Surgery: Anaesthetics and peri-operative Flashcards
How are patients classified under the American society of anaesthesiologists classification?
ASA I - VI
I - healthy
II - mild systemic disease, smoke, pregnant etc
III - Severe systemic disease, poorly controlled, BMI > 40, end stage renal disease with dialysis
IV - the above, with threat to life - MI, CVD
V - not survive without operation - aneurysm / ischaemic bowel
VI - brain dead
If concerned about cervical spinal injury what should be done to open the airway
Simple positional manoeuvre
Jaw Thrust
Main device used to open the airway
Oropharyngeal airway
What are laryngeal masks not suitable for?
Patients with Reflux
High pressure ventilation going through
What can errors in endotracheal tube insertion lead to? How should it be monitored?
Oesophageal intubation
Monitor end-tidal CO2 (capnography)
Need to be paralysed + suitable for high pressure ventilation
List IV induction agents for anaesthesia
Propofol - Gaba agonist, rapid, moderate cardiac, hypotension, pain on entry (TRPA1), anti-emetic
Sodium thiopentone - rapid, not maintainance, laryngospasm, brain
Ketamine - NMDA antagonist, suitable if haemodynamically unstable (no drop in blood pressure) , nightmares - strongest
Etomidate - cardiac safety (less hypotension), adrenal suppression, vomiting, myoclonus
What should amount of blood should be given during each type of surgery?
Unlikely - group and save e.g. appendiectomy
Likely - cross match 2 units - ruptured ectopic
Definite - 4-6 units - total gastrectomy, AAA
What are the inhaled anaesthetics used?
Volatile liquid e.g isoflurane - myocardial depression, malignant hyperthermia - induction
Nitrous oxide - avoid in pneumothorax - labour
Types of IV access
Venous
Peripheral cannula - no vasoactive drugs
Central line - skill, haemorrhage, multiple infusions
Intraosseous - paediatric
Tunnelled - long term, paediatric
PICC - peripheal central cannula
Types of IV cannula
Orange 14g - 270ml/min flow rate
Grey 16 g - 180ml/min flow rate
Green 18g 80ml/min
Pink 20g 54ml/min
Blue 22g 33ml/min
Features of Lidocaine
Not used in arrythmia patients (Na channels)
Renal excreted
Can cause liver dysfunction
Interacts: Beta blocker, cipro, phenytoin
How is local anaesthetic toxicity treated?
IV 20% lipid emulsion
Max doses of local anaesthetic
Maximum total local anaesthetic doses
Lignocaine 1% plain - 3mg/ Kg - 200mg (20ml)
Lignocaine 1% with 1 in 200,000 adrenaline - 7mg/Kg - 500mg (50ml)
Bupivicaine 0.5% - 2mg/kg- 150mg (30ml)
adrenaline prolongs action
What is malignant hyperthermia
Post anaesthetic induction
excess release Ca2+
autosomal dominant
NMS
Causes of Malignant hyperthermia and how is it treated?
Halothane, suxamethonium, antipsychotics
CK raised
Dantrolene - prevents Ca2+ release
Types of muscle relaxants
Suxamethonium - depolorising neuromuscular blocker, in acetylcholine, fast (choice for rapid intubation - fasciculations) - hyperkalaemia, malignant hyperthermia and lack of acetylcholinesterase
Atracurium - non depolorising, histamine reaction on use, broken down in tissues, reverse with neostigmine
Vecuronium - non depolar, neostigmine reversal
Pancuronium - quick, neostigmine reversal
When are nasopharyngeal airways contraindicated?
Skull fractures
What is suxamethonium contraindicated for?
Penetrating eye injuries, acute angle glaucoma - increases intra-ocular pressure
What are the nutrition options in surgical patients?
Oral
Naso gastric - aspiration, no head injury
Naso jejunal - avoids stomach / aspiration, technical
Feeding jejunostomy - surgical, long term, risk of peritonitis
Percutaneous endoscopic gastrostomy - aspiration
Total parenteral nutrition - central vein phlebitic - fatty liver and deranged LFT’s
Main fluid to give post operatively
Hartmanns - balanced - sodium, potassium, chloride and lactate
Early causes of post-op pyrexia (0-5 days)
Blood transfusion
cellulitis
UTI
systemic reaction
atelectasis
Late causes of post-op pyrexia
VTE
Pneumonia
wound infection
anastomotic leak
think 4 Ws wind, water..
What is Postoperative ileus and what should be done?
reduced bowel peristalsis -> pseudo obstruction
- distension, pain, N/V, no flatus, no oral diet
deranged electolytes can cause - check potassium, magnesium and phosphate
NBM, NGT if vomiting, fluids, total parenteral nutrition
What is needed before preping a patient for surgery?
Tests - group and save, clotting, urine, preganancy, sickle cell, ecg
Assess DVT rf
Drink fluids until 2 hrs before surgery - reduce headaches e.g. water, tea without milk
Non clear fluids / food - 6 hr before surgery
Diabetes during surgery - complications
Complications - hypoglycaemia, wound/resp infections, AKI, prolonged stay
Diabetes during surgery - medication adjustments
good control - adjust insulin reigmen
poor control - varaible rate insulin
oral - manipulate on the day unless - meal missed, poor glycaemic control, renal injury risk - VRIII used
Metformin - normal, if three times a day emit lunch dose
Sulfonylureas - normal, omit morning dose if morning operation, omit before doses if afternoon operation
DPP IV & GLP-1 - normal
SGLT-2 - emit on day of surgery
Once daily insulin e.g. lantus - reduce dose by 20%
Twice daily insulin e.g. novomix - normal, half morning dose and leave evening dose unchanged
Examples of special preparation for surgery
thryoid - vocal cord check
phaeo - alpha and beta blockade
carcinoid - octreotide
Main 3 parts of surgical checklist and what needs to be checked before anaesthesia
before anaesthesis
before incision of skin
before patients leaves operating room
confirm patient, mark site, pulse oximeter on patient and working, allergies, difficult airway, risk of more than 500ml blood loss?
Risk factors for perioperative hypothermia
ASA grade of 2 or above
Major surgery
Low body weight
Large volumes of unwarmed IV infusions3
Unwarmed blood transfusions
Complications of perioperative hypothermia
Coagulopathy - hypothermia reduces clotting
prolonged recovery
reduced wound healing - vasoconstriction
infection
shivering
VTE prophylaxis of patients in hospital
mechanical - stockings
pharm - fondaparinux SC, LMWH (reduce in renal), UFH use with CKD
Stop COCP 4 weeks before surgery, mobilise and hydrate
Post surgery VTE prophylaxis
Hip - LMWH 10 days then aspirin 28 days / stockings with heparin for 28 days
Knee - 14 days same as above
Fragility fractures - VTE one month if risk of VTE > bleeding - LMWH start 6 hrs post surgery or fondaparinux
Stages of wound healing
Haemostasis
Inflammation
Regeneration
Remodeling (longest)
Problems with scars in wound healing
Hypertrophic -too much collagen, holds boundaries of orginal wound
Keloid - extend beyoung boundaries
Drugs that impair wound healing
NSAIDS
Steroids
Immunosupressive agents
anto-neoplastic drugs
How can anastomotic leaks be diagnosed?
Abdominal CT
Excessive administration of sodium chloride causes what
hyperchloraemic acidosis
When can patients use saline post surgery
48 hrs
showering ok as well
tap water 48 hrs after wound has separated
What is impaired during the perioperative period?
Thermoregulation
