Waxing and waning tracheal tube obstruction: A diagnostic dilemma!

Sir,

A 26-year-old victim of road traffic accident was brought to the emergency department in an unconscious state with nasal bleeding. His airway was secured immediately using size 8, oral cuffed PVC endotracheal tube (ETT). He was posted for subdural hematoma drainage two hours later. General anesthesia was administered using standard technique after confirming ETT position and patency, and the patient was positioned (anti-Trendelenburg). After 15 min, airway pressure (Paw) increased from 19 to 28 cm H2 O, EtCO2 increased from 32 to 51 mmHg, and SpO2 was 98%. Auscultation revealed bilateral reduced air entry and wheeze. Bronchospasm due to inward migration of ETT with carinal impingement following surgical positioning was considered. ETT position was reconfirmed and kinking was excluded. Bronchodilators (salbutamol and combination of levosalbutamol with ipratropium bromide inhaler puffs, theophylline injection) and hydrocortisone intravenous (IV) was administered. A lubricated suction catheter was advanced through the ETT and a small quantity of blood-tinged secretion was suctioned. The Paw decreased to 23 cm H2 O, EtCO2 to 42 mmHg, and the reservoir bag compliance improved. Waxing and waning of airway resistance occurred several times. Finally, there was a marked increase in Paw 38 cm H2 O, the reservoir bag felt stony hard, and it was impossible to ventilate even after changing the anesthesia circuit. The suction catheter could not be advanced through the ETT. Cuff deflation resulted in no improvement in ventilation excluding cuff herniation. We could not visualize the ETT lumen using a fiberoptic bronchoscope, as it was not available in the emergency operation theatre. Suspecting ETT obstruction, we replaced it with a new one, following which we could ventilate our patient. The removed ETT had an impacted blood clot covering the tube tip and Murphy's eye [Figure 1]. After completion of surgery, the patient was shifted to the ICU for further management.

Figure 1

Blood clot covering the endotracheal tube tip and Murphy's eye

Xue et al., reported three cases of ETT obstruction caused by blood clot.[1] They speculated that local tracheal injury following traumatic intubation, cuff over inflation, or tube movement during changes in head position could result in bleeding and clot formation.[1] Endotracheal intubation has the potential to cause tracheal trauma and subsequent clot formation.[2] Our patient had a history of nasal bleeding. It is plausible that he either aspirated blood or sustained tracheal injury during intubation, leading to local bleeding and pooling of blood in the dependent part of the ETT in supine position and clot formation. Surgical positioning and positive pressure ventilation led to distal clot migration and obstruction. Catheter advancement probably created a new channel for air passage through the clot or between the clot and ETT, improving ventilation. The waxing and waning of airway resistance occurred due to distal displacement and movement of clot in its vertical axis, leading to opening and closing of air channels. Later, the clot migrated and got impacted, completely blocking both the tip and Murphy's eye of the ETT impeding ventilation.

Previous reports of blood clot-induced ETT obstruction describe inability to advance a catheter through the ETT.[13] In our case, the catheter could be negotiated through ETT initially because of partial block. Therefore, while inability to advance a catheter beyond the tube tip may indicate intraluminal obstruction, the ability to advance it does not exclude obstruction, especially when the obstruction is partial. It may be prudent to use a fiberoptic bronchoscope as a diagnostic aid for early assessment of an adverse respiratory event in an intubated patient.