Pre-induction Anaesthesia Flashcards
What are the patient factors that need to be verified pre-induction?
- Correct patient for correct procedure
- R/v of medical conditions and recent changes to health status, e.g. URTI
- Confirm fasting times + drug intake and allergies
- R/v of baseline parameters, medication charts, investigation results
- Remind patient of anaesthesia plan, reinforce risks
- Obtain consent
- IV cannulation (establish IV access) (inject LA lignocaine as needle gauge is large)
What are the equipment and drugs that need to be checked induction?
Check anaesthesia machine (ensure it is working, have soda lime, no leaks in gas circuit, etc), check suction
- Fresh gas flow (FGF)
- Manual mode (when patient spontaneous breathing), ventilator mode (when patient not spontaneously breathing; machine ventilates pt)
- Pink granules = soda lime; chemically removes expired CO2
Dilute and draw drugs – amnesia (sedation), analgesia, akinesia (muscle relaxant)
Check airway equipment: ETT + laryngoscope or LMA, tapes, syringe to inflat
Warm fluids
Standby blood products (if needed)
What patient vitals are under standard ASA monitoring?
ECG, pulse oximetry (SpO2), non-invasive BP (NIBP), ETCO2, partial pressure of anaesthetic gases (see Monitoring)
- ECG, SpO2: continuous
- NIBP: every 3-5 mins (machine measured)
- ETCO2: concentration, waveform morphology is important (at higher levels of anaesthesia training)
- Gas analyser (ETO2, ET(gases)): important to record, in order to prevent delivery of hypoxic gas mixture
What patient vitals are under non standard ASA monitoring?
Temperature:
- Nasopharyngeal (NP)/ oropharyngeal (OP) probes
- E.g. in laparotomy with high evaporative losses
JVP/CVP line: Trending intravascular volume status, e.g. in surgeries with anticipated major blood loss (or in patients with poor cardiac reserve)
IA line
EEG
- Neurological monitoring (increasingly performed routinely/standard)
- Ensures appropriate depth of anaesthesia (deep enough + not too deep)
What are the advantages of IV induction of anaesthesia?
☺ Fast onset – within 1 arm- brain circulation (if using propofol)
☺ Smooth and predictable
☺ Non-noxious to airway
☺ Allow for rapid sequence induction [RSI] (reduce aspiration risks)
☺ Suitable for most patients
What are the advantages of inhalational induction of anaesthesia?
☺ good for those w/ difficult IV access (e.g. paediatric, poor venous access, severe anxiety or needle phobia)
☺ good for those w/ airway anatomy that may collapse* and lead to airway obstruction w/ loss of muscle tone/spontaneous respiration, e.g. mediastinal mass, epiglottitis, airway FB
Reason: inhalational agents act MUCH slower than IV – effects of sedation but allows spontaneous breathing, just require pressure support on ventilator. Spontaneous breathing generates negative intra-thoracic pressure 🡪 keeps airway patent
What are the disadvantages of IV induction of anaesthesia?
☹ requires IV access – may be difficult in paediatric patients or difficult IV access (e.g. small veins)
☹ Fast onset of respiratory depression and apnoea – requires early support of airway and ventilation
☹ S/E of specific drugs, e.g. hypotension, cardiorespiratory depression
What are the disadvantages of inhalational induction of anaesthesia?
☹ noxious smell of gas
☹ requires patient (+parent) cooperation
☹ slow onset (also quick offset once stopped)
☹ risk of laryngospasm, coughing or involuntary movements
☹ environmental pollution
In what kind of surgeries are laryngeal mask airway used?
- Used in non-abdominal surgery (e.g. TKR, TURP, etc)
- Used in short surgeries w/o need for airway protection
- Used when ventilation is expected to be easy (when high pressures are not expected, e.g. patient is not obese)
What are the indications for intubation (ETT)?
Required for controlled airway and mechanical ventilation
Shared airway surgeries, e.g. ENT, maxillofacial (surgeries where definitive airway is important)
Difficult position during surgery, e.g. prone
Long surgeries
Surgeries requiring paralysis and relaxation
Protection against aspiration
Required for tracheal suctioning
How to confirm that ETT is intubated?
- Direct visualisation of intubation
- Misting of ETT with ventilation
- Bilateral chest rise, compliance of lung inflation
- Clinical auscultation at 5 points (epigastrium (r/o gurgling), bilateral apices and bases (r/o endobronchial and adventitial sounds))
- Detection of end tidal CO2 (ETCO2)
- CXR (not routinely done)
What are the complications of intubation?
- Trauma to lips, teeth/crown, larynx
- Laryngeal oedema and stridor post-operatively
- Nasal intubation 🡪 may cause epistaxis
- Hypoxaemia 2’ to failure to oxygenate/intubate
- Bronchospasm
- Haemodynamic effects – arrhythmias, hypertension (HTN)
What is permissible to eat > 8 hours before operation?
Food and fluids as desired
What is permissible to eat > 6 hours before operation?
Light meal (e.g. toast + clear liquids**); infant formula; non-human milk
What is permissible to eat > 4 hours before operation?
Breast milk
