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
Pancreatic resection
Whipples = pancreaticoduodenectomy - distal stomach, duodenum, bile duct, gall bladder. Distal pancreatectomy = spleen as well
intra-op - glycemic monitoring, restrictive fluid balance
Anaesthetic considerations following lung transplant
Denervated lung
- suppressed cough reflex
- impaired sputum clearance
- possible heart denervation
Care with intubation - avoid disrupting anastomosis - cuff just distal to vocal cods and monitored
strict fluid balance - beware pulmonary oedema
single lung transplant - may have different compliance and differential ventilation
perioperative implications of immunosuppression
- immunophilin binding - tacrolimus, ciclosporin - prevent T cell activation. associated with renal dysfunction
- nucleic acid synthesis inhibitors - azathioprine - block lymphocyte proliferation
- steroids - blod inflammtory cytokines
Anaemia, thrombocytopenia, leucopenia.
strict asepsis
Penetrating eye injury
Normal IOP 10-21mmhg.
rise in IOP may cause extrusion of vitreous humour
RSI, avoid ketamine and sux
drug to obtund laryngoscopy reflex
volatile or TIVA, avoid N20
Head up position, PaCO2 4.5-5, sats 94-98%
avoid coughing, straining on emergence (LMA exchange)
Raised IOP
- ensure adequate depth, avoid obstructed venous blood flow
- mannitol, acetazolamide 500mg iv
Management of kidney stones
non-invasive
- extracorporeal shock wave lithotripsy
invasive
- ureteric stenting
- lasering
- percutaneous nephrolithotomy
- open or laparoscopic removal
PCNL considerations
positioning
- lithotomy for stent
- then prone or prone oblique for nephrostomy insertion
- reinforced ETT, head arm leg chest pelvis support
Nephrostomy risk - pneumothorax, renal pelvis rupture
Phaechromocytoma
catecholamine secreting tumour of the adrenal medulla
classic presentation - headaches, sweating, palpitations
- HTN 90%
- Incidental
1/3 autosomal dominant. May be associated with other tumours - MEN 2, Von-Hippel Lindau, Neurofibromatosis
Dx - plasma metaneprhins, urine VMA
imaging
Pre-op management of phaeochromocytoma
MDT
Sympathetic blockade
BP control
- Alpha blockage first then beta (unopposed alpha - hypertensive crisis)
- Alpha - doxzosin (selective a1), phenoxybenzamine (non-selective)
HR control
- Beta - selective B1 e.g. atenolol.
Myocardial function - echo for function
Restore circulating volume - fluid intake
reverse glucose / electrolyte derangement (hypoglycaemic agents)
Aim for BP < 130/80 (old was aim for orthostatic hypotension, nasal congestion)
Intra-op management phaeo
monitoring - arterial, CO, CVC
Open - epidural
Avoidance of perioperative catecholamine release
- intubation, surgical stimulus
- avoid sympathomimetic drugs - ketamine, ephedrine
- use magnesium, remifentanil
minimise response to tumour handling
- Phentolamine - alpha antagonists vasodilator. bolus 1-2mg, short duration
- sodium nitroprusside, GTN - vasodialtor
- esmolol - selective B1 antagonist. rapid onset / offset. 500ug.kg
Hypotension following tumour removal
- Stop hypotensives, optimise fluid
- noradrenaline
- vasopressin
Post op
- critical care
- BP support
- Glcaemic support
- hypoadrenalism - steroid
Perioperative risk assessment
allows targeted optimisation
provides information for patient selection and informed consent
History examination
Risk score
Risk prediction models
Functional assessment
Risk scores
simple, population based risk
ASA 1-6
Lee’s revised cardiac risk - not applicable to emergencies
Risk prediction models
Aim to provide individualised risk
P-Possum - emergency and elective major general and urological and vascular. physiological and operative variables. 30d morbidity and mortality
NELA - 30d mortality in em laparotomy in UK. physiological and operative variables
ACS-NSQIP - big data set, 30 d mortality, morbidity, return to theatre qol. time consuming
SORT - 30 day mortality, 6 variables (non-cardiac non-euro)
functional risk assessment
global cardiorespiratory assessment
6min walk test
incremental shuttle walk
CPET
dynamic, non-invasive cardiorespiratory assessment during exercise to determine functional capacity
