Mean arterial pressure alarm compared to hypotension prediction index in preventing intraoperative hypotension

Intraoperative hypotension (IOH) is common in surgical patients and gives an
increased risk for 30-day mortality, acute kidney injury and myocardial injury.
A method to predict hypotension could help anaesthesiologists to treat in a
proactive, instead of a reactive way, to ultimately prevent hypotension. Hatib
et al. developed an algorithm to predict hypotension 15 minutes before the
blood pressure drops: the Hypotension Prediction Index (HPI). However, it is
suggested that the positive effect of the HPI could also be due to the
increased clinician awareness and it is found that there is a high correlation
between the HPI signal and the MAP signal. It is hypothesised that the positive
effect of the HPI could also be achieved with a mean arterial (MAP) treatment
threshold of for example 72 mmHg. In this research the performance in
preventing IOH triggered by a MAP based alarm is compared to the performance of
the HPI. It is hypothesised that their predictive performance would be
comparable.

Primary Objective:
The performance in preventing intraoperative hypotension of a MAP treatment
alarm of 72 mmHg compared to the performance of the HPI alarm.

Secondary Objectives:
- The correlation between the MAP signal and HPI signal
- The incidence and severity of intraoperative hypotension
- The incidence of acute kidney injury, myocardial injury and 30-day mortality
after surgery

This is a monocentre randomized controlled trial (RCT). This RCT consists of
two arms which are explained below:

1. HPI treatment alarm: The HemoSphere advanced monitor with HPI software will
be connected to the arterial line of the patient. The anaesthesiologist and
anaesthesia nurse are provided with an alarm when the HPI value exceeds 85.

2. MAP treatment alarm of 72 mmHg: The HemoSphere advanced monitor with HPI
software will be connected to the arterial line of the patient. The
anaesthesiologist and anaesthesia nurse are provided with an alarm when the MAP
value drops below 72 mmHg.

The HemoSphere Advanced Monitor with hypotension prediction index (HPI)
software is the investigated product in this research. With the help of the HPI
algorithm, hypotension can be predicted up to 15 minutes before the blood
pressure drops. When the chance of a hypotensive event in the future increases,
the value for HPI increases ranging from 0 to 100.

The HemoSphere advanced monitor with HPI software will be connected to the
arterial line, this provides no extra risks for the participants. The monitor
has a CE-mark and will be used within the intended use and is already part of
standard care in our hospital. The anaesthesiologists and nurse anaesthetist
are free to decide themself whether treatment will be initiated and which
treatment is most appropriate.