General Flashcards
(110 cards)
1
Q
NCEPOD Category 1
A
“Immediate”
- Immediate life-, limb- or organ saving intervention
- Within minutes of decision to operate
- Resuscitation simultaneous with surgical intervention
E.g. ruptured AAA, fracture with major NV deficit, trauma laparotomy
2
Q
NCEPOD Category 2
A
“Urgent”
Acute onset or deterioration of conditions that threaten life or limb survival
Within hours of decision to operate
Listed on emergency list
E.g perforated bowel with peritonitis, critical limb ischaemia
3
Q
NCEPOD Category 3
A
“Expediated”
Stable patient requiring early intervention
Within days of decision to operate
Elective list with spare capacity
E.g. tendon and nerve injuries, ORIF
4
Q
NCEPOD Category 4
A
“Elective”
Surgical procedure planned or booked in advance of route admission
E.g. elective AAA repair, laparoscopic cholecystectomy
5
Q
Name 6 never events?
A
- Wrong site surgery/block
- Retained throat pacl
- Maladministration of potassium-containing fluid
- IV administration of epidural local anaesthetic
- Transfusion of ABO incompatible blood products
- Misplaced nasogastric
6
Q
Principles of diabetic management
A
Individualised plan regarding usual diabetic medication
- Potential 20% dose reduction in basal insulin
- Continue some OHGA e.g. metformin but omit others e.g. gliclazide
Maintain BSL 6-10mmol/L
Check BSL prior to induction, 1hrly
intraop and post op
Maintain normal electrolytes
Use strategies to enable early return to normal diet and usual diabetic regimen e.g regional, TIVA, 1st on list
Avoid pressure damage to feet
7
Q
NICE criteria for bariatric surgery
A
- BMI criteria
BMI >40
BMI>35-40 + significant disease could be improved with weight loss (e.g. T2DM + HTN) - Weight loss not achieved despite appropriate non-surgical strategies
- Genrally fit for anaesthesia + surgery
- Commits to long term FU
- Intensive mx. in MDT tier 3 obesity service
- Physician
- Sugeons
- Specialist nurses
- Dieticians
- Psychlogist
- Physiotherapist
8
Q
Types of bariatric surgery
A
Restrictive
e.g. sleeve gastrectomy
Malabsorbtive
e.g. Roux en y
9
Q
What drug dosing is used in obese patients for following:
Propofol
Fentanyl
Suxamethonium
Rocuronium
A
Propofol LBW
Fentanyl LBW
Suxamethonium TBW
Rocuronium IBW
10
Q
What is LBW
A
Lean Body Weight (LBW):
Males = 50 + 0.9kg for every cm over 150cm
Females = 45 + 0.9kg for every cm over 150cm
11
Q
What is IBW
A
Males = height – 100
Females = height – 110
12
Q
Special equipment required for obest
A
Intubation positioning aid
Hover mattress
Bariatric trolley
Bariatric bed
13
Q
Surgery for patients with gastric band
A
Increased risk of pulmonary aspiration
- Oesophageal dysmotility and dilatation above the band
ETT required!
Band deflation considered pre-op on individual basis dw bariatric team
14
Q
What are obesity red flags precluding day surgery and needing further ix.
