Critical Care Flashcards
A good anaesthesia?
Insensitive to pain
Reversible loc
Muscle relaxation
Types of anaesthetics
Amides- lidocaine
Esters- cocaine
Moa of anaesthetics?
Reversible inhibition of sodium channels (which are proteins therefore increased protein affinity leads to increased efficacy)
Prevent action potentials
Why does lidocaine not work in bacterial environment
Exists as an ionised base- In acidic environment cannot penetrate cell membrane
Lidocaine/bupivicaine/prilocaine dose
3 (7 with epi) max 200(500)
2 (3) max 150(150)
6
Indication and complications of spinal anaesthesia?
Surgery below the umbilicus T10 Hypotension-splanchnic pooling Damage during insertion Dislodgement/infection via catheter Haematoma post removal- cord compression
Definition of burns
Tri zone injury
Central area of coagulative necrosis
Surrounded by static area of inflam and ischaemia
Surrounded by hyperaemia
How to calculate survival of burns patients
Bull chart guides survival
TBSA + age > 100 = >20% mortality
Lund and bower chart for tbsa
Why place a pulmonary artery catheter?
Ra pressure assumed to be equivocal to la pressure- no valves
Can calculate temp, o2 sats, ef, co, pressures
Aetiology of brain injury
1- at time of injury
2- hypoxia, hypotension, RICP, hypercarbia
Cerebral perfusion pressure equation
MAP- ICP
MAP= diastolic + 1/3sbp
What controls cerebral vasodilation
Co2 levels
Why dilated pupils in head injury
Cniii palsy Runs through tentorium cerebellum Swelling leads to compression of this Loss of parasympathetic Symph from t1
Indications for parenteral nutrition
Complications?
Compromised gi tract
Hyper catabolic state
Does not maintain bowel mucosa
Monitoring required
Tpn jaundice- tpn is hepatotoxic?
Line sepsis
Different types of dialysis?
Haemodialysis- uses a ppm where small molecules removed by DIFFUSION- cheaper and simpler
Haemofiltration- continuous convection of molecules across membrane
Peritoneal dialysis
Functions of kidneys?
Homeostasis- Electrolyte balance, Acid base balance, Fluid balance Plasma filtration Metabolise drugs Excrete waste Hormones- epo, renin, calcitrol(Vit d)
Types and indications for ventilation
Bipap- type 2 resp failure
Cpap- splints airways open and overcomes compliance- type 1 resp failure, cardiogenic and non cardiogenic pulmonary oedema
Reasons for itu admission?
Pathology reasons
Monitoring/expertise reason
High risk procedure
Preoptimisation
Definition of brain stem death?
Patient comatose
Coma cause known
Irreversible damage
Reversible causes excluded
Brain stem death assessment?
Cnii light reflex
Cniii & vi occulovestibular reflex (turning head and eyes follow)
Can v & vii corneal
Cnviii oculocephalic reflex (water in ear)
Cn ix x gag reflex
Motor response to pain
Ventilatatory response following apnoea testing
Scoring system for pancreatitis?
Glasgow score/Apache/Ransom
Glasgow score: PANCREAS PaO2 <8 Age>55 Neutrophils>15 Ca <2.0 Renal- Urea >16 Enzymes LDH >600/AST >200 Albumin <32 Sugar >10
Reasons for hyperglycaemia and hypocalcaemia in Acute pancreatitis?
Hyperglycaemia- destruction of Beta cells
Hypocalcaemia- fat saponification, exocrine enzymes release due to pancreas destruction, leads to breakdown of fat to free fatty acids which chelate calcium
What are the pancreatic exocrine enzymes?
Trypsin, amylase and lipase
What is the pH equations?
Henderson-Hasslebach equation
pH= power of hydrogen
=pKa (acide dissociation constant) + log (base concentration)/acid concentration
What is the chloride shift principle?
In peripheral capillaries, CO2 is taken into cells via Cl- transporter and converted into HCO3- by carbonic anhydrase
Then excreted again for Cl-
Contributes to buffering process
?Affects Hb affinity for O2
What is a buffer system?
