Relationship between duration of intraoperative hypotension and postoperative delirium in patients undergoing head and neck cancer surgery with free flap reconstruction: a retrospective observational study.

[PURPOSE] Postoperative delirium (POD) is a frequent complication after surgery, especially in elderly patients undergoing head and neck cancer surgery with free flap reconstruction. This study aimed to assess the associations between intraoperative hypotension (IOH), its duration, and occurrence of POD.

[METHODS] This retrospective study included 239 patients aged 65 years or older who underwent head and neck cancer surgery with free flap reconstruction. IOH was defined at seven mean arterial pressure (MAP) thresholds, ranging from 55 to 85 mmHg, in 5 mmHg increments. The duration of each IOH was compared between patients with or without POD before and after initiation of microsurgery. Multivariate analysis was conducted to assess the independent association of each IOH duration with the risk of POD.

[RESULTS] POD occurred in 43 (18.0%) of the 239 patients. Before the initiation of microsurgery, the cumulative duration of hypotension below MAP thresholds of < 70 to 80 mmHg was significantly longer in patients with POD. After the initiation of microsurgery, the cumulative duration of hypotension below MAP thresholds of < 55 to 85 mmHg was also significantly longer in patients with POD. In multivariate analysis, the cumulative duration of hypotension below MAP thresholds of 70, 75, and 80 mmHg before and after the initiation of microsurgery was independently associated with POD (p < 0.05 at each threshold).

[CONCLUSION] Prolonged IOH, particularly below MAP thresholds of 70, 75, and 80 mmHg, was significantly associated with POD in elderly patients undergoing head and neck cancer surgery with free flap reconstruction.