Clinical Flashcards
Inheritance malignant hyperthermia
Autosomal dominant
Definition of Malignant Hyperthermia
Inherited disorder of skeletal muscle in which defect of ryanodine receptor leads to uncontrolled calcium stimulation of actin/myosin cross linking
Clinical features of Malignant Hyperthermia
CVS
- Tachycardia, hypotension
RS
- increased ETCO2
- Increased minute ventilation if SV
Other
- Muscle rigidity
- Acidosis
- Hyperthermia
- Rhabdomyolysis
- DIC
Management of MH susceptible patient
Volatile free anaesthetic machine
If not available flush circuit with 100% O2 for 30 mins
Charcoal filters absorb residual volatile
TIVA, avoid volatiles, suxamethonium
Invasive monitoring and know where dantrolene is
Management of MH crisis
- Switch to clean circuit e.g. c-circuit
- Switch to TIVA
- Stop surgery
- Active cooling
- Dantrolene 2.5mg/kg plus repeat 1mg/kg
- Treat arrhythmias
- Treat hyperkalaemia
- Treat acidosis - bicarb
- Treat coagluopathy
- If rhabdo RRT
- Counsel, refer to Leeds
Indications for carotid endarterectomy
50-99% stenosis
Timing of CEA
Following mild stroke or TIA, carotid doppler and referral within 24hrs. Surgery within 2 weeks
Complications of CEA
- Stroke 2-5%
- MI
- Bleeding / infection
- Recurrent laryngeal and superior laryngeal nerve injury
- Cerebral hyper perfusion syndrome
GA for CEA
Ads
- Airway control
- CO2 control
- Patient immobility
Disads
- Lack of direct neurological monitoring
- Higher rates of intraoperative shunt
- Hypotension from drugs
- Dleyaed recovery pair neurological assessment
LA for CEA
Ads
- Direct neurological monitoring
- Avoid risk of hypertension laryngoscopy
- Reduced shunt
Disads
- Patient anxiety and pain
- Cooperation
- Risk of conversion to GA
GALA trial
3000+ patients RCT GA vs LA
30d stroke / MI / death no different
RA cheaper and reduced wound haematoma
Monitoring cerebral perfusion under GA
- Transcranial doppler - doppler on petrous temporal bone to measure middle cerebral artery flow
- Stump pressure - pressure distal to x-clamp reflects circle of willis perfusion
- Near infrared spectroscopy - measures arterial, venous and capillary oxygenation given regional cerebral oxygenation value
Cerebral hyper perfusion syndrome
Dysregulated cerebral blood flow after restoration of blood flow
severe ipsilateral headache, seizures, neurology (hypertensive encephalopathy
Gullian Barre Syndrome
Autoimmune demyelinating peripheral polyneuropathy affecting motor neurones. Causes a classical ascending motor weakness, ultimately affected the respiratory muscles leading to ventilatory failure
Clinical features
- Ascending muscle weakness, progressive
- Symmetrical distrubution
- Flaccid paralysis
- Hyporeflexia
- Reduced vital capacity
- Bulbar weakness, poor secretion clearance
- Autonomic disturbance
- Neuropathic pain
- Following GI/resp infection
Pathophysiology
Autoimmune attack of peripheral nerves - IgG –> myelin sheaths preventing AP transmission
Diagnosis
- Clinical
- Exclude other causes e.g. MRI
- LP - raised protein
- Nerve conduction studies
Indications for intubation
Bulbar involvement - poor cough, swallow
Hypercapnoea
Respiratory weakness - FVC < 1 L
Management
Incentive spirometry
Intubation and ventilatory support, likely tracheostomy
Analgesia
Autonomic - may need BP support
ITU care - nutrition, VTE, pressure areas, VAP bundles
PLEX or IVIG
Physiological changes of pregnancy
CVS
- CO increases 50% by term, increased HR and SV (further increase during labour)
