
Regional analgesic techniques 127
Management of complications during postoperative epidural analgesia 129
Intrathecal (spinal) analgesia 131
Other techniques 131
Combining analgesic techniques 131
Difficult pain problems 131
FURTHER USEFUL INFORMATION 131
8 The acutely ill adult patient on the ward 133
Section 1: Recognition and assessment 133
Clinical scoring systems (track and trigger systems) 134
Critical care outreach teams 135
Receiving a call 135
The principles of assessment 136
Initial approach to the patient 137
Primary assessment and resuscitation 137
Airway assessment (A) 137
Look for chest movement 137
Listen for sounds of air movement and any associated abnormal noises 138
Feel for expired air 138
Assess breathing (B) 138
Look for the signs of abnormal breathing 138
Also look for 139
Listen for signs of respiratory disease 139
Feel the chest for 139
Assess the circulation (C) 140
Look for 140
Listen for 140
Feel for 141
Assessing neurological state – disability (D) 141
Examine the pupils for size and reactivity to light 141
Other important checks 142
Exposure/examination (E) 142
What to do next? 142
Communicating information about patient deterioration 143
Section 2: Management of common emergencies 143
Acute shortness of breath 144
Acute lower airway problems 146
Look for 146
Listen for 146
Feel for 146
Acute upper airway obstruction 144
Look for 144
Listen for 144
Feel for 144
Reduced conscious level (reduced GCS) 144
Upper airway swelling/tumour 144
Start treatment 145
External compression after surgery 145
Start treatment 145
Blocked tracheostomy 145
Acute severe asthma 146
Start treatment with 146
Establish basic monitoring 146
Gain IV access 146
Refer to ITU if 149
Pneumonia 149
1. History 149
2. Examination 149
Start treatment 149
Obtain IV access 149
Establish basic monitoring and record vital signs 149
3. Investigations 149
Pneumothorax 150
Look for 150
Listen for 150
Feel for 150
Start treatment with 150
Establish basic monitoring 150
Gain IV access 150
Investigations 150
Tension pneumothorax 150
Start treatment 150
Pulmonary oedema 151
Look for 151
Listen for 151
Feel for 151
Start treatment 151
Establish basic monitoring 151
Gain IV access 151
Investigations 151
Further measures 152
Pulmonary embolism 152
Look for 152
Listen for 152
Feel for 152
Other findings include 152
Start treatment 153
In severe cases 153
Investigations 153
Hypotension 153
Look for 153
Listen for 153
Feel for 154
Hypovolaemic shock 154
Start treatment 154
Investigations 155
Sepsis and septic shock 155
Start treatment 156
Cardiogenic shock 156
Start treatment 156
Investigations 157
Low urine output 157
Start treatment 158
Investigations 158
Chest pain 159
Unstable angina 159
Non-ST-segment-elevation myocardial infarction (NSTEMI) 160
ST-segment-elevation myocardial infarction (STEMI) 160
Start treatment 160
Cardiac arrhythmias 161
Tachycardias 161
Bradycardia 162
Cardiac arrest 162
Actions on attending a cardiac arrest 162
Reduced conscious level 166
Hypoglycaemia 166
Start treatment 166
If the patient is unconscious 166
Investigations 166
Opioid narcosis 167
Start treatment 167
Stroke/intracranial haemorrhage 167
Start treatment 167
Following the initial assessment and stabilization the priorities are 168
Status epilepticus 168
Start treatment 168
If seizures continue 168
Refractory status epilepticus 168
Investigations 168
Reduced level of consciousness secondary to hypoxaemia or hypovolaemia 169
FURTHER USEFUL INFORMATION 169
Answers to short-answer questions 171
Answers to true/false questions 183
Index 189