MAP / Pulse Pressure / Shock Index
MAP / Pulse Pressure / Shock Index - a deterministic tool in Sophie Well's Clinical Math & Conversions group.
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What this is
Compute four bedside hemodynamic indices from a single set of vitals: mean arterial pressure (MAP = DBP + (SBP - DBP)/3), pulse pressure (SBP - DBP), shock index (HR / SBP), and modified shock index (HR / MAP). Each index has a published reference range Sophie Well displays alongside the result: MAP target >=65 mmHg for organ perfusion, shock index >=1.0 as the classic occult-hypoperfusion threshold, modified shock index >=1.3 as a stronger predictor of transfusion need in trauma and sepsis.
When to use it
Use this at the bedside or chart review when a single blood-pressure number doesn't tell the whole story - tachycardia with a normal-looking systolic, a narrowing pulse pressure that suggests early shock, or a stable MAP masking compensated bleeding. The shock index in particular catches occult hypoperfusion that triage scores miss: a heart rate of 110 with a systolic of 105 looks acceptable in isolation but yields a shock index of 1.05, which has been associated with higher transfusion and mortality risk in trauma, postpartum hemorrhage, and severe sepsis. Reference math only; treat the patient, not the index.
References
Allgower & Burri 1967 (shock index). Standard physiology for MAP and PP.
Worked example: MAP 93.3; PP 40; shock index 0.92; modified shock index 1.18.
Sophie Well is a reference and educational tool. Not medical, legal, or financial advice. Does not replace clinician judgment, professional billing review, or legal counsel.