The main concern before postoperative tracheal extubation is laryngeal edema formation with the subsequent risk of tracheal reintubation. Laryngeal edema may develop after multiple conventional tracheal intubation attempts and other airway interventions, during the surgical procedure, particularly involving head and neck surgery, or after prolonged head-down positioning of the patient.
There are no reliable tests with acceptable positive and negative predictive values for tracheal extubation tolerance (8). The cuff-leak test (CLT) may assess laryngeal obstruction and the subsequent risk of tracheal reintubation (11). The original qualitative CLT estimates air movement around the occluded tracheal tube (TT) after deflation of the cuff; the quantitative CLT measures the cuff-leak volume calculated as the difference between the expiratory tidal volumes before and after cuff deflation. Unfortunately, the CLT is rather unreliable for individual risk prediction mainly because the TT may act as stent keeping the anterior laryngeal aperture at least partially open. However, a negative CLT, indicating severe laryngeal obstruction, should initiate further airway evaluation before subsequent decision-making.
Laryngoscopic Airway Evaluation
Direct laryngoscopy (DL) with the patient still anesthetized may be well tolerated but not at light planes of general anesthesia; provided visualization of laryngeal structures, the extend of laryngeal edema formation may be evaluated. Video laryngoscopes may be a better option as they enable visualization of laryngeal structures not necessarily in the line-of-sight with DL, require less lifting force, and provide image magnification (14, 23).
Endoscopic Airway Evaluation
Nasopharyngolaryngoscopy using a flexible bronchoscope (FB), as proposed by Rosenblatt and co-workers (26) for preoperative airway examination, may be a valuable alternative to laryngoscopic airway evaluation. This technique is easy to perform even by less experienced endoscopists, provides airway information on hypopharyngeal and laryngeal structures, and is well tolerated with minimal patient discomfort.
Airway evaluation before tracheal extubation may underestimate the extend of laryngeal edema formation as the TT may prevent total collapse of surrounding tissue; following removal of the TT, edematous tissue may bulg over the entire laryngeal aperture totally obstructing the upper airway.
Evaluation of vocal cord function in patients with high risk of damage to recurrent laryngeal nerves during surgery requires tracheal extubation; this may be performed under videolaryngoscopic view (14), by tracheal extubation over a FB, or by flexible endoscopy through an appropriately positioned laryngeal mask airway (LMA) after TT change to a LMA.
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