The Vitals: When to Pull the Tube

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Sunil Ramaswamy
Sunil Ramaswamy
Hospitalist, Critical Care Fellow, guitarist, world-wanderer, and espresso enthusiast. Love all things critical care.

The Pre-brief

Knowing when to extubate someone in the ICU is an art and a skill that a good intensivist will develop over the course of their practice. How then, does an intensivist know when to pull the tube out? Is there some secret formula or magic sauce that critical care physicians have access to that will tell them with 100% certainty that their patient will breathe well without the tube?

No. No there is not.

That would be too easy. They don’t call it the PRACTICE of medicine for nothing.

So how can you know when a patient is safe to extubate?

The first thing you’ll want to do is to make sure that your patient’s underlying cause of respiratory failure has been corrected (for example, is your COPD exacerbation patient still wheezing diffusely, or do they sound clear? How about that CHF exacerbation patient? Are they net negative? Do they appear to be clinically dry now?). You also will want your patient to be hemodynamically stable and with good oxygen saturation on minimal vent settings (40% FiO2 and 5 of PEEP). 

The next thing you’ll want to look at is how your patient fared on their “spontaneous breathing trial” or “pressure support trial”. In very simple terms, this essentially involves having the ventilator stop giving breaths and having the patient breathe on their own. The ventilator will give a small amount of positive end expiratory pressure (PEEP) to help overcome the intrinsic resistance of the ET tube. These weaning trials typically are done daily to assess for readiness to come off the ventilator. 

The weaning trial is a very important indicator of readiness to extubate. A trial is considered to be successful when a patient has made it 30-120 minutes on pressure support (1). Clinicians will use several criteria to label a SBT as a failure. Some of the more common ones are listed below.

Failure Criteria
Respiratory Rate > 38
SpO2 < 92%
Tidal Volume < 325mL
Elevated blood pressure 40mmHg above baseline or heart rate > 140
Excessive anxiety or agitation
Rapid Shallow Breathing Index > 105 (See MATH section below)

There are some clinical tools and assessments that you can use to assess your patient’s readiness to come off the tube.

Your eyes:
Examine your patient! Typically I’ll ask patients to take a deep breath while on pressure support. After that, I’ll ask them to cough (2). The final thing I’ll ask is if they can lift their head off the bed, stick their tongue out, follow my finger with their eyes, and grab my hands (3). These questions and tests will give you a good assessment of your patient… you can see if they are able to generate good tidal volumes, have an intact cough reflex, and raise their head off the bed in case they start to cough/aspirate. If they can pull these three maneuvers off, you can be more confident that they’ll do ok.

Your ears:

Assess your patient for a cuff leak (4)! It should be pretty audible without having to get up close to your patient. A cuff leak means that there’s less likely of a chance of having airway swelling and developing post-extubation stridor, which has been shown to cause extubation failure. In a systematic review, absence of a cuff leak can predict postextubation laryngeal edema (odds ratio 18.16) and reintubation (OR 10.80) (5). Ask your RT to help with this, but you want to deflate the cuff and auscultate over the trachea. You should hear air movement or a whistle. 

Your communication skills:

Talk to your RT and RN! You need to know about your patient’s secretions… Are they copious? Are they thick? Increased secretions may hinder your patient’s ability to do well post extubation (3). Is there any concern for oropharyngeal bleeding in the airway? How did they do on their spontaneous breathing trial? How long did they make it? All these bits of information will help you assess your patient’s readiness for extubation.

Math? Science? FORMULAS?!

Some clinicians will use the RSBI (Rapid Shallow Breathing Index) as a way to help predict successful extubation (6). RSBI = f/Vt (f is respiratory rate and Vt is tidal volume in L). If RSBI is > 105, the extubation is likely to fail. 

Ultimately, a combination of the above measure should hopefully help you make the decision to extubate or not.

The Debrief

We hope these tips help you evaluate your patients for extubation, and we hope that you and your patients will have success. Ultimately, despite all the positive signs in the world, your patient can still fail extubation and require reintubation. There are some methods for post extubation management that seem to help prevent reintubation, but we’ll discuss these in the next post. We’ll also cover special circumstances regarding extubation, such as when to have a conversation about tracheostomy (if a patient has had multiple failures of extubation, or just is not able to wean of the ventilator at all), when to offer a trial of extubation if a patient is DNR/DNI, and how to terminally extubate patients who have elected to go down a comfort-measures route.

References

  1. MacIntyre NR, Cook DJ, Ely EW Jr, Epstein SK, Fink JB, Heffner JE, Hess D, Hubmayer RD, Scheinhorn DJ; American College of Chest Physicians; American Association for Respiratory Care; American College of Critical Care Medicine. 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. 2001 Dec;120(6 Suppl):375S-95S. doi: 10.1378/chest.120.6_suppl.375s. PMID: 11742959.
  2. Beuret P, Roux C, Auclair A, Nourdine K, Kaaki M, Carton MJ. Interest of an objective evaluation of cough during weaning from mechanical ventilation. Intensive Care Med. 2009 Jun;35(6):1090-3. doi: 10.1007/s00134-009-1404-9. Epub 2009 Jan 24. PMID: 19169666.
  3. Salam A, Tilluckdharry L, Amoateng-Adjepong Y, Manthous CA. Neurologic status, cough, secretions and extubation outcomes. Intensive Care Med. 2004 Jul;30(7):1334-9. doi: 10.1007/s00134-004-2231-7. Epub 2004 Mar 4. PMID: 14999444.
  4. Potgieter PD, Hammond JM. “Cuff” test for safe extubation following laryngeal edema. Crit Care Med. 1988 Aug;16(8):818. doi: 10.1097/00003246-198808000-00020. PMID: 3396380.
  5. Zhou T, Zhang HP, Chen WW, Xiong ZY, Fan T, Fu JJ, Wang L, Wang G. Cuff-leak test for predicting postextubation airway complications: a systematic review. J Evid Based Med. 2011 Nov;4(4):242-54. doi: 10.1111/j.1756-5391.2011.01160.x. PMID: 23672755.
  6. Yang KL, Tobin MJ. A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. N Engl J Med. 1991 May 23;324(21):1445-50. doi: 10.1056/NEJM199105233242101. PMID: 2023603.

Other References:

  1. Girard TD, Alhazzani W, Kress JP, Ouellette DR, Schmidt GA, Truwit JD, Burns SM, Epstein SK, Esteban A, Fan E, Ferrer M, Fraser GL, Gong MN, Hough CL, Mehta S, Nanchal R, Patel S, Pawlik AJ, Schweickert WD, Sessler CN, Strøm T, Wilson KC, Morris PE; ATS/CHEST Ad Hoc Committee on Liberation from Mechanical Ventilation in Adults. An Official American Thoracic Society/American College of Chest Physicians Clinical Practice Guideline: Liberation from Mechanical Ventilation in Critically Ill Adults. Rehabilitation Protocols, Ventilator Liberation Protocols, and Cuff Leak Tests. Am J Respir Crit Care Med. 2017 Jan 1;195(1):120-133. doi: 10.1164/rccm.201610-2075ST. PMID: 27762595.
  2. Tobin MJ. Extubation and the myth of “minimal ventilator settings”. Am J Respir Crit Care Med. 2012 Feb 15;185(4):349-50. doi: 10.1164/rccm.201201-0050ED. PMID: 22336673.

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