咽反射是沒用的 – just as we thought

The painful dogma of “GCS ≤8 = intubate” is nicely challenged by the A&E Academic Unit at Prince of Wales Hospital in Hong Kong, who provide some further evidence that patients with a higher GCS may have absent airway protective reflexes, and patients with a lower GCS may have intact reflexes.


AIM: To describe the relationship of gag and cough reflexes to Glasgow coma score (GCS) in Chinese adults requiring critical care.

METHOD: Prospective observational study of adult patients requiring treatment in the trauma or resuscitation rooms of the Emergency Department, Prince of Wales Hospital, Hong Kong. A long cotton bud to stimulate the posterior pharyngeal wall (gag reflex) and a soft tracheal suction catheter were introduced through the mouth to stimulate the laryngopharynx and elicit the cough reflex. Reflexes were classified as normal, attenuated or absent.

RESULTS: A total of 208 patients were recruited. Reduced gag and cough reflexes were found to be significantly related to reduced GCS (p=0.014 and 0.002, respectively). Of 33 patients with a GCS≤8, 12 (36.4%) had normal gag reflexes and 8 (24.2%) had normal cough reflexes. 23/62 (37.1%) patients with a GCS of 9-14 had absent gag reflexes, and 27 (43.5%) had absent cough reflexes. In patients with a normal GCS, 22.1% (25/113) had absent gag reflexes and 25.7% (29) had absent cough reflexes.

CONCLUSIONS: Our study has shown that in a Chinese population with a wide range of critical illness (but little trauma or intoxication), reduced GCS is significantly related to gag and cough reflexes. However, a considerable proportion of patients with a GCS≤8 have intact airway reflexes and may be capable of maintaining their own airway, whilst many patients with a GCS>8 have impaired airway reflexes and may be at risk of aspiration. This has important implications for airway management decisions.

What is the relationship between the Glasgow coma scale and airway protective reflexes in the Chinese population?
Resuscitation. 2011 Jul 23. [Epub ahead of print]
Related post: Do all comatose patients need intubation?

4 thoughts on “咽反射是沒用的 – just as we thought”

  1. Cliff, yes interesting paper! I am not sure if having an absent gag reflex puts you at risk of aspiration. Consider all the sword swallowers out there!
    I agree about your suggestion that GCS < 8 = need to secure airway is dogma open to challenge. But given that there is a significant association in a large percentage of those with GCS < 8 and loss of those reflexes, it is prudent to pay attention to airway patency. That does not have to be an ETT I totally agree.
    as you know, I have been using ketamine sedation, often infusions on acutely agitated patients with a psychiatric illness during aeromedical retrieval , for now over 4 years. We have never had a case of aspiration. Many of these patients are routinely GCS 8-10. We monitor them with non invasive capnography and it is a great way to look for early airway obstruction…which has not occurred with ketamine sedation but we have had one case of it occurring with bolus midazolam sedation.
    And no none of the patients were Chinese.

  2. Hi Cliff
    Surprisingly there is little to no good evidence to be found on such an important topic. The study you mention in your post “Do all comatose patients need intubation?” puts an emphasis on intoxicated patients.
    Being a rather inexperienced doc in the ED I always get scared by those young kids coming in at 2am with ethanol intoxication and a low GCS. A couple of weeks ago I had a GCS 7 patient, vomiting within 4 minutes after my primary survey. She didnt aspirate. Should I have intubated her?
    I am not aware of any method to clearly find out if a patient can secure their airway or not. How do you handle ethanol intoxication patients with reduced GCS, which clinical rule do you use to decide who you intubate, or do you never intubate an acute ethanol intoxication?
    Thanks for all your great work!

    1. Thanks for your comments. I think if you’re concerned about the airway you need to intubate. One of the major take-homes from this paper is: “many patients with a GCS>8 have impaired airway reflexes and may be at risk of aspiration“.
      My point wasn’t that you shouldn’t intubate someone with a low GCS, but rather the GCS shouldn’t be the only thing you go on, as there is no clear cut-off GCS level when everyone suddenly loses their airway protective reflexes.
      Cliff

  3. GCS <8 is a good guide for juniors. It's a warning sign, along with other indicators for intubation. There is no quick way to teach that years of experience will fine-tune your ability to decide on at-risk and safe-to-observe airways (particularly in the monitored ED environment post OD (including alcohol), but I think that I will continue to use it in introductory talks to junior staff.
    I don't think it's dogma, just a trigger. This study adds little other than confirming what we already know – GCS is part of the overall airway patency/risk assessment which includes a lot of things. The 10% (or so) of normal people with no gag reflex will continue about their lives peacefully unintubated regardless.

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