Misc 7 Flashcards
What is the mechanism behind dilutional hyponatraemia e.g. in heart failure?
Activation of RAAS and also ADH release from posterior pituitary
Both lead to fluid retention but only one of these leads to Na retention so relative hyponatraemia (TBS actually high)
3 ways in which patients lose heat intraoperatively?
Radiation - from skin (there is also vasolidation which worsens this)
Evaporation - body surfaces and open cavities
Conduction into air and theatre table
Also cold fluids/anaesthetic agents, and shivering prevented due to paralysis
Normal response to hypothermia?
Symp response - shivering, piloerection, periph vasoconstriction
RFs for intra/post op hypothermia?
Pre op hypothermia
Worsening ASA grade
Major/exposed or prolonged surgery
Combined GA and regional
What is the classic ECG finding in hypothermia and what is it? When is it seen?
J - Osborn wave
Usually seen at less than 32 degrees
Upward deflection between QRS and ST
Complications of hypothermia in relation to surgery?
Coagulopathy
Decreased metabolism and CO
Decreased drug metabolism - prolonged mechanism of action
Discuss division of total body water e.g. for 70kg male?
TBW = 42L 28L = intracellular 14L = extracellular 11.5L = interstitial 3.5L = intravascular
Hartmanns composition?
Na 131 Cl 111 K 5 Ca 2 Bicarb (as lactate) 29
0.9% NaCl composition?
154 Na
154 Cl
What is the classification system for traumatic pelvic fractures? What are the 3 types?
Young and Burgess
AP compression - open book fracture
Lateral compression
Vertical shear - fall from height, superior displacement of one hemipelvis on the other
What level do you apply a pelvic binder at?
Greater trochanters
Discuss management of major bleeding due to pelvic fracture?
Any hypotenisve major trauma should have pelvic binder
Then discuss with IR if active bleeding and pelvic fracture
If no target - preperitnoeal packing
If large vessel injury not amenable to IR - vascular opinion
Where do the majority of bleeds come from in pelvic fractures with blunt trauma?
Pelvic venous plexus
Lethal triad of trauma?
Hypothermia, acidosis and coagulopathy
What is the difference between Early Total Care and Damage Control Surgery?
DCS = haemorrhage control, compression of major cavities and decontamination ETC = early definitive treatment of injuries after period of initial resus
Pathophysiology of Type 1 hypersensitivity reactions?
Antigens bind to IgE antibodies on mast cells and basophils/eosinophils
Then degranulate to produce histamine, heparin, platelet activating factor
Increase in leukotrienes, prostaglandins
Above cause vasodilation, smooth muscle spasm, capillary leak due to increased vascular permeability and excessive epithelial glandular secreteion
Treatment of type 1 hyypersensisitvty reaction?
IM adrenaline 500 micrograms (0.5ml 1/1000) - can repeat after 5 mins if doesnt help
Chlorphenamine 10mg IV/IM
Hydrocortisone 200mg IV
IV fluid challenge 500ml
How to size guedels and nasopharyngael airways?
Guedel = incisor to angle of mandible
NP airway = external nare to tragus
What effect may jaundice have on pulse oximetry?
Bilirubin can falsely lower reading
Complications of colloids?
Anaphylaxis
Coagulopathy
3 causes of increased CVP?
Fluid overload/ventricular failure
Cardiac tamponade
Chronic respiratory disease
Level 0 - 3 care?
0 = normal ward patient 1 = ward with critical care input 2 = HDU = single organ failure, 2:1 nursing 3 = ICU = multi organ failure, 1:1 nursing
Caring for post op trache patient?
Humidified oxygen
Regular tube care and suction
Emergency kit availability
Under what circumstance would you be fully immune to tetanus?
When you’ve had 5 doses - 3 in early months then 2 boosters
What causes tetanus?
Clostridium tetani
What is the neurotoxin produced by c tetani?
Tetanospasmin
Differences between exotoxin and endotoxin?
Exo= gram pos or neg, immunogenic Endo = gram neg only, non-immunogenic
Alpha 1 activation causes?
Vasoconstriction and increased duration of contraction
Beta 1 activation causes?
Positive inotropy and chronotropy with minimal vasoconstriction
Beta 2 activation causes?
Vasodilation
Dopamine1/2 activation causes what?
Kidneys - induces diuresis
What is dobutamine most useful for and why?
Beta 1/2 activation to cause improved cardiac contractility and reduce afterload
Why is norad preferred in e.g. septic shock?
Acts primarily on alpha 1 to cause vasoconstriction with relatively little tachycardia
2 ways of calculating MAP?
(SBP + (2xDBP))/3
(COxSVR) + CPP
What is CVP monitoring useful for?
Gives indication of volume status (cardiac filling)
What is preload?
Ventricular filing - how fmuch its stretched pre systole (end of diastole)
Why would you consider ET intubation for mechanical ventilation?
Airway reasons - low GCS, facial/upper airway trauma etc., obstruction from inhalation smoke etc
Breathing - respiratory failure due to lung pathology, due to neuromuscular failure or to manage head injuries
Just intubated somoene and they are still hypoxic? What do you do?
call for help, apply 100% O2
Check tube position, if in doubt take it out
Check tube blockage
Check for kinking/disconnection
Manually bag to assess compliance - ?bronchospasm
Rule out pneumothorax
Check ventilator working properly
Define ventilation?
Tidal volume x respiratory rate
3 basic types of mechanical ventilation?
Prsesure controlled
Volume controlled
Pressure suport - supports patients own work of breathing
Normal tidal vlume by weight?
7ml/kg
Immediate, early and late complications of mechanical ventilation?
Immediate - airway trauma, failure, dental damage
Early - baro/volume trauma - pneumothorax/pneumoed/emphysema, raised intrathoracic pressure and reduced preload leading to CV collapse
Late - VAP, respiratory muscle atrophy, tracheal stenosis, tracheal fistula
3 rerquirements for weaning ventilation?
Resolution of intiial reason for ventilation
Adequate gas exchange - reducing O2 req
Adquate resp drive and power - spontaneous breathing trials
Managing new AF (acute) that doesnt resolve with correction of cause?
If stable - oral cardioversion e.g. amiodarne, digoxin
If unstable - DC or chemical cacrdiovert
Give 4 specific post op complications of open AAA repair?
Abdo copmartment syndrome
Bleeding
Lower limb ischaemia
Post op ileus
What postiion for remove central line? Why?
Head down or supine
To reduce risk of air embolus
How might teunnelled lines need to be removed?
In theatre - larger incision needed to dissect to plastic retaining cuff
5 causes of ischaemia?
Obstruction of arterial supply Obstruction of venous outflow e.g. compartment syndrome Anaemia CO poisoning Pulmonary disease and poor oxygenation
Likelihood of reinfarction if major surgery within 1 month post MI? Vs over 6 months?
30%
vs 5%
Clopidogrel lasts for how long?
8 days - lifespan of platelets
Mechanisms of actino of aspirin?
COX 1 (blocks thromboxane A2 formation, platelet aggregation) and COX 2 (analgesia ,antiinflammatory/pyriexa) inhibition
Mechanism of action of clopidogrel?
Prevents platelet aggregation oby irreversibly inhibitring plaetelet ADP receptor