General Anesthesia for Biopsy of Pediatric Mediastinal Mass with Tracheobronchial Compression

Background: Mediastinal masses present anesthesiologists with significant challenges during the peri-operative period. These challenges include but are not limited to managing tracheobronchial compression, atelectasis, adequate ventilation, venous compression, and adequate systemic circulation. Bronchial compression can cause air trapping, meaning air can enter a section of the lung with enough pressure, but the compression prevents air from escaping the lung. This presents a problem for positive pressure ventilation (PPV). If using PPV, the positive pressure can surpass the compression when entering, but air cannot escape, causing an increased volume of entrapped air. This leads to two significant issues: 1) Decreased healthy lung volume leading to inadequate ventilation, and 2) Mediastinal deviation causing kinking of the IVC, leading to decreased preload and insufficient circulation. We recommend sustained spontaneous ventilation and lateral positioning to prevent these issues. Case Presentation: A 7-month-old_ male, without significant past medical history, presents with a left-sided mediastinal mass. The mass caused left bronchial compression with subsequent air trapping in the lower lobe. An echo was performed to make sure the patient could tolerate general anesthesia to biopsy the mass. The echocardiogram resulted in no abnormal findings. The anesthesia team decided to use spontaneous breathing in order to prevent further air trapping. While the patient was under anesthesia the oxygen saturation began to decrease, and one of the anesthesia team members decided to give PPV. An x-ray was taken in the OR showing increased air trapping. The arterial line showed a physiologic tamponade causing a decreased systolic pressure of 50mmHg on each inspiration the patient took. Conclusion: Even when an echocardiogram results in no abnormal findings, it is still unsafe to use PPV ventilation because physiologic tamponade can be produced with increased air trapping. This is no longer postulated but is shown with the x-ray and arterial line findings.