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
Hypertensive disorders in pregnancy
BP > 140/90 before 20 weeks = chronic HTN
After 20 weeks = PIH
PET Definition
BP > 140/90
20 weeks
+ End-organ dysfunction
1. Proteinuria (1+ / >30mg/mmol UPCR)
2. Creatinine > 90
3. ALT > 70
4. Neuro symptoms / signs
5. Haem DIC / platelets < 150
6. Uteroplacental dysfunction
Severe PET Definition
- BP > 160/110
- Platelets < 100
- Liver enzymes 2x ULN + RUQ pain
- Double creatinine
- Pulmonary oedema
- Headache
- Visual disturbance
PET Pathophysiology
Stage 1 - Abnormal placentation + vascular remodelling
- Hypoxic placenta from reduced perfusion
Stage 2 - Endothelial dysfunction
- imbalance of pro and antiangiogenic factors and inflammatory mediators
- decreased perfusion due to vasoconstriction and activation of coagulation cascade
- fluid shift - leaky capillaries
- vasoconstriction - high SVR - inc pulmonary pressure, renal, hepatic dysfunction. cerebral. vasospasm leads to seizures
- decreased placental blood flow
Management of HTN in pregnancy
NICE suggests treat if BP > 150/100
1. labetalol 200mg TDS a1 and beta blocker
2. methyldopa 250mg QDS NA false neurotransmitter
3. Nifedipine 20-90mg OD.. ca channel
4. Hydralazine - IV 5mg.. vsaodilator
5. MgSO4 4g + 1g/hr
Pros and cons of jet ventilation
advantages
- improved surgical access
- reduced peak pressure
- avoidance of ETT ignition if laser is used
disadvantages
- barotrauma
- malposition
- airway soiling
- efficacy of gas exchange difficult to measure
Can have low frequency (10-30) or high frequency (120-600)
Jet ventilation settings
Driving pressure - 103-405kpa
frequency 1-10Hz. automatic rate of 100-150
I:E > 3 for emptying
EEP limit - gas trapping may occur due to rate. indicates alveolar distension
Mechanisms of gas exchange during HFJV
Pendelluft - intrapulmonary gas redistribution due to asynchronous alveolar ventilation
Taylor dispersion - asymmetrical velocity profile. molecules in central zone diffuse to lateral zones
cariogenic mixing - beating heart
bulk flow (LFJV)
NICE CT Head in TBI
- GCS < 13 on presentation
- GCS < 15 2 hrs after
- Suspected open or depressed skull fracture
- Any sign of BOS fracture
- Post traumatic seizure
- Focal neurology
- More than 1 episode of vomiting
C-Spine clearance
Clinically
- awake, fully orientated, no head injury, sober, no neck pain, no distracting injury, no abnormal neurology
- if all of above - assess movement. if normal can be cleared
Indications for CT c-spine
Head injury plus
- GCS < 13
- intubation
- clinical suspicion
- Multitrauma CT regardless
If alert and stable
- age 65
- dangerous mechanism
- focal neurology
- parasthesia in upper limbs
If none of above - neck pain / tenderness and pre-condition - ct
Transfer
Patient - stable
Personnel - doctor + assistant
Equipment - monitoring / pumps / airway / O2
Drugs - RSI, seizure, osmotherapy
Notes
COPD diagnosis
Complemented with clinical and radiological
Spirometry - airflow obstruction FEV1/FVC < 0.7
- FEV1% < 80 % = mild
50 - 80% moderate
30-50 severe
< 30 very severe
Untreated COPD
- exp airflow imitation - airway inflammation, hyperplasia, mucous, fibrosis, bronchospasm
- hyperinflation, increased TLC and FRC. exertion dyspnoea
- VQ mismatch
- chronic hypoxia - palm hypertension, polycythaemia, cor pulmonale
HOCM Echo
- abnormal systolic anterior motion of mitral valve
- LV hypertrophy
- septal hypertrophy
- narrowing of LVOT
- MR
HCM
Intrinsic myocardial disorder leading to inappropriate LVH in absence of underlying cause such as pressure overload. Men. Autosomal dominant
Risk factors for sudden death
- LVH > 30mm
- NSVT
- family history