- SVR falls during pregnancy
- Total blood volume increases by 40%
- Aortocaval compression from 20/40
- Blood pressure falls in first trimester
RS
- difficult airway
- Bronchodilation
- Increased MV by 50% at termdue to increased TV
- Reduced FRC NS EWSUXWS XOMPLInxw
- increased O2 consumption 20%
Neuro
- Reduced MAC by 40%
- Increased epidural pressure and venous engorgement
Liver
- Reduced plasma protein synthesis e.g. albumin, cholinesterase
GI
- Increased intragastric pressure
- Reduced oesophageal sphincter tone
Renal
- Increased renal blood flow by 50% and GFR
Haem
- Red cell production increases but dilutional anaemia
- Procoagulant state, increased fibrinogen
- lower platelet
MSK
- Ligamentous laxity
Endo
- Peripheral insulin resistance, relative hyperglycaemia (hPL)
- increased oestrogen - increase uteroplacental blood flow stimulate uterine growth
- Progesterone - systemic physiological changes
Paediatric hypovolaemia
Mild < 5%
Mod 5-10%
Severe > 10%
Blood volume
- Weight (age + 4) x 2
- 70-80ml/kg
Drowning definition
respiratory impairment due to submersion in liquid
Drowning pathophysiology
- voluntary breath holding
- apnoea - hypercapnoea and hypoxia
- chemoreceptors eventually overcome voluntary breath holding leading to respiratory movement
- acute lung injury - washout of surfactant, atelectasis, direct toxic,, bronchospasm, osmotic gradient
- hypothermia - bradycardia, peripheral vasoconstriction
- CVS - catecholamine, masive vasoconstriction
Management of drowning
ABC
BLS
Active warming
lung protective ventilation
correct hypovolaemia
Methods of rewarming
passive
- dry patient
- remove wet clothes
- insulation
peripheral active
- forced air warmers
- heat pads
central active warming
- warm iv fluid
- body cavity lavage
- ECMO
Post-operative cognitive dysfunction
Decline in cognitive function arising after surgical procedure, may persist for up to year. Memory and executive dysfunction.
Similar risk factors to post-operative delirium
- Age > 65
- Pre-existing cognitive impairment
- Cardiac surgery
- History of CVA
- Poor education
- Poor functional status
Anaesthesia not main cause (GA and RA similar incidence for same surgicall procedure
Inflammatory response to surgery?
Prolonged BIS < 40?
NCEPOD classifications
1 - Immediate - immediate threat to life or limb - within minutes of decision
2 - Urgent - potential threat to life or limb - within hours
3 - Expedited - early treatment required but not immediate threat to life or limb - within days
4 - Elective - planned or booked in advance. Time to suit patient and hospital.
NELA
Nationwide audit of patients undergoing emergency laparotomy.
Pre-op / intra-op / post-op data collection
Compare hospital performance over time
Standards
- CT reported prior to surgery
- Abx 1hr of sepsis diagnosis
- Risk of death documented
- appropriate timescale to theatre
- high risk patients - consultant led care and ICU
NELA risk calculator
Clinical judgement…
Risk assessment tool e.g. age, comorbidities, blood results, pathology
5% + high risk
Predicting post op FEV1
pre-op FEV1% x (19 - segments removed) / 19
Surgery cut offs
- FEV1 > 1.5L suitable for lobectomy
- FEV1 > 2 suitable for pneumonectomy
If less than above
- % PPO FEV1 > 40% suitable
If % PPO FEV1 < 40% –> CPET
Vo2 max > 15ml/kg/min –> surgery
Glaucoma
Condition where free flow of aqueous humour is impaired, leading to raised intraocular pressure.