A
Poor functional capacity
Abnormal ECG
Poorly controlled HTN, CCF, IHD
Bicarb >27 ?OHS
Sats <94% on air
OS-MRS >3
Metabolic sx
High NSQIP ACS risk
15
Q
What is a MET
A
Ratio of work metabolic rate to resting metabolic rate
Defined by Duke Activity Status Index
1 MET = BMR of a 70kg 40yr old male sitting quietly
(3.5mlO2/kg/hr (250ml/min)
4 METS
Walking 5.6kmh, level, brisk, firm surface
Stair climbing at slow pace
<4 METS correlates well with reduced perioperative survival
16
Q
Acute severe features of asthma
A
HR >110
Inability to talk in sentences
PEFR 33-50%
RR >25
17
Q
Life threatening asthma features
A
PaO2 <8kPa or sats <92%
PEFR<33%
Silent chest
PacO2 normal or high >4.6kPa
Bradycardia or arrythmia
Exhaustion, confusion, coma
18
Q
What risk factors associated with AAGA
A
Timing - induction, transfer, emergence
Logistics - out of hours/emergency, junior anaesthetist
Surgery - obstetrics, thoracics, neurosurgery, cardiac
Patient - young female adults
Drug - TIVA with muscle relaxant, thiopentone
19
Q
NAP 5 AAGA incidence
A
Overall: 1:19000
Incidence with NMBD: 1:8000
Incidence without NMBD: 1:136000
Cardiac: 1:8000
C.section: 1:670
20
Q
Why might a patient on TIVA have AAGA
A
Innapropriately low set target propofol concentration
Correctly set but inadequate
Incorrectly entered demographics
Drug error e.g. propofol 1% instead of 2%
Delivery issue - tissued cannula, infusion set disconnection at pump or cannula site
TCI pump failure
21
Q
What is bronchiectasis
A
It is a respiratory disease with multiple causes characterised by
- Permanent dilatation of the airways
- Chronic PRODUCTIVE cough
Key pathology involves infectious or non-infectious insult results in activation of inflammation
Neutrophil activation, impaired mucociliary clearance, microbial colonisation
22
Q
Signs of cor pulmonalae
A
Parasternal heave
Ascites, ankle swelling
23
Q
Name some causes of bronchiectasis
A
Post-infectious lung damage - severe pneumonia, whooping cough, measles, TB
Mechanical obstruction - tumour, foreign body, lymph nodes
Abnormal cilia: primary ciliary dsykinesis, CF
Chronic inflammatory: chronic aspiration, ABPA, lung transplant rejection
24
Q
Immediate management of haemoptysis
A
This is an emergency situation, I would attend rapidly to the patient and conduct an A-E assessment whilst mobilising additional help.
I would treat issues whilst simultaneously assessing
Apply oxygen, most likely nasal cannulae if ongoing haemoptysis
Gain wide bore IV access, send bloods including FBC, U+E, LFT, clotting, x-match 4 units
Give crystalloid if hypotensive and consider activating MTP and getting O-negative blood
Give TXA 1g
Perform a blood gas and CXR
If can determine from lung where lesion is then put bad lung down to prevent contamination of good lung
Consider intubation if airway at imminent risk
25
What are the airway management options in haemoptysis
Options include inserting
1) Large uncut single lumen ETT
2) Double-lumen ETT
1)
Insert as wide a diameter as possible to facilitate suctioning and bronchoscopy
Consider placing a bronchial blocker into affected lung
Consider placing ETT into non affected lung so this can be isolated and prevented from contamination
2)
Allows isolation of bleeding lung and selective ventilation of non bleeding lung
Insertion may be challenging due to bleeding
Internal diameter may not accomodate standard flexible bronchoscopy and therefore may be difficult to suction blood and clots
26
Specific additional management options for haemoptysis
Tamponade affected lung with bronchial blocker
Lavage with ice-cold saline 50mls to promote vasoconstriction
Injection of vasoconstrictor 1:20000
Rigid bronchoscopy to allow laser, diathermy, cryotherapy
Interventional radiology if a bronchial source on CT angio
27
Classical triad of carcinoid syndrome
DR Fred
Diarrhoea (+wheeze)
Right heart failure
intermittent Flushing
28
What are carcinoid crises
Exagerrated, profound cardiovascular and respiratory responses featuring
- Bronchospasm
- Tachycardia
- Labile blood pressure
May be precipitated by anaesthesia or surgery
29
What is the pathophysiology of carcinoid
Carcnoid tumours arise from enterochrommafin cells in GI tract or broncho resp tract
Cause disease either by
1) Systemic release of VASOactive peptides
- Histamine, serotonin, VIP, prostaglandins, substance P, bradykinin
2) Local effects such as int. obstruction or resp compromise
Carcinoid heart disease = fibrous thickening of endocardium causing RHF mixed tricuspid/pulm disease
30
Carcinoid dx
Serum chromogranin A
Urinary 5-HIAA
CT with contrast
31
Pre-op optimisation of carcinoid key bits
Hx/Exam/Ix/Optimisation
Octeotride 100mg sc tds for 2 weeks and induction
Cardiovascular work up with ECG and echo, consider valve surgery
Symptom management
- Bronchodilators
- Anti-diarrhoeals
- Heart failure management
32
Intra-op management carcinoid key bits
Additional dose octeotride
Invasive monitoring - art, CVC, temp, catheter
Avoid certain drugs
- Morphine, atracurium (histamine)
- Suxamethonium (may increase mediators)
Severe hypotension - give 10-20mcg octeotride IV
Severe hypertension - labetalol/esmolol
Consider epidural for reducing crises
33
What is ECT?