- Unexplained syncope
Pathophysiology of HCM
- defects in sarcomeric proteins - myofibril disarray and fibrosis
- ventricular hypertrophy with poor compliance and diastolic dysfunction
- impaired filling and raised LV filling pressures
- hypertrophy of septum and LVOTO
- MR
Ischaemia - obstructed coronary flow
- raised LVEDP - reduced CoPP
- greater demand due to mass
Obstruction of LVOT - prominent septum - dynamic LVOTO
- SAM of MV leaflet
HCM treatment
- counselling and genetic testing
- beta blockers
- diuretics
- amiodarone
- ICD / pacemaker
- Myectomy
- transplant
Anaesthetic considerations in HCM
optimisation
invasive monitoring inc TOE
avoid drop in SVR and sympathetic surges
defib pads
sinus rhythm low normal rate
maintain preload. A1 agonists to maintain SVR
good pain relief to avoid sympathetic surges post op
avoid inotropy
Types of cardiomyopathy
CM : heart muscle is abnormal structurally and functionally in absence of ischaemia, HTN, valvular disease
Primary
- Dilated
- enlargement leads to deficient actin/myosin cross linking. systolic failure, embolic
- Hypertrophic
- Restrictive
- stiff ventricles, impaired diastolic filling and dysfunction. hazardous anaesthesia (-ve inotropy, IPPV, vasodilation all problematic)
- ARVC
- myocardial cells replaced by adipose or fibrous tissue.
Secondary
- Toxins : alcohol
- Ischaemia
- Inflammatory : viral myocarditis
- Metabolic : amyloidosis
- Peripartum
Autonomic dysreflexia
- Spinal cord injury above T6 (due to splanchnic circulation)
- Stimulus (pain, surgical, distended bladder) below lesion leads to peripheral sympathetic activation below lesion
- Inhibition of sympathetic response not transmitted due to spinal cord lesion leading to uncontrolled sympathetic activation
- Above lesion - parasympathetic - flushing, sweating, bradycardia
- below lesion - sympathetic overactivity - pale cool skin
Heart transplant indications
- advanced heart failure NYHA III-IV
- Optimal medical treatment inc resynchronisation
- recurrent life threatening arrhythmias
- cardiogenic shock, MCS
- refractory angina
Contraindications - advanced irreversible renal / hepatic / resp failure
- Pulm HTN > PASP 60
- malignancy last 5 yrs
- diabetes / obesity / substance misuse
Denervated heart
Absent PNS / SNS
- HR 100
- no response to direct autonomic influence e.g atropine
- absent baroreceptor reflex e.g. pneumoperitneum, valsava
- excessive response to direct acting catecholamines (reduced to indirect)
- intrinsic regulation of CO - SV preload dependent
Anaesthesia for patient with heart transplant
consideations
- denervation physiology
- PPM / ICD
- Underlying disease
- SE of immunosuppressants (steroid, renal, liver, electrolyte)
- immunosuppression and opportunistic infections
- difficultt access. avoiding RIJ
- intro monitoring including 5 lead ecg, art line, toe
Heart transplant rejection
acute
- 3 months
- cellular / antibody mediated
- arrhythmias, failure.
-endomycoardial biopsy, augment immunosuppressants, Plex
chronic
- immune mediated
- accelerated concentric intimal proliferation of donor coronaries
- nil treatment
DCCV in child
1-2J/Kg for SVT
(age + 4) x 2
Monitoring etc
IV access if possible
If not starved RSI
if starved gas induction and maintenance +/- ETT
amiodaorne 5mg/kg
Cystic Fibrosis
Autosomal recessive inherited condition causing abnormality in Na / Cl transport in various organs leading to viscous secretions
Mutation in CFTR - defect causes Cl to be trapped in cells and in sweat
Sweat test, gene test
CF effects
Resp
- thick secretions - inadequate fluid secretion
- dehydration of mucus and pericillary liquid - mucus adhesion to airway surface and failure to clear.