Base and acid system that resists changes in pH
Aetiology of metabolic acidosis?
Gain of H+ ions or loss of bicarb
High anion gap- Methanol, uraemia, DKA, lactic acidosis (Mud Piles)
Normal anion gap- Addisons, Bicarb loss- RTA , Chloride excess , Diarrhoea
Causes of metabolic alkalosis?
Gain of bicarb or loss of H+
Vomiting, blood transfusions (citrate),
Diuretics/genetic renal conditions= Barrters
Causes of respiratory alkalosis?
Anxiety/Pain
PE
Paracetamol
Asthma
When to use CPAP vs BiPAP?
CPAP- recruits collapsed alveoli
Pulmonary oedema/type 1 resp failure
BiPap- type 2 resp failure with acidosis
Categorisation of acute limb ischaemia?
Stage I- Not threatened
Stage 2a- salvagble if prompt- decreased CRT, partial sensory loss, inaudible doppler, good power
Stage 2b- slow CRT, partial sensory loss, decreased power, inaudible doppler
Stage 3- Nil CRT, paralysis, parasthetsia, no doppler
What is ARDS?
Acute resp failure and non cardiogenic pulmonary oedema
Resulting in hypoxia decreased lung compliance
Diffuse pulmonary infiltrates, normal PAWP, hypoxia
What are the causes and management of ARDS?
Lung- infection, aspirate, smoke, drowning
Systemic- DIC, polytrauma, CPB, massive transfusion, acute pancreatitis, sepsis, Fat emobolus
Management- Supportive, PEEP and proning
What is the mortality of ARDS?
30-60%
90% if associated with sepsis
Indications for surgical airway?
Cant intubate, cant ventilate
Laryngeal trauma/oedema/FB/Upper airway obstruction
Complications of poorly controlled pain?
Sympathetic response- tachycardia and increased metabolic demand Decreased resp effort Decreased GI motility- ileus Decreased mobility Psychological effects Chronic Pain
What is the process of pain transmission?
Painful/damaging stimuli
Identified by nocioceptors
AP transmitted by A-Delta/C fibres
To spinal cord and up via spinothalamic tract
To thalamus and then to somatosensory cortex
What is the MOA of paracetamol/NSAIDs?
Paracetamol- unknown aetiology
NSAIDs- Inhibit COX => decreased prostagladins
Alternatives to medical pain relief?
Hot and cold packs Rubbing- gated theory of pain Acupuncture TENS Machine Splinting #s
What is the management of new acute AF?
Rhythm control if indicated first
Within first 48 hours of presentation
DC cardiovert if haemodynamically unstable/ electively
Chemical cardioversion- flecanide vs amidodarone if not
Or Ablation
Rate control if not for rhythm control
Anticoagulate- CHASDVASC vs HASBLED
What are the complications of a blood transfusion?
Immune complications:
Acute haemolytic reaction-ABO incompatibility
Acute febrile reaction- minor histocompatability complex reactions
Anaphylaxsis
TRALI
GvHD
Non-immune Overload Hypocalcaemia (citrate) Hyperkalaemia (broken down cells) Hypothermia Infections
How many pints/litres of blood in an average human?
4-5 litres
8/9 pints/units
What is a massive transfusion?
In 4 hours >/ 50% of circulating volume replaced
In 24 hours >/ 100 % of circulating volume replaced
What can you do for a Jehovah’s witness?
All blood products? Involve Watchtower representative Rehydrate- IVT EPO/Iron tablets TXA Good haemostasis intra operatively Cell saver device
Medical management of IBD?
Sulfasalazine
Methotrexate
Azothioprine
Infliximab
Reversible brain stem death differential Dx?
Hypothermia Hypoglycaemia Hypothyroidism Addisons Toxins C spine injury
Formulas for calculating burns resuscitation?
Parkland’s formular- 4ml x TBSA x weight
Resusication over first 24 hours
Mount Vernon
When to refer to a specialist burns unit?
