Clinical 2 Flashcards
Intraoperative awareness
recall of events during general anaesthesia either due to inadequate delivery of anaesthetic or patient resistance to sufficient dose
Classification of AAGA
Implicit awareness: implicit memories without conscious recall, but may alter behaviour
Explicit awareness: conscious recall
Michigan classification classes
0 - no awareness
1 - isolated auditory perception
2 - tactile stimulation without pain
3 - pain
4 - paralysis without pain
5 - pain and paralysis
Risk factors
Patient
- previous awareness
- obesity
- young females
- difficult airway
Anaesthetic
- TIVA ??
- Thiopentone
- Muscle relaxants
Surgical
- GA ceasarean
- cardiac
Organisational
- out of hours
- junior anaesthetist
Awareness incidence
1:19,000
1:8200 cardiac
1:670 cesarean
no neuromuscular blocking drugs 1:136,000
Criteria for referral for bariatric surgery
BMI > 40
BMI 35-40 with disease that might improve with weight loss
weight loss not achieved despite all appropriate strategies
long term follow up commitment
Tier 3 obesity service - MDT
Weight loss procedures
Restrictive - small gastric pouch, limited outlet
- sleeve gastrectomy
- gastric band
Malabsorptive
- limit size of stomach shortens route of absorption
- roux-en-y bypass
General considerations in bariatric surgery
difficult procedures e.g. venous, arterial, RA
difficult airway
positioning
monitoring - IABP may ne needed
equipment - hover mattress, bariatric table
Carcinoid syndrome
results from secretion of vasoactive substances by carcinoid tumours leading to flushing, diarrhoea, right heart failure.
Carcinoid crises
- exaggerated profound cardiorespiratory responses with bronchospasm, tachycardia, labile BP
- might be precipitated by surgery, anesthesia
Carcinoid tumours
arise from enterochromaffin cells - neuroendocrine cells, 2/3 gut 1/3 bronchi
primary tumour symptoms - release of vasoactive substances e.g. histamine, serotonin, VIP or mass effect
carcinoid heart disease - right heart filure
work up carcinoid
CT
urine HIAA - serotonin metabolite or serum chromaffin A
ocrtreotide - somatostatin analogue, reduces mediator release pre op
CVS work up
symptomatic - bronchodialtors, antidiarrhoeals, treatment of heart failure
Anaesthesia for carcinoid
- continue octreotide
- IABP pre induction
- avoid histamine release (atracrium, morphine)
- severe hypotension - IV octreotide 10-20ug
- hypertension - labetalol
- epidural may reduce crises
Cataract surgery
GA
Ads - controlled, anaesthesia and akinesia, high patient satisfaction
Disads - costly, personnel, equipment, risk of GA, starvation
RA
Ads - time and cost efficient, anaesthesia and akinesia excellent, no fasting
Disads - less controlled than GA, complications
Topical
- Ads - time and cost efficient, no effect on vision, avoid risks of GA and ocular risks of RA
- Disads - least controlled, purely sensory
Day case cataract - continue anticoagulants and antiplatelts INR < 3.5
Eye RA
Sharp needle
- Retrobulbar - highest complications. lat 1/3 lower orbital ridge, advance until equator estimated then medial and superior. intraconal.