- retained mucus - chronic infections and bronchiectasis
- eventually cor pulmonale, death
GIT
- pancreas - failure of secretion, retention of enzymes and auto digestion
- intestine - fails to flush secreted mucus, obstruction, steatorrhoea
- biliary - thickened secretions, FBC
Sweat
- highly concentrated
Fertility
- men obliteration of vas
- women thick cervical mucus
Pre-op optimisation of CF
baseline ABG and spirometry
bronchodilator
mucolytic
prep chest physiotherapy
prep sputum culture
Anaesthesia and CF
RA where possible
If GA
- ETT for suctioning
- inhalation agents with bronchodilator properties
- humidified gases
- bronchodilators, mucolytics, chest physio in post op period
Pneumonias
HAP - 48hrs + after admission to hospital (MRSA, serratia, pseudomonas)
Healthcare associated pneumonia - hospitalised 2 days in last 90, nursing home, receiving chemo
CAP - symptoms of acute LRTI with focal chest signs and system feature e.g. fever. strep. pneumonia most common
Atypical - different clinical and radiological findings. mycoplasma, legionella, chlamydia
VAP
Noscomial pneumonia > 48hrs after mechanical ventilation
common 9-28% mechanically ventilated patients with high mortality
Diagnosing VAP
Clinical : fever, purulent secretions
Micro : bacteriological evidence of pulmonary infection
Radio: x-ray evidence
CPIS
- temp, secretions, leucocytosis, gas exchange, micro, radiological.
VAP microorganisms
Early onset - strep, H.influenzae, MSSA
Mostly gram -ve - E.Coli, klebsiella, enterobacter, serratia
late - pseudomonas, MRSA, ESBL
Risk factors
patient - age, ARDS, lung disease, MF, gastric aspirates, URT colonisation
interventional - prolonged ventilation, NMBD, PPI, supine position
Preventing VAP
care bundles
general - hand hygiene, sterile equipment, barrier nursing
reduce digestive colonisation - oral decontamination with chlorhexidine, SDD
reduce aspiration - semi-recumbant position, subglottic suctioning, cuff pressures
minimise duration of ventilation - daily sedation holds, early tracheostomy
gastric protection - enteral feeding,, H2 blockers vs PPI
Sickle Cell testing
screening test - patients blood mixed with dexoygenatingagent to determine > 10% HbS. doesn’t diagnose sickle cell disease
Hb electrophoresis - quantify HbS
Sickle cell genetic abnormality
Chromosome 11 - glutamine substituted for valine on Beta chain –> HbS which is unstable and precipitate out of solution in deoxygenated state
Sickling crises
Painful crises - vast-occlusive due to sickle shape RBC obstructing blood flow resulting in ischaemia and pain
Aplastic crisis - worsening of anaemia, parvovirus
Splenic sequestration - spleen unable to clear all defective rbcs
haemolytic crisis - accelerated haemolysis
Manifestations of sickle cell
Resp
- acute chest syndrome
Neuro
- recurrent infarcts
Haem
- anaemia
MSK
- bone marrow dysplasia
renal
- renal failure
GI
- asplenism
- gallstones
GU
- priapism
Acute chest syndrome
dyspnoea,, cough, haemoptysis, pain
recurrent pulmonary infarctions
new infiltrates on CXR
ABx, fluid, oxygenation
Anaesthetic implications of sickle cell
maintain oxygenation
- sickling < PaO2 5.5 (polymerisation of HbS)
maintain hydration
normothermia
regional / good analgesia
avoid tourniquets / stasis
Transfusion aiming for Hb > 10g/dL
RBC structure
biconcave disk - allows high surface area to volume ratio and negotiation of tight vascular passages
large amount of protein but no nucleus, mitochondria or ribosome
membrane disorders - deformity and reduced lifespan - spherocytosis, ovalocytosis
Hereditary spherocytosis
congenital haemolytic anaemia, autosomal dominant
genes involved in attachment of cytoskeleton to membrane - loss of SA, spherical and osmotically fragile cells which become trapped in spleen
- blood film, osmotic fragility test
features
- haemolytic anaemia, jaundice, splenomegaly
treatment
- folate, red cell transfusions, splenectomy
Red cell disorders
Haemoglobinopathy
enzymopathy - G6PD
Membrane disorder
disorders of red cell production - thalassaemia, myelodysplasia, aplastic anaemia
Thalassaemia
genetic defect in Hb synthesis - decreased or absent synthesis of either a or b chains
- imbalance in global chain synthesis - reduced Hb production and precipitation of excess
- african, asian, mediterranean heritage
B thalasaemia
- autosomal recessive.