Electroconvulsive Therapy is a form of psychiatric treatment in which an electric shock is delivered to the cerebral hemisphere to deliver a grand mal seizure
It is used in the treatment of refractory psychiatric disorders such as severe depression
34
What are the physiological effects of ECT
3 main physiological effects
1. Increase CMRO2
2. Increased Myocardial O2 demand
3. Musculoskeletal contractions
In more detail
1. Autonomic effects
- Initially **parasympathetic** discharge --> bradycardia and asystole
- Then **sympathetic** discharge --> adrenaline increased >15x, hypertension +++, arrythmia, sweating, lacrimation, increased myocardial and cerebral O2 consumption
2. Cerebral
- Increase in ICP and CMRO2
3. MSK
- Violent contraction may cause fracture
4. Metabolic
- Increased glucose metabolism
35
ECT contraindications
Raised ICP
Recent stroke - bleed/infarct
Recent MI <3months or unstable angina
Uncontrolled heart failure
Severe hypertension
Severe osteoporosis
Unprotected aneurysm
36
Key "how to" for ECT
Pre-op
- Thorough hx/exam/ix
- ?contraindications ?doses previous ECT
- ?current meds - lithium inc. NMB, MOA = hypertensive crisis
Intra-op
- IV access, trained assistant etc
- Propofol induction
- Face mask and bite guard
- Sux 0.5mg/kg to reduce muscle contractions
- Hypocapnoea may promote seizure
- Atropine may be required
- If seizure >2mins then terminate with benzo
Post-op
- Recovery in appropriate area
37
What are the common causes for laparotomy
Intestinal obstruction (50%) and perforation (25%) together account for 75% of ex. laparotomy
Other causes:
Intestinal ischaemia
Abdominal abscess
Colitis
Anastamotic failure
Haemorrhage
Peritonitis
38
39
How are patients deemed high risk for ex. laparotomy
1. Clinical judgement
2. Risk assessment tool e.g. NELA
Risk assessment based on:
- Age
- PMHx/ASA status
- Clinical observations
- Anticipated pathology
- Blood test results
Gives % 30-day mortality
40
Name some exclusions from NELA
Pathology relating to:
1. Oesophagus
2. Appendix
3. Gallbladder
4. Vascular pathology
5. Gynae pathology
Complications of NON-GI surgery
Trauma
Patient request
41
What are some of the principles of enhanced recovery
1. Assessing risk and fitness for surgery
2. Pre-operative optimisation
3. Reducing fasting effects with carbohydrate loading
4. Utilising minimally invasive techniques
5. Clear and structured post op management with multimodal analgesia, early mobilisation, early enteral nutrition
42
Name some benefits of enhanced recovery
1. Reduced stress response to surgery
2. Decreased ileus
3. Decreased cardiopulmonary morbidity
4. Improved muscle strength
5. Decreased LOS and associated costs
6. Potential cancer survival benefits
43
What is prehabilitation
Multimodal process improving a patient's functional status before an operation, to improve their body's ability to cope with physiological stress and therefore improve outcome
Includes:
