Deck 3 Flashcards
Fat embolism definition
Circulating fat globules in circulation and pulmonary parencgyma
Triad of fat embolism syndrome
Respiratory insufficiency: Increased RR, SOB, cyanosis
Cerebral features: drowsiness, rigidity
Petechial rash: sternum, axilla, mouth
Causes of fat embolism
Traumatic:
- fractures
- Hip/knee arthroplasty
Non-traumatic:
- pancreatitis
- liposuction
- bone marrow transplant
Mechanical theory of fat embolism pathophysiology
Fracture leads to damage to vasculature at that site
Fat globules enter circulation and taken to pulmonary circulation causing damage
They gain access to systemic circulation via arterio-venous shunts and cause ischaemia by obstructing various vessels
Biochemical theory of fat embolism pathophysiology
Stress hormones such as steroids and catecholamines release activated lipase
Free fatty acids increase vascular permeability and induce pulmonary damage
Different forms of fat embolism
Subclinical: minor haematological change, decreased PaO2, no resp distress
Non fulminant (subacute): triad, resolves after 72hrs
Fulminant: resp failure, altered mental state, death
CXR appearance of fat embolous
Snow storm appearance
bilat fluffy infiltrates
Which brain imaging to use for fat embolism
T2 weighted MRI shows high intensity areas within white matter
CT has limited use, may display minimal cerebral oedema
Which brain imaging to use for fat embolism
T2 weighted MRI shows high intensity areas within white matter
CT has limited use, may display minimal cerebral oedema
Causes of enterocutaneous fistula
Abdo surgery 75%
Inflammation: Crohns or infection
Classification of fistulas by output
Low output<200ml/day
Moderate 200-500
High output >500ml//day
Fistula mx
SNAP
Sepsis: abx + drainage
Nutrition: Decompression + TPN to allow healing (In high output fistulas)
Adequate fluid and electrolyte
Plan and protect: conservative vs surgical, protect skin
Which fistulas could be treated conservatively
- no obstruction or sepsis
- not complicated with IBD
Imaging for fistulas
CT with oral contrast or contrast injected through the fistula
MRI used for complex anal fistulation
Complications of TPN
Metabolic:
- K, Mg, phosphate
- glucose (most common)
Line related:
- as per Central line
Rule of 2/3 for portal HTN
2/3 cirrhosis gets portal HTN
2/3 of protal HTN develop oesophageal varices
2/3 oesophageal varics present with acute bleeding
Rule of 2/3 for portal HTN
2/3 cirrhosis gets portal HTN
2/3 of protal HTN develop oesophageal varices
2/3 oesophageal varics present with acute bleeding
Sites of porto-sysyemic anastomosis
Umbilical Upper anal Varices Bare area of liver Retroperitoneal
TIPS procedure
Transjugular intrahepatic portosystemic shunt
Hepatic vein cannulated via IJV
Stent inserted between hepatic vein and branch of portal vein to reduce portal pressure
Complication of TIPS
Encephalopathy as portal blood diverted from liver
Occlusion
False localising sign
Weakness on lateral gaze
Due to brain herniation and its impact on CN6 (long intra-cranial path)
Classical presentation of extra dural haemorrhage
Concussion
Lucid period (conscious): haematoma expanding
Loss of consciousness: ICP increases as per Monro-Kellie
doctorine
Secondary brain injury definition
Any injury that occurs hours or days after primary injury
Due to cellular damage
Prevention of secondary brain injury
- Rapid sequence intubation to keep sedation and control ventilation (hyperventilate pt)
- nurse at 45 degrees (reduces oedema)
- Central line to monitor ICP -> hypertonic saline, mannitol, dex
Why want to hyperventilate a pt to prevent secondary brain injury
High O2 and low CO2 leads to decrease cerebral perfusion -> cerebral oedema
Normal levels of
CPP
MAP
ICP
CPP >65mmHg
MAP> 90mmHg
ICP < 25mmHg
How is cerebral flow autoregulated
Autoregulated between SBP 50-150
Myogenic: stretch in artery causes vasoconstriction
Chemical: low o2 and high co2 causes vasodilation
Causes of increased CSF
Increased production: choroid carcinoma
Decreased circulation: Aqueduct stenosis, haemorrhage
Decreased reabsorption (sinus thrombosis, haemorrhage)
Anaphylaxis meds
IM adrenaline 1:1000, 500 micrograms
Chlorphenamine 10mg IM or IV
Hydrocortisone: 200mg IM or IV
How does pulse oximetry work
Infra-red light and red light emitted and reabsorbed
Oxygenated and deoxygenated haem habsorbs different amounts
Ratio is calculated to give the percentage oxy haem
Factors interfering with accurate pulse oximetery
Nail varnish
Poor peripheral circulation
CO
Jaundice (under estimates)
Factors interfering with accurate pulse oximetery
Nail varnish
Poor peripheral circulation
CO
Jaundice (under estimates)
Risks with colloid solutions
Dextran 70 interfers with vWF and platelet adhesion
Anaphylaxis
Interferes with cross matching process
Causes of increased CVP
Right sided HF
Caridac tamponade
Causes of decreased CVP
Poor circulatory volume
Vasodilation
Levels of care
Level 0 = ward
Level 1 = ward + input of critical care
Level 2 = HDU (one organ failure)
Level 3 = ICU (>1 organ failure or advanced support for one organ eg ventilation or bypass)
Complications of tracheostomy
Early:
- bleeding : thyroid isthmus, anterior jugular
- injury : trachea, recurrent laryngeal n
- blockage: mucous or blood
- displacement
Intermediate: infection
Late: tracheal stenosis
Complications of tracheostomy
Early:
- bleeding : thyroid isthmus, anterior jugular
- injury : trachea, recurrent laryngeal n
- blockage: mucous or blood
- displacement
Intermediate: infection
Late: tracheal stenosis
Post op care for tracheostomy pts
Humidified O2
Regular suction and cleaning of inner tube
Emergency equipment at bedside
Examples of hypovolaemic hyponatraemia
Burns
Diarrhoea
Diuretics
Causes of hyervolaemic hyponatraemia
Heart failure
Polydipsia
IV overload
Examples of pseudohyponatraemia
High lipids/albumin in blood (eg myeloma)
Dilutes the concentration of Na
Examples of pseudohyponatraemia
High lipids/albumin in blood (eg myeloma)
Dilutes the concentration of Na
Causes of SIADH
Drugs: psych meds, opiates
Lung path: PE, tumours
Brain: tumours, meningitis
Sx of low Na
Headache
Confusion
Weakness
Seizure
Consequence of rapid correction of Na level
Centra pontine myelinolysis
Demyelination of pons:
- lethargy, locked in syndrome, coma
How fast can you correct low Na
No faster than 10mmol per 24hrs
How fast can you correct low Na
No faster than 10mmol per 24hrs
Methods of intra op heat loss
Radiation (50%)
Conduction (to air and operative table)
Evaporation
ECG of hypothermia
J waves (upward deflection after QRS)
