What is the utility of the vasoactive inotropic (VAI) score in the Intensive Care Unit (ICU)?

Utility of Vasoactive Inotropic Score in the ICU

The vasoactive inotropic score (VIS) is a valuable prognostic tool in the ICU that effectively predicts mortality, morbidity, and resource utilization across various critical care populations, making it an essential metric for risk stratification and clinical decision-making. 1, 2

What is the Vasoactive Inotropic Score?

The VIS is a weighted sum calculation that quantifies the degree of cardiovascular pharmacological support a patient requires. It objectively measures hemodynamic support needs by incorporating different vasoactive and inotropic medications with appropriate weighting to reflect their relative potency.

Standard VIS Calculation Formula:

• VIS = dopamine dose (μg/kg/min) + dobutamine dose (μg/kg/min) + 100 × epinephrine dose (μg/kg/min) + 100 × norepinephrine dose (μg/kg/min) + 10 × milrinone dose (μg/kg/min) + 10,000 × vasopressin dose (U/kg/min)

Clinical Applications and Prognostic Value

Mortality Prediction

• Higher VIS scores strongly correlate with increased mortality across multiple patient populations:
  • In cardiac surgery patients, a maximum VIS ≥10 is associated with significantly higher mortality rates 3
  • In traumatic brain injury patients, VIS ≥10 correlates with 81.1% mortality versus 21.5% in those with lower scores 4
  • In ECMO patients, pre-ECMO VIS serves as an independent predictor of survival (AUC = 0.68, p = 0.001) 5

Morbidity Prediction

• VIS effectively predicts important clinical outcomes:
  • Prolonged ICU length of stay
  • Extended mechanical ventilation duration
  • Delayed time to negative fluid balance
  • Risk of cardiac arrest
  • Need for mechanical circulatory support
  • Requirement for renal replacement therapy
  • Neurological injury 3

Resource Utilization

• Higher VIS correlates with increased resource utilization, making it valuable for:
  • ICU capacity planning
  • Resource allocation
  • Clinical research stratification

Applications in Specific Patient Populations

Cardiac Surgery Patients

• Originally developed and validated in pediatric cardiac surgery patients
• Now widely applied in adult cardiac surgery including:
  • Coronary artery bypass grafting
  • Cardiac transplantation
  • Left ventricular assist device implantation 2

Septic Shock

• Helps quantify vasopressor requirements
• Correlates with outcomes in septic shock patients 2

Traumatic Brain Injury

• VIS ≥10 associated with shorter ICU stays but significantly higher mortality (81.1% vs 21.5%) 4

ECMO Patients

• Pre-ECMO VIS helps guide appropriate cannulation strategy (V-V vs V-VA)
• Patients with pre-ECMO VIS ≥61.4 have significantly lower odds of survival 5

Implementation in Clinical Practice

Monitoring Protocol

• Calculate VIS at regular intervals (typically every 4-6 hours)
• Track maximum VIS over first 48 hours post-admission
• Document trend of VIS over time to assess response to interventions

Clinical Decision Support

• Electronic medical record systems should incorporate automated VIS calculation
• Establish institutional thresholds for escalation of care based on VIS trends
• Use VIS to guide team discussions regarding prognosis and goals of care

Limitations and Considerations

Standardization Issues

• No universally recognized version includes all commonly used vasoactive drugs
• Recent proposals suggest including terlipressin, methylene blue, and angiotensin II 1

Context Matters

• VIS should be interpreted within clinical context, not in isolation
• Different patient populations may require different threshold values
• VIS complements but does not replace clinical judgment

Medication Dosing Variability

• Institutional practices regarding vasopressor dosing may affect VIS calculation
• Weight-based versus fixed dosing can impact score interpretation

Conclusion

The vasoactive inotropic score provides an objective, quantifiable measure of cardiovascular support that strongly correlates with clinical outcomes in critically ill patients. Its utility spans multiple ICU populations, making it a valuable tool for prognostication, resource planning, and clinical research. Electronic medical record systems should incorporate automated VIS calculation to help clinicians identify patients at risk for mortality and important complications such as acute kidney injury.