Intraoperative hypotension (IOH) is defined as a mean arterial pressure (MAP) of < 65mmHg during surgery. Patients undergoing major gastrointestinal (GI) surgery, such as esophagectomy with reconstruction, are at a high-risk of IOH because such surgeries typically require more than 3h to complete and require blood transfusion or inotrope administration. Critically, these surgeries involve organ removal or substitute connection, which require wound or flap anastomosis. IOH is believed to be associated with postoperative anastomosis necrosis. It increases the risk of postoperative intrathoracic or abdominal infection, resulting in septic shock, postoperative major organ dysfunction and mortality.

The data of TWA-MAP< 65mmHg in the HPI guidance group will be significantly lower than that in the group without HPI guidance.

Intraoperative hypotension (IOH) is defined as a mean arterial pressure (MAP) of < 65mmHg during surgery. Patients undergoing major gastrointestinal (GI) surgery, such as esophagectomy with reconstruction, are at a high-risk of IOH because such surgeries typically require more than 3h to complete and require blood transfusion or inotrope administration. Critically, these surgeries involve organ removal or substitute connection, which require wound or flap anastomosis. IOH is believed to be associated with postoperative anastomosis necrosis. It increases the risk of postoperative intrathoracic or abdominal infection, resulting in septic shock, postoperative major organ dysfunction and mortality.

The Hypotension Prediction Index (HPI) is an algorithm made commercially available in 2019. On the basis of arterial waveform features, HPI predicts hypotension defined as MAP < 65 mmHg for at least 1 min. In two previous randomized trials(RCTs), the primary outcome was the severity and duration of hypotension, defined as a time-weighted average mean arterial pressure (TWA-MAP) less than 65 mmHg (formula: (total area under MAP<65mmHg(mmHg*hours))/(surgery length (hours));normal range:0.01-0.5mmHg).A higher data of TWA-MAP<65mmHg indicates severe and longer IOH. However, according to the results of the previous two RCTs, the effects of HPI guidance during surgery remain inconclusive.

We aim to investigate whether HPI guidance can be used to reduce the duration and severity of hypotension during major GI surgery. Our hypothesis is that the data of TWA-MAP< 65mmHg in the HPI guidance group will be significantly lower than that in the group without HPI guidance. Postoperative major complications and mortality will be followed.

Methods: Sixty patients aged 20 to 80 years undergoing elective GI surgery 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 will be recorded on postoperative day 3,7 and 30. The mortality rate from the time of hospitalization to postoperative 30 days will be recorded.

The data of TWA-MAP< 65mmHg in the HPI guidance group will be significantly lower than that in the group without HPI guidance.

Inclusion Criteria:

• patients receiving elective major gastrointestinal surgery

Exclusion Criteria:

• emergent surgery
• pregnant women

due to the ethical concern

participants and care provider and outcome assessor are blinded