Can the Endotracheal Tube Become a Threat to Airway Patency?

Dear Editor,

Although intubation is considered as the gold standard to maintain airway safety, the intubation tube itself may at times pose as a danger (1, 2). We would like to share a rare problem with our colleagues pertaining to a smooth general anaesthesia process after obtaining patient’s consent. The trachea of a patient (43 years, 63 kg, 162 cm and ASA I) who was undergoing general anaesthesia was intubated with an endotracheal tube (ETT; Chilecom Medical Devices Co. Ltd., China) of a 7.0 mm internal diameter; the ETT was fixed at a depth of 20 cm from the mouth angle. Anaesthesia circuit was fixed to prevent tube kinking while keeping the patient’s head in neutral position. Peak airway pressure was 21 cm H₂O during mechanical ventilation with tidal volume of 500 mL, 10 breaths min⁻¹ and an end-expiratory pressure of 5 cm H₂O, whereas end-tidal CO₂ (EtCO₂) was 32–33 mmHg. After 50 min, peak airway pressure started to increase and reached up to 40 cm H₂O within few minutes. Because of pressure limitation, the tidal volume decreased to 200 mL with EtCO₂ of 20 mmHg. No problems were encountered when breath sounds, anaesthesia circuit, cuff of ETT and muscle relaxation were checked. Laryngoscopic inspection of ETT revealed no problem in the oral cavity, but a 14-Fr suction catheter did not pass through the ETT during tracheal aspiration attempt. The patient was extubated and reintubated with a new tube. Starting at the distance of 17 cm of the removed tube, a kink was observed that almost obstructed the lumen (Figure 1a, b). After approximately 20 min at room temperature, the kinking that narrowed the lumen of the intubation tube had significantly disappeared (Figure 2).

Figure 1.

a, b. Kinked ETT from different views

Figure 2.

The restoration of luminal patency of kinked endotracheal tube at room temperature

Polyvinyl ETTs are relatively resistant to kinking at room temperatures. However, at body temperatures, the tubes soften and may kink causing lumen occlusion even at very low angles (3). The exit point of the cuff line to the pilot balloon is often reported as the location of kinking (3). Head position other than neutral position (4) or shifting the position of the ETT (5) may also contribute to kinking. For our patient, although the tube was secured at the distance of 20 cm at the right corner of the mouth, kinking started at approximately 3 cm from this point at the pharynx-larynx intersection. During laryngoscopic control with a Macintosh blade, we saw the dorsal side adjacent to the palate but could not detect the kink. In case of unaccounted airway pressure elevations (6), ETT must be controlled considering possible lumen blocking because of tube kinking within the mouth.