Open angle - chronic, slow draining due to clogging of trabecular mesh
Closed angle - iris completely blocks fluid access to trabecular network. pain ++ and visual loss
Intra-occular pressure
11 - 21mmHg
Contents - blood, aqueous, vitreous humour
Scleral compliance (old age)
Tone of extra-ocular muscles (external compression)
Drainage of aqueous
Closed angle glaucoma
Aqueous humour ciliary body –> Canal of Schlemm (veins)
If angle between iris and cornea is blocked, then drainage is affected leading to raised IOP
Anaesthesia and IOP
Induction agents - reduce IOP apart from ketamine
Muscle relaxants - sux increases 10mmHg, NDMR reduces
Hypoxia, hypercarbia, neck ties, coughing increase IOP
Decrease acutely
- head up, avoid hypoxia, hypercarbia, coughing
- Acetazolamide (reduces aq humour production)
- Mannitol
- Propofol
Pupillary light reflex
Afferent = optic nerve
Central mediator = occipital lobe (pre-tectal nuclei, Erdinger-Westphal Nucleus)
Efferent = oculomotor nerve via ciliary ganglion (short ciliary nerve)
Crossover at Edinger-Westphal - consensual
Corneal reflex
Afferent = V1 (ophthalmic or nasociliary)
Trigeminal nerve, trigeminal ganglion
Central mediator = pons
Efferent = facial motor neurones to orbicularis oculi
Maintaining spinal cord perfusion during aortic surgery
- Mild hypothermia - protective
- Maintaining spinal cord perfusion pressure
- SCPP = MAP - CSFP
- Maintain at 70. MAP > 80, CSFP < 15
- Neurophysiological monitoring
- Distal aortic shunting e.g. partial left heart bypass
Pneumoperitoneum
CVS
- Increase in afterload
- Reduction in preload - IVC compression
- Overall reduction in CO
- Vagally mediated bradycardia
Resp
- Reduced FRC
- Reduced compliance
- Increased airway pressures
- Increased CO2
- Endobronchial intubation
- Gas embolism
Renal
- Reduced renal blood flow
GI
- Acid aspiration
Advantages and disadvantages of laparoscopic surgery
Ads
- Reduced trauma
- Faster healing
- Reduced stress response
- Reduced pain
- shorter LOS
Disads
- Longer procedures
- Learning curve
- Pneumoperitoneum
- PONV
Drugs used to treat malignancy
- Control of disease progression - cytotoxics
- Immunomodulating drugs - immunoglobulins
- Symptom control - analgesia, antiemetics
- Bone - alendronic acid
Classify cytotoxic drugs
- Anti-metabolites (impair building blocks of DNA) - 5-FU, methotrexate
- Alkylating agents - alter DNA - cyclophosphamide, cisplatin
- Cytotoxic antibiotics - bleomycin, doxorubicin
- Topoisomerase inhibitors - used to mobilise DNA during transcription, replication, repair e.g. etoposide
- Hormonal treatments - steroid, tamoxifen
- Monoclonal antibodies - trigger immune response to cells e.g. trastuzumab
Side effects cytotoxicity
Pulmonary
- fibrosis (bleomycin)
- pneumonitis (cyclophosphamide)
Cardiac
- doxorubicin - cardiomyopathy
- Arrhythmias, torsades cyclophospamide
Renal
- failure with cisplatin
Hepatic
- fatty, tranaminitis - methotrexate
CNS
- peripheral neuropathy, autonomic dysfunction - methotrexate
HAEM
- myelodepression and neutropenic sepsis
ICU weakness
Weakness occurring in critically ill patients without other plausible explanation
- bilateral, flaccid
- cranial nerve sparing
- invasive ventilation
- developing after onset of critical illness
- MRC < 48 twice
Types of ICUAW
- Critical illness myopathy
- Critical illness polyneuropathy
- Critical illness neuromyopathy
Similar presentations, distinguished on basis of nerve conduction studies, muscle biopsies
- NCS - determine conduction velocities, compound motor action potentials, sensory nerve action potentials (CMAPS, SNAPS)
- EMG
Treatment supportive / preventative measures
Care Bundle Definition
Group of interventions that when administered together lead to improved patient outcomes
- VAP
- Sepsis 3 hr / 6hr
- CVC
Capacity
Capable or competent individual is someone over 18 years old who has the mental capacity to make decision on their own behalf regarding treatment
Competent 16-17 year olds can give consent
Every adult assumed to be capable (unless proven otherwise)
Treatment given in best interests so long as requirements of MCA adhered to
Children - only those with parental responsibility can give consent
Specific consent issues in adolescents
- under 18 refusing treatment deemed essential - may be made ward of court and treatment carried out lawfully
- 16-17yr old not competent to give consent - parent should be sought
- Under 16 with sufficient understanding may consent (Gillick competence) (not refuse)
IMCA
Provided for 16+
No one able to support and represent and lack capacity
- serious medical treatment
- long term care
Consent forms
Form 1 - adults, competent children
Form 2 - parental consent for child
Form 3 - awake patients throughout procedure
Form 4 - adults unable to consent
Causes of arrhythmias
Enhanced automaticity
Triggered activity
Abnormal impulse conduction (reentry)
WPW treatment
Risk stratification for those at risk of sudden death
Tachyarrhythmias - pharmacological / DCCV
Drugs - adenosine, beta blockers verapamil avoided (slow normal conduction pathways, favouring accessory pathway)
Ablation of Bundle of Kent = definitive treatment
WPW and anaesthesia
May unmask SVT in perioperative period
GA - avoid light planes, avoid drugs induced tachycardia (glycolic, atropine, ketamine). Propofol / sevo / iso safe. Short acting muscle relaxants to avoid neostigmine
RA preferable (avoid light planes, stimulation from laryngoscopy etc)
AF may lead to VF
SVT
VT may be difficult to treat
Treat underlying cause, avoid digoxin and verapamil. DCCV, vagal manoeuvres.
