Dysautonomia following breast surgery: Disproportionate response to postoperative hematoma

BACKGROUND: Up to 10% of patients undergoing breast surgery suffer from bleeding complications. Some experience severe hypotension and bradycardia of unclear etiology. Similar to the vasovagal hyperstimulation provoked by abdominal insufflation during laparoscopic surgery, we hypothesize that chest wall stretch from postoperative breast hematoma may mechanically stretch the vagus nerve, triggering dysautonomia disproportionate to the degree of blood loss. METHODS: A single-institution retrospective review of patients requiring reoperation for hematoma evacuation following breast surgery between 2011 and 2021 was performed. The relationship between hematoma volume and hemodynamic instability, as well as hematoma volume and vasovagal symptoms, was measured. RESULTS: Sixteen patients were identified. Average hematoma volume was 353 mL, and average minimum mean arterial pressure was 64 mm Hg (range: 34–102 mm Hg). Fifty-six percent of patients reported symptoms including dizziness, somnolence, and/or syncope. Accounting for body surface area, patients with larger hematomas had similar minimum mean arterial pressures compared to those with smaller hematomas, 55 and 73 mm Hg, respectively (P = .0943). However, patients in the large hematoma group experienced over 3 times as many vasovagal symptoms, 88% and 25%, respectively (P = .0095). CONCLUSION: Patients with large hematomas reported significantly more vagal symptoms compared to those with small hematomas despite similar mean arterial pressures. In addition, the trend of lower mean arterial pressures and heart rates more closely resembles vagal hyperstimulation than hypovolemic shock. Early hematoma evacuation to relieve vagal nerve stretch and parasympatholytics to reverse dysautonomia are targeted interventions to consider in this patient population rather than fluids, vasopressors, and blood products that are used in cases of hemodynamic instability due to hypovolemia alone.