Hemodynamic Instability Index (HIS)

The Hemodynamic Instability Index (HIS) describes what an emergency patient requires for blood pressure maintenance.

Patient Findings	Grade
neither hypotension on presentation nor by report	0
no hypotension on presentation but by report	1
hypotension on presentation, responsive to fluid administration	2 – 4 (see below)
hypotension on presentation, unresponsive to fluid administration	5

Fluid Administration Required to Initially Maintain Blood Pressure	Ongoing Needs to Maintain Systolic Blood Pressure > 100 mm Hg	Grade
< 2 liters	none	2
>= 2 liters	none (<= 250 mL per hour)	3
>= 2 liters	> 250 mL per hour	4

where:

• I will use <= 100 mm Hg to describe hypotension, although ideally there should be age and gender ranges.

• The combination of requiring < 2 liters for initial blood pressure maintenance with ongoing needs is not covered.

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Purpose: To describe a patient's blood pressure status relative to fluid resuscitation using the Hemodynamic Instability Index (HIS).