Endoscopic ultrasound (with an echobronchoscope)-guided fine-needle aspiration for diagnosis of a mediastinal lesion in a mechanically ventilated patient: A case report and systematic review of the literature.

Endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) is routinely used for accessing mediastinal lymph nodes and masses. However, in patients with respiratory failure, who are being mechanically ventilated through an endotracheal tube, EBUS-TBNA may not be feasible due to several reasons. In such patients, the esophageal route offers a useful alternative for accessing mediastinal lesions. Herein, we describe a 50-year-old man with a mediastinal mass, who was being invasively ventilated for respiratory failure. Endoscopic ultrasound (with an echobronchoscope)-guided fine-needle aspiration was performed, which revealed a diagnosis of small cell carcinoma. Appropriate cancer chemotherapy resulted in successful liberation of the patient from mechanical ventilation. We have also performed a systematic review of literature for reports of endoscopic diagnostic procedures for mediastinal/hilar lesions in critically ill patients.

Introduction

Endosonographic procedures, including endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) and endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) are routinely used for accessing mediastinal and hilar lymph nodes and masses.[12] In patients with hypoxemia, excessive cough, raised intracranial tension, or with central airway obstruction due to lesions compressing the trachea; EUS-FNA may be safer than EBUS-TBNA as it employs the esophageal route.[3] However, patients with central airway obstruction requiring mechanical ventilation are often managed in respiratory care units, where EUS-FNA may not be available. In this situation, the pulmonologist can use the EBUS scope for performing a technique known as EUS (with an echobronchoscope)-guided FNA (EUS-B-FNA). This procedure has been reported to have a good diagnostic performance in the evaluation of mediastinal lesions.[34] Herein, we describe a patient with respiratory failure due to airway obstruction by a mediastinal tumor, who was being mechanically ventilated. The diagnosis could be successfully established using EUS-B-FNA.

Case Report

A 50-year-old man presented to the emergency department with stridor of 1-week duration. He also complained of progressive cough and breathlessness for 2 months. There was a significant reduction in appetite and he had lost 5 kg of his body weight. On admission to our facility, the patient was drowsy. Physical examination revealed an afebrile patient with a heart rate of 120 beats/min, respiratory rate of 38 breaths/min, and blood pressure of 80/50 mmHg. His oxygen saturation was 91% while breathing 40% oxygen. Contrast-enhanced computed tomography (CT) of his chest revealed the presence of a mass in the subcarinal region encasing the lower trachea and main bronchi and consolidation in the right upper lobe [Figure 1].

Figure 1

Mass in the subcarinal region encasing both the main bronchi and causing compression of the pulmonary vessels

The patient was intubated with an endotracheal tube (7.0 mm internal diameter) and mechanically ventilated. Resuscitation with fluids and vasopressors was performed. He was initiated on intravenous co-amoxiclav (1.2 g thrice a day). Shock recovered after 48 h and tachycardia resolved. However, the patient could not be weaned off the ventilator over the next 5 days. On the 6th day, EUS-B-FNA of the subcarinal mass was performed. Cytological examination showed loosely cohesive clusters and dispersed population of small-sized tumor cells with hyperchromatic nuclei showing focal nuclear molding suggestive of small cell carcinoma of the lung [Figure 2].

Figure 2

Photomicrograph of the aspirate from the mediastinal mass obtained by endoscopic ultrasound (with an echobronchoscope)-guided fine-needle aspiration showing loosely cohesive clusters and dispersed population of small-sized tumor cells with hyperchromatic nuclei showing focal nuclear molding suggestive of small cell carcinoma. Background shows nuclear debris (H and E, ×40)

The final clinicoradiological stage was IIIb (T4 N3 M0), but the patient had a poor performance status (Eastern cooperative oncology group score of 4). Placement of a metallic tracheobronchial Y-stent was considered but was not performed as the patient's legal representative refused consent. Chemotherapy with cisplatin 100 mg (85% of 60 mg/m2 of body surface area [BSA]) and irinotecan 160 mg (90% of 100 mg/m2 of BSA) were administered. After a week, the patient was successfully weaned off the ventilator and was discharged to home care. The patient received three more cycles of chemotherapy. However, the disease progressed and the patient succumbed to his illness 3 months after the diagnosis.

Discussion

The index case illustrates the utility of EUS-B-FNA in accessing mediastinal lesions in mechanically ventilated patients, where EBUS-TBNA may be technically difficult or not feasible. A diagnosis of advanced lung cancer was made and the administration of palliative chemotherapy enabled liberation from mechanical ventilation.

Mediastinal or hilar lesions in critically ill patients can be approached endoscopically by the pulmonologist through the airway using TBNA that can be performed with or without EBUS guidance. Both conventional and EBUS-guided TBNA have been described in patients with respiratory failure, who are mechanically ventilated through an endotracheal tube;[567] however, they are not performed frequently. This is because a small-sized endotracheal tube does not allow the entry of the echobronchoscope (insertion tube diameter, 6.9 mm). Further, as the procedure requires a few minutes, significant hypoxia may occur in patients with a poor respiratory reserve. The index patient was being ventilated with a small-sized endotracheal tube (internal diameter of 7.0 mm) and he had significant hypoxemia. Thus, TBNA was not technically feasible in the index case.

EUS may be useful in such patients as the access is through the esophagus, thus not compromising ventilation.[891011] EUS offers access to lymph node stations 5 (para-aortic), 8 (paraesophageal), and 9 (pulmonary ligament) in addition to stations 4 L (left lower paratracheal) and 7 (subcarinal). However, this procedure is usually performed by gastroenterologists and many respiratory Intensive Care Units may not have easy access to this technology, especially at the bedside. EUS-B-FNA, which is performed by the pulmonologist with the same echobronchoscope used to perform EBUS-TBNA overcomes this limitation. Moreover, the introduction of the EBUS scope (6.9 mm in diameter) may be easier than the introduction of the EUS scope (12–14 mm in diameter) in patients who also have esophageal narrowing.[12] Due to these reasons, EUS-B-FNA was preferred in the index patient. CT-guided FNA was not employed as it would have entailed a high risk of pneumothorax due to the central location of the mass.

A systematic review of the PubMed database using the search string: (EBUS OR “endobronchial ultrasound” OR “endoscopic ultrasound” OR echobronchoscope OR echoendoscope OR endosonography OR “transbronchial needle aspiration”) AND (ICU OR “intensive care unit” OR “critically ill” OR “mechanical ventilation*” OR “mechanically ventilated” OR intubated OR “endotracheal tube”) yielded 10 reports (62 patients) of endoscopic interventions (conventional TBNA, EBUS-TBNA, EUS-FNA, or EUS-B-FNA) for mediastinal/hilar lesions in critically ill patients [Table 1].[567891011131415] Forty-six patients could be diagnosed successfully resulting in an overall yield of 74.2%; there were no major complications. Moreover, the diagnostic information obtained from the procedure led to a change in the treatment decision in most of these patients (49/62; 79%). In our case, EUS-B-FNA allowed institution of appropriate chemotherapy and facilitated liberation of our patient with advanced lung cancer from mechanical ventilation, an event not commonly encountered in clinical practice.[16]

Table 1

Published reports of endoscopic diagnostic interventions for accessing mediastinal/hilar lesions in critically ill patients

Conclusion

The index case demonstrates that EUS-B-FNA is a valuable addition to the armamentarium of the pulmonologist for diagnosing mediastinal lesions in critically ill patients, including situations such as respiratory failure, which preclude a diagnostic bronchoscopy and EBUS-TBNA.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.