Discuss the clinical features, possible causes, and management of perioperative upper airway obstruction including laryngospasm

Perioperative upper airway obstruction may be due to:

• Pre-op

  • OSA (e.g. due to hypertrophic tonsils)

  • epiglottitis

  • pharyngeal abscess

  • trauma

  • anaphylaxis

  • croup (tracheobronchitis)

  • laryngomalacia

  • tracheomalacia

• Intra-op

  • due to poor mask ventilation technique

  • laryngospasm

• Post-op

  • stridor

  • post-intubation croup

  • laryngeal oedema

  • laryngospasm

Clinical features of upper airway obstruction include

• Stridor – inspiratory stridor and prolonged inspiration

• Voice changes (muffled voice = supraglottic obstruction, hoarse voice or aphonia = glottis obstruction)

• Inability to swallow secretions

• Respiratory distress – evidenced by rocking chest and abdomen during breathing and use of accessory muscles (tracheal tug, flaring nostrils, intercostal chest retraction, tachypnea and tachycardia)

• Hypoxemia & desaturation
  

Laryngospasm

powerful and prolonged contraction of the glottis and supraglottic laryngeal adductor muscles ->

leading to closure of vocal cords and false cords and infolding of the arytenoids which seals off the larynx at 3 levels ->

results in hypoxemia and can result in post-obstruction pulmonary oedema or even cardiac arrest

Common causes of laryngospasm periop

• Secretions or blood in airway during induction or emergence

• Painful stimulus in the setting of inadequate depth of anaesthesia

Mx of laryngospasm

• 100% Oxygen

• Remove stimulus

• PEEP

• Jaw thrust

• Prop 1-2 mg/kg (alleviate spasm in 75% of cases)

• Sux (IV 1.5 mg/kg or 4 mg/kg via deltoid)

Risk factors for Laryngospasm

Patient factors

• Current or recent URTI within last 2 weeks (up to 10x increased risk)

• Young age

• Passive smoking

• Asthma

• Nocturnal dry cough

• Wheezing during exercise

• History of hayfever or eczema

• FHx of asthma, eczema or hayfever

Surgical factors

• Blood or secretions in upper airway

• Shared airway

• Sudden surgical stimulation

• Emergence (compared to induction)

Anaesthetic factors

• Inhalational rather than IV induction

• Thiopentone > sevo > propofol

• Light anaesthesia particularly during instrumentation of the airway

• Invasive airway management (lowest risk with face mask and LMA)

• Probably no difference between deep or awake extubation

Causes of critical airway obstruction in children

LUMINAL

• FB aspiration

• Stenosis

• Papillomatosis

• Haemangiomas

• Cysts

Wall

• Tracheobronchitis

• Laryngospasm

• Tracheomalacia

• Laryngeal cleft

• Tracheobronchomalacia

Extraluminal

• Tumous

• Epiglottitis

• Abscess

• Vocal cord palsy

Laryngomalacia

inspiratory stridor within first 2/52 of life exacerbated by feeding, agitation, supine, airway obstruction caused by collapse of supraglottic structures on inspiration -> Mx = aryepiglottoplasty

Tracheomalacia and tracheobronchomalacia

• airway collapse during expiration due to insufficient rigidity of the cartilaginous framework of the trachea-bronchial tree – usually presents within 12/12 of life, biphasic stridor, expiratory wheeze, recurrent LRTI, cough, cyanotic episodes and apneas

• Management of critical airway obstruction will depend upon the pathology but may often require surgical management with ENT using rigid bronchoscopy under GA with inhalational induction and spontaneous breathing (which may be difficult given risk of worsening dynamic airway obstruction with anaesthesia) – or alternatively paediatric tracheostomy (which is difficult and associated with significant morbidity and mortality)

FB ASPIRATION

• What

• Presentation

• Exam

• Ix

• First aid

• Gold standard

What

• Life-threatening emergency

• Kids 1-3

• Due to distractions when swallowing, immature swallowing, no molars

Present

• Cough

• Wheeze

• SOB

• Fever

• If near glottic inlet

  • Airway distress

  • Hoarse voice

  • Stridor (high mortality 45%)

Exam

• Reduced A/e

• Wheeze focal or gen

• Signs of superimposed pneumonia

Ix

• May be normal

• May show radiolucency of FB eg. tooth (note organic substances won’t show up)

First aid

• 5 x back blows then 5 x chest thrusts

• No abdo thrusts → liver injury

Gold standard

• RIGID Bronch using optical forceps

FB Anaesthetic Plan

Preop

• Hx, exam and Ix as above

• IV equipment

  • Remi - 2 mg in 33 ml → 60 mcg/ml

  • Take 2 ml of this and make up to 20 ml with N saline

  • 120 mcg in 20 ml

  • 6 mcg/ml

  • When infused at 1 ml/kg/hr ——> 0.1 mcg/kg/min

  • NEXT

  • Propofol 20 ml in SD

  • Glyc 10 mcg/kg

  • Dexa 0.2 - 0.5 mcg/kg

• Airway equipment

  • Lig 4 mg/kg in 5 ml LL syringe with MAD tip (for surgeons)

  • Co phenylcaine with standard nozzle

  • Appropriate range of cuffed and non cuffed ETT

  • If using circuit for maintaining oxygenation in case put HMA on machine side

  • 8 or 10 Fr O2 tubing connected to aux O2 outlet on machine

INTRAOP

• Gas down

• IV access L hand or foot

• Spray cophenylcaine both nostrils (Lig 5 mg/spray)

• Prop at 10 mg/kg/hr (older so 2-3yrs may need more)

• Remi and 0.1 mcg/kg/min

• Reduce volatile

• Second IV if possible and hook up minimum extension line

• Dexa and glyc

• Turn sevo off. You want SS TIVA prior to surgery start

• Measure nostril to angle of mandible - place ETT in L nostril and secure to left cheek THIS IS YOUR NP airway

• Surg is happy do laryngoscopy spray cords with half the lig, then MAD tip beyond cords and spray

• Check NP JUST visible at top of oropharynx

• If pt responding to laryngoscopy and RR > 15-20

  • Increase remi

• If RR OK then deepen with more prop boluses

• If RR slow and irreg

  • Reduce remi

• If RR irreg and responding

  • Add sevo into circuit

• Connect disposable T piece to NP ETT run 100% O2 to max of 0.5 L/kg/min

HAND over to surgeons

• Sit on L side of pt and hand on abdo

• Usually first look is with telescope and layrngoscope

  • oxygenate using NP ETT

• Suspension laryngoscope

  • O2 catheter to aux O2 outlet → placed inside the cone of the SL

• If ventilating bronch is used

  • T piece on side port of bronch once it is in trachea. Remember to occlude end of T piece

  • When down affected bronchus do not occlude t piece as this may push FB down further

IF NEED TO APPLY CPAP QUICKLY

• If instruments in the mouth

  • Connect t piece to NP ETT - occlude other nostril and mouth

• If NO instruments in the mouth

  • FM back on and use T piece for O2 flow

  • CPAP ok

  • BIPAP bad

ONCE FB OUT

• Intubate with cuffed ETT

• Recruits

• Wake up

• PEEP on as re expanded lung prone to collapse