Anaesthesia for ECT. Session 1. Dr Richard Cree Consultant in Anaesthesia & ICU. Roseberry Park Hospital and The James Cook Hospital, Middlesbrough

Transcription

1 Anaesthesia for ECT Session 1 Dr Richard Cree Consultant in Anaesthesia & ICU Roseberry Park Hospital and The James Cook Hospital, Middlesbrough

2 Anaesthesia for ECT CHAPTERS 1. The principles of anaesthesia 2. Anaesthetic pharmacology Induction agents Muscle relaxants 3. The physiological effects of ECT 4. Anaesthetic assessment Contraindications for ECT Patient assessment Investigations

3 Chapter 1 The Principles of Anaesthesia

4 The Principles of Anaesthesia What is anaesthesia? without sensation Oliver Wendell Holmes, 1846 reversible lack of awareness General anaesthesia

5 The Principles of Anaesthesia History Alcohol Mesopotamia 3000BC Opium Sumeria 2000BC Mafeisan China 300BC Dwale UK Morphine Germany 1804 Nitrous Oxide UK 1844 Ether USA 1846 Chloroform UK 1847 Cocaine 1877 Thiopentone Curare 1940s Halothane 1950s

6 The Principles of Anaesthesia How do Anaesthetics Work? Biochemical mechanism unclear Myriad sites of action Anaesthesia triad 1. Anaesthesia 2. Analgesia 3. Muscle relaxation

7 The Principles of Anaesthesia Aim of ECT Anaethsesia Short period of unconsciousness to allow 1. The muscle relaxation 2. The ECT stimulus 3. The seizure Return to full consciousness Protection from the adverse physiological effects of the above

8 Chapter 2 Anaesthetic Pharmacology

9 The Principles of Anaesthesia Anaesthetic Drugs Induction agents 1. Propofol 2. Thiopentone 3. Etomidate 4. Methohexitone 5. Sevoflurane 6. Ketamine Muscle relaxants 1. Suxamethonium 2. Others

10 Anaesthetic Drugs Propofol PROS Rapid onset Short action Nice! - Less nausea Suppresses haemodynamic response CONS Raises seizure threshold Short seizures but no effect on efficacy Painful

11 Anaesthetic Drugs Thiopentone (Thiopental) PROS Longer seizures than Propofol CONS Raises seizure threshold Cardiac arrhythmias Less effect on haemodynamic stability

12 Anaesthetic Drugs Etomidate (Hypnomidate) PROS Lowers seizure threshold useful in refractory seizures Long seizures CONS No suppression of haemodynamic response Nausea Painful Abnormal movements Adrenal suppression?

13 Anaesthetic Drugs Methohexitone (Methohexital/Brevital) PROS Gold standard Rapid onset, rapid recovery No effect on seizure threshold or duration CONS Expensive Unlicensed since 2000 Difficult to obtain

14 Anaesthetic Drugs Sevoflurane Inhalational anaesthetic No effect on seizure Useful for difficult venous access Attenuates post-ect uterine contraction in 3 rd trimester of pregnancy Requires anaesthetic machine, vapouriser & scavenging

15 Anaesthetic Drugs Ketamine PROS Longer seizures Less memory deficit? CONS Slow onset Longer acting Emergence phenomena - hallucinations Less attenuation of haemodynamic response

16 Anaesthetic Drugs Opioids PROS Attenuate haemodynamic response Alfentanil & remifentanil prolong seizures Single agent in refractory seizures? CONS Fentanyl shortens seizure duration Prolong recovery time

17 Anaesthetic Drugs Muscle Relaxants Suxamethonium Depolarising muscle relaxant PROS Rapid onset Short acting CONS Fasciculation & muscle pain Suxamethonium apnoea Malignant hyperpyrexia Masseter spasm

18 Anaesthetic Drugs Muscle Relaxants - Atracurium, Rocuronium Non-depolarising muscle relaxant PROS CONS It isn t suxamethonium! Slow onset Long acting maintain anaesthesia & ventilation

19 Chapter 3 The Physiological Effects of ECT

20 The Physiological effects of ECT ECT stimulus results in. 1. Increased cerebral blood flow 2. Generalised tonic-clonic seizure 3. Cardiovascular effects Parasympathetic Sympathetic 4. Complex neuro-endocrine effects why it works!

21 Physiological effects of ECT Increased Cerebral Blood Flow Cerebral blood flow (CBF) increases by over 100% in ECT Munroe-Kelly doctrine Brain in a tight, rigid box the skull Brain 80% Blood 12% and CSF 8% Increasing CBF Increased intra-cranial pressure (ICP) Risks recent strokes or haemorrhages, aneurysms, AV malformations, brain tumours etc.