- homozygotes (major) severe transfusion dependent anaemia
- heterozygous (trait) mild to moderate anaemia
features - anaemia, extra medullary haumatopoeisis, infections, transfusion morbidity
blood smear, hb electrophoresis
chelation therapy, stem cell transplant
G6PD Deficiency
X-linked disorder
G6PD enzyme - oxidation of glucose-6-phosphate and NADP+ to NADPH (reduced form)
NADPH is cofactor for many reactions and maintains glutathione
reduced glutathione scavenges dangerous oxidative metabolites
red cells rely on G6PD as it is only source of NADPH to protect against oxidative stress
haemolysis occurs
- infections
-fava beans
- oxidants
- surgery
neonatal jaundice, haemolysis, splenomegaly
avoid oxidant drugs, stop offending factors, folic acid and transfusions
Anaesthetic considerations for patients with pacemaker
Patient
- indication
- underlying cardiac function
- comorbid cardiac disease
- anticoagulatns
Pacemaker
- age, type, ICD
- last check
surgical
- diathermy
- proximity to ppm
Rate modulation
means of monitoring physical activity incorporated - speed up pacemaker with exercise
Diathermy
- interference and affect function
- heating damage heart
pre-op - check function
intrap-op - bipolar biter than monopolar
- if monopoly - plate far away, short bursts
- external defib
post-op - check function
ICD
- elective - switch off to prevent accidental shock due to electrical equipment
- emergency - magnet should switch off
Pulmonary Hypertension
Mean PAP > 20mmHg at rest
Mild 25-34
Mod 35 - 44
Severe > 45
Systolic PAP > 35mmHg suggestive
WHO Classification
1 - Pulmonary arterial hypertension (idiopathic)
2 - Due to left heart disease (sys/dia/valve)
3 - Due to chronic lung disease (copd/ild/osa)
4 - due to chronic pulmonary thromboembolic disease
5 - due to systemic disease e.g. sarcoid
Pathophysiology
- palmonary vasculature - remodelled and constricted just to above mechanisms
- RV - pump against greater afterload, hypertrophy and failure
- LV - failure due to right/left interdependence and reduce LV preload
- CoPP - greater RV pressures can compromise blood flow leading to ischaemia
clinical features PulmHTN
- dyspnoea
- syncope
- weakness
- TR / PR murmur
- elevated JVP
- hepatomegaly
- peripheral oedema
Treatment options
offload rv - furosemide
oxygen
pulmonary vasodilators e.g. sildenafil / epoprostanol / endothelin receptor antagonists / NO
Inodilators e.g. milrinone
underlying cause
reprerfuson
lung transplant
Anaesthesia
- IV induction agents / NMBD / volatiles safe (avoid N2O)
- invasive monitoring and CVC
- inhaled prostacyclin
caution with neuraxial - reduced SVR and CoPP - avoid increased PVR, reduced SBVR, myocardial depressionI
Factors increasing PVR
- hypoxia
- hypercarbia
- acidosis
- pain
- cold
- anxiety
- PEEP
- drugs e.g. adrenaline, N2O protamine, TXA2
Enhanced recovery
targeted approach to minimise disruption in usual activities and return to normal function as soon as possible after surgyer
pre-op - minimise starvation, avoid bowel prep, optimise nutrition and hydration
itra-op - goal directed fluid, CO monitoring, multimodal analgesia
post-op - return to oral intake and mobility as soon as possible, remove lines and catheters
Anaemia perioperative care
associated with worse healing, longer LOS, mortality. 2-3x complication rate.
