# The impact of duration below target mean arterial pressure value on mortality in critically ill patients

## TL;DR

This study shows that how long critically ill patients have low blood pressure below 65 mmHg strongly predicts their risk of dying within 48 hours or 30 days.

## Contribution

The study introduces a novel focus on the cumulative duration of low MAP as a mortality predictor in critically ill patients.

## Key findings

- Duration of MAP below 65 mmHg (ΔtMAP<65) was significantly higher in patients who died within 48 hours or 30 days.
- ΔtMAP<65 for ≥180 minutes increased 48-hour mortality risk over 170 times.
- Monitoring cumulative hypotension duration could improve survival through early interventions.

## Abstract

Literature lacks exploration of how the duration of low mean arterial pressure (MAP) affects mortality. This study aimed to determine whether the duration of MAP below 65 mmHg is associated with mortality in critically ill patients (CIPs).

A prospective observational study was conducted with patients who were admitted to the emergency department (ED) from July 1 to December 31, 2023, with a follow-up in the ED critical care unit for at least six hours. The average MAP and the total duration that the MAP remained below 65 mmHg (ΔtMAP<65) during this period were calculated.

In the study with 103 CIPs, ΔtMAP<65 was significantly higher in patients who died within 48 hours (247 [210-300] vs. 90 [30-135]) (p<0.001). ΔtMAP<65 was also significantly higher in patients who died within 30 days (195 [150-270] vs. 45 [15-75]) (p<0.001). Average MAP and ΔtMAP<65 highly predict 48 hours mortality, with AUC values of 0.887 and 0.957, respectively. ΔtMAP<65 for ≥180 minutes increased the risk of 48 hours mortality 173.25 (36.58-820.40) times. Average MAP and ΔtMAP<65 predicted 30 days mortality with AUC values of 0.890 and 0.963, respectively. ΔtMAP<65 for ≥135 minutes increased 30 days mortality 166.66 (20.78-1336.66) times.

This study shows that the duration of MAP below 65 mmHg is associated with mortality in CIPs. When ΔtMAP<65, lasting over 135 minutes significantly increases the 30 days mortality risk. If it exceeds three hours, the 48 hours mortality risk also rises substantially. Monitoring cumulative hypotension duration in critical care may enhance survival through earlier interventions.