if unable to increase oxygen delivery to match increase in perioperative oxygen consumption likely to have complications
aid risk prediction, resource allocation, comorbities identified
CPET
measurements - expired gas, 12 lead, SPO2, BP
Metabolic gas exchange - VO2, VCO2, RER (VCO2/VO2)
9 panel plot
? maximal effort
? ECG changes
Key variables
- VO2 peak max rate of o2 consumption < 15ml/kg/min high risk
- AT - point at which o2 demand exceeds delivery - rise in CO2 excretion
- vent efficiency for CO2 VE/VCO2 - lugns ability to excrete co2
Cpet contraindications
- Acute MI 3-5days
- unstable angina
- unctonrolled arrhythmias
- acute PE
- Pulmonary oedema
Intraoperative aims of kidney transplant
- Ensure perfusion of graft - MAP > 90
- paralysis particularly during anastomosis
- immunosuppression - reduce early rejection, methylprednisolone and biological agent after induction
- CVC, art line (although wary of fistula sites)
- drugs adjustment according to renal function
- multimodal analgesia avoiding NSAIDs
- Mannitol . dopamine nil evidence
- careful fluid
Atlanto-axial subluxation
Axis (C2) and atlas (C1)
AAI - Ligament laxity, erosion of peg, leading to movement of peg of C2 away from C1
movement in flexion can lead to spinal cord compression
can move ant, post, lateral
4mm space = AAS in adults
Robotic surgery
Ads
- greater surgical dexterity (6 degrees of freedom)
- allow visualisation in 3d
- remove unwanted movements - tremor
Disads
- loss of haptic feedback
- need space
- longer
- expense of robot
- poor access to pt
- undocking in emergency takes time
Anaesthetic considerations of robotic surgery
- glaucoma / intracranial pathology trend. pos
- likely ability to cope with pneumoperitoeum
- intraop
- airway - limited access. well secured
- PEEP, TV 6-8, plat press < 30. MV sufficiency to handle co2
- CVS monitoring
- NMB.. must be kept completely still
- NGT
- analgesia multimodal, regional
- careful positioning
- leak test priot to extubation
Massive UGI bleed
A-E
Risk assess - Blatchford (risk of needing intervention) Rockall - pre and post endoscopy risk of re-bleed
GA - airway control, less frightening, better control, better procedural conditions
May need ketamine, volume rhesus, vasopressors, minimise DOA
Varices - band/adrenaline/thermal. need abx and terlipressin. balloon tamponade with sengstacken-blackmore tube, 48hr
TIPS
porphyria
group of inherited disorders leading to altered heme synthesis, usually autosomal dominant
Acute - AIP
non-acute - porphyria cutanea tarda
Acute attack - when haem synthesis is increased, leads to buildup of intermediates. physiological stress, alcohol, fasting, drugs
clinical features - neurovisceral - CNS, PNS, ANS - abdominal pain, nausea, vomiting, tachycardia, distal weakness, seizures, psychiatric
Diagnosis - porphyrin precursors - porphobilinogen, ALA
Porphyria and anaesthesia
precipitants of crisis
- starving - reduce time, RSI
- unsafe drugs - barbiturates, ketamine, etomidate, halothane, deemed, abx clairhtyrmocine
- check with specialist / BNF
remvoe precipirNRA
- GIVE haem arginate - large vein/
Anaesthetic consdierations of prone position
Airway
- ETT dislodgement
- Endobronchial
Breathing
- If abdominal contents not free, can splint diaphragm and reduce compliance
CVS
- abdominal compression reduced venous return and CO
Occular
- POVL - CRAO, ION
Compression
- brachial plexus
- face
breasts
genitals
ankles
knees
Complications of prone positioning
Brachial plexus injury - poor positioning of arms
Facial damage (head rings leads to pressure sores, pressure necrosis)
Ophtalmic injury
Lat cutaneous nerve of thigh
Macroglossia - impaired venous drainage
Clinical features of infective endocarditis
Sub-acute
- fever
- weight loss
- night sweats
- anemia
- embolic phenomenon- laneway lesion, splinter haemorrhages
Acute
- dyspnoea from pulmonary oedema
- shock - cardiogenic, septic
- septic emboli - cerebral, gut, renal,
Risk factors for endocarditis
Cardiac
- rheumatic heart disease
- bicuspid aortic valve
- valve replacement
- indwelling pacemaker
Non-cardiac
- immunosuppression
- IVDU
- indwelling long line
Dukes criteria
2 major, 1 major + 3 minor, or 5 minor
Major
