Anaesthetics & Clinical Biochemistry Flashcards
Pre-Assessment
History (2)
PMH: MI, asthma/COPD, rheumatic fever, liver/renal disease, dental problems, neck problems (eg. RA), reflux/vomiting, recent GA
FH: malignant hyperthermia, sickle cell disease
Pre-Assessment
Examination (4)
General: frailty, obesity, observations
Airway and dentition
Neck ROM
Cardio and resp exam
Pre-Assessment
Investigations (7)
ECG: >60 + ASA >3 OR any CVD OR severe renal disease
FBC: >60 + ASA >2 OR severe renal disease
U&E + creatinine: >60 + ASA >3 OR any age + ASA >4 OR any renal/CV disease
Pregnancy test
Sickle cell tests: if any FH, African/Afro-Caribbean
CXR: if scheduled for critical care or any recent respiratory illness
LFT: alcoholism, malignancy, jaundice
Pre-Assessment ASA Classification (6)
ASA I: normal healthy patient
ASA II: mild systemic disease/smoker/drinker/obesity/pregnancy
ASA III: severe systemic disease
ASA IV: severe systemic disease that is a constant threat to life
ASA V: moribund and not expected to survive procedure
ASA VI: declared brain dead- organs being removed for donor purposes
Pre-Assessment Special Considerations (8)
No food <6h before procedure No fluids <2h before procedure All diabetics should be 1st on list and omit medication other than insulin (variable rate infusion) Stop warfarin 5d before Aspirin: stop for non-cardiac surgery Clopidogrel: stop for 5d before NSAIDs: stop due to renal and anti-platelet effects COCP: stop 4wks before
Principles of Anaesthesia
Triad of anaesthesia (3)
Hypnosis: unconsciousness by general anaesthetic agents (eg. propofol IV) and opiates
Analgesia: removal of noxious stimuli to prevent arousal and reflex response to pain by opioids and local anaesthetic (eg. remifentanil)
Relaxation: immobility for artificial ventilation or body cavity surgery by muscle relaxants, GA agents and opiates
Conduct of Anaesthesia
Induction (2)
IV: establish IV access, pre-oxygenate with 100 O2, give co-induction agents eg. fentanyl, give sleep inducing agent (GA) eg. propfol
Inhalational: indicated by patient request, difficult IV access, children, airway obstruction, either sevofluorane + O2 OR nitrous oxide + sevofluorane, establish IV access once asleep
Conduct of Anaesthesia
Airway (3)
Initially: triple manoeuvre (head tilt, chin lift, jaw thrust) with bag mask ventilation
Subsequent maintenance: laryngeal mask airway or endotracheal intubation
Protection: only if cuffed tube in trachea to protect airway from inflammation (endotracheal intubation) - indicated if muscle relaxants
Conduct of Anaesthesia
Ventilation (1)
Indications: use of muscle relaxants for specific procedure or as part of a balanced anaesthesia for a long procedure
Conduct of Anaesthesia
Maintenance (3)
Inhalational: agent + either spontaneous breathing through LMA OR ventilated and have muscle relaxants
Total IV anaesthesia: maintenance is with propofol and remifentanyl
High dose opiates with mechanical ventilation: rarely use due to risk of awareness
Perioperative Monitoring and Care
Monitoring (9)
General: sweating and lacrimation indicate complication
Respiration: rate + depth
Temp: risk of hypothermia
BP: use intra-arterial line if long case or high risk case
Pulse oximetry
ECG
CVP: helps differentiate hypovolaemia from reduced cardiac function
Urine output
Capnography: low end tidal CO2 can indicate emboli
Perioperative Monitoring and Care
Care (3)
Temp: hypothermia risk, warm environment with warming blankets and warmed IV fluids
Loss of protective reflexes: corneal reflexes so taping of eyes shut
Positioning: use cushioning to prevent pressure sores
Perioperative Complications
Failure to intubate (4)
Plan A: tracheal tube
Plan B: LMA
Plan C: bag/mask ventilation or wake up patient if able
Plan D: needle/surgical cricothyroidectomy
Perioperative Complications
Bronchospasm (1)
Occurs as part of own entity or with anaphylaxis
Perioperative Complications
Laryngospasm (1)
Cords firmly shut
Perioperative Complications Malignanct hyperthermia (2)
Rare autosomal dominant (chr 19) life-threatening condition
Triggered by suxamethonium or volatile agents causing excessive release of calcium
Perioperative Complications
Aspiration (1)
Due to active vomiting or passive regurgitation
End of Anaesthesia
Reversal (4)
Change inspired gases to 100% O2
Stop anaesthetic drug infusions
Use a peripheral nerve stimulators to check spontaneous muscle relaxant reversal has occurred, then reverse with neostigimine and an anticholinergic (eg. atropine) to prevent muscarinic side effects (bradycardia, salivation)
Once spontaneously breathing, remove tube and administer O2 via facemask for as long as required
Post-Operative Care
Post-operative analgesia (3)
Initial: strong opioids eg. morphine and peripherally acting drugs eg. paracetamol
Restoration of oral route: weak opioids eg. codeine and peripherally acting drugs
Final: peripherally acting drugs alone
Post-Operative Care
Post-operative fluids (2)
Prescribe for requirements and always use Hartmann’s as electrolyte balanced
If haemodynamically stable then restart oral intake
Post-Operative Care
Post-operative VTE prophylaxis (9)
Any surgery >90min at any site or >60 min at lower limbs/pelvis Any patient >60 Anyone with thrombophilia Anyone with previous thrombosis BMI >30 COCP/HRT If pregnant or <6w post-partum If >1 significant medical co-morbidity Early mobilisation, compression stockings
Post-Operative Complications
Nausea + vomiting (4)
25% of post-op patients
Vomiting centre in medulla: higher centres stimulated by sedatives, middle ear stimulated by nitrous oxide
At higher risk if female, opioid/nitrous oxide use
Use ondansetron, prochloperazine or cyclizine
Post-Operative Complications
Pyrexia (1)
Look for underlying cause (eg. peritonism, chest infection, UTI, wound infection, meningisim, endocarditis)
Post-Operative Complications
Confusion (1)
Due to hypoxia, drugs (opiates, sedatives), urinary retention, MI/stroke, infection