> 5%/>10% TBSA affected in adults/kids
<5yo/NAI/>60yo
Strange burn type- high pressure/electrical/steam/chemical
Hands, face, perineum, flexures, cicrumfrential burns
Inhalation injuries
Immunosuppressed/pregnant
Levels of burns?
Superfisical epidermal- Sunburn, red, painful, peels, good CRT, no blisters
Superficial dermal- Red, painful, delayed CRT, blistering, moist
Deep dermal- mottled red, sort of painful, non blanching
Full thickness- scortched leathery skin, no pain, no crt
What are should you do post CV line insertion?
CXR to exclude pneumothorax and check position
US scan to ensure in tip of SVC
What muscles lie over subclavian vein on approach to insert line?
Pec Major and subclavius
How is CO measured?
Fick’s principle
HR x SV
SV = afterload = preload
Draw a CVP trace?
Like JVP wave
Definition of compartment syndrome?
Elevated interstitial pressure in a closed osteofacial compartment leading to microvascular comprimise
Downward spiral of decreased venous return leading to decreased aorto-venous gradient and therefore decreased perfusion
Chance of full function returning when fasciotomies performed for compartment syndrome?
<12 hour- 2/3 patient get full function back
>12 hour- only 10%
Sheridan et al.
What is rhabdomyolysis?
Release of toxic muscle cell components (myoglobin) into systemic circulation
Aetiology of Rhabdomyolysis and complications?
1o- congential- duchennes
2o- Trauma, burns, hypothermia, ischaemic reperfusion injury, excessive excerise, toxins
Myoglobin release
Complications- AKI =>failure, DIC, Electrolyte abnormalities
Commonest level of C spine #?
C5
What to check for if c spine #?
Vertebral artery injury- CTA and MRA needed
What is a hangman’s #?
Bilateral pars interarticularis # of C2 (Between pedicle and lamina)
Difference between spinal shock and neurogenic shock?
Spinal shock- 2o to trauma, complete transection of spinal cord
Neurogenic shock- loss of symphathetics => bradycardia and hypotension
What is autonomic dysfunction
Spinal injury above T6
Leading to symphathetic response below level- peripheral vasoconstriction
And parasymph above lesion- vasodilation and bradycardia
Why does biliary pathology lead to prolonged clotting time?
As decrease functionality of gall bladder
Therefore decreased biliary production/secretion from GB
Therefore less fat breakdown and vitamin absorption
Vitamin K clotting factors (require Vit K for activation) affected
2,7,9,10
Where are ALT/AST produced?
Which is more liver specific?
Produced by hepatocytes
ALT more liver specific
AST produced by heart, kidney, liver, brain, intestine, placenta
Where are ALP and GGT produced?
ALP by bile duct epithelium/bones/placental tissue
GGT by hepatocytes and bile duct epithelium
What is the function of bile?
Excretory route for lipophilic substances
Emulsifier of fats
Elimination of cholesterol
What is the lifecycle of bilirubin?
RBCs broken down by spleen to Haem and globin
Haem broken down to Biliverdin
Then to bilirubin and iron
Bilirubin then bound to albumin and brought to liver
Conjugated by enzymes with glucuronic acid in Liver
Thus making it water soluble and allowing it to be excreted in the bile
Bile is then either converted to stercobilinogen and excreted in faeces
Or reabsorbed in distal ileum and converted in urobilinogen and excreted in urine
What microorganisms are screen for routinely on a blood transfusion?
HIV
Hep B/C
CMV
Syphilisi
What is CCK?
Produced by duodenum when fat detected
Leads to gall bladder contraction sphincter of oddi relaxation
What are the causes of DIC?
Infection Trauma Malignancy Massive blood transfusion Placental abruption
What are the consequences of hypothermia?
Hypoxia- left shifting of Hb-O2 curve
SNS activation- vasodilation and shviering
Enzyme dsyfunction
Coagulopathy
How to classify diverticulitis?
Hinchley classification Stage 0- mild diverticulitis Stage 1- + pericolic abscess Stage 2- distal abscess Stage 3- purulent peritonitis Stage 4- faeculent peritonitis
Stage 3/4- Operative drainage
Stage 0/1/2- IR
Suitable for Abx if abscess <3cm
What are the causes of a fat emoblism?
