Airway management - throat surgery

 

Airway assessment:

Source

·     Patient

·     Surgeon

·     Notes

History

·     Red flags: infection, cancer, radiotherapy, trauma, congenital

·     HOPC: dyspnoea, postural symptoms, exercise tolerance, *time course*

·     Medical Hx: resp disease, CVS disease

·     Anaes Hx: prev BMV, LMA, laryngoscopy

·     Fasting status

Examination

Airway procedures:

·     Difficult BMV: ↑age, no teeth, beard, obese, stiff jaw

·     Difficult LMA: small mouth

·     Difficult ETT: ↑MP, ↓TMD, ↓MO, ↓neck ROM, dentition, obesity

·     Difficult FONA: obesity

Routine assessment:

·     General inspection: body habitus, WOB, colour, stridor

·     Vital signs

·     Resp

·     CVS

Investigations

·     Nasendoscopy (bedside)

·     CT neck

 

Airway considerations:

Surgeon

·     Prefer small airway (e.g. MLT)

·     Laser: oxygen-less field

·     Posterior glottic lesion: tube-less field

Anaesthetist

·     Protection

·     Oxygenation

·     Ventilation

 

Airway options:

1.LMA

·     e.g. iGel

·     Admits flexible bronchoscope

2.ETT

·     Normal

·     Reinforced

·     RAE

·     MLT

·     Laser

·     Nasal

3.HFNP

·     Spont vent (“STRIVE Hi”) – FiO2 variable

·     Apnoea (“THRIVE”) – FiO2 1.0

4.Jet

Frequency:

·     High (Monsoon) –

·     Low (Manujet) –

o   Select 1atm -> 250mL/sec

Location:

·     Supraglottic – default option

o   Surgeon’s rigid bronchoscope

·     Transglottic – if subglottic stenosis

o   Hansaker tube (laser RESISTANT) – N.B. can cut off cage if too wide

o   LaserJet (laser SAFE)

·     Infraglottic - rare

o   Ravussin cannula

5.Trachie

·     Surgeon’s decision

 

Airway timing:

Awake

·     Video laryngoscopic intubation

·     Flexible bronchoscopic intubation – nasal, oral

·     Tracheostomy

Anaesthetised

·     Anything

 

Use of HFNP:

Spont vent

Airway:

·     FiO2: 1.0 at induction, 0.3 if lasering

·     Flow rate: 50L/min awake, 70L/min upon LOC

·     Laryngoscopy + topicalization (Cophenylcaine forte) at 5mcg/mL

·     Suspension laryngoscopy at 6.5mcg/mL

·     LMA inserted upon completion

Drugs:

·     Propofol Cpt, start 2mcg/mL, ↑by 0.5-1mcg/mL “Cp – Ce = 1”)
Duration 15-20mins

·     Remifentanil 0.025mcg/kg/min

·     Metaraminol infusion titrated

Apnoea

Airway:

·     FiO2 1.0 throughout

·     Flow rate: 50L/min awake, 70L/min upon LOC

·     Paralysis -> apnoea

Drugs:

·     Propofol

·     Remifentanil

·     Metaraminol

·     Muscle relaxant

 

Use of jet ventilation:

Monsoon settings

·     Settings: RR 150/min, i-time 50%, 0.5-2.5 atm, FiO2 0.21-1

·     Peak pressure alarm: prevent airway injury

·     Pause pressure alarm: prevent breath stacking

Manujet settings

·     Settings: RR 6-8/min, 1-3.5 atm, FiO2 1.0 only

Complications

·     Barotrauma -> ensure low RR, rise and fall, peak pressure alarm

·     Volutrauma / breath stacking -> ensure low RR, pause pressure alarm

·     Hypoventilation -> monitor ABG, intubate at end of case

·     Aspiration -> fasting, paralysis, monitor field

 

 

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