Deciding to Intubate

When does a patient need endotracheal intubation? (1)

We need to ask three questions.

(1) Can the patient maintain his airway and can he protect his airway against aspiration?

(2) Can the patient maintain ventilation (the elimination of carbon dioxide) and can the patient maintain oxygenation (oxygen saturation)?

(3) Is the patient’s likely clinical course going to require intubation?

The answers to these questions determine the patient’s need for intubation.

(1) Can the patient maintain his airway and can he protect his airway against aspiration. 

The alert conscious patients can maintain airway patency with the airway musculature and can use protective reflexes to prevent aspiration of gastric contents.  If a patient can speak in a clear normal voice, then this is good evidence that the airway is patent and the protective reflexes are operating.

When a patient is seriously ill or severely injured, his ability to maintain airway patency and to protect against aspiration  are often compromised.

If a spontaneously breathing patient cannot maintain a patent airway (as evidenced, for example, by the need to maintain the airway with a jaw thrust  or head tilt), then a nasopharyngeal airway or an oropharyngeal airway may be needed to maintain patency.

However, in general, any patient who requires such an airway for patency also requires endotracheal intubation for protection against gastric aspiration.

The presence or absence of the gag reflex is not an adequate marker for the need of airway protection.

Also, the presence of adequate spontaneous ventilation in an obtunded patient does not necessarily mean that the airway reflexes are present and able protect the airway against gastric aspiration.

The presence of spontaneous or volitional swallowing is the best evidence for airway reflex presence and protection. If you note pooled secretions in the back of the mouth and throat, this  indicates that the patient can’t protect his airway.

Any patient who is unable to maintain his airway and/or to protect his airway requires endotracheal intubation.

(2) Can the patient maintain ventilation (the elimination of carbon dioxide) and can the patient maintain oxygenation (oxygen saturation)?

Even if the patient airway is patent and protected, he or she may need endotracheal intubation to facilitate ventilation. For example a patient with severe asthma or a severe exacerbation of COPD may need entubation because he is tiring and requires ventilatory support.

Similarly, a patient who is unable to maintain adequate oxygenation despite supplemental oxygen (for example, with a non-rebreather mask) needs entubation and ventilatory support (often with positive end expiratory pressure).

Other examples might be a patient with cardiogenic pulmonary edema or with acute respiratory distress syndrome. In both of these cases fatigue can rapidly occur and intubation and ventilatory support may be indicated.

So most patients who need emergency endotracheal intubation need it because of : inability to maintain a patent airway, inability to protect the airway, inability to ventilate, or inability to oxygenate.

However, there is one more question to ask.

(3) Is the patient’s likely clinical course going to require intubation?

“However, there is a large and important group for whom intubation is indicated, even though none of these four fundamental failures is present at the time of evaluation. These are the patients whose conditions, and airways, are predicted to deteriorate, either because of dynamic and progressive changes related to the presenting condition or because the work of breathing will become overwhelming in the face of catastrophic illness or injury.”

Examples might include a stab wound to the neck, smoke inhalation, or severe trauma with hypotension.

Sometimes it may appropriate to intubate the patient prior to transfer to another area such as the CT scanner or transfer to another hospital. In either case the need for sudden emergency airway management might be difficult or impossible.

“Not every trauma patient or every patient with a serious medical disorder requires intubation. However, in general, it is better to err on the side of caution by performing an intubation that might not, in retrospect, have been required, than to delay intubation, thus exposing the patient to a potentially disastrous deterioration.”

“When evaluating a patient for emergency airway management, the first assessment should be of the patency and adequacy of the airway. In many cases, the adequacy of the airway is confirmed by having the patient speak. Ask questions such as ‘What is your name?’ or ‘Do you know where you are?’ The responses provide information about both the airway and the patient’s neurologic status. A normal voice (as opposed to a muffled or distorted voice), the ability to inhale and exhale in the modulated manner required for speech, and the ability to comprehend the question and follow instructions are strong evidence of adequate upper airway function. Although such an evaluation
should not be taken as proof that the upper airway is definitively secure, it is strongly suggestive that the airway is adequate for the time being. More importantly, the inability of the patient to phonate properly, inability to swallow secretions, or the presence of stridor, dyspnea, or altered mental status  precluding responses to the questions should prompt a detailed assessment of the adequacy of the airway and ventilation (see Box 1-1).”

BOX 1-1. Four Key Signs of Upper Airway Obstruction
• Muffled or “Hot Potato” voice (as though the patient is speaking with a mouthful of hot food)
• Inability to swallow secretions, either because of pain or obstruction
• Stridor
• Dyspnea

“The first two signs do not necessarily herald imminent total upper airway obstruction;
stridor, if new or progressive, usually does, and dyspnea also is a compelling symptom.”

And finally, it is important to recognize that the assessment of the adequacy of ventilation and oxygenation is a clinical one. Arterial blood gases are not necessary or helpful in making the decision to intubate. Oxygen saturation is monitored by non-invasive oximetry in situations in which it is reliable (adequate blood pressure, pulse rate by oximeter the same as that of the ekg montor).

(1) The Manual of Emergency Airway Management. Ron Walls and Michael Murphy. 4th edition, 2012. Chapter 1.

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