Impact of intraoperative hypotension on postoperative nausea and vomiting in patients undergoing orthognathic surgery

To evaluate the risk factors for postoperative nausea and vomiting (PONV) in patients undergoing orthognathic surgery, with particular emphasis on elucidating the potential relationship between PONV and the depth and duration of intraoperative hypotension (IOH).

We conducted a retrospective cohort study of patients who underwent orthognathic surgery between November 2022 and August 2024. Mean arterial pressure (MAP) was extracted from electronic medical records. Methods to evaluate IOH: 1. total area under curve (AUC); 2. time-weighted average (TWA) MAP; 3. cumulative time below absolute threshold values; 4. cumulative time in the lowest MAP categories. MAP thresholds were defined by absolute limits (≤ 65, ≤ 60, ≤ 55 mmHg).

Of the 287 patients enrolled, five patients were excluded. At all absolute thresholds, patients experiencing PONV demonstrated significantly greater AUC and TWA than non-PONV patients (p < 0.05). Furthermore, at ≤ 60 and ≤ 55 mmHg threshold, PONV patients also exhibited significantly longer cumulative time of hypotensive (p < 0.05). When MAP is in 50-60 mmHg range for > 10 min (OR: 6.00, 95 % CI: 1.02-35.37), and when MAP is in ≤ 55 mmHg range for ≥ 5 min (OR: 0.42, 95 % CI: 0.20-0.90), were significantly associated with PONV (p < 0.05).

IOH may represent an additional important risk factor for PONV in patients undergoing orthognathic surgery, especially when MAP is in 50-60 mmHg range for > 10 min, or ≤ 55 mmHg range for ≥ 5 min.