Ix - FBC, iron studies, TSat, haematinincs, ferritin, U+E, reticulocytes
- ferritin < 30 or TSat < 20% - iron deficiency (PO iron recheck in 4/52)
- ferritin 30-100, CRP > 5, renal impairment - iron deficiency + functional - treatment as above
- ferritin > 100 TSat < 20 - functional - tree as above
- ferritin > 100 and TSat > 20 - b12/folate low - replace. b12/folate normal - specialist
Cholesteatoma
abnormal collection of keratinised squamous epithelium which is locally invasive - bony erosion can lead to CNS complications
Symptoms
- unilateral hearing loss (sensorineural)
- dizziness
- unilateral pain
- headaches
- symptoms of meningitis, brain abscess
Hypotensive anaethesia
PONV
- hydration
- TIVA, avoid N20
- avoid prolonged starvation
- multiple antiemetics
Facial nerve monitroign
exits skull base through the stylomastoid foramen requires monitoring in mastoid surgery. injury needs immediate decompression
Pre-op cardiac risk assessment
- identify patients at risk of perioperative cardiac events
- assess medical status of these patients and risk posed by planned cardiac
- strategies for improving long term cardiac outcomes
Assessing cardiac status
History and examination
- recent MI, decompensated heart failure, stable angina, symptomatic arrhythmias or valve disease
Functional status
- METs (< 4 = high risk, > 10 very low)
Ix
- ECG, echo
- stress testing
- cangiography
- BNP
- CPEX
Cardiac risk scoring systems
NYHA functional classification
1 - Asymptomatic
2- mild symptoms, slight limitation of activity
3 - symptoms and
4 - symptoms at rest
Goldman’s original - 9
- JVP
- 3rd heart sound
- MI last 6 mo
- arrhythmia
- 5 ectopics
- age > 70
- emergecny
- intrathoracic, abdominal or aortic surgery
- poor general health
Lee’s revised = 6
- High risk procedure
- IDDM
- CVA
- creat > 177
- CCF
- IHD
> 3 11% mortality..
Risk scores and risk prediction models
population based mortality
- ASA
cardiac complications
- Lee’s
Post-op pulmonary complications
- ARISCAT
30 day mortality
- P-POSSUM - 12 physiological + 6 surgical variables
- NELA - emergency bowel surgery. estimate intra-op findings
- SORT - 6 pre-op variables. easy to use
none of above have morbidity component
ACS-NSQIP - most comprehensive, least user friendly
APACHE / ICNARC ICU mortality
Complex Regional Pain Syndrome
Diagnosis of exclusion
- continuing pain out of proportion to initial trauma
- one sign in two categories
- one symptom in three categories
- no other diagnosis
Categories
1. Sensory - allodynia, hyperalgesia
2. Vasomotor - temperature asymmetry, skin colour changes
3. Sudomotor - oedema, sweating asymmetry
4. Trophic - reduced ROM, dysfunction, hair/nail/skin
Types of CRPS
1 - tissue injury but no nerve injury. trivial trauma
2. significant nerve injury (sciatic, tibial, median, ulnar)
Allodynia / hyperalgesia
Allodynia = perception of pain when non-painful stimulus is performed
Hyperalgesia = increased painful response to stimulus that is normally paindul
CRPS treatment
MDT
Medical - simple, opioid analgesics, antidepressants, anticonvulsants
CBT / psychotherapy
Physical - physio, TENS, functional restoration
Regional - intrathecal, regional nerve, sympathetic block e.g. stellate ganglion
Surgical - sympathectomy, spinal cord stimulator
Others - NMDA antagonists, capsaicin, calcitonin, hyperbaric, IVIG…
Anaesthetic consdierations for lung transplant
- fasting status - may arrive at short notice
- coagulation - if liver disease ? epidural
- Left DLT
- AAGBI + Art + CVC + PA catheter
- Immunossuppression - MMF, methylpred
- ABX ? pseudomonal cover
- Blood products
- Access to pulmonary vasodilators, ECMO
- Post-op epidural analgesia for BL thoracotomy
Eaton-Lambert Myasthenic syndrome
- autoimmune, paraneoplastic
- proximal arm and leg weakness (difficulty getting out of chair).
