Preoperative Assessment and Resuscitation Dr Mark Lambert Consultant Anaesthetist Royal National Throat, Nose and Ear Hospital Airway

Scary things in anaesthesia 1 - Bad airways 2 – Sick kids 3 – Sick kids with bad airways

Airway First in the hierarchy of survival Anaesthetists have the lead role for airway management in hospitals Most airways are easy…

Learning outcomes Recognise airway anatomy Prepare a framework for managing the airway in theatres Discriminate easy and difficult airways Outline plans for failed airway management

Anatomy

The Glottis

Why do anaesthetists need to manage the airway? Anaesthetic drugs –Depress/abolish airway reflexes –Cause relaxation of upper airway muscle tone –Cause respiratory depression / apnoea In an emergency –Acute airway obstruction –Failure to oxygenate/ventilate

Pharyngeal structures

A typical anaesthetic... Fighty Alan, 18 from Wigan, needs his broken hand fixed You give your best anaesthetic 5 seconds later : he’s asleep 15 seconds later : apnoea What are you going to do next?

Intubate Ventilate with facemask Put in an LMA Fibreoptic laryngoscopy Cricothyroidotomy Tracheostomy Call for help Go for coffee Start the crosswordAsk your ODA/ODP/anaesthetic nurse to bail you out

Always think about…. Oxygenation

Preoxygenation Minimal oxygen stores in the body Functional residual capacity – 2500ml Oxygen demand – 250ml/min Allows time before desaturation –But rising CO 2

Beyond preoxygenation… THRIVE : –High flow oxygen –Apneoic mass transfer of oxygen –Prolonged apnoea time without desaturation

Facemask ventilation The most important anaesthetic skill ??? Harder than it looks One person / two person Adjuncts Know where your facemask is Back up self inflating bag location

Facemask ventilation adjuncts Oropharyngeal airway Size : Incisor to angle of jaw (or ask your ODA)

Facemask ventilation adjuncts Nasopharyngeal airway Size : –Women 6 –Men 7 Use plenty of lube (and go carefully if you suspect basal skull fracture)

Back to Alan He’s easy to facemask ventilate Will we hold a mask on his face for the entire case? Other airway options include –Laryngeal mask airway –Endotracheal tube

Laryngeal mask airway (LMA) Blind insertion Cuff to improve seal Hands free Sits above the glottis Variety of second generation devices available but all work on a similar principle

LMA position Like a facemask over the larynx Doesn’t protect against aspiration of gastric contents May be helpful in difficult facemask ventilation

Endotracheal tube “A secure airway is a cuffed tube in the trachea” –Allows ventilation –Protects against aspiration Normally placed under direct vision (laryngoscopy)

Direct Laryngoscopy Uses a metal blade with a light source to create a direct line of sight to the glottis Can be stressful (for you and the patient) Laryngoscopes come in a variety of shapes and sizes

Video-laryngoscopy Uses a camera and screen to allow visualisation of the glottis without direct line of sight

Fibre-optic Laryngoscopy Fibreoptic scope used to provide an indirect view of the glottis/trachea Scope then used as a guide to pass ETT into trachea

The view from a laryngoscope

The Glottis

Recognising when airway management is going to be difficult History –Previous anaesthetic problems –Congenital disorders associated with difficult airway (Anatomy) –Co-morbid conditions (Pathology) Examination –General appearance –Specific tests Special investigations –Rarely used (nasal endoscopy/CT)

Specific airway tests Mallampati Mouth opening Neck movement –Thyromental distance Jaw protrusion

Oral / tracheal axis

Sometimes it’s obvious

But…. Tests are notoriously unreliable and focus on difficult intubation Difficult facemask ventilation is more worrying than difficult intubation –Beards / big neck / high BMI / Elderly Trust your instincts! –Ask for senior advice or help early

Planning for failure Always have a plan B for managing the airway (and communicate this to the rest of the team) –If not possible to place an endotracheal tube what next? Plan B – LMA (and call for help) Plan C – Facemask ventilation + Guedel (+/- wake up) Plan D – Emergency cricothyroid puncture Guidelines exist to help plan for the unexpected but it’s much easier if you’ve identified trouble beforehand

Extubation Taking the airway device out can be as risky as putting the device in Increasing recognition of this –Improved training –Guidelines (Difficult airway society) If you had difficulties at intubation then extubation also likely to be troublesome…

Key Points Always think ‘oxygenation’ Consider whether mask ventilation or intubation (or both) will be a problem –Trust your instincts –Ask for help early Have a back-up plan ready and make sure everyone else knows what it is

Learning outcomes Recognise airway anatomy Prepare a framework for managing the airway in theatres Discriminate easy and difficult airways Outline plans for failed airway management

Please ask your questions now…. Thank you