LANDING THE ANESTHESIA PLANE: WHEN SHOULD YOU EXTUBATE THE TRACHEA?

Clinical Case for Discussion: You’re anesthetizing a 60-year-old woman for a thyroidectomy. The surgeon tells you, “If this woman bucks on the endotracheal tube on awakening it could cause a neck hematoma and damage my surgical closure. Can you extubate her deep?”

Discussion: The patient has a normal airway, and she is healthy and slender. You decide to comply with the surgeon’s request and remove the endotracheal tube (ET tube) at the end of surgery while the patient is still fully anesthetized. You turn off the nitrous oxide, allow the patient to breath 100% oxygen and 3% sevoflurane, and suction the patient’s throat. You deflate the cuff on the ET tube and remove the tube. Once the tube is withdrawn, you turn off all anesthetics. At this point the patient coughs and her mouth fills with yellow gastric contents. You suction the mouth again, but the patient develops upper airway obstruction. The oxygen saturation drops to 80%. Your diagnosis is laryngospasm. You attempt to apply continuous positive airway pressure with an anesthesia mask, but her oxygen saturation falls to 70%. Panicked, you inject 100 mg of IV succinylcholine to re-paralyze the patient, and you perform laryngoscopy and reintubate her. After the ET tube is replaced, the oxygen saturation returns to 100%. You suction through the lumen of the ET tube, and you find yellow gastric material inside the lungs. You diagnose aspiration.

After a 10½ hour flight from Seoul, Korea, an Asiana airplane crashed on landing at San Francisco Airport this July. Aviation and anesthesia have similarities. The takeoff and landing of an airplane, just as induction and emergence from anesthesia, are more complex events than piloting the middle of a plane flight or managing the maintenance phase of a long anesthetic.

The timing of the removal of the endotracheal tube at the end of an anesthetic requires skill and judgment. Does deep extubation ever make sense? During my first year after residency training, a gray-haired anesthesia attending at my new medical center told me, “Richard, in private practice you never extubate anyone deep.” Twenty-seven years later, I’m writing to convince you he was right.

Let’s define “deep extubation.” Per Miller’s Anesthesia, 7^th Edition, 2009, Chapter 50, “Extubation may be performed at different depths of anesthesia, with the terms ‘awake,’ ‘light,’ and ‘deep’ often being used. ‘Light’ implies recovery of protective respiratory reflexes and ‘deep’ implies their absence. ‘Awake’ implies appropriate response to verbal stimuli. ‘Deep’ extubation is performed to avoid adverse reflexes caused by the presence of the tracheal tube and its removal, at the price of a higher risk of hypoventilation and upper airway obstruction. Straining, which could disrupt the surgical repair, is less likely with ‘deep’ extubation. Upper airway obstruction and hypoventilation are less likely during ‘light’ extubation, at the price of adverse hemodynamic and respiratory reflexes.”

The medical literature describes deep extubation as extubating a patient who is still breathing 1.5 times the minimal alveolar concentration (MAC) of inhaled anesthetic. A 2004 study examined 48 children tracheally extubated while deeply anesthetized with 1.5 times the MAC of desflurane (Group D) or sevoflurane (Group S). No serious complications occurred in either group, and the time to discharge was not significantly different between groups. The study concluded that deep extubation of children can be performed safely with desflurane or sevoflurane. (Valley RD, Anesth Analg. 2003 May;96(5):1320-4, Tracheal extubation of deeply anesthetized pediatric patients: a comparison of desflurane and sevoflurane.)

In a prospective trial, 100 children age<16 years, each with at least one risk factor for perioperative respiratory adverse events (e.g. current or recent upper respiratory tract infection or asthma) were randomized to extubation under deep anesthesia or extubation when fully awake for adenotonsillectomy. There were no differences in perioperative respiratory adverse events (laryngospasm, bronchospasm, persistent coughing, airway obstruction, or desaturation <95%). Tracheal extubation in fully awake children was associated with a greater incidence of persistent coughing (60 vs. 35%, P = 0.028), whereas the incidence of airway obstruction relieved by simple airway maneuvers in children extubated while deeply anaesthetized was greater (26 vs. 8%, P = 0.03). (von Ungern-Sternberg BS, Eur J Anaesthesiol. 2013 Jan 21, The effect of deep vs. awake extubation on respiratory complications in high-risk children undergoing adenotonsillectomy: A prospective, randomized, controlled trial).

Seventy healthy patients between 2 and 8 yr of age who had elective strabismus surgery or tonsillectomy were randomly assigned to group 1 (awake extubation) or group 2 (anesthetized extubation). The incidence of airway-related complications such as laryngospasm, croup, sore throat, excessive coughing, and arrhythmias was not different between the two groups. The authors concluded that the anesthesiologist’s preference or surgical requirements may dictate the choice of extubation technique in otherwise healthy children undergoing elective surgery. (Patel RI, Anesth Analg. 1991 Sep;73(3):266-70. Emergence airway complications in children: a comparison of tracheal extubation in awake and deeply anesthetized patients).

In an informal poll of the private practice anesthesiologists at Stanford University, the incidence of deep extubation (i.e. patient extubated asleep while breathing >1.5 MAC of inhaled anesthetic) approached zero. Why do I and my colleagues avoid deep extubation? If you have a life-saving and life-preserving device such as an endotracheal tube safely in place in your patient, and your goal is to maintain the values of Airway, Breathing, and Circulation, why remove that life-preserving device prematurely without any evidence that such a removal is beneficial? Why leave your anesthetized patient with an unprotected airway?

I cannot cite you outcome data that shows awake extubation provides superior outcomes to deep extubation, but with modern short-acting anesthetics such as propofol, sevoflurane, and desflurane, a well-trained anesthesiologist can decrease anesthetic depth quickly and have their patient very awake within minutes after the conclusion of surgery. Per Miller’s Aesthesia, “Rapid recovery of consciousness shortens the at-risk time during extubation and may reduce morbidity, particularly in obese patients. … Nitrous oxide, sevoflurane, and desflurane all contribute to rapid recovery, particularly after prolonged procedures.”

If your patient vomits on emergence and the ET tube is still in situ, the cuff on the ET tube will protect their lower airway. And if you choose to extubate your patient awake, the occurrence of laryngospasm will be, in this author’s experience, rare.

It’s true that coughing on an ET tube can disrupt surgical repairs, increase intracranial pressure, increase intraocular pressure, or cause hypertension and tachycardia, but Per Miller’s Aesthesia, “Marked increases in arterial blood pressure and heart rate occur frequently at the time of ‘light’ extubation. These effects are alarming but normally transient, and there is little evidence of adverse consequences.”

My advice: Use light levels of general anesthetics on your intubated patients, and learn how to wake your patients from general anesthesia quickly at the conclusion of surgery. Don’t suction the patient until you are ready to remove the ET tube, because the suction catheter stimulates early coughing.

The ET tube is your friend. I’d recommend you don’t pull it out until you’re certain you don’t need it any more.

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