2026 FSA Podium and Poster Abstracts

Introduction: Tension pneumothorax is a rare but life threatening intraoperative complication that requires rapid recognition and intervention. Classically, it presents with sudden hypoxemia, rising peak inspiratory pressures, and hemodynamic instability with hypotension and tachycardia. However, these findings may be subtle or even absent in certain clinical scenarios or patient populations. In anesthesia practice, mild hypotension is encountered frequently and often attributed to side effects of anesthetic agents that cause vasodilation and fluid shifts that are often seen perioperatively. This can create a cognitive bias that delays consideration of more serious etiologies. Furthermore, in patients ventilated with pressure support ventilation (PSVpro) modes, airway pressures are inherently lower, which may obscure one of the key physiologic clues to developing a pneumothorax, rising peak inspirator pressures. A pectoral nerve block is a commonly used regional anesthesia technique used in breast surgery. When performed without ultrasound guidance, however, the risk of inadvertent pleural puncture increases, and a pneumothorax can be an unfortunate consequence. We present a case of a 40-year-old female with a history of right breast cancer undergoing right mastectomy with reconstruction in whom an unrecognized tension pneumothorax was incidentally discovered during surgical closing counts after a lost needle prompted intraoperative chest imaging. This case underscores how subtle presentations may mask serious complications and highlights the importance of vigilance when using landmark based regional anesthesia techniques.

Methods: A targeted literature review was performed using PubMed and UpToDate with the search terms: tension pneumothorax, intraoperative pneumothorax, Pectoral nerve block complications, landmark versus ultrasound-guided regional anesthesia, and positive pressure ventilation. Relevant articles were reviewed to contextualize the pathophysiology, diagnostic challenges, and anesthetic considerations of intraoperative tension pneumothorax, particularly in patients ventilated with PSVPro and receiving regional anesthesia for breast surgery.

Results: Tension pneumothorax can cause rapid cardiopulmonary decompensation through impaired venous return, mediastinal shift, and ventilation perfusion mismatch. In patients receiving positive pressure ventilation, it often manifests as increasing airway pressures, hypoxemia, and hypotension. However, when ventilating using a PSVPro mode, peak pressures may remain low and compensatory spontaneous breathing may mask evolving physiologic compromise.

Conclusion: This case highlights the potential for subtle presentations of tension pneumothorax during PSVPro ventilation, particularly when associated with landmark-based pectoral nerve blocks. A high index of suspicion is essential, as mild hemodynamic changes may be the only clinical clue. Vigilant monitoring and early consideration of pneumothorax in the differential can prevent life threatening deterioration. Ultrasound guidance should be considered for regional anesthesia near the pleura to minimize risk.