Airway Management for Massive Anterior Mediastinal Tumor Resection in an Infant: A Strategy Involving Spontaneous Breathing-Preserving Endotracheal Intubation under Intravenous Anesthesia

Tracheal intubation under sedation in uncooperative infants is challenging. The case of a 4-month-old infant with a massive anterior mediastinal tumor and upper respiratory tract symptoms, for whom effective preoxygenation was provided with a high-flow nasal cannula (HFNC), allowing for safe tracheal intubation in combination with a supraglottic device and local anesthetic, is reported. With careful planning of anesthesia and creative problem solving, airway management for anterior mediastinal tumors can be performed safely with the selection of an appropriate airway device. This may be a good airway management strategy for infants with mediastinal tumors or who may be expected to have ventilation difficulties.


Introduction
Preoxygenation is difcult in pediatric patients due to lack of cooperation, and even in cases of difcult airways, conscious intubation is extremely difcult and dangerous, so it is rarely performed.However, in cases in which ventilation difculties are anticipated before general anesthesia, endotracheal intubation may be necessary under sedation while preserving spontaneous breathing.Tis report describes the safe performance of tracheal intubation without causing pain or the cough refex in the patient while preserving spontaneous breathing during anesthesia induction for anterior mediastinal tumor resection in an infant with upper respiratory symptoms.

Case Presentation
A healthy 4-month-old male infant (height 60 cm and weight 7.4 kg) was scheduled for removal of a massive anterior mediastinal tumor.He had been wheezing for several weeks and was diagnosed with bronchitis at the clinic and prescribed an expectorant, but cyanosis was gradually observed.Transcutaneous oxygen saturation (SPO 2 ) was 60% in the supine position and 99% in Fowler's position and crying decreased SPO 2 and worsened wheezing.Chest computed tomography (CT) showed a tumorous lesion in the anterior mediastinum, with compression of the heart and the distal area of the carina (Figure 1).Te anterior mediastinum tumorectomy was scheduled for one week later, and the patient was managed in the pediatric intensive care unit with a head-up position of over 30 °and high-fow nasal cannula (HFNC) therapy (FiO 2 30%, 15 L) until then.

Airway Management
General anesthesia was administered with rescue equipment including extracorporeal membrane oxygenation (ECMO) on standby.
After tracheal intubation, it was confrmed that ventilation was possible with pressure support of 25-30 cmH 2 O, with anesthesia maintained with 0.8% sevofurane and remifentanil 0.1c, and spontaneous breathing preserved with manual ventilation until the sternal incision.After the sternum was incised, the tidal volume was maintained sufciently, and controlled ventilation could be used.From induction of anesthesia to sternotomy, the patient was managed with FiO 2 100%, but after sternotomy, FiO 2 was gradually lowered to 40%.No muscle relaxants were used from the induction of anesthesia to the end of the surgery.
On postoperative day (POD) one, the patient was extubated after the trachea was observed using a bronchoscope in the PICU.Due to slight evidence of tracheomalacia, HFNC (FiO 2 30%, 15 L) was used until POD2.Te patient was stable for discharge home on POD8.

Discussion
Pediatric anterior mediastinal tumors are characterized by a high risk of cardiopulmonary complications [1,2], and general anesthesia with use of muscle relaxants should be avoided [3].Because most anterior mediastinal tumors showing rapid onset of symptoms in children are lymphomas or leukemias [4,5], chemotherapy and radiation therapy could be considered frst-line treatment [6].It is important to discuss the indication for the surgical procedure under general anesthesia with multiple specialists [4].In the present case, total tumor resection was scheduled, and the defnitive diagnosis of this case was immature teratoma of the thymus.
Even with endotracheal intubation, especially in the supine position, the gravity of the chest wall and the tumor reduce lung compliance, and there is a high risk that ventilation will become impossible due to the loss of bronchial muscle tone.Moreover, since the difcult airway guidelines are inefective in this critical situation, a spontaneous breathing technique is most commonly advocated [1].
Tere is no cause-and-efect relationship established between anesthetic technique and complications [2], and there is no established method for inducing general anesthesia and conducting airway management in patients with anterior mediastinal tumors presenting with orthopnea, wheezing, and cyanosis.Generally, endotracheal intubation that preserves spontaneous breathing in pediatric patients is difcult and is, therefore, not often selected.In the present case, by selecting an appropriate airway device, careful anesthesia planning, and with creative problem solving, it was possible to safely manage the airway during anterior mediastinal tumor resection without any complications.
Even though there are no defnitive studies comparing the efcacy of the airway management process between facemasks and HFNC for pediatric cases, HFNC is attracting increased attention and may provide safe preoxygenation [7].HFNC can be a feasible option for children who are noncompliant to the tight-ftting facemask [8] during the induction of general anesthesia and highly susceptible to rapid desaturation.Since supraglottic airway devices are now being used in children as a frst-choice airway device and as a conduit for tracheal intubation [9], the i-gel was selected in the present case as a route to facilitate easy provision of local anesthesia under spontaneous breathing to the upper airway.Moreover, the combination of an epidural catheter made it possible to efectively administer local anesthesia to the intended area; in this case, the vocal cord and the trachea, with a small volume of fuid.
In our view, the method presented is efective and can be used as a strategy for tracheal intubation in uncooperative pediatric patients for whom there are concerns about the use of muscle relaxants or who are expected to experience difcult ventilation.