A 45-year-old intellectually handicapped man is admitted to your Intensive Care Unit for airway management. He is currently nasally intubated following an evacuation of a large dental abscess that had caused airway compromise. Describe how you would assess his readiness for extubation.
Readiness for extubation requires an assessment of factors that necessitated intubation in the first place and standard criteria.
Standard criteria would include:
• Adequacy of oxygenation (usually on FiO2 ~ 0.4 and PEEP 5)
• Ventilation (minimal respiratory support eg low level of PS £ 10). Some other ventilatory indices may be used (eg rapid shallow breathing index, negative inspiratory force, P0.1, CROP, Vt 4-6 ml/kg, Vmin 10-15 L/min)
• Protection of airway (adequate cough ± gag)
• Ability to clear secretions
• Appropriate neurological state (obeys command, orientated)
• Stable haemodynamics not requiring support
• Sepsis controlled
• Metabolic / biochemical parameters normal
Specifics for this man would also include:
• Assessment of airway swelling with direct/indirect visualization
• Discussion with treating surgical team regarding timing and management of ongoing swelling
• Adjust criteria for neurological state given his intellectual handicap
This is a straightforward question about criteria for extubation. A curveball is thrown in the form of an intellectual handicap, but it is not anything too extraordinary.
The normal criteria for extubation readiness are outlined below.
|Airway protection assessment||
|Gas exchange criteria||
|Lung mechanics criteria||
... in the model answer, one may also want to mention that 30% of patients who DONT satisfy these criteria can still be successfully extubated.
The Specific criteria for this patient
Things to consider before a difficult extubation:
Andrew D Bersen wrote chapter 27 of the Oh's Manual, which regards mechanical ventilation.
Table 27.3 on page 363 of the 6th edition of Ohs Manual is a nice list of the various indices meantioned above (eg. the rapid shallow breathing index).
On page 362, Bersen references this Chest article from 2001, where the evidence for extubation criteria is summarised.
MacIntyre NR (chairman), Evidence-based guidelines for weaning and discontinuing ventilatory support: a collective task force facilitated by the American College of Chest Physicians; the American Association for Respiratory Care; and the American College of Critical Care Medicine. CHEST December 2001 vol. 120 no. 6 suppl 375S-396S.
Recommendations regarding which conditions favour extubation has been put forward in a 2007 practice guidelines statement by the AARC:
AARC GUIDELINE: REMOVAL OF THE ENDOTRACHEAL TUBE; RESPIRATORY CARE •JANUARY 2007 VOL 52 NO 1
Karmarkar, Swati, and Seema Varshney. "Tracheal extubation." Continuing Education in Anaesthesia, Critical Care & Pain 8.6 (2008): 214-220.
Mitchell, V., et al. "Difficult Airway Society Guidelines for the management of tracheal extubation." Anaesthesia 67.3 (2012): 318-340.
Kriner, Eric J., Shirin Shafazand, and Gene L. Colice. "The endotracheal tube cuff-leak test as a predictor for postextubation stridor." Respiratory care 50.12 (2005): 1632-1638.
Loudermilk, Eric P., et al. "A prospective study of the safety of tracheal extubation using a pediatric airway exchange catheter for patients with a known difficult airway." CHEST Journal 111.6 (1997): 1660-1665.