1. THRIVE
Transnasal Humidified Rapid- Insufflation Ventilatory Exchange
A physiological method of increasing apnoea time in patients with
difficult airways
Anaesthesia, 2014. Patel & Nouraei
Joanna Gordon, ST7
2. Mechanisms of action
• Warmth & humidification allows higher flows
• Flush dead space in nasopharynx CO2
• Mechanical splinting supraglottic resistance
• Warmed, humidified – less constriction, more compliance
• Distending pressure – up to 6cm H2O pharyngeal pressure
• Apnoeic oxygenation
3. • Reducing rates of intubation in resp failure
• Reducing rates of re-intubation on ITU and PACU
• Home device as alternative to CPAP/BiPAP for OSA &
CLD
• Areas of increasing interest:
– Pre-oxygenation in high risk pts (adults)
– Oxygenation during difficult airway management
Uses
4.
5. Sample
• Case series
• 25 adult patients
• Difficult airways - anatomical or rapid
SpO2 likely
• Stenosis, vocal fold pathology, OSA,
hypopharyngeal obstruction
6. Methods
• 40 degrees head up tilt
• Optiflow at 70L/min, 10 minutes
• Prop 2-3mg/kg, Fent 1-2μg/kg, Roc 0.5mg/kg
• TIVA maintenance, propofol 0.2-0.3mg/kg/min
• Jaw thrust on LOC
• BMV confirmed then discontinued
1. MAC laryngoscopy
2. VL
3. VL difficult blade
• Apnoea time = NMB to PPV or jet vent or SV
7. Results
• 15M, 10F
• Mean age 49 (25-81)
• Median BMI 30 (18-52)
• 10 benign larynx, 2 OSA, 4 head & neck masses
• 9 had stridor
• Median MP = 3
• Median C&L = 3
• Mean apnoea time = 17mins (5 – 65)
12. Limitations
• Observational & cross sectional
– routine clinical care
• Optiflow only until definitive airway secured
• Airway expert management ? generalisable
• Techniques not far from our practice
• Conclusion – can extend safe apnoeic window
Flush dead space – alveolar ventilation is larger fraction of minute ventilation
Inspiration normally causes retraction of nasopharyngeal boundaries causing increased resistance – high flow causes splinting which reduces resistance along that airway pathway
Studies have shown just 5mins cold dry gas causes bronchoconstriction and less compliance of lung ? Muscarinic receptors
Apnoeic oxygenation – as oxygen is removed and CO2 is excreted in alveoli, that pressure gradient as long as a patent airway exists between the lungs and the oxygen delivery device, drives oxygen into the lungs
BMI 52 – spasmodic dysphonia , SpO2 of 90% after 5mins
BMI 34 – severe tracheobronchomalacia, SpO2 of 92% after 7mins, acute airway compromise
2 patients with longest apnoea times had THRIVE throughout their pharyngolaryngeal surgery – 32 & 65 mins
Correlation coefficient R is 0.13 – not much correlation
P value is 0.5
4 patients had Arterial CO2 measured – 2x long apnoea times, 2 where art line inserted for other indications
EtCo2 via definitive airway device
Correlation coefficient is R = 0.82 – good correlation
P<0.0001
b) Classical apnoeic oxygenation rate of CO2 rise is 0.35 to 0.45 kPa/minute – similar to if airway obstructed
THRIVE is just > 0.1kPa/ minute
Airway management can be quite high stress time anaesthetists feel quite pressured, stop-start process because of the constant time limitation to each attempt at securing the airway and that in itself can lead to more trauma and a cycle of the airway becoming increasingly difficult to manage.
High flow nasal oxygen does show real promise as a technique to reduce that pressure & help move airway management towards a much smoother, continuous process which is unhurried and less stressful.
