Anaesthesia for ECT - Royal College of Psychiatrists - R Cree - SESSION 1hghfgh.pdf · Anaesthesia for ECT Session 1 Dr Richard Cree Consultant in Anaesthesia & ICU Roseberry Park

Anaesthesia for ECT Session 1Dr Richard CreeConsultant in Anaesthesia & ICU

Roseberry Park Hospital andThe James Cook Hospital, Middlesbrough

Anaesthesia for ECT

CHAPTERS

1. The principles of anaesthesia2. Anaesthetic pharmacology

Induction agents Muscle relaxants

3. The physiological effects of ECT4. Anaesthetic assessment

Contraindications for ECT Patient assessment Investigations

Chapter 1 The Principles of Anaesthesia

The Principles of Anaesthesia

What is anaesthesia?

“without sensation” Oliver Wendell Holmes, 1846

“reversible lack of awareness”General anaesthesia


History

Alcohol – Mesopotamia 3000BC Opium – Sumeria 2000BC Mafeisan – China 300BC Dwale – UK 1200-1500 Morphine – Germany 1804 Nitrous Oxide – UK 1844 Ether – USA 1846 Chloroform – UK 1847 Cocaine – 1877 Thiopentone - 1934 Curare – 1940s Halothane – 1950s


How do Anaesthetics Work?

Biochemical mechanism unclear Myriad sites of action

Anaesthesia triad

1. Anaesthesia2. Analgesia3. Muscle relaxation


Aim of ECT Anaethsesia

Short period of unconsciousness to allow 1. The muscle relaxation2. The ECT stimulus 3. The seizure

Return to full consciousness Protection from the adverse physiological

effects of the above

Chapter 2 Anaesthetic Pharmacology


Anaesthetic Drugs

Induction agents1. Propofol2. Thiopentone3. Etomidate4. Methohexitone5. Sevoflurane6. KetamineMuscle relaxants1. Suxamethonium2. Others

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

Anaesthetic Drugs

Thiopentone (Thiopental)

PROS Longer seizures

than Propofol

CONS Raises seizure

threshold Cardiac arrhythmias Less effect on haemodynamic stability

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?

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

Anaesthetic Drugs

Sevoflurane

Inhalational anaesthetic

No effect on seizure Useful for difficult venous access Attenuates post-ECT uterine contraction

in 3rd trimester of pregnancy

Requires anaesthetic machine, vapouriser & scavenging

Anaesthetic Drugs

Ketamine

PROS Longer seizures Less memory deficit?

CONS Slow onset Longer acting Emergence phenomena - hallucinations Less attenuation of haemodynamic

response

Anaesthetic Drugs

Opioids

PROS Attenuate haemodynamic response Alfentanil & remifentanil prolong seizures Single agent in refractory seizures?

CONS Fentanyl shortens seizure duration Prolong recovery time

Anaesthetic Drugs

Muscle Relaxants Suxamethonium

Depolarising muscle relaxant

PROS Rapid onset Short acting

CONS Fasciculation & muscle pain Suxamethonium apnoea Malignant hyperpyrexia Masseter spasm

Anaesthetic Drugs

Muscle Relaxants- Atracurium, Rocuronium

Non-depolarising muscle relaxant

PROS It isn’t suxamethonium!

CONS Slow onset Long acting

– maintain anaesthesia & ventilation

Chapter 3 The Physiological Effects of ECT

The Physiological effects of ECT

ECT stimulus results in ….

1. Increased cerebral blood flow2. Generalised tonic-clonic seizure3. Cardiovascular effects

Parasympathetic Sympathetic

4. Complex neuro-endocrine effects – why it works!

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.


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


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



2. Sympathetic nervous system During the seizure Effects mediated by adrenaline Effects fade over 10-20 mins Tachycardia Hypertension

Effects attenuated by Anaesthetic agents - propofol Cardac drugs – e.g. beta-blockers Short acting opiates



Ensure optimal treatment ofunderlying

cardiovascular conditions

Chapter 4 Anaesthetic Assessment

Anaesthetic Assessment

ASA GradeAmerican Society of Anaesthesiologists (ASA) grading system

Grade Description Example

I Healthy

II Mild systemic disease –no functional limitation

Well controlled hypertension, diabetes, asthma

III Moderate systemic diseaseDefinite functional limitation

COPD with exercise limit. Diabetes with complications. Exertional angina

IV Severe systemic diseaseConstant threat to life

Unstable angina. COPD-breathless at rest

V Moribund – Expected to die in 24hours

Critically ill ICU patient undergoing emergency surgery


ASA GradeASA grade – Anaesthetic assessment for ECT

ASA Grades 1 & 2

ASA Grade 3

ASA Grade 4

Can be seen by Anaesthetist immediately prior to ECT. Routine investigations & assessment only required.

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.


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


Contra-Indications to ECT

3. Musculo-skeletal disease Unstable cervical or lumbar spine - acute

injury or chronic disease Severe osteoposis Unstabilised fractures

4. Phaechromocytoma5. Deep venous thrombosis6. Pregnancy7. Cochlear implant?


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


Full blood count

Rationale – to check O2 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


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


Other Blood Tests

Clotting & INRDetect over anti-coagulation inpatients taking warfarin

Sickle Cell Anaemia ScreenDetect risk of sickle cell crisis in patients ofAfrican, Caribbean, Mediterranean or Asianethnic origin


Other Blood Tests

Thyroid function

Liver functionPatients with known liver disease or alcoholexcess and those taking drugs affecting liver function – e.g. olanzipine, carbamazepine

Pregnancy testAny woman of childbearing ageAllows discussion of risks vs. benefits of ECT


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


X-Rays

Chest X-ray and / or pulmonary function tests only after discussion with anaesthetist

Other imaging / tests only on specialist advice

Any Questions?

Documents

Anaesthesia for ECT - Royal College of Psychiatrists - R Cree - SESSION 1hghfgh.pdf · Anaesthesia for ECT Session 1 Dr Richard Cree Consultant in Anaesthesia & ICU Roseberry Park