Targeting and monitoring mean arterial pressure in critical illness: A mixed-methods service evaluation

TL;DR

This study evaluates MAP targets in ICU patients, finding that adherence is inconsistent and personalization is limited.

Contribution

The study introduces a mixed-methods approach to assess MAP target adherence and clinical opinions in critical care.

Findings

67% of consultants reported a standard MAP target of 65 mmHg.

83% of patients experienced hypotension exceeding 10% of monitoring time.

MAP was significantly lower in patients on vasopressors compared to those not on vasopressors.

Abstract

In sepsis and cardiac arrest, arterial hypotension is associated with poorer outcomes, including renal injury and mortality. Guidelines recommend a mean arterial pressure (MAP) target of ⩾65 mmHg, but supporting evidence is limited. We undertook a service evaluation which aimed to: (1) assess clinical opinion regarding the optimal MAP target in intensive care (ICU); and (2) evaluate MAP target adherence at the Royal Infirmary Edinburgh ICU, quantifying levels of hypotension.

We utilised a concurrent triangulation mixed-methods approach, integrating semi-structured consultant interviews and quantitative analysis of patient-level blood pressure data. Blood pressure data were collected at 1-min intervals for the first 72 h of arterial monitoring. We defined hypotensive insults by five sequential minutes below MAP target.

We interviewed 18 consultants. Twelve (67%) reported a standard target of 65 mmHg. The importance of evidence-based, individualised, and flexible targets was emphasised. We included 208,570 min of monitoring time across 66 patients. At admission, 53 (80%) patients received a target of 65 mmHg. Mean (SD) MAP was lower in patients on vasopressors than those not on vasopressors (77.6 (14.2) vs 86.9 (17.3) mmHg, p = 0.0001). Hypotension affected 55 (83%) patients and accounted for >10% of monitoring time in thirteen (20%). Median pressure-time index (PTI) was 3.4 mmHg * h; 24 (36%) patients had a PTI >10 mmHg * h.

The optimal MAP target varied by patient, yet target personalisation remained limited in practice. Target adherence varied, with observed MAP both exceeding and undershooting set targets. Future research will explore the feasibility and implications of achieving tighter blood pressure control.

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