22 Physiological effects of ECT The Seizure Risks of the tonic-clonic convulsion: 1. Damage to teeth, tongue and mouth - Direct effect of the stimulus 2. Long bone fractures 3. Avulsion fractures 4. Cervical spine injury e.g. rheumatoid disease or ankylosing spondylitis

23 Physiological effects of ECT Cardiovascular Effects Autonomic nervous system effects 1. Parasympathetic nervous system During the stimulus Effects mediated by acetylcholine Bradycardia rarely asystole Salivation May be exacerbated by suxamethonium Can prevent with glycopyrrolate or atropine

24 Physiological effects of ECT Cardiovascular Effects 2. Sympathetic nervous system During the seizure Effects mediated by adrenaline Effects fade over mins Tachycardia Hypertension Effects attenuated by Anaesthetic agents - propofol Cardac drugs e.g. beta-blockers Short acting opiates

25 Physiological effects of ECT Cardiovascular Effects Ensure optimal treatment of underlying cardiovascular conditions

26 Chapter 4 Anaesthetic Assessment

27 Anaesthetic Assessment ASA Grade American Society of Anaesthesiologists (ASA) grading system Grade Description Example I II Healthy Mild systemic disease no functional limitation Well controlled hypertension, diabetes, asthma III Moderate systemic disease Definite functional limitation COPD with exercise limit. Diabetes with complications. Exertional angina IV V Severe systemic disease Constant threat to life Moribund Expected to die in 24hours Unstable angina. COPD-breathless at rest Critically ill ICU patient undergoing emergency surgery

28 Anaesthetic Assessment ASA Grade ASA grade Anaesthetic assessment for ECT ASA Grades 1 & 2 Can be seen by Anaesthetist immediately prior to ECT. Routine investigations & assessment only required. ASA Grade 3 ASA Grade 4 May need further assessment, investigations and specialist opinion prior to ECT. Consider conducting treatment in main operating theatre suite. Will require thorough assessment, investigation and specialist opinion prior to ECT. Treatment will need to be conducted in main operating theatre suite. Full consideration of risks vs. benefits.

29 Anaesthetic Assessment Contra-Indications to ECT Relative contra-indications: 1. Increased intra-cranial pressure Brain tumour Recent stroke Untreated cerebral aneurysm or AVM 2. Cardiovascular disease Recent acute coronary syndrome Unstable angina Untreated cardiac failure Aortic or thoracic aneurysm Severe valvular heart disease

30 Anaesthetic Assessment Contra-Indications to ECT 3. Musculo-skeletal disease Unstable cervical or lumbar spine - acute injury or chronic disease Severe osteoposis Unstabilised fractures 4. Phaechromocytoma 5. Deep venous thrombosis 6. Pregnancy 7. Cochlear implant?

31 Anaesthetic Assessment Investigations Local guidelines as agreed with your anaesthetist Results must be available for the anaesthetic assessment before first treatment Often do not need repeating during treatment period New tests may not be required if already performed within the previous three months

32 Anaesthetic Assessment Full blood count Rationale to check O 2 carrying capacity Perform in All patients over 60 yrs ASA grades III or IV Any cardiorespiratory disease Renal disease Diabetes Some antipsychotics e.g. Olanzapine

33 Anaesthetic Assessment Urea & Electrolytes Electrolyte disturbance arrhythmias affect seizure threshold Perform in All patients over 60 yrs ASA grades III or IV Any cardiorespiratory disease Renal disease Poor fluid intake / dehydration Diabetes Lithium

34 Anaesthetic Assessment Other Blood Tests Clotting & INR Detect over anti-coagulation in patients taking warfarin Sickle Cell Anaemia Screen Detect risk of sickle cell crisis in patients of African, Caribbean, Mediterranean or Asian ethnic origin

35 Anaesthetic Assessment Other Blood Tests Thyroid function Liver function Patients with known liver disease or alcohol excess and those taking drugs affecting liver function e.g. olanzipine, carbamazepine Pregnancy test Any woman of childbearing age Allows discussion of risks vs. benefits of ECT

36 Anaesthetic Assessment Electrocardiogram Rationale detect myocardial ischaemia & previous cardiac damage, risk of arrthymias Useful baseline Perform in All patients over 60 yrs ASA grades III or IV Cardiorespiratory disease Diabetes

37 Anaesthetic Assessment X-Rays Chest X-ray and / or pulmonary function tests only after discussion with anaesthetist Other imaging / tests only on specialist advice

38 Any Questions?