Guedel airway: size from central incisors to angle of jaw npa



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RSI

A

Gag reflex absent in 15%; hypoxia develops more quickly in children, pregnant, obese; if ETT, pre-oxygenate on 100% O2 for 3 mins, or 8 quick breaths



Guedel airway: size from central incisors to angle of jaw

NPA: female size 6, male size 7, tall male size 8

Face mask: 60ml dead space

BVM: bag 1500ml (500ml in paeds, 240ml in prem); reservoir bag 2600ml (600ml in paeds and prem)

Self inflating bag: dead space too large for children <25kg; no reliant on fresh gas flow for bag reinflation; aim to deliver 500ml (1/4 reservoir bag volume); keep airway p <20 to prevent stomach inflation

Intubation



MacIntosh: size 3 normal, size 4 large

Miller: straight Robertshaw: gently curved McCoy: hinged blade tip (difficult intubation)

Video: improved glottic visualisation in 20% in inexperienced hands; none better than standard laryngoscopy in ED use; expensive, fogging, secretions, slow setup; can supervise intubator, Airtraq (cheap), Video-Mac, C-Mac, Glidescope

ETT: use uncuffed if <8yrs; insert 20-23cm in adults; inflate pilot balloon until air leak stops (keep p <25 to prevent mucosal ischaemia)

Indications for ETT: airway protection, GCS <8, ventilatory assistance, hyperventilation required (eg, coning, TCA OD), high insp O2 delivery, selective lung ventilation (eg. Massive haemoptysis, bronchopleural fistula), HC ingestion, hyperthermia (for muscle relaxation), drug delivery

Cricoid: risk of oesophageal rupture if actively vomiting; may make view more difficult; may occlude airway; may decr lower oesophageal sphincter tone and incr reflux; makes LMA more difficult; can do BURP

Checking tube placement: ETCO2 (may be low in cardiac arrest, small amounts may be detected in oesophagus); oesophageal detector device (most useful in arrest when ETCO2 low; may get false +ive if TOF); misting; direct inspection of tube passing though cords; auscultation of lungs (less accurate than ETCO2) and stomach; normal airway p’s; no abdo distension; CXR (@ level of aortic knuckle); palpation of ETT cuff at neck

ETT complications: dental / oropharyngeal trauma, aspiration 1:7000; death 1:100,000; oesophageal perf; gastric distension; decr BP (drugs, autoPEEP), incr BP (inadequate sedation), pneumoT, atelectasis, arrhythmia, incr ICP, hypoxaemia, SE of drugs, bradycardia common in children so consider atropine

Laryngospasm: from incomplete paralysis, touching cords, irritation, aspiration, FB, hypoCa, post-extubation, failed intubation attempt  give rpt small dose propofol / thio  sustained positive airway p to break spasm  if needed, half dose sux and re-intubate

Difficult Intubation



Epidemiology: in 1-3% ED tubes; impossible in 0.5%; predictable in 90%

Congenital: Pierre Robin, achondroplasia, Marfans etc…

Anatomical: fat, neck + neck mvmt / instability, teeth, palate, long alveolar-mental, short thyro-mental, decr jaw mvmt, decr distance between occiput and SP C1, incr posterior depth of mandible, prev OT / masses, trauma



3:3:2: mouth opening / thyro-mental / thyro-hyoid

Mallampati: 1: pillars, uvula, soft palate

2: uvula, soft palate

3: soft palate

4: none of above



Cormack-Lehane: 1: vocal cords

2: post commissure

3: arytenoids

4: epiglottis




Failed airway: 3 unsuccessful attempts or 1 min by experienced operator / failure to maintain sats

diffair2

Mng: don’t persist with laryngoscopy >1min; use best person available; if can BVM:

  1. HELP! Get difficult airway trolley

  2. STOP and BVM with 100% O2

  3. Make change: position of head, adequate relaxation, IV line still working, Miller blade if immobile anterior tissues, McCoy blade if poor neck mobility, reconsider indication for tube, BURP

  4. Stylet / bougie (in oesophagus if can insert 45cm without resistance)

  5. LMA: possibly intubating LMA (6mm tube) or railroad bougie (15-20% failure rate); optimal cuff p 60

  6. Pros: better than BVM for protecting airway, convenient, easier than ETT, good pre-hospital, good if difficult BVM, can be used in paeds

  7. Cons: less protection against aspiration, seal leak if airway p >15, small proportion patients can’t be ventilated, may get laryngospasm from bronchial secretions

  8. CI: inability to open mouth, pharyngeal pathology, airway obstruction @/below larynx, decr pul compliance, incr airway resistance

