Table 1

Description and rationale for the four chosen clinical scenarios

Hazardous clinical scenarioClinical safety impactPrevalence in MIMIC-III datasetSafety-driven refinement of RL modelUpdated safety evidenceCaveats or uncertainties
A: giving no vasopressors and low or no fluids (≤20 mL/hour) to a patient with low BP.Sustained untreated hypotension leading to organ failure and death.24 25MAP <55:
29 089/984 269 (2.9%).
Clinician’s action:
15 630/29 089 (53.7%).		Add 30 points of intermediate penalty if the condition is met.The modified ‘safe’ policy had lower rate of unsafe behaviour than original AI policy, in three scenarios and the difference was not significant in the fourth (see figure 4)No clear threshold for defining hypotension26
B: giving the maximum vasopressors dose (>0.65 µg/kg/min) to a patient with high BP.Excessive blood pressure leading to increased risk of organ failure, bleeding and stroke.MAP >95:
118 869/984 269 (12.1%).
Clinician’s action:
2986/118 869 (2.5%).		No clear threshold for defining hypertension. Some patients may have a clinical indication for high BP targets (eg, TBI).
C: giving no fluids to a patient with low BP and low CVP.Hypotensive and likely hypovolaemic patient left untreated.MAP≤55 and CVP≤5:
661/984 269 (0.06%).
Clinicians action:
356/661 (53.8%).		Measuring the fluid volume status is very difficult. CVP is a poor proxy but the closest approximate we have available in the data.27
No clear threshold of CVP for defining hypovolaemia or hypervolaemia.
D: giving the maximum dose of fluids (>240 mL/hour) to a patient with normal BP, high cumulative fluid balance and high CVP.Giving excessive fluids to a septic patient who is unlikely to be hypovolaemic is harmful, leading to fluid accumulation, known risk factor for organ failure and poor outcomes.28 29MAP≥75 and cumulative balance >10 L and CVP ≥15:
9409/984 269 (1%).
Clinicians action: 3517/9409 (37.4%).

  • BP, blood pressure; CVP, central venous pressure (expressed in mm Hg); MAP, mean arterial pressure (expressed in mm Hg); TBI, traumatic brain injury.