A 74-year-old man (body height, 148 cm; body weight, 42 kg) presented with symptoms of the common cold for a few days and was transferred to our hospital due to worsening dyspnea. On arrival, his initial vital signs were as follows: Glasgow Coma Scale score, 6 (E1V1M4); respiratory rate, 18 breaths/min; percutaneous oxygen saturation, 94% under assisted ventilation with bag valve mask; heart rate, 84 b.p.m.; and blood pressure, 169/70 mmHg. He had weak breathing, and his oxygen saturation fell sharply when assisted ventilation was stopped. Results of arterial blood gas analysis revealed severe hypercapnia and respiratory acidosis (Table 1).
Based on the clinical presentation, we planned to intubate the patient for mechanical ventilation. However, tracheal intubation was extremely difficult because of severe cervical-thoracic kyphosis resulting from vertebral tuberculosis. First, we administered fentanyl i.v. and tried to intubate him by video laryngoscopy; although the glottis was easily visualized, we made one attempt at intubation with an endotracheal tube (ETT) with an internal diameter (ID) of 8.0 mm (outer diameter [OD] 10.9 mm), which was unsuccessful because the abnormal curvature of the trachea prevented tube advancement. Next, we attempted to intubate by bronchoscopy with a diameter of 5.9 mm but failed to advance the bronchoscope beyond the abnormal curve. Finally, we managed to intubate with an ETT with an ID of 5.0 mm (OD 6.9 mm). However, this provided inadequate ventilation; percutaneous oxygen saturation decreased to 70% and did not improve. Supraglottic airway devices were not used because the patient's neck was short and the range of neck motion was limited.
After the multiple failed attempts at ventilation by ETT, we judged that it was necessary to undertake a surgical tracheostomy to secure his airway. However, simple cricothyrotomy was not expected to resolve the issue of severe tracheal deformity (Fig. 1A). Additionally, surgical tracheostomy for severe tracheal deformity required time, but the patient lacked the oxygen capacity needed to maintain saturations while the procedure was carried out. Therefore, we decided to use venovenous ECMO for surgical tracheostomy. We chose the femoral-femoral configuration of venovenous ECMO because of the patient's short neck and limited neck motion. A 22 French gauge (Fr) drainage cannula (NSH heparin-coating cannula; Senko Medical Instrument Mfg., Tokyo, Japan) was placed percutaneously in the right atrium and the superior vena cava through the right femoral vein, and a 20 Fr return cannula (NSH heparin-coating cannula) was placed percutaneously in the inferior vena cava through the left femoral vein. Venovenous ECMO increased his percutaneous oxygen saturation to 90%, allowing a tracheostomy to be placed beyond the severe abnormal curve. We inserted the flexible spiral type of tube with an ID of 8.0 mm (GB Adjustfit Tracheostomy Tube; Fuji Systems, Tokyo, Japan). After tracheostomy, the patient was admitted to intensive care. A computed tomography scan after admission confirmed the presence of a severe tracheal deformity that was curved at a sharp angle (Fig. 1E,F). Lung rest ventilation was instituted for the duration of intensive care admission.
Based on the history of events and examination findings, we diagnosed the cause of the respiratory failure to be pneumonia and initiated a course of antibiotics. The patient's oxygenation gradually improved (Fig. 2), allowing ECMO to be withdrawn on day 8. Hypercapnic respiratory failure persisted due to the chest deformity, but intensive rehabilitation made it possible to wean him off the ventilator during the daytime. He was transferred to another hospital for continued rehabilitation on day 46 and had no neurological deficits.