  9. Fibreoptic if breathing spontaneously

  10. Or BVM and allow to wake up

  11. Surgical (<10yrs, tracheostomy; >10yrs, cricothyroidotomy)

If unable to ventilate at any time, immediately proceed to LMA, then surgical if that fails

Fibreoptic airways



Good if: difficult anatomy, poor neck movement

Cons: expensive, needs training, operator dependent, vision easily obscured

Surgical airway




Indication: inability to establish ETT in patient who cannot be ventilated / oxygenated adequately by other methods

CI: neck mass, no neck, bleeding diathesis

Open cricothyroidotomy CI in <10yrs (as is narrowest part of airway and only circumferential support of upper airway) – use needle cricothryoidotomy or tracheostomy



Complications: haematoma / bleeding (thyroid IMA artery), pre-tracheal placement, pneumoT, subC emphysema, trachael tear, oesophageal damage, recurrent laryngeal nerve damage


Anatomy: cricoid is 1st rigid structure above sternal notch; CT membrane is 1/3 distance from manubrium to chin

Open cricothyroidotomy: vertical incision skin  horizontal incision CT membrane  open with arterial forceps  hold with tracheal hook; use 6mm tube (never >7mm)

Needle cricothyroidotomy: 14G IVL  insert at 90deg  when aspirate air angle 45deg and go caudally  connect to 3mm ETT / 2ml syringe then 7.5-8mm ETT; allows short term oxygenation (ie. 45mins) but not ventilation (CO2 levels will rise) with 15L O2 via Y connector; occlude 1: release 4; airway is not protected

Ventilation


See p361 Oh’s

Pressure limited: decelerating waveform optimises distribution of ventilation; changes in compliance change volume delivered

Volume limited

Dual control: uses both of above

Assist/control: patients trigger (usually 1-2cmH20) to receive assisted breath; least WOB; good in resp distress; may cause resp alkalosis, more reduction in VR, higher mean airway p, autoPEEP and hyperexpansion

IPPV: no triggering; most reliable TV and MV

SIMV: specified number of volume present breaths/min, can breathe between mandatory breaths; +/- PS (without this, spontaneous breaths cause incr WOB, 5-10cmH20 needed to offset resistance of tubing)

IFR: high  less uniform distribution, decr insp time, decr mean airway p and CV complications, not well tolerated; low  even distribution, decr VR

PEEP: improves oxygenation (may take 1hr to see difference), distributes air favourably, recruits collapsed alveoli, prevents collapse of alveoli, helps restore FRC, improves alveolar fluid distribution  decr distance between capillary and alveolar space

Indications: paO2 <60 despite FiO2 >50%; diffuse acute pul disease; non-compliant lungs

Not helpful: only 1 lung/zone affected; empysema; CV compromise

Common settings: TV 600ml (6-8ml/kg), RR 12-14, I:E 1:2, PAP 40mmHg; PEEP 5; FiO2 100%  40%, IFR 60L/min

Goals: PaO2 60-90, PaCO2 40, pH 7.35-7.45, FiO2 40-60%, IPP <35

Compliations: CO usually fine in normovolaemic patients with good myocardial reserve; hypotension (incr intrathroacic p  decr VR): if occurs, maintain euvolaemia and decr PEEP, may need inotropes / vasopressors; incr CVP, PCWP; incr ICP, decr renal blood flow, hepatic congestion; decr CO  decr systemic O2 delivery; incr O2 admixture of blood; incr non-capillary shunt flow; causes high VQ units  incr physiological dead space  may cause CO2 retention; may incr WOB if not PS; lung hyperventilation (gas trapping, auto-PEEP); barotrauma (incidence related to peak static airway p, minimised if PAP <50); bronchospasm; mucosal drying and cilial paralysis
Low system p: check circuit connections, check seal with patients

High system p: check neck position, check for obstruction

Low airway p: cuff leak, pilot balloon rupture, check connections

High airway p: check patency of ETT, suction ETT, check for kinking or jaw clamping, check for cuff prolapse, spontaneous respiration, epigastric distension, bilateral BS’s, wheeze (?asthma, anaphylaxis, LVF, aspiration, pneumoT)

RSI in special cases



HI (also applies in post-cardiac arrest):

Indications: GCS <9, agitation, elective hypocapnia, hypoxaemia

Goals: avoid low O2, avoid low / high BP, avoid cough / gag (incr ICP)

Difficulties: C spine immobilisation, ETOH, full stomach

Technique: inline stabilisation while remove collar

Lignocaine 1mg/kg (not useful) or fentanyl 1mcg/kg or 0.3mg/kg vec to blunt incr ICP; give 1-2mins before

Use thio (2.5-5mg/kg; or fentanyl)  sux (1 – 1.5mg/kg)