1. Structured exercise program, community/hospital based
2. Behaviouraly and lifestyle modification - smoking cessation, alcohol reduction
3. Nutrition optimisation. Carb loading with clear drinks up to 2hrs.
4. Psychological interventions
44
What is free flap reconstruction
A surgical technique in which autologous tissue detached from remote donor site and transferred to recipient site with circulation restored by microvascular anastamosis
45
Key principles of free flap surgery
Appropriate patient selection - avoid pts with hypercoagulable states, sickles cell disease, polycythaemia
Smoking cessation 4 weeks prior v. important
- Nicotine vasoconstriction
- CO related hypoxia
- Hypercoagulability due to inc. platelet aggregation
Key principles are:
1. Minimising primary ischaemia of free flap (surgical)
2. Optimising flap perfusion and minimising secondary ischaemia
- Hagen Pouiselle
Therefore
- Aim for low/normal haematocrit 30-35% whilst also ensuring adequate DO2
- Optimise fluid, consider goal directed
- Normothermia
- Low SVR, avoid vasopressors
46
How to identify flap failure
Arterial
Venous
Oedema
Monitor
1. Flap colour
2. CRT
3. Skin turgor
4. Skin temp
5. Pinprick bleeding
6. Transcutaneous doppler
Early return to OT if flap failed
HDU often required
47
Complications of reverse Trendelenburg
Venous pooling - reduced preload and hypotension
Cerebral hypotension - cognitive dysfunction
Increased risk of venous air embolism, especially when surgery above level of heart
## Footnote
Commonly used for lap chole
48
Consequences of trendelenburg position (head down)
**Respiratory**
Abdominal weight on diaphragm
- Increased vent pressures required
- Reduced FRC
- Reduced compliance
- Increased atelectasis
- V/Q mismatch
Laryngeal oedema - do a leak test
Pulmonary aspiration
ETT dislodgement into bronchi
**Cardiovascular**
- Increased pre-load and increased SVR
- Hypotension may result when levelled
- Decreased renal/splanchnic/portal blood flow
**Neurological**
- Reduced cerebral venous drainage --> raised ICP
- Cerebral oedema ---> post op cognitive dysfunction
- Peripheral neuropathy, brachial or lower limb
- Compartment syndrome
**Opthalmic**
- Elevated IOP
- Chemosis
- Gastric contents in eyes causing chemical injury
49
How to reduce complications of trendelenburg
Limit steepness and flatten regularly
Inspect the face
Protect the eyes
Meticulous positioning, padding, using 'beanbag' as opposed to shoulder bolsters
NG tube to drain gastric contents
50
Consequences of pneumoperitoneum
**Respiratory**
- Increased IAP causing diaphragmatic splinting and atelectasis
- Higher airway pressures required
- Reduced compliance
- Reduced FRC
- Results in atelectasis, V/Q mismatch, shunt, hypoxaemia
- CO2 absorption
**Cardiovascular**
- Decreased preload due to impaired venous return
- Increased SVR due to compression of aorta + release of vasoactive substances e.g. vasopressin, RAS activation, catecholamines
- BP may be HIGH or LOW
**Neurologucal**
- Increased IAP causes increased Intrathoracic pressure therefore dec. venous drainage
- Increased ICP
**GI**
- Decreased in liver and kidney arterial and venous flow
- Decrease in GFR
- Decrease in mucoasal blood flow
51
Key points - pre-op assessment of robotic surgery
Key considerations are
1. Major surgery
2. Necessitates completely still position
3. Pt. needs to be able to tolerate steep trendelenburg and pneumoperitoneum for prolonged period
4. Consider relative contra-indications e.g. glaucoma, severe cardiac/resp disease
Patient will likely be on enhanced recovery program/prehab, minimal fasting, carb loading
52
Key points - robotic surgery intra-op
Airway secured - minimal access, high risk of endobronchial
Breathing - high PEEP, adequate MV for CO2 from pneumoperitoneum, 6-8ml/kg TV, Plat pres <30cmH2O
Circulation - be prepared for labile BP due to positioning and vagal bradycardia
NMBDs - roc + sux vs. single intubating dose + remi
Analgesia - local to port sites + short acting opioid
NG tube for passive reflux
Positioning - padded straps
Leak test prior to extubation
53
When is AIDS defined
HIV+ve with CD4+ T cell count <200 cells/uL
Or presence of aids defining illness
- Oesophageal candidiases
- CMV retinitis
- Kaposi's sarcoma
- CNS lymphoma
- PJP
- Cerebral toxoplasmosis
54
What is hypertension?
Defined as a systolic BP > 140mmHg or a diastolic BP > 90mmHg
90% of hypertension is 'essential' HTN, 10% have secondary
55
Name causes of secondary hypertension
Renal
1. Renal artery stenosis
2. CKD
Endocrine
1. Cushings
2. Conns
3. Phaeo
4. Acromegaly
Pre-eclampsia
OSA
Aortic co-arctation
56
How can hypertension be classified in terms of severity
Stage 1 >140/90
Stage 2 >160/100
Stage 3 > 180/110
Stage 4 > 210/120
57
Complications of hypertension
LVH
Retinopathy
Nephropathy
Atherosclerotic mediated diseases
- IHD
- Stroke/IHD
- PVD
Malignant HTN - papilloedema, encephalopathy, end-organ damage
58
What does AAGBI recommend regarding diabetes cut off
HbA1c is a measure of average blood glucose levels over the past 2-3 months. Poorly controlled diabetes, as indicated by a high HbA1c, can increase the risk of complications during and after surgery.
