<prompt> Modified shock index formula is:Hea rateSystolic BPHea rateDiastolic BPHea rateMean aerial pressurePulse rateSystolic BP  <response>: Shock IndexSI Modified Shock Index MSI SI is defined as hea rate divided by systolic BP Better marker for assessing severity of shock than hea rate BP alone. Utility in trauma patients , sepsis, obstetrics, myocardial infarction, stroke other acute critical illnesses. Correlated with need for interventions such as blood transfusion invasive procedures including operations SI is known as a hemodynamic stability indicator Si does not take into account the diastolic BP MSI is defined as hea rate divided by mean aerial pressure High MSI indicates a value of stroke volume low systemic vascular resistance, a sign of hypodynamic circulation Low MSI indicates a hyperdynamic state. MSI has been considered a better marker than SI for moality rate prediction. Ref: Sabiston 20th edition Pgno: 52 