- oscillating cardiac mass on echo
- 2 separate positive blood culture
Minor
- fever
- embolic lesions
- risk factor
- immunilogical phenomena e.g. osler node
- micro evidence not reaching major
organisms
- strep viridans, bovis
- staph aureus, coag negative
- enterococci
marfans
rare autosomal dominant connective tissue disorder affecting multiple systems due to defect in fibrillar gene
Clinical features
Resp
- spont pneumothorax
- emphysema
CVS
- Aortopathy - dissection
- dilated aortic root
- aortic regurgitation
- MV / TV prolapse
Occular
- retinal detachment
MSK
- tall
- aracnodactylyl
- scolious
- pecvtus excavatum
- hypermobility
Aortic regurgitation in Marfans
- dyspnoea, PND, fatigue, exertional chest pain
- wide pulse pressure, Quinke sign, waterhammer pulse
- early diastolic murmur
ECG - LVH
CXR - boot chaped heart
Echo - regurgitant fraction - % return to the LV from aorta mild < 30% severe > 60%
Haemodynamic goals in AR
- rate - high normal 80-90 (reduce diastolic time)
- SVR - low normal
- euvolaemia
- maintain contraciltty
- maintain sinus rhythm
Anaesthetic considerations of marfans
- airway - prognathism, TMJ dislocation
- breathing - pneumothorax, pulm complications from kyphoscoliosis
- CVS - risk of dissection- obtund laryngoscopy, control BP
positioning - hyper mobility
Thoracic pre-op assessment
high risk surgery
pneumonectomy 5-10% mortality
Assessment
- cardiac. Lees
- mortality . thoracoscore
- dyspnoea- ppo
BPF presentation
early
- dyspnoea
- persistent bubbling from chest drain
- fall in air fluid level serial CXR
- tension pneumothorax
late
- fever
- non-specific signs
- dyspnoea
ventilation strategy BPF
- isolate the fistula and ventilate one lung
- low TV, low PEEP, low pressure pressure control if IPPV. SV if poss
- hfjv
- vv-ecmo, allowing ultra low volume ventilation
Treatment - large bor chest drain
- abx for empyema
- endobronchial occlusion
- surgical thoracoplasty / stapling
rigid bronchoscopy indictations
diagnositc
- lesion inspection
- biopsy
therapeutic
- removal of foreign body
- stent insertion
Anaesthetic considerations for rigid bronchoscopy
- airway and ventilation - shared, conventional ventilation difficult, obstruction, unprotected
- cvs - stimulating
- maintenance - unreliable volatile delivery, conventional circuit not used - tiva
- stimulation - coughing, need topicalisation
- iatrogenic bleeding
Ventilation options during bronchoscopy
- positive pressure - jet ventilator, lo frequency 4 atmospheres. passive exhalation. can’t control fio2 or co2. barotrauma
- apnoeic oxygenation - high flow, need patent airway, high co2, variable timeframe
- SV - may be difficult due to opiate, paralysis
jet ventilation
small tidal volumes from high velocity jet
venturi effect entrains air
pasive expiration
HFJV supraphysilgocail 1-10Hz
- bulk convection
- pendelluft
- supraglottic, subglottic, transtracheal
massive haemoptysis
airway - DLT or single lumen endobronchial
non-surgical management
- tamponade (lung deflation)
- vasoconstrictor - adrnelaine
- laser / cryotherapy
- IR
Amniotic fluid embolism
fetal material enters maternal circulation
phase 1 - mast cell degranulation, pulmonary artery vasospasm, pHTN, RV failure, hypoxaemia, hypotension
phase 2 -LV failure, endothelial activation, DIC
Multiple pregnancy
exagerrated version of singleton pregnancy
resp
- FRC further reduced, O2 consutpion cufrther increased - desaturation
- CVS - blood volume up to 40% greater than singleton, Hb less increase, greater physiological anaemia. CO 20% greater than singleton. greater aorocaval compression. grater blood loss. geater PET risk
- CNS - greater cephalad spread of regional
- GI - greater abdomina pressure - more reflux
Obstetric consideration
- if twin 1 cephalic, can consider vaginal birth
- 2 CTG
- shorter 1st stage
- twin 2 can be prolbematinc to deliver
MBRRACE 2023
Direct
- Haemorrhage
- PE
- Sepsis
- PET
- AFE
Indirect
- mental health
- Covid-19
- Sepsis
- Cardiac
Deprivation, ethnic minority ++
Maternal death = up to 42 days
direct = obstetric complications of preganncy
indirect = pre-existing disease or disease occuring during pregnancy unrelated to pregnancy itself
