Investigating HPI effect in oral cancer surgery

Intraoperative hypotension, defined as a mean arterial pressure (MAP) below 65 mmHg, is common during oral cancer resection with reconstruction-a lengthy procedure averaging 13 hours. Prolonged anesthesia increases the risk of intraoperative hypotension, which would lead to a higher need for vasopressor administration and fluid transfusion. Additionally, surgical anastomosis sites are vulnerable, and hypotension has been linked to increased risks of anastomotic necrosis, septic shock, organ failure, and mortality.

The Hypotension Prediction Index (HPI) is a machine-learning-based algorithm introduced in 2019 that analyzes arterial pressure waveform characteristics to provide real-time monitoring and early prediction of hypotensive episodes-defined as a MAP <65 mmHg lasting for at least one minute-during surgery. Recent randomized controlled trials have evaluated the effectiveness of HPI-guided management in preventing intraoperative hypotension. These studies commonly use the "time-weighted average (TWA) MAP <65 mmHg" as the primary outcome, calculated as the area under the threshold (in mmHg×hours) divided by the total duration of surgery (in hours). The lower the value, the shorter and less severe the intraoperative hypotension. However, limited studies have specifically investigated the impact of HPI-guided management on the duration and severity of intraoperative hypotension and postoperative complications in patients undergoing oral cancer resection with reconstruction.This study aims to evaluate the effectiveness of HPI-guided management in reducing the duration and severity of intraoperative hypotension in patients undergoing oral cancer resection with free flap reconstruction. The investigator hypothesize that the TWA-MAP <65 mmHg will be significantly lower in the HPI-guided group compared to the standard care group. Postoperative major complications will be followed during postoperative 30 days. One hundred patients aged 20 to 80 years undergoing elective oral cancer resection with free flap reconstruction will be randomized to receive hemodynamic management with or without HPI guidance. Clinicians caring for patients assigned to the HPI guidance group will be alerted when the index exceeded 85 (range 0 to 100) indicating the later occurrence of MAP< 65mmHg for at least minutes and a treatment protocol based on advanced hemodynamic parameters recommended vasopressor or inotrope, fluid administration, or observation. Primary outcome is the data of TWA-MAP<65mmHg. Postoperative complications and mortality will be followed up to postoperative 30 days.

Inclusion Criteria:

• elective oral cancer surgery with free flap reconstruction

Exclusion Criteria:

• severe arrhythmia

due to ethical concern

Patients were blinded to their group allocation, and outcome assessors were also blinded.