Have atropine ready incase brady

Elevate head 20-30deg (aids venous drainage); avoid compression of neck

Afterward, maintain good sedation with 1-5mg/kg/hr thio + vec 4mg / panc 8mg

Avoid hypotension (if decr BP, give IVF / metaraminol), hypertension (if incr BP, give 20-100mg thio or

morphine to 30mg) and raises in ICP (eg. Unnecessary suctionning)

Maintain euvolaemia and euNa (not fluid restriction; ?2/3 maintenance); steroids if tumour oedema; ulcer

prophylaxis

Aim PCO2 35-40, paO2 100, MAP >80 (use vasopressors if needed), CVP 0-2, BSL <8 (trt with insulin if >10)

Can consider fibrescopic if C spine inj and airway hard


Post-cardiac arrest: try to avoid cerebral reperfusion inj (due to free radicals, decr ATP/ADP/AMP/NADP, anaerobic metabolism  lipid peroxidation and membrane damage, enzyme dysfunction etc…; initial incr cerebral blood flow with ROSC  cerebral vasospasm after 1hr  decr cerebral blood flow 60-90% and incomplete ischaemia  mismatch of cerebral O2 demand and delivery for 12-24hrs; generalised endothelial damage  DIC / ARDS
Hypovolaemia:

Technique: use ketamine 1.5-2mg/kg or fentanyl 3mcg/kg or etomidate 0.3mg/kg or thio 1.5mg/kg or propofol 1mg/kg; avoid PEEP intially unless critically hypoxic; use midaz / fentanyl for ongoing sedation
Asthma:

Indications: only intubate if life threatening and max therapy failed (eg. Progressive hyperCO2 and acidosis, decr O2,

fatigue, confusion, pre-arrest)



Aims: limit PAP, avoid gas trapping

permissive hypercarbia to help this (CI if incr ICP / severely impaired myocardial Fx; risk of cerebral oedema,

decr myocardial contractility, vasoD, pul vasoC; can give NaHCO3 if pH <7.2 and don’t want to change

ventilator settings)



Technique: use ketamine 2mg/kg IV  20-60mcg/kg/min INF (or fentanyl / midaz) + sux; isoflurane is bronchoD

start sitting up and lie down only when spontaneous resps stopped

hand ventilate  place on volume cycled ventilator once airway p and TV acceptable (TV 8ml/kg, RR 4-10, IFR

100L/min, MV 8-10ml/min, PAP <30, PEEP <5, FiO2 1.0)

titrate RR to lowest tolerable pH

titrate insp time to airway p <55

low I:E – 1:5 or more (not possible on Oxylog 3000)

titrate FiO2 to O2 goals; permissive hypercarbia

Chest expiratory pressure; heliox (decr resp distress, decr WOB, incr GE); continuous nebs (incr dose 2-4x as ETT is

barrier to delivery)


Obesity: Physiology: resting hypoxaemia and hypercarbia, decr TLC, decr VC, decr chest wall compliance, incr abdo

cavity contents, incr airway resistance, decr ERV, decr basilar ventilation, VQ mismatch, decr FRC, less

O2 reserve with preoxygenation, 50% shorter time to desat, incr O2 consumption, incr CO2 production,

inefficient resp muscles, incr hiatus hernia and GORD, decr gastric pH, may need incr drug doses (if

lipophilic drug), incr neck circumference (best predictor of difficult); SaO2 inaccurate

Technique: position well with head and shoulders above chest (external auditory canal level with sternal notch);

don’t use sniffing position; pre-oxygenate sitting up (do 10mins) perhaps with CPAP 10; use laryngoscope with



wider angle; use PEEP

Total body weight: propofol, sux, fentanyl, etomidate, atracurium

Ideal body weight: ketamine, roc, vec, benzos, tidal vol
Pregnancy: elevate R hip 10-12cm; elevate head and shoulders on pillows; use standard doses; preoxygenate well

ARDS: TV 4-6ml/kg, incr RR to maintain MV (RR 16-20), aim PaO2 55-80 and SaO2 88-95%; this assoc with decr mortality and decr duration of mechanical ventilation

Epiglottitis: do in OT or at least with anaesthetists, have surgical airway kit ready; sevoflurane / halothane induction (rapid, some bronchoD, non-irritating)  slowly anaesthetise over 5-10mins (small, minimally reactive pupils = ready to go)  aim where bubbles coming from, use 0.5mm smaller tube

Croup: <5% admitted need ETT; most common <1yrs; always use adrenaline NEB first; use uncuffed tube 1mm smaller

Maxfax trauma: hypoxia, bleeding, obstruct when sedated; get skilled help, ensure good suction, have OT and surgical airway ready, have 3x good laryngoscopes; fibreoptic may be safest

Burns: anticipate need for ETT early as oedema; nasotracheal may be suggested
Notes from: Dunn


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