Causes of intrauterine death
Fetal
- congenital infections
- congenital malformations
- cord prolapse
Maternal
- PET
- antepartum haemorrhage
- placental abruption
- chorioamnionitis
Eisenmenger Syndrome
Condition whereby a longstanding cardiac defect with left - right shunt (e.g. VSD, ASD) leads to right sided pulmonary hypertension and RV hypertrophy and reversal of shunt (R –> L) leading to cyanotic heart disease.
Pathophysiology of Eisenmengers
Initial Left –> right shunt as SVR»_space; PVR
Increased right sided blood flow leads to remodelling of pulmonary vasculature and pulmonary hypertension, eventually PVR = SVR leading to bidirectional
Signs and symptoms of eisenmengers
Insidious onset. exertion dyspnoea, fatigue, syncope, angina, haemoptysis.
cyanosis, clubbing, dysrhythmias, polycythaemia, CCF
Anaesthesia and Eisenmengers
Maintain SVR
Avoid increases in PVR (pain, acidosis, hypoxia, hypervarbia)
Avoid air in IV line - may cause stroke
predmedication with benzodiazepines
Fractured mandible
associated injuries
truisms may or may not be due to pain
LeFort fractures
1 - horizontal fracture separates inferior maxilla from superior 2/3 of face
2 - pyramidal mid face separated from the rest of the facial skeleton and skull base
3 - face separated from the skull base
Considerations in anaesthetising facial fractures
- prepare for difficult airway
- route of repair (intramural, subconjunctival)
- if signs of difficulty mask ventilation or intubation then awake technique
- mandible fracture usually nasal tube but if base of skull fracture contraindicated
- throat pack, facial nerve monitoring, intermaxillary fixation post-op
Atlanto-axial subluxation
increased mobility or laxity between C1 (atlas) and odontoid peg of C2 (axis)
Space between peg and C1 should be < 3mm
Anterior subluxation - 4mm + C1 body vertebra moves forward on C2
Posterior - destruction of peg, backward movement of C1
Rheumatoid arthritis
Autoimmune inflammatory polyarthropy. affects joints, synovitis of joints and loss of articular cartilage. women > men 30-55. Seropsotive for RF
Pain and staginess
reduced bone density
AIRWAY
- AAI - risk of spinal cord compression
- sub-axial subluxation - fixed flexion
- TMJ - reduced moth opening
- cricoarytenoid - strifor
Extra-articular manifestations of RA
RESP
- pulmonary fibrosis
- pulmonary hypertension
CVS
- arteriosclerosis, IHD, stroke
- Pericardial effusions
HAEM
- anaemia
CNS
- peripheral neuropathy
RENAL
- amyloid, nephropathy
EYE/SKIN
- episcleritis
- thin papery skin
MEDICATIONS
- NSAIDS - renal failure, GI
- methotrexate - immunosuppression
- Steroids - obesity, hyperglycaemia etc
Anaesthetic considerations in RA e.g. TKR
pre-assessment particular attention
- airway
- drug history
- routine ix + neck x-rays
intra-op
- positioning
- asepsis given immunocompromise
- steroid replacement
- NSAID caution
- PCA and hand deformity
REGIONAL vs GA
- regional ideal if no contraindication, positioning for spinal may be difficult