The dogma of intubation for GCS≤8: a critical review

Ahhh, the good old GCS≤8! If you've ever worked in emergency medicine, you know well that echoing mantra: "GCS 8 or less, intubate". A dogma so deeply rooted that we'd almost expect to find it carved on hospital walls, right after the Hippocratic Oath.

But like all respectable dogmas, this one also deserves some uncomfortable questions. Is it really always necessary to intubate a patient just because their GCS has dropped to 8 or less? Or perhaps, as with many medical issues, the most honest answer is "it depends"?

Don't misunderstand me: the risk that patients with low GCS lose their protective airway reflexes is real. But modern medicine teaches us that clinical decisions can rarely be based on a single number, however venerable. So let's take a closer look at the scientific evidence, you might discover that in some clinical contexts, the situation is less straightforward than it seems.

Risks of intubation

Endotracheal intubation, while often life-saving, is not without significant risks:

• Increased mortality and complications: In patients with isolated traumatic brain injury and GCS 7-8, immediate intubation has been associated with greater mortality (odds ratio 1.79) and more complications (odds ratio 2.46) [2]

• Cardiovascular instability: About 43% of patients undergoing intubation experience significant hemodynamic instability [5]

• Severe hypoxemia and cardiac arrest: These occur in 9% and 3% of intubation procedures, respectively [5]

• Aspiration: Although intubation is often performed to prevent it, the procedure itself can sometimes cause aspiration if not performed under optimal conditions These risks underscore the importance of careful evaluation of the risk-benefit ratio in each patient.

Alternatives to immediate intubation

When deciding not to proceed immediately with intubation in patients with GCS≤8, several alternative airway management strategies exist:

• Non-invasive ventilation and preoxygenation: The use of low or high-flow nasal cannulas and maintaining the head in an elevated position can optimize oxygenation while monitoring the patient [6]

• Supraglottic devices: These can serve as a bridge to definitive airway management or as a primary tool in certain clinical situations [6]

• Face mask ventilation: Effective face mask ventilation, confirmed by capnography and observation of chest expansion, can be a crucial rescue maneuver between failed intubation attempts [7] These alternatives represent bridge strategies that allow continuous monitoring while assessing the need for definitive intubation, particularly useful in contexts such as acute intoxications where the clinical picture can evolve rapidly.

Contrasting scientific evidence

Acute intoxications In cases of non-traumatic acute intoxication, GCS score alone might not reliably predict the need for intubation. Studies have shown that patients with GCS≤8 due to intoxication do not necessarily require intubation and can be safely observed in the emergency department. A prospective study conducted by Duncan and Thakore [4] compared intoxicated patients with GCS≤8 managed with and without intubation. The results showed that:

• Analysis of physiological parameters indicated only a minimal prevalence of respiratory failure in the group requiring intubation

• Clinical evaluation by experienced medical personnel was fundamental in determining the need for intubation

• The authors conclude that "GCS alone is not a good predictor of the need for intubation" in intoxicated patients A recent meta-analysis published in 2024 by Lambert et al. [1] on 15,959 patients with non-traumatic acute intoxication revealed that:

• Only 30% of patients with GCS≤8 were actually intubated

• Despite aspiration rates being higher in the GCS≤8 group (19%), mortality rates remained low (1%) in both groups

• Significant heterogeneity in intubation rates (I² = 92%) indicates great variability in clinical practices

Trauma in prehospital settings Supporting the traditional approach, a retrospective study by Hussmann et al. [3] conducted on 21,242 patients with severe trauma and GCS≤8 showed that:

• 89.3% of patients received prehospital intubation

• Mortality tended to be lower in intubated patients compared to non-intubated ones

• Patients sedated before intubation presented significantly lower mortality and better early neurological outcomes compared to those intubated without sedation This study confirms the value of prehospital intubation in traumatized patients with GCS≤8, but also highlights the crucial importance of intubation technique, particularly the appropriate use of sedation.

Isolated traumatic brain injury In contrast with the previous study, research published in 2021 by Mowery et al. [2] on 2,727 patients with isolated traumatic brain injury and GCS of 7 or 8 produced surprising results:

• 23.4% of patients were not intubated at all

• After correcting for numerous confounding factors, immediate intubation was independently associated with:

  • Higher mortality (odds ratio 1.79; 95% CI 1.31-2.44; p < 0.001)

  • More overall complications (odds ratio 2.46; 95% CI 1.62-3.73; p < 0.001)

The authors suggested that a more selective intubation policy, targeted at specific patients (age ≤45 years with high injury severity), would have improved clinical outcomes by reducing unnecessary intubations.

Decision factors beyond GCS

In light of these contrasting evidences and documented risks of intubation, the need to consider additional factors beyond the simple numerical value of GCS clearly emerges:

1. Etiology of altered state of consciousness: Reversible metabolic causes might require a different approach compared to structural causes

2. Clinical dynamics: A rapidly improving GCS might justify a conservative approach

3. Patient characteristics: Age, comorbidities, and airway anatomy can influence the risk-benefit ratio

4. Care setting: Continuous monitoring, team experience, and transport times are determining factors

Conclusions

So, at the end of this scientific journey, what remains of our beloved dogma "GCS 8 or less, intubate"? As with many memorable slogans, the truth hides in the nuances.

GCS≤8 remains an excellent warning bell, a trusted friend who whispers to us "pay attention here!". But the data suggest that it's time to move beyond the automatism of intubation based exclusively on GCS.

In prehospital trauma, the endotracheal tube often remains the main road. But in intoxications and isolated traumatic brain injury, sometimes the deviation can get us to our destination more quickly, with less traffic and fewer accidents along the way.

Whether you're an airway veteran or a young doctor new to the laryngoscope, remember: numbers are useful, but it's patients we treat, not their scores. And the best medicine happens when we combine the best scientific evidence with that precious, irreplaceable clinical judgment that no algorithm can ever replicate.

References

[1] Lambert K, et al. Outcomes and Practices of Endotracheal Intubation Using the Glasgow Coma Scale in Acute Non-Traumatic Poisoning: A Systematic Review and Meta-Analysis of Proportions. J Clin Med. 2024. PMID: 39150325.

[2] Mowery NT, et al. Isolated traumatic brain injury: Routine intubation for Glasgow Coma Scale 7 or 8 may be harmful! J Trauma Acute Care Surg. 2021;90(5):907-914. PMID: 33605710.

[3] Hussmann B, et al. The Impact of Prehospital Intubation With and Without Sedation on Outcome in Trauma Patients With a GCS of 8 or Less. J Trauma Acute Care Surg. 2016;80(3):398-406. PMID: 26797107.

[4] Duncan R, Thakore S. Predictors of the need for rapid sequence intubation in the poisoned patient with reduced Glasgow coma score. Emerg Med J. 2009;26(7):510-2. PMID: 19546273.

[5] Mosier JM, et al. The Physiologically Difficult Airway. West J Emerg Med. 2015;16(7):1109-1117. PMID: 26759664.

[6] Apfelbaum JL, et al. 2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway. Anesthesiology. 2022;136(1):31-81. PMID: 34762729.

[7] Natt BS, et al. Management of the Difficult Airway. N Engl J Med. 2020;382(26):2518-2526. PMID: 32579813.