Indications for Intervention
This page was once titled indications for intubation but I have found this inaccurate. Intubation is only one tool in the arsenal for airway protection; its indications reflect the need for airway protection but do not per se mandate intubation. The medical community, including anesthesiologists, have become much less laissez-faire towards intubation; it has many detriments and questionable superiority. Be mindful that the traditional teaching of can’t protect airway, can’t oxygenation/ventilation, or expected decline in clinical status means that the patient needs some sort of intervention. Not necessarily biting on plastic.
1. Can’t Protect Airway
Despite the conviction behind this statement, there is no objective way to determine whether the airway is “protected”. Clinical judgement is the gold standard, which is frustrating to teach due to the interpersonal variability. The litmus test for most practitioners are: Can the patient talk? Can they swallow and manage secretions?
Can Talk and Can Manage Secretions.
Fulfilling both criteria does not mean the airway is aspiration proof. Everyone has choked on their saliva while fully sober and has felt stupid for it. There is a basal level of aspiration that is clinically insignificant and a gradient towards clinically significant. This basal level increases in the elderly, stroke patients, and those with neuromuscular/anatomic disorders. Even if basal aspiration events reach clinically significant levels, it makes little sense to intubate these patients because this mandates sedation and sacrifices consciousness. However, these patients still benefit from intervention! Speech consult, soft foods, spicier foods, and aspiration precautions are less sexy than the smooth curves of the laryngoscope but are more prudent.
Patients that talk and swallow can still have airway compromise, just not at disastrous levels yet. An exam should be focused at looking in the nose and mouth, as well as hearing the patient breath without a stethoscope. Chewing gum should be removed. Oral or nasal bleeding should be addressed so to not overwhelm the glottal reflexes and produce aspiration. Singed nasal hair is an ominous sign of thermal injury and impending swelling. Signs of angioedema also signals possible airway closure. Upper airway sounds do not stop at stridulous and nonstridulous. Snoring, snuffy nose, and runny nose all signify airway pathology that can be dealt with using NPA or afrin. Whether these issues shall be dealt with depends on the practitioner. But with airway, I lean toward shoot first and ask questions later.
Cannot Talk, Can Manage Secretions.
Talking is a crude measure of level of consciousness. Consciousness facilitates but is not necessary for airway reflexes, which are primarily brain stem. Thus, depressed consciousness is not per se a reason for intervention. The patient that cannot talk needs an etiology. Reversing the cause in a timely manner is the most effective airway plan.
In heroin overdose, narcan IS the airway intervention. Alcohol and benzo intoxication are trickier because their reversal can provoke seizures. But both will resolve within a reasonable amount of time. Most ETOH intoxications do not require intubation; you can simply wait them out.
Trauma is a different animal because TBI can involve the brain stem, usually has a protracted recovery, or needs surgical interventions that require sedation and paralysis. “GCS 8, intubeight” is a heuristic that gained popularity due to its alliteration; but there is no actual data. Nor will there ever be any data given the interpersonal variability of GCS scoring.
Can’t Manage Secretions.
This is bad and signifies significant supraglottic airway obstruction. Transferring the patient to the OR where tracheostomy can be a backup maneuver is the safest course of action if the patient can tolerate the delay. Allow the patient to assume whatever position is comfortable and avoid anxiety or pain provoking maneuvers at all costs.
If you have to do this in the ED, awake intubation is likely the safest choice. Oral fiberoptic intubation is easiest and best tolerated if the tongue is not prohibitively large. Mark the crichothyroid membrane and prepare the neck for emergent cricothyrotomy. I have not found much utility in using the ultrasound to find the cricothyroid membrane but it may be useful to delineate the thyroid.
2. Can’t Maintain Ventilation, Oxygenation and Alkalinization
I bore the wrong perspective on this criteria for a long time. Ventilation, oxygenation, and alkalinization are respiratory functions. Supplemental oxygen, BiPAP, BVM, and mechanical ventilation are the actual therapies for respiratory derrangements. Airway managements are adjuncts that all invariably interrupt oxygenation and ventilation. Thus, airway management takes a subservient role.
The semantics of “preoxygenate to intubate” is incorrect in respiratory distress because this implies that preoxygenation is the pretreatment for the therapy of intubation when, in fact, oxygenation IS the therapy. When this is inadequate, intubation is performed as the pretreatment for the therapy of mechanical ventilation.
The decision for airway interventions is dependent on the choice of respiratory intervention as well as the patient’s ability to protect their airway (see above). Supplemental oxygen and high flow nasal cannula is the least invasive and can be used on the awake or obtunded patient; no airway interventions are required with these respiratory adjuncts.
NIPPV such as BVM, BiPAP or CPAP are less invasive and also do not require airway interventions. However, BiPAP is traditionally contraindicated for patients with AMS. There is concern that PPV distends the stomach with air, increasing risk of aspiration. Realistically though, BiPAP causes aspiration because obtunded patients vomit into the mask and do not have the capacity to pull the mask off. It is still sensible to try BiPAP in patients with altered mental status so long as someone is at the head of the bed ready to respond to such events.
BiPAP is especially efficacious in patients whose depressed level of consciousness is caused by hypoxemia or hypercarbia because it directly reverses the respiratory encephalopathy and such patients perk up rapidly. The challenge arises in determining causality: did respiratory insufficiency cause encephalopathy or did encephalopathy cause respiratory insufficiency? The latter group exemplified by opiate overdose patients or TBI patients will not demonstrate improved mental status with BiPAP.
Regardless, it may be prudent to try NIPPV such as BVM or BiPAP, depending on the scenario's time-sensitivity. Even if NIPPV does not improve mental status, it usually improves oxygenation - bolstering respiratory reserves for the inevitable apneic phase of intubation. This is the premise behind delayed sequence intubations. In such cases, BiPAP is the pre-pretreatment for the pretreatment of intubation for the therapy of mechanical ventilation … I emphasize this because it is important to focus on the endgame in medicine and not be distracted by the steps in between.
3. Expected Decline in Clinical Status
- Expected decline in clinical course (trauma, burns)
- Airway protection during procedures (ie. endoscopy)
- Need to lay still for CT scan; unstable patient who needs CT