June 21, 2012

Ketamine is a Heckuva Drug

There seems to be some persistent confusion/conflation of DSI, NIV for preoxygenation, and awake intubation. I don't intend to get into all of the individual details here, and some others have some other good posts/discussion on some of the differences (see Minh's concise post on DSI vs NIV for preox; and Minh & EMCrit on DSI podcast cover all of these throughout), but I think a single place to discuss the 3 very different ketamine-enhanced airway maneuvers that Scott Weingart talks about might help.

First:
Preoxygenation is necessary for safe intubation, particularly with paralysis (i.e. RSI). Oxygen can be delivered by any method; the most common for preox is a non-rebreather mask. Some patients shunt and need PEEP so Scott Weingart advocates NIV (aka CPAP) for preox in some patients.

This gives us #1:
NIV for preoxygenation
Indication: patient pending intubation, with shunt
Drugs: RSI meds AFTER preoxygenation
Goal: delivery of oxygen with PEEP
Next:
What is DSI? Whereas RSI is the simultaneous dosing of sedative + paralytic AFTER adequate preoxygenation, some patients cannot comply with preoxygenation for whatever reason, usually delirium. The idea of DSI is to sedate the patient while keeping them breathing and protecting their airway so that you can preoxygenate them, then paralyze them for intubation. Confusion because this was also propagated by Weingart. You can use any oxygen delivery method that works (NRB, NIV, nasal prongs, BMV, tent, blowby) to get the oxygen in.
DSI - delayed sequence intubation
Indication: delirious, hypoxic patient

Drugs: sedative*, preoxygenation, then paralytic

Goal: procedural sedation for preoxygenation

What's the difference? NIV is a type of oxygen delivery; it's about pushing the little O2 molecules around. DSI is about the meds you give to get the patient tolerating any oxygen delivery method.

Weingart has done some podcasts on awake intubation, and both people who might follow me have heard me talk about DSI & awake intubation, but they are completely different.

and lastly:
Awake intubation is for patients you think may be difficult to intubate. It is not about oxygen delivery. It is about the short-necked, prognathic, microcephalic, obese, bearded, C5-C6-fixated, irradiated-thyroid, laryngeal tumored, trauma patient who is satting perfectly but you may not be able to find the cords in time if you paralyze him, even with a heat-seeking bougie and magical Glidescope. Ketamine is a good choice because it makes the patient happy while still breathing and protecting their airway (but the patient still tolerates the laryngoscope because you topicalized them with lidocaine).
Awake intubation
Indication: predicted difficult airway
Drugs: sedative and topical lidocaine
Goal: keep patient breathing while you intubate

Review:

  • RSI = preox then sedative + paralytic (no bagging)
  • NIV for preox is about delivering O2 and PEEP in any patient you may be intubating
  • DSI is procedural sedation for the procedure of preoxygenation for the delirious, hypoxic patient
  • Awake intubation is for predicted difficult airways


*you want to preserve respiratory drive and airway reflexes, so options may be limited to ketamine, dexmedetomidine, and maybe droperidol. I know that 2 of those are really "dissociatives" and not sedatives but I like the parallelism with RSI

1 comment:

  1. no reason to stop CPAP during apneic period; if thye needed it for preox they'll need it to prevent deox

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