Anaesthetics Flashcards
When is a jaw thrust the preferred airway manoeuvre
cervical spine injury
oropharyngeal airway indications & pros
in an acute airway problem
as a bridging measure, before definitive airway
For v short procedures
pros: easy to insert & use. No paralysis required.
laryngeal mask airway indications, pros & cons
Commonly used, esp for day surgery
not suitable for high-pressure ventilation
(sits in pharynx and aligns to cover airway)
pros: easy to insert
cons: poor control over gastric reflux
Tracheostomy indications
Slow weaning from ETT
reduces work of breathing & dead space
percutaneous tracheostomy commonly used in ITU
cons: dries secretions, humidified air usually used in ITU
Endotracheal tube indications
optimal control of airway once cuff inflated
used for long/ short-term ventilation
higher ventilation pressures can be used
Cons: errors may lead to oesophageal intubation - detected with capnography
Paralysis required
ASA grades
- (healthy)
non-smoker, minimal alcohol - (mild systemic disease - i.e. no functional limitations)
current smoker, social drinker, pregnancy, BMI 30-40, DM, HTN, mild lung disease - (severe systemic disease- functional limitations)
poorly controlled DM, HTN, COPD, BMI>40, end stage renal disease & regular dialysis, MI or CVA hx, alcohol dependence , etc. - (severe disease constant threat to life)
- recent (<3mo) MI or CVA, cardic ischemia, valve dysfunction, severely reduced EF, sepsis, ARD, ESRD w/out dialysis - (not suspected to survive without operation)
- AAA, massive trauma, intra-cranial bleed w mass effect, multi organ failure - brain dead pt for organ harvest
Propofol indication, MoA, features
IV
Indication & pros - commonly used for sedation induction & maintenance, in ITU for ventilated pts, high risk vomiting pts - some anti emetic properties, rapid metabolism
MoA- potentiates GABA
cons - moderate myocardial depression, pain on injection, hypotension
Sodium thiopentone MoA, indication, cons
MoA- barbiturate, potentiates GABA
Indication- rapid sequence induction (v rapid onset) due to high lipid solubility
cons - laryngospasm, marked myocardial depression, metabolites build up, not for maintenance infusion, no analgesic effects
ketamine indication, moa,
moa - NMDA receptor antagonist,
indication - induction of anaesthesia, strong analgesic properties, little myocardial depression (good for those who are haemodynamically unstable- i.e. trauma )
cons - may induce state of dissociative anaethesia resulting in nightmares
Etomidate MoA, indication, cons
MoA - potentiates GABA
Indication - induction of anaesthesia, favourable cardiac safety profile w little haemodynamic instability
Cons - adrenal suppression (so not for Maintainance infusion!), post op vomiting is common, no analgesic properties
Volatile liquid anaesthetic examples, indication, MoA, cons
isoflurane, desflurane, sevoflurane
indication - indication & Maintainance
MoA- unknown but combination of GABA, glycine & NDMA
cons- myocardial depression, malignant hyperthermia, (halothane = hepatotoxic)
Nitrous oxide: examples, indication, cons
indication: Maintainance of anaesthesia and analgesia (e.g. labour)
adverse effects: may diffuse into gas filled area. Avoid in pneumothorax
Cannula colour/ size order
biggest - Orange 14G (lava)
Grey 16G (rock)
Green 18G (grass)
Pink 20G (flower)
Blue 22G (sky)
Local anesthetic toxicity can be treated with…
IV 20% lipid emulsion
Malignant hypothermia causes
halothane
suxamethonium
other drugs: antipsychotics (neuroleptic malignant syndrome)
susceptibility inherited in autosomal dominant fashion
malignant hyperthermia Ix and mx
(hyperpyrexia and muscle rigidity)
Investigations
CK raised
contracture tests with halothane and caffeine
Management
dantrolene - prevents Ca2+ release from the sarcoplasmic reticulum
Deporalising neuromuscular blocker adverse effects & CI
(suxamethonium a.k.a succinylcholine)
hyperkalaemia, malignant hyperthermia, fasciculation and lack of acetylcholinesterase
increases IOP so CI in pts w penetrating eye injuries or acute narrow angle glaucoma
nasopharyngeal airway indication & contraindication
ideal for seizure pts as you may not be able to put in OPA
CI - base of skull fractures
causes of post op pyrexia
‘the 4 W’s’ (wind, water, wound, what did we do? (iatrogenic).
Early causes of post-op pyrexia (0-5 days) include:
- Physiological systemic inflammation (day1-2)
- - Pulmonary atelectasis (1-2)
- Urinary tract infection (d 3-5)
- Blood transfusion
- Cellulitis
Late causes (>5 days) include:
- Venous thromboembolism
- Pneumonia
- Wound infection
- Anastomotic leak
- iatrogenic (Abx or anaesthetic agents)
Mx of postoperative ileus
check deranged potassium, magnesium and phosphate are not the cause
- nil-by-mouth initially, may progress to small sips of clear fluids
- nasogastric tube if vomiting
- IV fludis to maintain normovolaemia
& additives to correct any electrolyte disturbances - total parenteral nutrition
occasionally for prolonged/severe cases
Summary of diabetic control during surgery?
- metformin
- sulfonylurea
- DPP IV inhibitors
- GLP-1 analogues
- SGLT-2 inhibitors
- Once daily insulin (Lantus, Levemir)
- twice daily biphasic or ultra-long acting insulins
If long fasting period w more than 1 missed meal/ poor diabetic control = variable rate IV insulin infusion
Otherwise, just change normal regime:
metformin- if taken TDS, omit lunchtime dose. otherwise normal.
sulfonylurea - omit on day of surgery. unless taking BD w morning surgery - only omit morning dose.
DPP IV inhibitors , GLP-1 analogues , SGLT-2 inhibitors -> take as normal
Once daily insulins (e.g. Lantus, Levemir) - reduce doses by 20% on the day before & day of surgery
Twice daily Biphasic or ultra-long acting insulins (e.g. Novomix 30, Humulin M3) - half morning dose, evening dose unchanged
which nerve is most likely to be injured in posterior triangle lymph node biopsy
Accessory
which nerve is most likely to be injured in Posterior approach to hip
Sciatic
which nerve is most likely to be injured in
which nerve is most likely to be injured when Legs in Lloyd Davies position
common perineal
which nerve is most likely to be injured in Axillary node clearance
Long thoracic
which nerve is most likely to be injured in Pelvic cancer surgery
Pelvic autonomic nerves
which nerve is most likely to be injured in thyroid surgery
Recurrent laryngeal nerves
which nerve is most likely to be injured in carotid endarterectomy
Hypoglossal nerve
which nerve is most likely to be injured during upper limb fracture repair
Ulnar and median nerves
WHO checklist 3 phases of an operation
1) Before the induction of anaesthesia (sign in)
2) Before the incision of the skin (time out)
3) Before the patient leaves the operating room (sign out)
Before the induction of anaesthesia, the following must have been checked:
- Patient has confirmed: Site, identity, procedure, consent
- Site is marked
- Anaesthesia safety check completed
- Pulse oximeter on & functioning
- known allergy?
- difficult airway/aspiration risk?
- risk of > 500ml blood loss (7ml/kg in children)?
COCP changes before surgery?
Advise women to stop taking their combined oral contraceptive pill/hormone replacement therapy 4 weeks before surgery