AAGBI Recommendation:
The AAGBI guidelines, along with other national guidelines, strongly advise optimizing glycemic control before elective surgery. This is achieved by aiming for an HbA1c below 69 mmol/mol (8.5%)
59
How would you assess end organ damage hypertension
ECG
Fundoscopy
Urine dip/creatinine/ alb:creat ratio
60
How would you test for 2ndary caues of HTN
Plasma metanephrines for phaeochromocytoma
Serum aldosterone: renin ratio for conn's
Plasma IGF1 and growth hormone suppresion test for acromegaly
61
Medical therapy for hypertension
Step 1
<55 or have T2DM = Ace-i
>55 or any age and black but without T2DM = Ca. antagonist
Step 2
If on Ace, add in Ca. blocker or thiazide
If on Ca. blocker, add in Ace/Thiazide
Step 3
All 3
Step 4
Consider Spiro/alpha block/beta block
62
Periop consequences of hypertension
Autoregulatory curve shifted due to higher pressures, results in hypoperfusion of organs. Resulting in:
Myocardial ischaemia/arrythmias/diastolic dysfunction
Cerebral ischaemia
Exagerrated cardiovascular responses e.g. intubation
Renal impairment
Bleeding
63
AAGBI hypertension guidelines
GP must control less than 160/100 prior to elective surgery referral
Latest BP must be documented in referral letter
<180/110 in preop clinic acceptable
If >180/110 then should be referred back to GP for HTN management
64
Sarcoid features
Upper Resp
- Pharyngeal/laryngeal involvement - OSA, stridor, difficult airway
Lower Resp
- Obstructive/restrictive/diffusion deficit
- Bilateral hilar lymphadenopathy
- 90% sarcoid patients have resp involvement
- Advanced disease = pulm. HTN
Cardiac
- Granulomatous infiltration of conducting system = arrythmias
- SVT/prolonged QT/vent arrythmia/HB
Renal
- Granulomatous interstitial nephritis
Haem
- Anaemia/low WCC
Ocular
- Chronic anterior uveitis in 80%
CN palsies
Diabetes insipidus
65
Tell me something about sarcoidosis
66
What is systemic sclerosis
Otherwise known as scleroderma it is a **rare, autoimmune connective tissue disorder**
Characterised by:
- Excessive collagen production and deposition
- Small vessel vasculopathy
Can be categorised as **diffuse cutaneous** or **limited cutaneous** depending on whether skin distal to elbows/knees is involved (in diffuse)
67
What are the features of limited cutaneous systemic sclerosis
Used to be known as CREST syndrome
C
R
E
S
T
68
# O
Organ systems involved in systemic sclerosis
1. Resp
- PAH
- ILD/fibrosis
- Asp pneumonia
2. CVS
- Myositis
- Fibrosis
- IHD
3. Renal
- Scleroderma renal crisis
4. Haem
- Anaemia of CD
- MAHA
69
Important things for a preassessment of systemic sclerosis patient
In addition to my usual anaesthetic assessment I would focus on the following areas:
- Most recent rheum clinic letters, severity and stability of disease and known organ involvement
- Drug hx including steroids/immunosuppresive drugs
- Cardiac disease - syncope/pre-syncope/palpitations/exercise Tol
- Resp disease - breathlessness, PFTs
- Presence of reflex
- Weight loss
Bloods including
- FBD, U+Es
Baseline ECG, CXR, PFTs +- cardiac ix e.g echo, angio
70
Systemic sclerosis and monitoring issues
Pulse ox poor trace raynaud's
Beware art line and raynauds
NIBP and thick skin
71
Intra-op issues and systemic sclerosis
Airway
- Reflux ?RSI
- Difficult airway, microstomia
IV access difficult
Analgesia - NSAIDS and renal disease, periop steroids
72
What is TUR syndrome
It is an iatrogenic syndrome arising from systemic absorption of large volumes of irrigation fluid. Causing:
1. Increased intravascular volume
2. Acute hyponatraemia + hypo-osmolarity
73
What irrigation fluid is commonly used in UK
1.5% glycine
Transparent
Osmolarity = 220mOsmol/L aka hypo-osmolar
74
Features of TUR sx
Neurological
- Headache
- Confusion
- Restlessness
- Seizures
- Temp blindness
Respiratory
- Dyspnoea
- Cyanosis
- Hypoxaemia
Cardiac
- Arrythmias
- Hypo- or hypertension
- Bradycardia
75
TUR pathogenesis
