- Design
- Open-label, two-centre, parallel-group randomised trial
- Population
- 100 adults having major noncardiac surgery with arterial monitoring
- Primary outcome
- Time-weighted average hypotension (MAP below 65 mmHg)
- Effect
- Median 0.07 vs 0.16 mmHg, P = 0.119
This open-label trial at two centres randomised 100 adults having major noncardiac surgery with invasive arterial monitoring. One group was treated when the Hypotension Prediction Index reached 85 or more; the other when mean arterial pressure fell to 73 mmHg or below. Both used the same treatment protocol.
Time-weighted average hypotension (MAP below 65 mmHg) was low in both groups: median 0.07 mmHg with the index and 0.16 mmHg with the MAP trigger (P = 0.12). Area under the hypotension threshold, hypertension burden, noradrenaline dose, hospital stay and 30-day mortality did not differ.
The authors note that earlier trials favouring the index were open-label, and that observational data suggested much of its benefit came from treating at higher pressures. This trial supports that reading: acting earlier at a higher pressure, which any arterial line allows, did about as well. The trial was small and designed to test superiority, so it does not prove the two approaches equivalent. But for most units, especially where the proprietary sensor is unavailable or expensive, a proactive MAP trigger in the low 70s is a reasonable way to limit hypotension.
- Consider a proactive treatment trigger around a MAP of 73 mmHg in major noncardiac surgery with an arterial line.
- Do not assume a prediction monitor is needed to keep hypotension time low.
- Agree the vasopressor and fluid protocol in advance, as both arms here did.
- Watch for hypertension when treating early; it did not increase in this trial but needs monitoring.
Why it matters
It suggests the index's advantage lies mainly in treating earlier, which needs no special equipment.
Don't overread it
A small open-label superiority trial; it does not show the two strategies are equivalent.
The statistics, in plain English
Time-weighted average hypotension combines how far and how long pressure fell below 65 mmHg; values under 0.2 mmHg are very low in both groups. The trial lacked the power to detect small differences in clinical outcomes such as mortality.
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