HPI-guided care was not superior to treating at MAP 73 mmHg

Design

Open-label, parallel-group randomised trial, 2 centres

Population

100 adults having major non-cardiac surgery with invasive arterial monitoring

Primary outcome

Time-weighted average MAP below 65 mmHg

Effect

Median 0.07 (HPI) vs 0.16 mmHg (MAP ≤73), P=0.119

This open-label trial at two centres randomised 100 adults having major non-cardiac surgery with arterial monitoring to Hypotension Prediction Index (HPI) guided treatment (trigger HPI 85 or more) or a higher MAP trigger (73 mmHg or less), using the same haemodynamic protocol.

Median time-weighted average hypotension below 65 mmHg was 0.07 mmHg with HPI and 0.16 mmHg with the MAP trigger (P=0.119). Area under the threshold was 22 vs 59.7 mmHg·min (P=0.172). Hypertension burden, noradrenaline dose, length of stay and 30-day mortality did not differ.

Earlier trials favouring HPI were open-label and may have carried performance bias. The argument has been that much of HPI's benefit comes from simply treating earlier, at a higher pressure. This trial tested that directly.

It was designed for superiority, so it shows HPI was not proven better, not that the two are equivalent.

• Compare any HPI evidence against a proactive MAP trigger, not a reactive 65 mmHg one.
• The numerical trend favoured HPI on hypotension burden; a larger trial could still find a difference.
• Clinical outcomes were not different in this small trial.
• Consider cost and monitoring requirements before adopting HPI.

Why it matters

It supports the view that treating hypotension earlier, not the proprietary algorithm, drives most of the benefit.

Don't overread it

With 100 patients and an open-label superiority design, this trial cannot show that HPI and a MAP trigger are equivalent.

The statistics, in plain English

A non-significant result in a superiority trial means the study did not prove a difference, not that there is none. Medians of 0.07 and 0.16 mmHg with P=0.12 suggest a possible difference too small for 100 patients to confirm.

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