Glycine absorbed into peri-prostatic venous plexus
Typical is 20ml/min
Metabolised to ammonia, glycolic acid, water ---> dilutional hyponatraemia
Sequelae 2ndary to:
- Cerebral oedema (hyponatraemia)
- Direct toxic effect of glycine (aka inhibitory neurotransmitter)
76
TUR pathogenesis
Stop procedure
Stop IV fluid
Supportive mx , A, B , C
Specific:
Diuretics for pulmonary oedema
Severe hyponatraemia with hypertonic
Correct 0.5-1.0 mmol/l /hr in first 24hrs
77
TUR prevention
Limit resection <60mins
Limit hydrostatic pressure of fluid
Spinal = earlier detection
Don't use hypotonic IV fluid
Treat hypotension with vasopressor rather than lots of fluid
78
What are some risk factors for latex allergy
1. Regular exposure e.g. healthcare worker
2. Spina bifida/urogenital abnormalities e.g. frequent self catheterisation
3. Atopy/eczema
4. Food cross-reactivity
- Banana
- Kiwi
- Chestnut
- Avocado
79
What type of hypersensitivity does latex allergy cause
Type 1 and Type 4
80
Mx of patient with latex allergy
Remove all latex products from theatre
Drugs with rubber bungs avoided
Rest OT to allow removal of particals - put 1st on list
81
What are the reasons for liver transplant
25% for HCC
90% for chronic liver disease
- Alcoholic liver disease
- Viral (hep b and c)
- Nan alcoholic fatty liver
- Autoimmune
Other 10% acute
82
State the extrahepatic manifestations of chronic liver disease
Resp:
- Splinting due to ascites (V/Q mismatch, shunt, FRC loss)
- Intrapulmonary shunting (hepatopulmonary syndrome)
- Portopulmonary hypertension
Neuro:
- Hepatic encephalopathy
Cardiac:
- Alcohol related cardiomyopathy
- High cardiac output
- Splanhnic/splenic vasodilation causes low SVR
Metabolic
- Malnutrition
- Low glucose stores
- Electrolyte abnormalities
- Hypoalbuminaemia
Haem
- Low plt (splenomegaly)
- Prolonged PT/INR due to deficiency of II, VII, IX, X
Renal
- Acute/chronic renal impairment
- Hepatorenal sx
83
What 3 clinical signs point to portal HTN
Formal dx is pressure >10mmHg
Triad
1. Ascites (starling forces)
2. Splenomegaly
3. Varices
84
What 5 things make up Childs Pugh
Bilirubin
Albumin
PT
Ascites
Encephalopathy
85
Perioperative mortality of Child Pugh C
30-80 periop mortality
86
What strategies can be used to reduce bleeding in liver resection
Surgical / Pharmacological / Haematological
Surgical:
- Vascular occlusion e.g. occlusion of portal vein and hepatic artery (dec. venous return, inc. afterload)
- Segmental vessel occlusion
Pharmacological:
- TXA
Haemodynamic:
- Low CVP, aim for CVP <5mmHg
- Restrictive fluids
- Minimise vent pressures
- Nitrates
87
What drugs may need to be reduced in liver disease
Midazolam
Rocuronium
Suxamethonium
Opioids - morphine/fentanyl
Local anaesthetis
88
Why is intraocular pressure increases avoided in penetrating eye injury
Prevent extrusion of vitreous humour
89
Methods of obtunding sympathetic response to laryngoscopy
Fentanyl 3-5mcg/kg
Alfentanil 20mg/kg
Lignocaine 1.5mg/kg
Beta-blocker: esmolol infusion
Remifentanil TCI
90
Intraop management of raised Intra OCULAR pressure
Look for cause and treat
Avoid precipitants
Ensure adequate depth
Avoid hypercarbia PaCO2 4.5-5.0
Avoid hypoxia aim sats 94-98%
Reduce obstruction to venous flow
Drugs Mannitol 0.5g/kg iv, Acetozolamide 500mg IV
91
What is the inheritance of MH
Malignant Hyperthermia is a life-threatening condition which may be triggered by suxamethonium and volatile agents
It has an autosomal dominant inheritance
92
Causes of MH
Abnormal RYR1 gene which encodes ryanodine receptor
In health:
Ryanodine opens allowing Ca++ to be released from SR, upon a conformational change in DHPR
In MH:
Abnormal RyR allows UNCONTROLLED Ca++ release from SR
Results in tetanic muscle contraction - consumes ATP, generates heat
Prolonged muscle contraction leads to rhabdo, hyper-K, renal failure
93
Anaesthetic management of MH susceptible patient
Pre-op counselling
Consider regional over general
If general req.