- repeated movements improve weakness
- rarely bulbar
- common autonomic dysfunction
- IgG antibodies PRE-SYNAPTIC VGKCa channels at NMJ - less ACh diffuses into NMJ. repeated stimulus - more ca and more Ach vesicles reach membrane
- SC lung cancer, rarely NSCLC and others
- Anaesthesia considerations - delayed gastric emptying, autonomic dysfunction, sensitive to NDMR and DMR, myay need post op ventilation
GA in head up or sitting positions
- reduced cerebral perfusion
- air embolism
- fluid sequestration in lower limbs - reduced venous return and CO
- airway access
- pressure points
GA in beach chair
Airway - Flexi LMA or south facing RAE
Breathing - SV to avoid reduction in venous return with IPPV
CVS - minimise cerebral hypo perfusion - IABP, BIS, cerebral oximetry
Positioning - limb support
Bazold-Jarisch reflex - venous pooling in limbs, rapid reduction in preload, SNS activation and myocardial contraction. Hypopnoea, bradycardia, hypotension
Intestinal motility
Segmental contraction - local mixing
Propulsive contractions - coordinated over larger areas
Smooth muscle negative RMP - contract with Na / Ca influx
- slow wave sub threshold 20-30x per min
- threshold reached with presence of food bolus
Influences
- enteric nervous system - SNS inhibits, PNS increases mtility and secretions
- endocrine - Vasoactive intestinal peptide - water and sodium excretion. motilin - migrating motor complex every 90mins through whole bowel
Pathophysiology of bowel obstruction
below obstruction - bowel empties and immobile
above - increased peristaltic activity. dilation with gas and fluid. oedema and fluid leaking into peritoneum leading to hypovolaemia and electrolyte imbalance. continued distension compromises the blood supply
Small bowel - nausea, vomiting, diaphragm impingement
large bowel - bacterial translocation
Physiological actions of calcium
- haemostasis
- excitation contraction coupling
- neurotransmitter release
- Cell signalling
- Bone strength
Homeostasis of calcium
- PTH from PT gland - increases osteoclast activity, increases renal reabsorption, increases hydroxylation of vit d which increases intestinal absorption
- vit.d - produced in kidney, increases reabsorption from kidney and enteral absorption. cholecalciferol - 25-hydroxylated in liver to form calcidiol. 1-a-hydroxylated in kidney to give active D3. 1-a hydroxylase is upregulated by PTH.
- calcitonin (thyroid gland)- reduced gut absorption, reduced 1-a hydroxylationg of Vit.D, inhibit osteoclast
EEG
Electroencephalogram - measures electrical activity of the brain. 19 scalp electrodes.
records patterns from synchronised depolarisation of groups of neurones.
Electrical activity is categorised based on frequency of waves
- delta waves - 0-4 Hz
- theta waves 4-8Hz
- alpha waves 8-13 hz
- beta waves 13-30hz
- gamma waves > 30 has
Uses - diagnosis of epilepsy, encephalopathy, prognostication in hypoxic brain injury, DOA monitoring
Processed EEG
EEG signal digitised, filtered, amplified and deconstructed. propriety algorithm to score 0-100 to help judge DOA. BIS / entropy / narcotrend
Anaesthesia and pEEG
Awake - small amplitude high frequency gamma and beta waves
Sedation - amplitude increases, beta and alpha waves
Anaesthetised - alpha and delta
Over-anaesthetised - alpha-delta with isoelectric burst suppression
Propofol / volatiles / midazolam have dose dependent relationship. Ketamine excitatory on BIS. N20 and opiates no effect
Ideal DOA monitor
- good correlation between index and hypnotic concentration
- clear transition from awake to asleep
- valid in all ages
- unaffected by other drugs
- unaffected by interference from monitors etc
Erythropoeisis
Production of RBCs. Bone marrow
1. common pluripotent stem cell
2. myeloid progenitor
3. erythroblast phases - B12/folate required. Hb production early. Globing in cytoplasm, heme in mitochondria
4. Reticulocyte - maturing cell loses nucleus, Hb synthesis by ribosomal RNA
5. Mature erythrocytes - 1-2 days after reticulocytes released into circulation, lose RNA
