To the Editor:
Dr. C. Troop’s case summary of a "can’t intubate/ can’t ventilate" outcome in a morbidly obese patient reflects an event feared by all anesthesiologists.1 Tracheal intubation, initially attempted with a standard technique, eventually proved ineffective during a complex situation compounded by difficult laryngoscopy. Two problems were present, as are possible in all patients requiring general anesthesia. Initially, the anesthesiologist was unable to reliably predict a difficult airway in order to alter management preemptively. Subsequently, when a difficult laryngoscopy was encountered, further attempts at standard intubation proved both ineffective and time-consuming, a recognized and recurring outcome acknowledged in the anesthesiology literature. The continuing acceptance of what is basically a flawed technique as the standard for routine intubation stems from the unquestioned acceptance of a 60-year-old procedure originally intended to secure the airway in MOST but NOT ALL patients. The response to the inevitable "difficult intubation" has led anesthesiologists to develop personal "tricks" that are added as supplements to textbook intubation. Each additional step, however, requires extra time to implement and does not guarantee success at the time when duration of hypoxia becomes critical to patient safety. The ideal solution is to routinely use a single technique that is safe and effective for the normal patient, and yet maximizes rapid tube placement with difficult laryngoscopy. At the very least, such an approach would, in the rare instance where intubation was impossible, considerably shorten the delay between recognizing failure and entering the difficult airway algorithm.
One system of routine intubation employing a MAC 4 laryngoscope blade and a standardized endotracheal tube-stylet combination has been executed successfully in thousands of patients.2 This system is based on 2 fundamental principles governing use of a styletted endotracheal tube. First the operator must purposefully control the endotracheal tube and deliberately place the tip at or between the vocal cords, and second, from that position slide the endotracheal tube forward into the glottis while the stylet remains stationary.
Key steps incorporated into this system include
- A correctly performed laryngoscopy tailored to the patient. This creates a laryngoscopic channel that allows access to the larynx and a path through which the endotracheal tube must pass without contacting any part of the channel.
- An endotracheal tube that is shaped to match a portion of the laryngoscopic channel.
- The appropriate direction of travel within the channel that permits intentional positioning of the endotracheal tube tip at the larynx.
- A definable endpoint to confirm when the tracheal tube tip passes between the vocal cords during grade I-III 1/2 laryngoscopic views.
As learning and skill improve with daily practice and experience, most difficult intubations gradually become routine and act as training for the anesthesiologist to respond quickly and effectively in critical situations.
Russell Stasiuk, MD
Vancouver, British Columbia
References —back to top—
- Troop CS. Difficult intubation in the obese patient. APSF Newsletter Winter 2005-2006;20(4):83.
- Stasiuk RBP. Improving styletted oral tracheal intubation: rational use of the OTSU. Can J Anesth 2001;48:911-8.