Hypotension prediction index did not beat a simple MAP-73 trigger

Design

Open-label, two-centre randomised controlled trial

Population

100 adults having major non-cardiac surgery with arterial monitoring

Primary outcome

Time-weighted average hypotension (MAP < 65 mmHg)

Effect

Median 0.07 vs 0.16 mmHg (p = 0.119)

Earlier trials suggested that the hypotension prediction index reduced intraoperative hypotension, but those trials compared it with treating at the usual 65 mmHg. This two-centre, open-label trial randomised 100 adults having major non-cardiac surgery with arterial lines to index-guided treatment (trigger at index 85 or above) or a proactive pressure target (trigger at MAP 73 mmHg or below), with the same treatment protocol in both arms.

Time-weighted average hypotension below 65 mmHg was 0.07 mmHg with the index and 0.16 mmHg with the MAP target (p = 0.12), and area under the threshold did not differ significantly either. Hypertension burden, norepinephrine dose, length of stay and 30-day mortality were similar.

The trial was designed to show superiority and did not, so it cannot declare the two strategies equivalent. But it supports the view that much of the index's apparent benefit comes from treating earlier — something achievable with a higher pressure trigger and standard monitoring.

• A proactive trigger at MAP 73 mmHg achieved hypotension control not significantly different from index-guided care.
• Where proprietary monitoring is unavailable, an earlier MAP trigger is a reasonable strategy.
• Use the same vasopressor and fluid protocol whichever trigger you adopt.
• The trial was small and powered for superiority, not to show the strategies are equal.

Why it matters

It questions whether an expensive predictive monitor adds value beyond acting sooner on the pressure you already measure.

Don't overread it

Not designed to show equivalence; 100 patients in two centres.

The statistics, in plain English

A p-value of 0.12 means the difference could easily be chance. 'Not superior' is not the same as 'equivalent' — a larger trial designed for equivalence would be needed to say that.

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