Controlled by EPO - secreted by kidney, stimulates differentiation of myeloid progenitor cells. hypoxaemia –> EPO
Anaemia
Hb < 130g/L men 120 women
insufficient production
- Fe/B12/folate deficiency
- EPO deficiency (CKD)
- chronic disease - hepcidin reduced iron absorption
Increased breakdown
- intravascular haemolysis - autoimmune haemolytic anaemia, mechanical, transfusion reaction
- extravascular -spherocytosis, sickle cell
excess loss
- acute / chronic blood loss
Iron handling
- dietary 15mg/day with 1-2mg absorbed
- Fe containing heme groups, dietary ferrous Fe2+ salts
- regulated by iron absorption
- plentiful stores - hepcidin - inhibits ferroportin and iron not absorbed from enterocytes
- low stores - reduced hepcidin
- in plasma - Fe2+ –> Fe3+ and bound to transferrin to bone marrow
- excess iron stored by ferritin
Periopertive anaemia
- oral iron 4 weeks
- iv iron 2 weeks
- oral may be ineffective if chronic disease causing excess hepcidin
Iron studies
Ferritin - total body iron stores
serum iron
TIBC - ability to bind iron to transferrin. if high = iron deficiency
Tsat = serum iron to TIBC. high = overload. low = iron deficiency
Iron defieicny
- low ferritin
- low iron
-High TIBC
- low T sat
Chronci disease
- normal feriritin
- low iron
- low / normal TIBC
Changes to fetal circulation at birth
- clamping umbilical cord leads to increased SVR. flow through ductus arteriosus decreases. LA > RA pressure - closure of foramen ovale
- first breath causes reduction in PVR (decreases HPVC) PA and right heart pressures decreases. proportion of CO reaching lungs 10 –100%
transitional circulation.
-physiological changes that follow birth may be reversed by hypoxia (HPVC), acidosis (inc PVR)
increased PVR can maintain foramen ovale and lead to right to left shunting
treatment to reverse hypoxaemia - surfactant, O2, CPAP, IPPV, NO
pulmonary maturation
surfactant is produced from 24 weeks, full lung maturation not until 35 weeks
infant respiratory distress syndrome - prem neonates without surfactant. treated by maternal corticosteroids, given surfactant
O2 transfer across placenta
- LArge gradient intervillous PO2 6.7, fetal PaO2 2.7
- HbF higher capacity than HbA (left shift)
- double bohr effect
- mat side higher PaCO2 shift maternal curve to right and allowing release of O2
- fetal side, low PaCO2 shifts HbF to left - increasing affinity
- mat side higher PaCO2 shift maternal curve to right and allowing release of O2
congenital cardiac defects
PDA
- failure of DA to close leads to L –> R shunt leas to RVH, PHTN, RV failure
VSD
- Left –> right shunt, eisenmengers
TOF
TGA
- aorta from right and PA from left
- mixing required for life - PDA, VSD or ASD
- PG infusion
Chromosome
Long molecule of DNA located in cell nucleus containing genetic information
23 pairs - 46 in total
Autosome - 22 pairs
Allosome - 1 pair - xx or xy
Diploid = 23 pairs
Haploid = 23 singles (sperm, egg
DNA
Two long strands coiled in a double helix
Composes of nucleotides
- Guanine, Adenine, Thymine, Cytosine
Triplet = codon –> 1 amino acid
Phenotype
Feature of a person encoded by a gene
Allele = 1 version of a gene. Each person has two - one from each parent.
Dominant allele masks effect of recessive
Autosomal dominant
- child inherets dominant defective gene and a non-defective. has disease
- MH, PCKD, Marfans
Autosomal recessive
- need 2 copies of defective allele to have disease
- child of two heterozygotes has 25% chance of disease, 50% chance of carrier, 25% chance of being free of disease
- CF, sickle cell, sux apnoea
x-linked recessive
- carried on X chromosome
- females usually protected by dominant allele
- DMD
Labour Pain pathways
1st stage
- cervical dilatation and uterine contractions
- poorly localised severe visdceral pain
- T10-L2 pelvic plexus
2nd stage
- well localised somatic pain
- perineum
- pudendal nerve
- S2-4
- may be less well covered by lumbar epidural
child pugh
- AScites
- Encephalopathy
- Albumn
- Bilirubin
- PT