Trauma/long bone reaming/massive soft tissue injury Bone marrow transplant Liposuction Acute pancreatitis Intralipid infusion
What is the pathophysiology of fat emoblism syndrome?
Fat globules gain access via damaged vasculature
Plaltelet bound lipids brokendown leading to free fatty acids in blood
Intravascular coagulation leads to emboli
What is the role of MRI in FES
Mortality of FES?
Looks for cerebral Oedema- can R/O FES
5-15%
What is the definition of a high output stoma and what are the consequences?
> 500ml/day
Dehydration, electrolyte imbalance, malnutrition
How do you manage a high output fistulas?
A2E then MDT
SNAP
Sepsis control Nutritional support- dieticians Anatomical assessment- fisutlogram/CT Adequate IVT/electrolytes Protect skin Plan- conservative vs surgical (tract excision)
Indications of central line?
CVP monitoring/CO monitoring
Interventions- TPN, vasoirritant medication, failed cannulation, haemodialysis
How do you manage variceal bleeding?
Endoscopy- band ligation/sclerotherapy Terlipressin Balloon tamponade TIPSS Surgical shunt Liver transplant
What is the rule of 2/3s with portal htn?
2/3 of cirrhotic patients develop portal htn
2/3 of patients with portal htn develop varices
2/3 of patients with varices present with an acute bleed
What are the causes of hydrocephalus?
Increased production- choroid plexus carcinoma
Decreased circulation- malignancy, infection, haematoma
Decreased reabsorption- thrombosis/haemorrhage
What does pulse oximetry detect?
Ratio of unsaturated vs saturated haemoglobin
What are the side effect of colloids?
Anaphylaxsis and affect platelet aggregation
What are the pathophysiology of the hypersensitivity reactions?
Type 1- IgE => mast cell degranulation leading to heparin, histamin and platelet activating factor release
Leads to profound vasodilation, increased vascular permeability and smooth muscle spasm
Type 2- cell mediated- Ag and ab- acute transfusion reactions
Type 3- immune complex mediated- goodpastures/lupus
Type 4- delayed- contact dermatitis- t cell
Type 5- stimulatory- grave’s, TSH receptor autoAbs
What are the causes of hyponatraemia?
Hypertonic (hyperglycaemic)
Isotonic (pseudohyponatraemia (myeloma))
Hypotonic
Hypervolaemic- failures
Hypovolaemic- D/V or diuretics/ burns/trauma
Euvolaemic SIADH SCLC Infection Addisons Drugs HypoT
When do you gain immunity from tetanus?
Tetanus immunisations
After 5 doses
3 given at a couple of months old
1st booster at 5 years old
2nd at 15yo
What is an exotoxin/endotoxin?
Exotoxin produced by gram +/- bacteria
Immunogenic proteins
With specific effects
Endotoxins
Just produced by gram -ve
Lipopolysacchorides from cell wall leading to general stress response
What is the mortality of NEC Fasc?
30%
What are the different types of adrenergic receptors?
alpha 1- vascoconstrioction and increased myocardial contraction duration
beta 1- intropy and chemotropy
beta 2- vasodilation/bronchoconstriciton
Dopamine 1/2- diuresis
What is starling’s law?
Myocardiac contractility is proportional to myocardial stretch
Make up of hartmannas and NaCl?
Hartmanns
Na 131, cl 111, bicarc 29, Ca 2, K 5
NaCl
Na 154, Cl 154
Where is hartmanns, nacl, dextrose and blood distributed?
Blood just intravascularly
NaCl and Hartmanns just ECF
Dextroses everywhere
Indications for intubation?
Airway- decreased GCS, facial/laryngeal trauma, inhalation injury
Breathing- resp failure, prevention of 2o brain injury
How to confirm ETT is in correct position?
Look listen feel Waveform capnography is gold standard Face mask misting Air entry No stomach rise CXR
How do you calculate ventilation?
Tidal volume x RR = 7ml/kg x 12/min
Why does tachycardia put one at increased risk of an MI?