- Avoid all triggering drugs
- Use vapour-free machine, flush with 100% maximal O2 at max flows for 30mins to clear all residual volatile agents and have new circuits fitted
- Activated charcoal filters at insp and exp limbs
Check MH box incl dantrolene available and all staff briefed
94
Approach to MH crisis
I would recognise this is a crisis and call for help early.
My priorities in this case would be to
1) caese the trigger
2) give dantrolene
3) general supportive measures
I would want multipled hands and would allocate tasks accordingly
In more detail I would
Announce to surgeons to stop
Caese trigger
Switch from volatile to TIVA and swap to clean breathing system e.g. Mapleson C circuit and hyperventilate with 100% O2
Dantrolene given in bolus of 2.5mg/kg initially then 1mg/kg
General support including:
1) activec cooling - ice cold saline, remove drapes, ice in axilla
2) treat hyperkalaemia, CaCl, gluc/ins, bicarb
3) treat arrythmias
4) treat acidosis
5) treat coagulopathy
Ensure adequate monitoring incl cvc, art line
Send gases, bloods, teg, ck
Refer patient and family counselling.
MH unit in Leeds
95
How does dantrolene work
Antagonist of the RyR receptor
Blocks Ca ++ release from SR
96
Anaesthetic implications of motor neuron disease
Bulbar palsy - aspiration risk
Resp muscle weakness - poor cough, post op vent failure
Depolarising muscle relaxanats - risk of hyperkalaemia
NDMDs - inc. sensitivity of native Ach receptors
97
What is porphyria?
A group of inherited disorders of haem biosynthesis
Genetic defect results in a deficiency in one of the enzymes involved in haem biosynthesis
Most types follow autosomal dominant inheritance
98
Name the acute porphyrias
Acute intermittent porphyria
Variegate porphyria
99
Name the non acute porphyris
Porphyria cutanea tarda
Congenital erytheopoietic porphyria
100
What are the 4 D's of Botulism
Diplopia
Dysphagia
Dysarthria
Dysphonia
101
Name 4 risk prediction models
P-POSSUM (Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity)
NELA
ACS NSQIP
SORT
102
P-POSSUM tell me more
- Applies to emergency and elective major general/urology/vascular
- Physiological variables + Operative variable
Estimates 30 day morbidity and mortality
Disadvantages:
- Some subjective elements
- Estimate intraoperative elements
- Overestimates mortality in high risk groups
103
NELA tell me more
Patients undergoing emergency laparotomy based on multicentre UK dataset
Estimates 30 day mortality
Specific to laparotomy
Disadvantages
- Doesn't estimate morbidity
- Requires estimation of intraoperative findings
104
ACS NSQIP
Multiple outcomes
30 day mortality and morbidity
Readmissions/returns to theatre
Many important QoL
Time consuming
105
SORT
30 day mortality predicted by 6 variables
Input:
- ASA
- Urgency
- Speciality
- Severity of surgery
- Cancer Y/N
- Age
No morbidity prediction
106
What is CPET
Dynamic, non-invasive assessment of the cardiopulmonary system at rest and during exercise
Aims to determine functional capacity
107
What is measured during CPET
Expired gas analysis and pulmonary flow measurements
Continuous 12-lead ECG
SpO2
NIBP
108
What is calculated during CPET
VO2 (oxygen consumption)
VCO2 (CO2 production)
RER = VCO2/VO2
AT = anaerobic threshold = point at which oxygen demand exceeds delivery
VE/VCO2 = ventilatory efficiency for CO2, measure of lungs ability to excrete CO2
9 panel plot
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Contraindications to CPET
Absolute and Relative
Absolute
- Acute MI
- Unstable angina
- Uncontrolled arrythmia
- Syncope
- Endocarditis
- Acute PE
- Pulmonary oedema
- Uncontrolled asthma
- Resp failure
Relative
- Left main stem stenosis
- Moderate stenotic valve
- Severe untreated HTN
- Arrythmias
- HOCM
- Pulmonary HTN
- Advanced pregnancy
- Orthopaedic impairment
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What drugs lower seizure threshold and should be avoided in epileptics
Enflurane
Methohexitone
Alfentanil/Pethidine/Tramadol
Dopamine antagonists may confuse picture with dystonic reactions