- Peribulbar - extraconal, medial cants
Blunt needle
- sub-tenons - tenon capsule thin layer or CT separates globe from optic nerve. sub-tenon potential space between sclera and tenon. better tolerated, less risk but chemises and subconjunctival haemorrhage
Sub-tenon block
- topical anaesthesia - tetracaine 0.5%
- lower nasal quadrant
- look up and out
- forceps to lift conjunctiva and and tenons fascia
- westcott scissors to cut
- passage of westcott scissors to make superio-medially
- sub tenon cannula - advance along contour of eyeball until syringe vertical
- aspirate and inject 3-5ml 0.5%
Robot assisted surgery
ads
- better ergonomics for surgeon
- 6 degrees of freedom
- elimination of undesirable movements e.g. tremor
Disads
- loss of haptic feedback
- patient movement potentially disastrous (robot fixed)
- human factors - poor access to patient
delayed emergence from anaesthesia
pharmacological
- benzos
- opioids
- NMBDs
- central anticholinergic syndrome
non-pharmacological
- metabolic - glucose, sodium, hypothermia
- neuro - intracranial event, seizures
sux apnoea
autosomal recessive
4 alleles - usual 96% homozygotes
0.001% homozygous for silent - no enzyme
- dibucaine number - higher the better enzyme function
acquired
- pregnancy
- ever, renal, cardiac failure
- malnurtiion
- cancer
ECT
30-45J energy 1-1.5s
aim for 20-50s seizure
unilateral - less cognitive effects, less effective
bilateral - normal
NELA standards
- CT scan reported prior to surgery
- Abx within 1 hr of sepsis diagnosis
- risk of death documented pre-op
- arrival to theatre in appropriate timescale
- high risk patients should have consultant anaesthetist, surgeon and HDU
Risk assessment tool - 5% + high risk (30day mortality)
Exclusions - oesophagus, appendix, gallbladder, vascular, gynae, trauma
ERAS
MDT approach to perioperative care aiming for faster, safe recovery and discharge. common features - education and engagements of MDT, patient education, early feeding and mobilisation, multimodal analgesi
enhanced recovery interventions
pre-op
- education
- prehabilitation
- optimising co-morbidities
- investigating and treating anaemia
admission
- minimis fasting
- glucose drink
anaesthesia
- multimodal analgesia including regional
- GD fluid
- minimis PONV
surgery
- minimally invasive, minimal drains
post-op
- early feeding and mobilisation
- multimodal analgesia with pain team input
- removal of lines as soon as possible
ERAS benefits
reduced stress response - neuroendocrine, inflammatory
reduced ileus
reduce cardiorespiratory complications
increased muscle strength
reduced LOS
Flaps
free - flap - autologous tissue detached from remote donor site and transferred to recipient, with circulation restored by microvascular anastomoses
pedicle - flap remains connected to donor site by intact vascular pedicle
Free flap surgery
wounds not suitable for primary closure
- mastectomy - DIEP, TRAM
- head and neck cancers
- post trauma
Stages
1. flap elevation and clamping of vessels
2. primary ischaemia - blood flow ceases, anaerobic metabolism 60-90mins
3. reperfusion - arterial and venous anastomoses
contraindicaions - sickle cell, polycythaemia
Anaesthesia aims in free flap surgery
minimise primary ischaemia = primarily surgical time
optimise flap perfusion and minimise secondary schema -optimised by normothermia, low SVR, adequate filling, 30% haematocrit (HP)
Flap failure
- arterial - defective anastomosis, thrombosis, spasm
- venous defective anastomosis, compression, thrombosis
- oedema - prolonged ischaemia, excessive fluid
HDU
- colour
- dopplers
- temperature
- CRT
donor site is painful
HIV / AIDS
retrovirus infecting CD4 t lymphocytes causing destruction and immunodeficiency
seroconversion –> asymptomatic
AIDS CD4 < 200 or AIDs defining illness - oesophageal candidiasis, kaposi sarcoma, CNS lymphoma, PCP
opportunistic infectins
- PCP
- fungi e.g. cryptococcus
- viruses eg cmv
- TB
HAART
2 nucleoside reverse transcriptase inhibitors
- tenofovir
+ 1
- integrase inhibitor
- non-nucleoside reverse transcriptase inhibitor
- protease inhibitor
SE neutropenia, anaemia, diarrhoea, hepatic
Specific principles in liver resection
Child-Pugh / MELD risk assessment
Bleeding - cross match, wide bore access
Coagulopathy correction
Pringle manoeuvre - occlusion of PV and HA - reduce bleeding but also reduce venous return and increase afterload
Low CVP < 5
TXA
Drug metabolism affected e.g. roc, opiate, middaz
Analgesia - consider epidural but coagulation
IPPV and PEEP reduced hepatic blood flow but increase bleeding risk