Coronary artery filling occurs during diastole
Diastole shortens during tachycardia
Why RJV preferential site for CVP measurement?
No valves between it and RA
Less NV damage risk
Causes of normal anion gap metabolic acidosis?
Addisons
Bicarb loss- RTA
Chloride excess
Diarrhoea/diuretics
RFs for AF?
Age/alcohol CXS disease Thyroid status Valvular disease DM
Hypovolaemia/hpoxia
Potassium
Acute MI
Sepsis
What is the MI re infarction rate when performing surgery?
<1 month = 30%
<6 months= 5%
What is the MOA of aspirin and clopidogrel?
Both prevent platelet aggregation
Clopidogrel via inhibition of ADP receptors
Aspirin via COX antagonism
Side effects of NSAIDs?
Heart failure- fluid retention AKI Stomach ulcers Coagulopathy Decreased inflammation Bronchospasm
Types of Nec Fasc?
1- polymicrobial- staph/hi
2- monomicrobial- GAS
3- clostridium
4- fungal
What is a pancreatic psuedocyst?
fluid filled collection with fibrous capsule
due to leakage of enzyme rich fluids
How do you manage a pancreatic pseudocyst?
Conservatively
50% resolve
10% infected
Drain- radiologically, endoscopically, open
What is a steroid?
Organic compounds with characterisitic four rings
Cholesterol/aldosterone/cortisol/testosterone/progesterone/thyroid hormone
What affect does aldosterone have?
Na/K/ATPase pump activity increase
Increase H20 retention and alkalosis
What hormones are produced by the anterior and posterior pituitary?
Anterior: ACTH TSH FSH LH GH Prolactin
Post pituitary:
Oxytocin
ADH
What are the effects of gluccocorticoids and how are they controlled?
Metabolic- hyperglycaemic effect- inhibit insulin
Non metabolic- Na in/K out- fluid retention
Anti inflam
immunosuppressant
Decrease stress response
CRH produced by hypothalamus leads to ACTH production by ant pituitary leading to cortisol production by cortex
Stimulated by low cortisol levels
Complications of gluccocorticoids?
Weight gain DM Ulcers Osteoporosis Bruising/muscle weakness Mood changes Cushing's Sick day rules!
What are the general principles for operating on someone taking glucocortiocoids?
Double dose day of surgery
IV hydrocortisone at induction
Alert anaesthetist- pre assessment
Beware of Addison’s
Abdo pain, N/V, shock, hypothermia
Criteria for day surgery?
Social factors- someone to take them home and keep an eye on them
Medical factors- patient fit
Surgical factors- Op generally doesnt result in serious post op complications
Able to mobilise post op
Good length of op/anaesthetic time
What is the ASA criteria?
1- fit and well 2- mild systemic disease 3- severe systemic disease 4- severe systemic disease at constant risk to life 5- moribund 6- Brain dead, organ transplantation
When to refer to the coroner?
Death <24 hours since admission
Suspicious/accidental/violent death
After op/procedure
Unknown cause of death
What to do facing a tracheostomy airway problem?
Help- anaesthetics/senior A2E O2 to face and trachy Trachy box- inner tubes/suctio catheters/scissors & tape Remove valve/inner tube Attempt to pass a suction catheter Deflate cuff if needed Remove trachy- if in doubt take it out Ventilate via mouth/nose- cover trachy with gauze
What are the types of transplant rejection?
Hyperacute- ABO mismatching
Acute- HLA mismatching
Chronic- MHC mismatching?
What is in FFP and cryoprecipitate?
FFP= all clotting factors, albumin, fibrinogen, vWF Cryo= F8, F13, fibrinogen and vWF
How does an osmotic diuretic work?
Eg. Mannitol
Filtered by the glomerulus but can not be reabsorbed
Leads to increased oslamlality which therefore is balanced out by diuresis
Why does Aortic stenosis lead to problems intraoperatively
AS leads to hypertrophied ventricle, which is stiff with decreased compliance
Therefore this ventricle has an increased metabolic demand- so is sensitive to changing arterial pressure
And has a lesser ability to respond to a changing afterload
